FAIXXX10.1177/1071100720950715Foot & Ankle Internationalde Cesar Netto et al 950715editorial2020

Letter to the Editor

Foot & Ankle International® 3–­1 Editorial: Expert Consensus on © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Adult-Acquired Flatfoot Deformity DOI:https://doi.org/10.1177/1071100720950715 10.1177/1071100720950715 journals.sagepub.com/home/fai

Adult-acquired flatfoot deformity (AAFD) represents a The group met in person on November 2, 2019, at the pathology in orthopedic foot and ankle surgery that we all Hospital for Special Surgery (HSS) in New York, New commonly see, yet in many different forms. Our experience York. The location was chosen given the relative ease of has grown over the years thanks to the research and clinical travel for members coming from across the country and experience and great insights of authors from all over the world. All travel and hotel costs were paid individually by world. However, with the onset of new surgical techniques, the participants. Each member was asked to give a talk in technology, and imaging modalities, the understanding of his relative area of expertise within AAFD, based largely the details of this complex pathology has grown exponen- upon previously published translational and clinical tially. Despite these advances, it is often confusing not only research. Each talk was 10 minutes long, followed by a dis- when to decide to operate but also which procedures to per- cussion of approximately 1 hour. The meeting was recorded form, how much correction to achieve, and even what to by audio in its entirely, and research assistants took written call the condition itself. notes throughout. For each talk, we generated a small series With that background in mind, we embarked upon a of consensus statements that could help us synthesize useful project starting at the beginning of 2019 to bring together a guidelines and summarize current thinking in the field. The group of experts to help collectively answer some of the topic of gastrocnemius/Achilles tightness, although cer- doubts we have and potentially resolve some of the differ- tainly important in the pathophysiology of the collapsing ences in opinion many have about treating AAFD. The flatfoot, was not chosen given its controversial nature, the rationale to bring a group together was to share and build difficultly to reach consensus, and the lack of data to sup- from a collective larger number of years of experience from port consensus statement rationale. Two weeks after the experts around the country and world. We all have our ideas meeting, the consensuses statements were sent out to all 9 about the physical exam, imaging, and treatment. The liter- members for voting. The vote for each statement consisted ature also lacks a more formal and uniform agreement on of agree or disagree. The strength of each consensus state- terminology and clinical and surgical algorithms. In addi- ment voted was based on the percentage of approval: unani- tion, literature reviews are limited by the nature of their mous (100%), strong (higher than 75%), and weak (in study design, and it can take years to advance the field in between 50% and 75%). Once the final statements were this fashion. We therefore sought to guide ourselves and selected, each member was asked to write a summary man- colleagues in a more immediate fashion. We also followed uscript with the rationale to support the statements related the precedent set by our colleagues to form consensus group to his talk based on the previous group discussion, clinical statements in the area of ankle cartilage injuries and muscu- experience, and literature support. Each manuscript was loskeletal infection.1,2 then sent out to all other members of the group for com- With this in mind, 2 of us (C.C.N., S.J.E.) performed a ments and editing. Once finalized, the body of work was literature search to identify experts in the field of AAFD. In submitted to Foot & Ankle International for peer review. the spring of 2019, we performed this search via PubMed We hope that you learn as much as we did from reading and selected a group of 9 experts in the field who had a these manuscripts, statements, and rationales. There are minimum of 10 peer-reviewed publications in impactful many questions that are still left unanswered. We attempted journals reporting on various aspects of the assessment and to point out clearly where there is agreement and were treatment of AAFD. Not surprisingly, these individuals are future work is needed to come to consensus. We believe well known in the field and have taught us through their that this is an important first start. Perhaps as important as publications and presentations at meetings, and all have at anything, we propose a new terminology and classification one point been faculty at orthopedic foot and ankle fellow- that is simple yet clinically meaningful. We recommend ship programs. We chose the specific number of individuals calling this condition progressive collapsing foot defor- (9) to provide a wide array of thoughts from thinkers from mity (PCFD). Throughout the manuscript, when conven- different parts of the country and world with varied training tional radiographs are mentioned, we decided to capitalize backgrounds. We chose an odd number of members to break and underline the word WEIGHTBEARING to repeatedly potential ties when the time for consensus voting began. emphasize the importance of obtaining weightbearing 2 Foot & Ankle International 00(0)

imaging when evaluating patients. We also are including a during late-stance phase to lock the transverse tarsal joint glossary of controversial terminology to help better define to provide a stable midfoot during toe-off phase of gait. and bring uniformity to some of the definitions that we use. Pronation of the foot is characterized by deviation of the We found that different words can be used to describe the foot in 3 planes of motion, including subtalar joint eversion same concept and that have regional and historical bases. It (hindfoot valgus), ankle joint plantarflexion (talus is plan- was difficult to come to consensus with some of this termi- tarflexed), and forefoot abduction (lateral deviation of nology also given the precedent in the literature. navicular around the curved talar head), allowing the medial We hope you are all safe during difficult times of arch of the foot to be closer to the floor. COVID-19 crisis. Supination of the foot is characterized by deviation of the Take care! foot in 3 planes of motion, including subtalar joint inversion (hindfoot varus), ankle joint dorsiflexion (talus is dorsi- Glossary: Nomenclature Describing flexed), and forefoot adduction (medial deviation of the navicular around the curved talar head), allowing the medial PCFD arch of the foot to be raised away from the floor. The term As noted above, the consensus group advocated for the use supination will describe the static position of the “cavus of the term progressive collapsing flatfoot deformity foot” in weightbearing stance. It can also be used to describe (PCFD) instead of adult-acquired flatfoot deformity the dynamic “supination” motion that occurs in the normal (AAFD) for various reasons. Taking the word adult out foot during late-stance phase of gait when inversion of the allows us to include younger patients without a history of foot stabilizes the transverse tarsal joint during heel rise. congenital foot disorder or coalition in the treatment algo- rithm for this pathology. The term progressive describes Forefoot Varus (aka Forefoot Supination) the natural history of the disorder. We have favored col- lapsing over flatfoot since many patients with a flat arch Forefoot varus is not to be confused with the term supination, do not have pathology or pain. The use of foot deformity which applies to the entire foot. Varus of the forefoot is exam- denotes that this is not just routine foot care but rather a ined with the hindfoot held in a neutral “reference” position true pathology that will help combat insurance denials that relative to the tibia and then the forefoot is viewed as being claim that “flatfoot” is routine foot care. It is only when rotated in the coronal plane around the central axis of the foot the “arch” progresses on to collapse that it becomes a toward the midline (or varus) direction. The first ray is visu- problem. We have used this terminology throughout the alized as being elevated above the fifth metatarsal (in the rationale statements. coronal plane) and can be characterized as only the first ray being elevated with the lesser rays plantigrade, or the entire forefoot may be rotated into varus (ie, global forefoot varus). Abduction Forefoot varus may be further characterized by the Abduction describes the position of the forefoot as being in degree of flexibility of the deformity when the examiner a laterally deviated position with respect to the hindfoot. pushes cephalad on the plantar aspect of the fifth metatarsal Typically, the forefoot is laterally deviated due to the navic- head while holding the hindfoot in the neutral “reference” ular rotating in eversion around the curved surface of the position. If the forefoot varus is correctible with this maneu- talar head. Abduction deformity can also occur in the mid- ver, it is termed flexible forefoot varus. If it does not correct, foot or forefoot joints (through the naviculocuneiform or the deformity is determined to have some component of tarsometatarsal joints) due to ligament instability or osteo- fixed deformity. In the literature, depending the publication arthritis causing lateral deviation of the midtarsal or meta- and author, the words forefoot supination and forefoot varus tarsal bones. may be used to express the same concept.

Foot Pronation and Supination Hindfoot Valgus Pronation and supination are terms used to describe the Valgus refers to the lateral deviation of the hindfoot away weightbearing posture of the foot in its normal base of from the midline of the body when viewing the heels of a standing with both feet on the ground. These terms can also patient from behind, either clinically or radiographically. be used to describe the direction of motion, as during the Radiographically, the distance of the weightbearing surface midstance phase of gait when the fully loaded foot dynami- of the calcaneus from the anatomical axis of the tibia is cally “pronates” to allow the dissipation of weightbearing typically described, but an angle of the calcaneus might be forces of walking and the same foot then “supinates” considered as well. As described in a number of the rationale de Cesar Netto et al 3 statements, ideal radiographic hindfoot position and clinical Declaration of Conflicting Interests hindfoot position might not always be the same. The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this arti- Cesar de Cesar Netto, MD, PhD, cle. ICMJE forms for all authors are available online. Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA Funding Email: [email protected] The author(s) received no financial support for the research, Jonathan T. Deland, MD authorship, and/or publication of this article. Hospital for Special Surgery, New York, NY, USA ORCID iDs Scott J. Ellis, MD, Hospital for Special Surgery, New York, NY, USA Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 6037-0685 Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 Acknowledgments We thank David B. Thordarson and Jeffrey Johnson for helping to References put together the glossary and nomenclature definitions. We also acknowledge the crucial work of Katrina E. Bang and Jonathan 1. Aiyer A, Raikin S, Parvizi J. 2018 International consensus Day, research assistants of, respectively, the University of Iowa meeting on musculoskeletal infection: findings of the Foot and and the Hospital for Special Surgery, for helping us to record and Ankle Work Group. Foot Ankle Int. 2019;40(1)(suppl):1S. keep the track of all information discussed. We also thank Paragon 2. Murawski CD, Hogan MV, Thordarson DB, Stone JW, 28 and TriMed for the support with food and beverages during the Ferkel RD, Kennedy JG. Editorial. Foot Ankle Int. 2018;39(1) 2 days of the consensus meeting. (suppl):1S-2S. FAIXXX10.1177/1071100720950722Foot & Ankle InternationalMyerson et al 950722research-article2020

Topical Review

Foot & Ankle International® 6–­1 Classification and Nomenclature: © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Progressive Collapsing Foot Deformity DOI:https://doi.org/10.1177/1071100720950722 10.1177/1071100720950722 journals.sagepub.com/home/fai

Mark S. Myerson, MD1, David Thordarson, MD2, Jeffrey E. Johnson, MD3 , Beat Hintermann, MD4, Bruce J. Sangeorzan, MD5, Jonathan T. Deland, MD6, Lew C. Schon, MD7,8,9,10, Scott J. Ellis, MD6 , and Cesar de Cesar Netto, MD, PhD11

Abstract Recommendation: The historical nomenclature for the adult acquired flatfoot deformity (AAFD) is confusing, at times called posterior tibial tendon dysfunction (PTTD), the adult flexible flatfoot deformity, posterior tibial tendon rupture, peritalar instability and peritalar subluxation (PTS), and progressive talipes equinovalgus. Many but not all of these deformities are associated with a rupture of the posterior tibial tendon (PTT), and some of these are associated with deformities either primarily or secondarily in the midfoot or ankle. There is similar inconsistency with the use of classification schemata for these deformities, and from the first introduced by Johnson and Strom (1989), and then modified by Myerson (1997), there have been many attempts to provide a more comprehensive classification system. However, although these newer more complete classification systems have addressed some of the anatomic variations of deformities encountered, none of the above have ever been validated. The proposed system better incorporates the most recent data and understanding of the condition and better allows for standardization of reporting. In light of this information, the consensus group proposes the adoption of the nomenclature “Progressive Collapsing Foot Deformity” (PCFD) and a new classification system aiming at summarizing recent data published on the subject and to standardize data reporting regarding this complex 3-dimensional deformity. Level of Evidence: Level V, consensus, expert opinion. Consensus Statements Voted: CONSENSUS STATEMENT ONE: We will rename the condition to Progressive Collapsing Foot Deformity (PCFD), a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot varus. Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. (Unanimous, strongest consensus) CONSENSUS STATEMENT TWO: Our current classification systems are incomplete or outdated. Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. (Unanimous, strongest consensus) CONSENSUS STATEMENT THREE: MRI findings should be part of a new classification system. Delegate vote: agree, 33% (3/9); disagree, 67% (6/9); abstain, 0%. (Weak negative consensus) CONSENSUS STATEMENT FOUR: Weightbearing CT (WBCT) findings should be part of a new classification system. Delegate vote: agree, 56% (5/9); disagree, 44% (4/9); abstain, 0%. (Weak consensus) CONSENSUS STATEMENT FIVE: A new classification system is proposed and should be used to stage the deformity clinically and to define treatment. Delegate vote: agree, 89% (8/9); abstain, 11% (1/9). (Strong consensus)

Keywords: flatfoot, adult acquired flatfoot deformity, AAFD, classification flatfoot, progressive collapsing foot deformity, PCFD, rupture posterior tibial tendon (PTT) 2 Foot & Ankle International 00(0)

Rationale Furthermore, it is accepted that stage I disease with no deformity regardless of the pathology of the PTT may Classification Systems never progress to stage II, and similarly, a stage II may not 1,10,14 The clinical applicability of any classification system progress to a stage III deformity. This has implications depends to a large extent on its usefulness in planning treat- for treatment, which the surgeon should base on the contin- ment, and it is with this goal in mind that any system should ued presence of pain despite adequate nonoperative care, be developed. The purpose is ultimately to make treatment and not because a more advanced stage may develop. The decisions more rational and individualized to each patient’s only exception to this may be a stage IV-A deformity that particular anatomic pathology. An ideal classification sys- can be treated with joint sparing procedures prior to inevi- tem should also be reproducible, understandable by all sur- tably progressing to a stage IV-B associated with ankle geons, provide a prognosis, and also allow researchers to joint arthritis. more effectively share data. Since Johnson and Strom’s initial 1989 classification 7,8 In 1989, Johnson and Strom proposed a 3-stage classifica- and the modification by Myerson in 1997, an increas- tion associated with dysfunction and ultimate rupture of the ingly complex combination of deformities of the midfoot, posterior tibial tendon calling it PTTD, and which was based hindfoot, and ankle has been recognized in association with on the condition of the PTT, the position of the hindfoot, and dysfunction and rupture of the PTT, not addressed by these flexibility of the deformity (Table 1).7 In this article, a fourth classifications. More importantly, those classification sys- stage was alluded to as a fixed rigid valgus deformity associ- tems did not describe variations, for example, the wide ated with arthritis of the ankle requiring a TTC arthrodesis, array of treatment options for the flexible foot deformity. and in 1997 this was formally added by Myerson as a stage Recognizing this wide variation in mobility of the medial IV deformity.8 The latter was subsequently divided in a column, abduction of the foot, and forefoot varus, Bluman revised classification by Bluman and Myerson into IV-A et al2 introduced a revised classification scheme in 2007 associated with supple tibiotalar valgus, and IV-B associated (Table 2). These authors took the original Johnson and with rigid deformities.2 It was also recognized by these Strom classification for flatfoot deformity and revised it authors that a valgus deformity of the tibiotalar joint caused into a system encompassing the various presentations seen by a rupture of the deltoid ligament is not necessarily associ- within each stage, with the most obvious expansion dealing ated with a rupture of the posterior tibial tendon (PTT). The with stage II disease. Table 2 summarizes the classification latter modified classification system is the one that was voted of Bluman et al, including pertinent findings and sugges- most used by the experts in our study group. tions for treatment for each of the described stages. In the 1997 manuscript, Myerson incorrectly described It is recognized, however, that the classification by this as a “continuum of PTT dysfunction” noting that “any Bluman et al is also limited and does not sufficiently grading or staging system of this dysfunction is somewhat describe nor include the anatomic and sufficient radio- arbitrary.”8 The stages of deformity in any classification graphic details of deformity. Parsons et al reported their system do not exist on a continuous spectrum because pro- results of treating stage II deformity with a modified Cobb gression is not linear and may affect different regions of the technique and a calcaneus osteotomy, and introduced a foot and ankle with or without a rupture of the PTT. modification to the Johnson classification by focusing on Deformity may, for example, include the tarsometatarsal the extent of varus of the midfoot and forefoot.9 They (TMT) joints, the naviculocuneiform (NC) joints, and may believed that stage II covers a wide spectrum of deformity be associated with a rupture or attenuation of the plantar ranging from a mobile hindfoot, midfoot, and forefoot to a fascia, the spring, and/or the deltoid ligament in the absence later stage where a fixed varus deformity in the midfoot and of a PTT rupture.5 forefoot is present, either correctible or fixed, and greater or

1Department of Orthopedic Surgery, University of Colorado School of Medicine, 12631 East 17th Avenue, B202, Aurora, CO 80045, USA. 2Cedars-Sinai Medical Center, Los Angeles, CA, USA 3Washington University School of Medicine, MO, USA 4Kantonspital Baselland, Liestal, Switzerland 5University of Washington, Seattle, WA, USA 6Hospital for Special Surgery, New York, NY, USA 7Mercy Medical Center, Baltimore, MD, USA 8New York University Grossman School of Medicine, New York, NY, USA 9Johns Hopkins School of Medicine, Baltimore, MD, USA 10Georgetown School of Medicine, Washington, DC, USA 11Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA

Corresponding Author: Cesar de Cesar Netto, University of Iowa, Department of Orthopaedics and Rehabilitation, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City-IA, 52242, USA. Email: [email protected] Myerson et al 3

Table 1. Johnson and Strom Classification, 1989.7

Stage I Stage II Stage III Variable mild, medial pain moderate, medial pain severe, medial, and lateral pain Examination Mild swelling and tenderness Moderate swelling and Not much swelling but marked Swelling and tenderness along PTT tenderness along PTT tenderness along PTT Heel-rise test Mild weakness Marked weakness Marked weakness ‘‘Too many toes’’ sign Absent Present Present Deformity Absent Present (flexible) Present (fixed) Pathologic features Normal tendon length Elongated with Disrupted with visible tears paratendinitis longitudinal tears Images No changes Gross deformity Deformity and diffuse arthritic changes Treatment Conservative, tenosynovectomy FDL transfer Triple arthrodesis

Abbreviations: FDL, flexor digitorum longus; PTT, posterior tibial tendon.

Table 2. Bluman et al Classification, 2007.2

Most characteristic Stage Substage Most characteristic clinical findings radiographic findings Treatment 1 A Normal anatomy Normal Immobilization, NSAIDs, cryotherapy Tenderness along PTT Orthoses Tenosynovectomy ±Systemic disease-specific pharmacotherapy B Normal anatomy Normal Immobilization, NSAIDs, cryotherapy Tenderness along PTT Orthoses Tenosynovectomy C Slight HF valgus Slight HF valgus Immobilization, NSAIDs, cryotherapy Tenderness along PTT Orthoses Tenosynovectomy II A1 Supple HF valgus HF valgus Orthoses Flexible forefoot varus Meary line disruption Medial displacement calcaneal osteotomy Possible pain along PTT Loss of calcaneal pitch TAL or Strayer and FDL transfer if deformity corrects only with ankle plantarflexion A2 Supple HF valgus HF valgus Orthoses Fixed forefoot varus Meary line disruption Medial displacement calcaneal osteotomy and Possible pain along PTT Loss of calcaneal pitch FDL transfer Cotton osteoectomy B Supple HF valgus HF valgus Orthoses Forefoot abduction Talonavicular uncovering Medial displacement calcaneal osteotomy and Forefoot abduction FDL transfer Lateral column lengthening C Supple HF valgus HF valgus Medial displacement calcaneal osteotomy and Fixed forefoot varus First TMT joint plantar FDL transfer Medial column instability gapping Cotton osteotomy or medial column fusion First-ray dorsiflexion with HF correction Sinus tarsi pain III A Rigid HF valgus Subtalar joint space loss Custom bracing if not operative candidate Pain in sinus tarsi HF valgus Triple arthrodesis Angle of Gissane sclerosis B Rigid HF valgus Subtalar joint space loss Custom bracing if not operative candidate Forefoot abduction HF valgus Triple arthrodesis ± lateral column Pain in sinus tarsi Angle of Gissane sclerosis lengthening Forefoot abduction IV A Supple tibiotalar valgus Tibiotalar valgus Surgery for HF valgus and associated deformity HF valgus Deltoid reconstruction B Rigid tibiotalar valgus Tibiotalar valgus TTC fusion or pantalar fusion HF valgus

Abbreviations: FDL, flexor digitorum longus; HF, hind foot; NSAIDs, nonsteroidal anti-inflammatory drugs; PTT, posterior tibial tendon; TAL, tendo-Achilles lengthening; TMT, tarsometatarsal; TTC, tibiotalocalcaneal. 4 Foot & Ankle International 00(0)

Table 3. Consensus Group Classification of Progressive Collapsing Foot Deformity.

Stage of the deformity

Stage I (flexible) Stage II (rigid)

Types of deformity (classes – isolated or combined)

Deformity type/location Consistent clinical/radiographic findings Class A Hindfoot valgus deformity Hindfoot valgus alignment Increased hindfoot moment arm, hindfoot alignment angle, foot and ankle offset Class B Midfoot/forefoot abduction Decreased talar head coverage deformity Increased talonavicular coverage angle Presence of sinus tarsi impingement Class C Forefoot varus deformity/medial Increased talus–first metatarsal angle column instability Plantar gapping first TMT joint/NC joints Clinical forefoot varus Class D Peritalar subluxation/dislocation Significant subtalar joint subluxation/subfibular impingement Class E Ankle instability Valgus tilting of the ankle joint

Abbreviations: NC, naviculocuneiform; TMT, tarsometatarsal.

less than 15 degrees. The focus on varus had already been varus of the midfoot, whether at the naviculocuneiform covered to a large extent by the Bluman classification2; (NC) and TMT articulations, occurs as a primary deformity however, Parsons et al believed that a more advanced stage or secondary to the chronic hindfoot deformity and rupture II disease may be associated with a mobile and correctable or attenuation of the secondary stabilizers of the arch. This hindfoot, where resting forefoot varus may not be correct- classification system may be useful for a surgeon who is not able.9 They concluded that it would be advantageous to familiar with treatment algorithms but does not change the address the deformity operatively before this later phase of need to evaluate each deformity individually because the fixed severe forefoot varus was reached, but recognized that ankle, hindfoot, and midfoot must always be assessed inde- this would have to be confirmed by further studies. As pendently of each other. stated already above, because disease is not on a continuum, Finally, it is unclear whether the entity classified by the latter statement would be difficult to prove. Johnson and Strom as stage I PTTD ought to be included in The midfoot has received more attention in recent clas- the description of PCFD. It is not clear what this stage refers sifications. Richter and Zech focused on the midfoot, spe- to, nor does stage I disease inevitably progress to stage II, cifically noting the TMT angles that were defined to be and frequently, this is a stable process associated with minor negative for abduction in the anteroposterior radiograph tendon inflammation and/or degeneration.14 In our consen- and for dorsiflexion on the lateral radiographs.11 They pro- sus group, the most important finding of stage I disease was posed a TMT Index that was defined as the sum of the the presence of PTT pain (5/9, 56%), followed by gastroc- anteroposterior and lateral TMT angles. They believed that nemius tightness and mild hindfoot valgus (2/9, 22%). the function of the PTT did not highly correlate with joint Some felt that there was no valid description of stage I dis- stiffness because they found collapsed flat feet that were not ease, and only 56% (5/9) felt that there was some indication stiff, and stiff feet without any rupture of the PTT. A more for surgery in this stage. The surgeries that were indicated recent classification system, also with a focus on the mid- were a gastrocnemius recession, PTT debridement, and cal- foot, was introduced by Raikin et al10 called the RAM clas- caneus osteotomy (5/9, 55%), followed by a medial cunei- sification, which divided the AAFD deformity into the form osteotomy, PTT tenosynovectomy, and arthroereisis individual components involved in the disease process. (1/9, 11%). These authors maintained the original grade I to III system Grading a patient according to any classification system as well as the (a) and (b) subclassification introduced by requires a thorough history and physical examination, but Bluman et al,2 but applied these separately to the rearfoot also weightbearing conventional radiographic evaluation, (R), ankle (A), and midfoot (M). They noted that varus and which could also include more modern technology such as abduction most commonly occurs at the transverse tarsal weightbearing computed tomography (WBCT) scan. joints, and that this deformity may also develop from the The expert consensus group agreed that a new classifica- midfoot. It still remains unclear, however, if collapse and tion system should be proposed (Table 3). This Myerson et al 5 new classification scheme is presented and is based on the the PTTs central role in the development of the deformity flexibility, and the type and location of deformity only, and but have added new subclassifications. These alternate, therefore does not include the original stage I disease state. more comprehensive systems increasingly acknowledge the It is based on deformities that are either flexible (stage I) or involvement of the midfoot in the development of the rigid (stage II) and further described by adding 1 or more AAFD, while noting the progressive effect of a dysfunc- (isolated or combined) types of present deformities (classes tional PTT on the rearfoot and subsequently the ankle. A-E): However, the anatomy of the flexible AAFD includes far Presented below are examples of how the classification more than a rupture of the PTT, most importantly the spring may be used: and deltoid ligaments,5 specifically the articular support provided by the sling effect of the spring ligament to the TN joint, which must be evaluated and always be taken into •• A 53-year-old woman patient presents with a flat- consideration when evaluating any AAFD. The relevance of foot, and on clinical examination, the hindfoot and the spring ligament has been neglected with respect to midfoot are flexible (stage 1). The hindfoot is in val- descriptive terminology and not included in classification gus (A), flexible forefoot varus is present (C), and systems over the decades.3,4,6,13 The first to recognize the there is no abduction deformity of the forefoot or potential for this instability was Johnson in 1989 in a sim- peritalar instability. On weightbearing radiographs, plistic illustration that highlighted the shifts of the navicular there is slight valgus deformity of the ankle joint that and calcaneus around a fixed talus.7 The term peritalar is reducible on clinical examination (E): This defor- subluxation (PTS) should be attributed to Hansen and col- mity would be classified as 1ACE. leagues, who detailed the anatomic and biomechanical •• A 34-year-old woman presents with a flatfoot defor- changes that take place in the hindfoot leading to the flat- mity. On clinical examination, the hindfoot is flexible foot.12 Dorsal translation of the navicular relative to the (1A), and when reducing the subtalar joint into a neu- talus occurs with a wedge-shaped opening on the plantar tral position, there is fixed forefoot supination of 25 surface of the TN joint, and this, coupled with uncovering degrees present (2C). There is considerable pain in the of the head of the talus secondary to lateral subluxation of sinus tarsi and under the tip of the fibula indicating the navicular on the talus, has led to the introduction of the peritalar subluxation (1D). The ankle is stable both on term dorsolateral PTS of the foot to describe the abnormal clinical examination and on weightbearing radio- biplanar relationship between the talus and the navicular graphs: This deformity would be classified as 1AD2C. resulting from dysfunction or rupture of the PTT.12 •• A 64-year-old man presents with a painful flatfoot. The consensus group has recommended renaming the On clinical examination, the hindfoot is in valgus condition to Progressive Collapsing Foot Deformity and the subtalar joint is rigid to manipulation (2A). (PCFD), a complex 3-dimensional deformity with varying There is instability at the first tarsometatarsal joint degrees of hindfoot valgus, forefoot abduction, and mid- with gapping on the lateral weightbearing radio- foot varus. We use the words progressive and collapsing graph, but the medial column is not rigid nor is there because they give a better idea of the worsening and any fixed forefoot varus (1C). There is abduction of evolving nature of the complexity of this 3D deformity. the forefoot that cannot be reduced (2B) but no sinus This will avoid the misleading and underestimated nature tarsi impingement to indicate severe peritalar insta- of prior terminology. It does not include the use of the bility either clinically or on weightbearing radio- term posterior tibial tendon, because the tendon itself is graphs. The ankle is stable both on clinical not the problem. It is also preferable not to use acquired examination and on weightbearing radiographs: This flatfoot as the terminology, because a lot of people are deformity would be classified as 2AB1C. born with flatfeet and are never symptomatic, and the flat- tening of the arch is only one of the 3-dimensional compo- Terminology nents of the deformity. Over the years, our understanding of the biomechanics of the medial longitudinal arch and development of the flat- Declaration of Conflicting Interests foot (currently termed the adult-acquired flatfoot deformity The author(s) declared no potential conflicts of interest with [AAFD] because of the various causes of the flatfoot in respect to the research, authorship, and/or publication of this arti- addition to the PTT rupture) has evolved. Numerous inves- cle. ICMJE forms for all authors are available online. tigators have since proposed variations of Johnson and Strom’s system in an effort to encompass the expanded Funding spectrum of AAFD and its associated deformities.2,7,8,10 The author(s) received no financial support for the research, All continue to maintain their system’s overall structure and authorship, and/or publication of this article. 6 Foot & Ankle International 00(0)

ORCID iDs 7. Johnson KA, Strom DE. Tibialis posterior tendon dysfunc- tion. Clin Orthop Relat Res. 1989;239:196-206. Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998 8. Myerson MS. Adult acquired flatfoot deformity: treatment of Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 dysfunction of the posterior tibial tendon. Instr Course Lect. Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- 1997;46:393-405. 6037-0685 9. Parsons S, Naim S, Richards PJ, McBride D. Correction and prevention of deformity in type II tibialis posterior dysfunction. Clin Orthop Relat Res. 2010;468(4):1025- References 1032. 1. Abousayed MM, Tartaglione JP, Rosenbaum AJ, Dipreta JA. 10. Raikin SM, Winters BS, Daniel JN. The RAM classification: Classifications in brief: Johnson and Strom Classification of a novel, systematic approach to the adult-acquired flatfoot. Adult-acquired Flatfoot Deformity. Clin Orthop Relat Res. Foot Ankle Clin. 2012;17(2):169-181. 2016;474(2):588-593. 11. Richter M, Zech S. Lengthening osteotomy of the calca- 2. Bluman EM, Title CI, Myerson MS. Posterior tibial tendon neus and flexor digitorum longus tendon transfer in flexible rupture: a refined classification system. Foot Ankle Clin. flatfoot deformity improves talo-1st metatarsal-Index, clini- 2007;12(2):233-249, v. cal outcome and pedographic parameter. Foot Ankle Surg. 3. Brodell JD Jr, MacDonald A, Perkins JA, Deland JT, Oh I. 2013;19(1):56-61. Deltoid-Spring ligament reconstruction in adult acquired flat- 12. Toolan BC, Sangeorzan BJ, Hansen ST Jr. Complex recon- foot deformity with medial peritalar instability. Foot Ankle struction for the treatment of dorsolateral peritalar sublux- Int. 2019;40(7):753-761. ation of the foot. Early results after distraction arthrodesis of 4. Deland JT. The adult acquired flatfoot and spring ligament the calcaneocuboid joint in conjunction with stabilization of, complex. Pathology and implications for treatment. Foot and transfer of the flexor digitorum longus tendon to, the mid- Ankle Clin. 2001;6(1):129-135, vii. foot to treat acquired pes planovalgus in adults. J Bone Joint 5. Deland JT, de Asla RJ, Sung IH, Ernberg LA, Potter HG. Surg Am. 1999;81(11):1545-1560. Posterior tibial tendon insufficiency: which ligaments are 13. Van Boerum DH, Sangeorzan BJ. Biomechanics and patho- involved? Foot Ankle Int. 2005;26(6):427-435. physiology of flat foot. Foot Ankle Clin. 2003;8(3):419- 6. Gazdag AR, Cracchiolo A 3rd. Rupture of the posterior tibial 430. tendon. Evaluation of injury of the spring ligament and clini- 14. Wake J, Martin K. Posterior tibial tendon endoscopic debride- cal assessment of tendon transfer and ligament repair. J Bone ment for stage I and II posterior tibial tendon dysfunction. Joint Surg Am. 1997;79(5):675-681. Arthrosc Tech. 2017;6(5):e2019-e2022. FAIXXX10.1177/1071100720950732Foot & Ankle InternationalThordarson et al 950732research-article2020

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Foot & Ankle International® 3–­1 Consensus for the Indication of Lateral © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Column Lengthening in the Treatment of DOI:https://doi.org/10.1177/1071100720950732 10.1177/1071100720950732 Progressive Collapsing Foot Deformity journals.sagepub.com/home/fai

David Thordarson, MD1, Lew C. Schon, MD2,3,4,5, Cesar de Cesar Netto, MD, PhD6 , Jonathan T. Deland, MD7, Scott J. Ellis, MD7 , Jeffrey E. Johnson, MD8 , Mark S. Myerson, MD9, Bruce J. Sangeorzan, MD10, and Beat Hintermann, MD11

Abstract Recommendation: Progressive collapsing foot deformity (PCFD) is a complex 3D deformity with varying degrees of hindfoot valgus, forefoot abduction, and midfoot supination. Although a medial displacement calcaneal osteotomy can correct heel valgus, it has far less ability to correct forefoot abduction. More severe forefoot abduction, most frequently measured preoperatively by assessing talonavicular coverage on an anteroposterior (AP) weightbearing conventional radiographic view of the foot, can be more effectively corrected with a lateral column lengthening procedure than by other osteotomies in the foot. Care must be taken intraoperatively to not overcorrect the deformity by restricting passive eversion of the subtalar joint or causing adduction at the talonavicular joint on simulated AP weightbearing fluoroscopic imaging. Overcorrection can lead to lateral column overload with persistent lateral midfoot pain. The typical amount of lengthening of the lateral column is between 5 and 10 mm. Level of Evidence: Level V, consensus, expert opinion. CONSENSUS STATEMENT ONE: Lateral column lengthening (LCL) procedure is recommended when the amount of talonavicular joint uncoverage is above 40%. The amount of lengthening needed in the lateral column should be judged intraoperatively by the amount of correction of the uncoverage and by adequate residual passive eversion range of motion of the subtalar joint. Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); abstain, 11% (1/9). (Strong consensus) CONSENSUS STATEMENT TWO: When titrating the amount of correction of abduction deformity intraoperatively, the presence of adduction at the talonavicular joint on simulated weightbearing fluoroscopic imaging is an important sign of hypercorrection and higher risk for lateral column overload. Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. (Unanimous, strongest consensus) CONSENSUS STATEMENT THREE: The typical range for performing a lateral column lengthening is between 5 and 10 mm to achieve an adequate amount of talonavicular coverage. Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. (Unanimous, strongest consensus)

Keywords: flatfoot, adult-acquired flatfoot deformity, AAFD, reconstruction, osteotomy, Evan’s osteotomy, lateral column lengthening, LCL, progressive collapsing foot deformity, PCFD

Rationale for a specific patient with a given deformity has not been answered. Although many decisions are made intraopera- Lateral column lengthening (LCL) has been used in progres- tively about the specific procedures to be performed, preop- sive collapsing foot deformity (PCFD) surgery for abduction erative clinical and weightbearing conventional radiographic deformity at the talonavicular joint. It is uncommonly per- evaluation can help to determine if an LCL would be appro- formed in isolation but is often used with other PCFD correc- priate in the operative correction of a deformity. tive procedures which will be covered in other sections of A careful clinical evaluation with appropriate history this consensus statement. The question of which corrective and physical examination is an important starting point. procedures are required to achieve an optimal operative result Clinically, the visible severity of the forefoot abduction can 2 Foot & Ankle International 00(0)

be helpful in determining if someone may benefit from an distraction arthrodesis of the calcaneocuboid joint has been LCL. As with all the reconstructive options, the deformity described, it does lead to more stiffness because of fusion of must be flexible in order to consider a corrective rather a a hindfoot joint and has a higher rate of nonunion.13,18 The fusion type of operation. Severity of the deformity is par- most commonly performed osteotomy is the Evan lengthen- ticularly important. The most severe deformities have a ing osteotomy performed parallel and slightly more than 1 greater likelihood of being stiff or, if they are flexible, sur- cm posterior to the calcaneocuboid joint.1,18,19 Other oste- gery can still fail to adequately correct the abduction and/or otomies described include the central Hintermann9,15 and plantarflexion deformity of the TN joint. central/step-cut Vander Griend osteotomies.5,10 Each of In general, although the severity of the deformity and these osteotomies have advocates and none has been found amount of foot abduction is evident on clinical examination, to be consistently more successful than the others.23 In gen- most surgeons use weightbearing conventional radiographic eral, the literature supports that each osteotomy is designed parameters to help guide their decision making. Many different to achieve the same goal of successfully lengthening the radiographic measures have been described. Consistent with calcaneus to correct the deformity as much as possible. previous authors, we agree that the talonavicular coverage Our consensus group most often uses a pre-shaped angle on an anteroposterior (AP) weightbearing view of the allograft wedge for the osteotomy, which avoids the morbid- foot is most helpful.22 The consensus is consistent with studies ity of autograft and allows one to use trial wedges while on LCL indications.4,23 Other measures of a PCFD that have sequentially lengthening through the osteotomy to maximize been discussed regarding the necessity for an LCL include the the chances for an ideal graft size.7 Some studies have shown lateral incongruency angle, AP talar–first metatarsal angle, and similar union rates with auto- vs allograft, with some sur- talar–second metatarsal angle.1,14,25 Although lateral weight- geons still preferring autograft.6,11,24 Other surgeons have bearing radiographs of the foot are important for assessing the used trabecular metal wedges with similar good outcomes to degree of talonavicular (TN), naviculocuneiform (NC), and allograft.12 first tarsometatarsal (TMT) plantar sagging, in general none of Performing the correct amount of lengthening is a critical these measures impact the necessity for an LCL. LCL can in portion of the operation.1,3,4 The amount will vary for each some feet correct the plantar TN sag but in others not be as case but the range of ideal graft size in our consensus group effective in correcting the sagittal plane component of the was 5-10 mm. A pin distractor can be placed across the oste- deformity. With a mild to moderate TN sag, LCL will often give otomy and opened gradually to allow for correction of the adequate correction in the sagittal plane, but with severe plan- forefoot abduction. The ideal amount of correction is tarflexion, inadequate correction is likely. Surgeons are cau- assessed both visually and with a simulated AP weightbear- tioned that if the patient does not apply full weight to the foot ing fluoroscopic view. Once an ideal amount of correction during image acquisition and does not let the arch sag, conven- has been achieved, passive hindfoot motion, especially ever- tional weightbearing radiographs can cause the surgeon to sion, should be assessed. It is the opinion of the majority of underestimate the deformity. This should be checked particu- surgeons in this group that if it is significantly restricted, larly if the images do not match the clinical deformity. then the amount of distraction at the osteotomy site needs to Weightbearing Saltzman axial heel views and ankle radiographs be decreased until the passive eversion is relatively unre- are also important for fully assessing a PCFD,21 but they do not stricted. Overcorrection will lead to a higher rate of lateral influence the decision to perform an LCL. Advanced imaging column pain and increased lateral foot pressures with a studies such as weightbearing CT scans and MRI have a role in higher rate of patient dissatisfaction.2,8,20 When using precut evaluating ACFD but likewise generally do not influence the allograft or metallic wedges, trial wedges are available to get decision whether an LCL is indicated. the most accurate size measurement of the actual wedge to In general, LCL procedures are lengthening osteotomies be implanted. Most surgeons agree internal fixation should of the anterior or midportion of the calcaneus. Although be used to stabilize the graft in the form of screws or plates.

1Cedars-Sinai Medical Center, Los Angeles, CA, USA 2Mercy Medical Center, Baltimore, MD, USA 3New York University Grossman School of Medicine, New York, NY, USA 4Johns Hopkins School of Medicine, Baltimore, MD, USA 5Georgetown School of Medicine, Washington, DC, USA 6Department of Orthopaedics and Rehabilitation, University of Iowa, Iowa City, IA, USA 7Hospital for Special Surgery, New York, NY, USA 8Washington University School of Medicine, St. Louis, MO, USA 9Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA 10University of Washington, Seattle, WA, USA 11Kantonspital Baselland, Liestal, Switzerland

Corresponding Author: Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon Pavilion, Room 01066, Iowa City, IA 52242, USA. Email: [email protected] Thordarson et al 3

Although many studies have been published on the opera- 8. Ellis SJ, Yu JC, Johnson AH, Elliott A, O’Malley M, Deland tive management of ACFD, almost all of them appropriately J. Plantar pressures in patients with and without lateral foot report on combinations of procedures used to correct this pain after lateral column lengthening. J Bone Joint Surg Am. complex deformity. This feature of the ACFD literature 2010;92(1):81-91. makes it difficult to separate the contributions of the various 9. Ettinger S, Mattinger T, Stukenborg-Colsman C, et al. Outcomes of Evans versus Hintermann calcaneal lengthening osteotomy components of each surgery to the final outcome. However, for flexible flatfoot. Foot Ankle Int. 2019;40(6):661-671. the literature does support that LCL has a much higher rate of 10. Griend RV. Lateral column lengthening using a “Z” osteotomy failure with overcorrection either radiographically, that is, of the calcaneus. Tech Foot Ankle Surg. 2008;7(4):257-263. adduction of the forefoot, or if it results in limited hindfoot 11. Grier KM, Walling AK. The use of tricortical autograft ver- eversion. Conversely, the best results are achieved when the sus allograft in lateral column lengthening for adult acquired deformity is fully corrected16,17; that is, aim for ideal radio- flatfoot deformity: an analysis of union rates and complica- graphic correction but be prepared to accept less than perfect tions. Foot Ankle Int. 2010;31(9):760-769. alignment if it leads to stiffness in eversion. 12. Gross CE, Huh J, Gray J, Demetracopoulos C, Nunley JA. Radiographic outcomes following lateral column lengthening Declaration of Conflicting Interests with a porous titanium wedge. Foot Ankle Int. 2015;36(8): 953-960. The author(s) declared no potential conflicts of interest with 13. Grunander TR, Thordarson DB. Results of calcaneocuboid respect to the research, authorship, and/or publication of this arti- distraction arthrodesis. Foot Ankle Surg. 2012;18(1):15-18. cle. ICMJE forms for all authors are available online. 14. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis Funding WH, Manoli A 2nd. Symposium: Adult acquired flatfoot deformity. Foot Ankle Int. 2011;32(1):95-111. The author(s) received no financial support for the research, 15. Hintermann B, Valderrabano V, Kundert HP. Lateral column authorship, and/or publication of this article. lengthening by calcaneal osteotomy combined with soft tissue reconstruction for treatment of severe posterior tibial tendon ORCID iDs dysfunction. Methods and preliminary results [in German]. Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- Orthopade. 1999;28(9):760-769. 6037-0685 16. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc- Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 tion. Foot Ankle Clin. 2017;22(3):613-624. 17. Iossi M, Johnson JE, McCormick JJ, Klein SE. Short-term Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998 radiographic analysis of operative correction of adult acquired flatfoot deformity. Foot Ankle Int. 2013;34(6):781-791. References 18. Kitaoka HB, Kura H, Luo ZP, An KN. Calcaneocuboid 1. Chan JY, Greenfield ST, Soukup DS, Do HT, Deland JT, distraction arthrodesis for posterior tibial tendon dysfunc- Ellis SJ. Contribution of lateral column lengthening to cor- tion and flatfoot: a cadaveric study. Clin Orthop Relat Res. rection of forefoot abduction in stage IIb adult acquired flat- 2000;381:241-247. foot deformity reconstruction. Foot Ankle Int. 2015;36(12): 19. Mosier-LaClair S, Pomeroy G, Manoli A 2nd. Operative 1400-1411. treatment of the difficult stage 2 adult acquired flatfoot defor- 2. Conti MS, Chan JY, Do HT, Ellis SJ, Deland JT. Correlation mity. Foot Ankle Clin. 2001;6(1):95-119. of postoperative midfoot position with outcome following 20. Oh I, Imhauser C, Choi D, Williams B, Ellis S, Deland J. reconstruction of the stage II adult acquired flatfoot defor- Sensitivity of plantar pressure and talonavicular alignment to mity. Foot Ankle Int. 2015;36(3):239-247. lateral column lengthening in flatfoot reconstruction. J Bone 3. Conti MS, Deland JT, Ellis SJ. Stage IIB flatfoot reconstruction Joint Surg Am. 2013;95(12):1094-100. using literature-based equations for heel slide and lateral column 21. Saltzman CL, el-Khoury GY. The hindfoot alignment view. lengthening. Tech Foot Ankle Surg. 2017;16(4):153-166. Foot Ankle Int. 1995;16(9):572-576. 4. Deland JT. Adult-acquired flatfoot deformity. J Am Acad 22. Sangeorzan BJ, Mosca V, Hansen ST Jr. Effect of calcaneal Orthop Surg. 2008;16(7):399-406. lengthening on relationships among the hindfoot, midfoot, 5. Demetracopoulos CA, Nair P, Malzberg A, Deland JT. Outcomes and forefoot. Foot Ankle. 1993;14(3):136-141. of a stepcut lengthening calcaneal osteotomy for adult-acquired 23. Saunders SM, Ellis SJ, Demetracopoulos CA, Marinescu A, flatfoot deformity. Foot Ankle Int. 2015;36(7):749-755. Burkett J, Deland JT. Comparative outcomes between step- 6. Dolan CM, Henning JA, Anderson JG, Bohay DR, Kornmesser cut lengthening calcaneal osteotomy vs traditional evans oste- MJ, Endres TJ. Randomized prospective study comparing otomy for stage IIB adult-acquired flatfoot deformity. Foot tri-cortical iliac crest autograft to allograft in the lateral col- Ankle Int. 2018;39(1):18-27. umn lengthening component for operative correction of adult 24. Vosseller JT, Ellis SJ, O’Malley MJ, et al. Autograft and acquired flatfoot deformity. Foot Ankle Int. 2007;28(1):8-12. allograft unite similarly in lateral column lengthening for 7. Ellis SJ, Williams BR, Garg R, Campbell G, Pavlov H, adult acquired flatfoot deformity. HSS J. 2013;9(1):6-11. Deland JT. Incidence of plantar lateral foot pain before and 25. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of after the use of trial metal wedges in lateral column lengthen- the adult acquired flatfoot deformity. Curr Rev Musculoskelet ing. Foot Ankle Int. 2011;32(7):665-673. Med. 2013;6(4):294-303. FAIXXX10.1177/1071100720950734Foot & Ankle Internationalde Cesar Netto et al 950734review-article2020

Topical Review

Foot & Ankle International® 5–­1 Consensus for the Use of Weightbearing © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions CT in the Assessment of Progressive DOI:https://doi.org/10.1177/1071100720950734 10.1177/1071100720950734 Collapsing Foot Deformity journals.sagepub.com/home/fai

Cesar de Cesar Netto, MD, PhD1 , Mark S. Myerson, MD2, Jonathan Day, MS3 , Scott J. Ellis, MD3 , Beat Hintermann, MD4, Jeffrey E. Johnson, MD5 , Bruce J. Sangeorzan, MD6, Lew C. Schon, MD7,8,9,10, David Thordarson, MD11, and Jonathan T. Deland, MD3

Abstract Recommendation: There is evidence that the use of WEIGHTBEARING imaging aids in the assessment of progressive collapsing foot deformity (PCFD). The following WEIGHTBEARING conventional radiographs (CRs) are necessary in the assessment of PCFD patients: anteroposterior (AP) foot, AP or mortise ankle, and lateral foot. If available, a hindfoot alignment view is strongly recommended. If available, WEIGHTBEARING computed tomography (CT) is strongly recommended for surgical planning. When WEIGHTBEARING CT is obtained, important findings to be assessed are sinus tarsi impingement, subfibular impingement, increased valgus inclination of the posterior facet of the subtalar joint, and subluxation of the subtalar joint at the posterior and/or middle facet. Level of Evidence: Level V, consensus, expert opinion.

Keywords: adult-acquired flatfoot deformity, AAFD, flatfoot, reconstruction, weightbearing CT, peritalar subluxation, PTS, progressive collapsing foot deformity, PCFD

Consensus Statements Voted tarsi impingement, increased valgus inclination of the posterior facet of the subtalar joint, subluxation 1. CONSENSUS STATEMENT 1—The following of the subtalar joint at the posterior and/or middle WEIGHTBEARING conventional radiographs facet, and subfibular impingement. (CRs) are considered mandatory by the consensus group in the assessment of progressive collapsing foot deformity (PCFD) patients: anteroposterior (AP) foot, AP or mortise ankle, lateral foot. The 1Department of Orthopaedics and Rehabilitation, University of Iowa, consensus group also strongly recommends a hind­ Iowa City, IA, USA foot alignment view when available. 2Department of Orthopedic Surgery, University of Colorado School of Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Medicine, Aurora, CO, USA 3 Abstain: 0% Hospital for Special Surgery, New York, NY, USA 4Kantonspital Baselland, Liestal, Switzerland (Unanimous, Strongest Consensus) 5Washington University School of Medicine, St. Louis, MO, USA 2. CONSENSUS STATEMENT 2—If WEIGHT­ 6University of Washington, Seattle, WA, USA BEARING computed tomography (CT) imaging 7Mercy Medical Center, Baltimore, MD, USA available, the consensus group strongly recommends 8New York University Grossman School of Medicine, New York, NY, USA 9 its use for surgical planning of PCFD patients. Johns Hopkins School of Medicine, Baltimore, MD, USA 10Georgetown School of Medicine, Washington, DC, USA Delegate Vote: Agree: 100% (9/9); Disagree: 0%; 11Cedars-Sinai Medical Center, Los Angeles, CA, USA Abstain: 0% (Unanimous, Strongest Consensus) Corresponding Author: Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and 3. CONSENSUS STATEMENT 3—The presence of Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon important WEIGHTBEARING CR/WEIGHT­ Pavilion, Room 01066, Iowa City, IA 52242, USA. BEARING CT findings to be assessed includes sinus Email: [email protected] 2 Foot & Ankle International 00(0)

Delegate Vote: Agree: 100% (9/9); Disagree: 0%; preoperative evaluation of PCFD patients. A list of the Abstain: 0% results of a survey regarding the most commonly used (Unanimous, Strongest Consensus) WEIGHTBEARING CR measurements performed by the consensus experts is presented in Figure 1. However, the Rationale recommended mandatory ones by the expert consensus group are the ones presented in Consensus Statement 1. WEIGHTBEARING conventional radiographs (CR) have While WEIGHTBEARING CRs remain the gold standard been the mainstay of evaluating progressive collapsing foot given their availability and affordability, multiplanar imaging deformity (PCFD), with several validated radiographic such as conventional computed tomography (CT) and measurements described for its assessment and staging.6,26,30 WEIGHTBEARING CT offers several unique advantages, In a blinded comparison of standing anteroposterior (AP) including improved spatial resolution that allows a multiplanar and lateral CR measurements, Younger et al30 demonstrated 3-dimensional assessment, minimizing rotational and posi­ that several radiographic parameters, including talar–first tional bias, as well as bony superimposition.4,5,11 In addition, metatarsal angle (Meary’s angle) and talonavicular (TN) studies have demonstrated the reliability and reproducibility of coverage angle,27 can reliably and consistently differentiate using WEIGHTBEARING CT in the evaluation of PCFD, between patients with symptomatic PCFD deformity and highlighting its ability to better quantify structural deformity controls.30 In another study by Arangio et al,3 it was deter­ compared to CR and nonweightbearing (NWB) ima mined that the lateral-medial cuneiform distance measured ges.15-17,20,23,31 One such study prospectively compared 19 mea­ on lateral WEIGHTBEARING CR is a useful parameter surements taken on WEIGHTBEARING CT and nonweight­ that assesses severity of a flattened arch, with PCFD patients bearing in patients with flexible PCFD and concluded that having a significantly flatter arch (11.04 mm) compared to while there was substantial intra- and interobserver reliability in healthy controls (18.38 mm). The authors concluded that both modalities, WEIGHTBEARING CT images demon­ decreased lateral-medial cuneiform distance is a strong strated a significantly better ability to detect severity of bony indicator of PCFD. Furthermore, Sensiba et al28 demon­ derangement in PCFD patients compared to nonweightbearing strated strong to almost perfect interobserver reliability for CT.16 In another study comparing radiographic measurements radiographic parameters made on WEIGHTBEARING CR between WEIGHTBEARING CT and WEIGHTBEARING AP (talar–second metatarsal angle), lateral (talar–first meta­ CR in patients with PCFD vs healthy controls, Haleem et al21 tarsal angle, medial cuneiform/fifth metatarsal distance), demonstrated that WEIGHTBEARING CT is more sensitive and hindfoot alignment view (tibial/calcaneal displacement, than CR in detecting significant deformity, including Meary’s calcaneal angulation), highlighting the usability and repro­ angle and talonavicular coverage angle in PCFD patients. The ducibility of these measurements. authors concluded that WEIGHTBEARING CT is therefore a Several studies have also demonstrated the association more informative tool for evaluating PCFD in the physiologic between WEIGHTBEARING CR correction and improved WEIGHTBEARING position compared to CR. Kunas et al22 patient-reported outcomes. One such study by Conti et al10 have also demonstrated that when compared to conventional demonstrated that the cuneiform articular angle (CAA) on nonweightbearing CT, WEIGHTBEARING CT was more WEIGHTBEARING lateral CR significantly correlates accurate in demonstrating pronounced deformity and increased with postoperative clinical outcomes. The authors found hindfoot valgus in PCFD patients, since it shows the bone rela­ that patients with a CAA of greater than or equal to −2 tionship with the foot under physiological standing load. When degrees (mild plantarflexion) had superior patient-reported comparing conventional CT and WEIGHTBEARING CT, outcomes compared to patients with less than –2 degrees Kunas et al22 have demonstrated that specifically on PCFD (moderate plantarflexion). In another study assessing hind­ patients, WEIGHTBEARING CT imaging proved to be corre­ foot alignment correction on hindfoot alignment view, lated more strongly with markers of the deformity than conven­ investigators not only demonstrated that a postoperative tional CT by revealing more pronounced hindfoot valgus. The hindfoot moment arm (HMA) of 0 to 5 mm varus correlates authors concluded that conventional nonweightbearing CT with a clinically straight heel but also concluded that this scans could be used to assess PCFD but not as a surrogate of correction results in the greatest improvement in patient- WEIGHTBEARING CT, with possible underestimation of the reported outcomes.9 Given the results of these studies, the deformity.22 expert consensus is that WEIGHTBEARING CRs are man­ One of the most important aspects of PCFD that has datory in the assessment of PCFD patients and that the min­ become much clearer and more easily and directly assessed imal assessment needed is composed of the following with the advent of WEIGHTBEARING CT is the coronal WEIGHTBEARING CRs: AP foot, AP or mortise ankle, plane hindfoot component of the deformity, previously and lateral foot. The consensus group also strongly recom­ described as peritalar subluxation (PTS),29 where there is an mends a hindfoot alignment view if available. Having these external rotation, eversion, and abduction deformity of the 3 or 4 WEIGHTBEARING CR incidences would allow foot underneath the talus through the triple joint complex. adequate radiographic assessment as well as the calculation Multiple parameters associated with the severity of PTS were of most of the measurements usually used in the staging and described and investigated in the literature. One very good de Cesar Netto et al 3

Figure 1. Most commonly used conventional radiographic measurements for the assessment of progressive collapsing foot deformity (PCFD) according to consensus votes from experts (total of 9 expert opinions), with percentage of votes. AP, anteroposterior; TMTJ, tarsometatarsal joint. example is the presence of sinus tarsi and subfibular impinge­ also showed a trend toward increased frequency of subfibular ments. In a study of symptomatic PCFD patients with lateral impingement in PCFD patients, with good to excellent intra- hindfoot pain, Malicky et al24 demonstrated that and interobserver reliability.19 The authors concluded empha­ WEIGHTBEARING CT reliably characterizes the presence sizing the utility of WEIGHTBEARING CT in reliably of sinus tarsi impingement and subfibular impingement, assessing causes for lateral pain in PCFD patients. which could potentially explain the presence of lateral symp­ Another WEIGHTBEARING CT parameter extensively toms. They also reported a unique and important finding that investigated as a factor influencing the diagnosis and the sever­ all patients with subfibular impingement also had concurrent ity of PTS in PCFD patients is related to the subtalar joint sinus tarsi impingement. The opposite findings, subfibular anatomy. In a novel and landmark study by Colin et al,8 the impingement in patients with sinus tarsi impingement, were investigators used WEIGHTBEARING CT to characterize the not mandatory and much less frequent, providing an idea of physiologic weightbearing morphology of the subtalar joint in chronology and that subfibular impingement could be a asymptomatic individuals. They demonstrated that in the nor­ marker of more pronounced deformity. The authors finally mal anatomy of the posterior facet of the subtalar joint, the concluded that the WEIGHTBEARING CT findings were articular facet becomes progressively more angulated into a consistent with lateral hindfoot pain in symptomatic PCFD valgus position from anterior to posterior along its longitudinal and would correlate with indirect CR evidence of lateral length, when measured by the subtalar vertical angle (SVA— impingement such as cysts and sclerosis in the sinus tarsi and angle between the talar posterior facet of the subtalar joint and subfibular areas.24 In a similar study comparing PCFD with a vertical line perpendicular to the floor). The authors con­ and without lateral hindfoot pain, Ellis et al19 demonstrated cluded that WEIGHTBEARING CT was an effective imaging that lateral hindfoot pain was associated with significant sub­ modality for assessing the joint’s morphology, demonstrating a talar joint degeneration, especially at the posterior facet. standard baseline threshold of normal anatomy, with implica­ However, with closer independent evaluation of the presented tions for surgical planning in reconstructive hindfoot surgery. images for posterior facet joint degeneration, it is easy to Following that study, Apostle et al2 determined that symptom­ notice that rather than demonstrating intra-articular degenera­ atic PCFD patients demonstrated an increased innate valgus tion, the images show clear signs of extra-articular involve­ orientation of the posterior facet of the subtalar joint when ment, consistent with sinus tarsi impingement. The authors assessed by the subtalar joint axis (STJA), which takes into 4 Foot & Ankle International 00(0)

consideration 2 landmarks within the talar bone (angulation to the use of the posterior facet.18 Middle facet subluxation was between the talar posterior facet of the subtalar joint and the found to be more pronounced than the subluxation of the poste­ talar dome measured in coronal plane WEIGHTBEARING rior facet by an average of almost 18% in PCFD patients, sug­ CT images). Subsequently, Probasco et al25 demonstrated that gesting that the middle facet may provide an earlier and more the alignment of the posterior facet of the subtalar joint could pronounced marker of progressive PTS in PCFD patients. be reliably assessed on coronal WEIGHTBEARING CT using The use of WEIGHTBEARING CT semiautomatic multi­ 2 angles: an angle between the inferior facet of the talus and the planar measurements has also been recently demonstrated to horizontal floor (inftal-hor), as well as an angle between infe­ be a reliable and more complete isolated measurement to rior and superior facets of the talus (inftal-suptal), respectively evaluate the 3-dimensional (3D) components of the similar to SVA and STJA. The authors found that when com­ PCFD.12,13 The use of the Foot and Ankle Offset (FAO),23 pared to controls, patients with PCFD had increased valgus which measures the relationship between the position of the inclination of the subtalar joint. While controls exhibited a foot tripod (weightbearing points of the first and fifth meta­ varus orientation at the anterior aspect of the posterior facet, tarsal heads as well calcaneal tuberosity) in relation to the which progressively went into valgus at the central and poste­ center of the ankle joint (most proximal and central point of rior aspects of the joint, PCFD patients maintained a valgus the talar dome), was shown to be slightly more reliable than orientation of the posterior facet throughout. A follow-up study traditional manual PCFD measurements and to represent in a by Cody et al7 demonstrated that not only do the inftal-hor and single measurement different components of the 3D defor­ inftal-suptal angles show increased valgus orientation of the mity.13 More specifically, almost 80% of the changes in FAO subtalar joint in PCFD patients, but more important, these measurements would be explained by variations in the hind­ WEIGHTBEARING CT angles significantly and positively foot moment arm (HMA) (P < .00001), subtalar horizontal correlate with multiple PCFD WEIGHTBEARING CR mea­ angle (P < .00001), talonavicular coverage angle (P = surements, including TN coverage angle, talar–first metatarsal .00004), and forefoot arch angle (P = .0001).13 The same angle, calcaneal pitch, and medial column height. Specifically, measurement was also shown to be a reliable and sensitive the authors demonstrated that a inftal-suptal angle threshold of tool for assessment of preoperative PCFD as well as postop­ 17 degrees or more would significantly differentiate PCFD erative correction, with patients demonstrating both signifi­ patients from controls, with this cutoff value of innate valgus cant improvement in FAO as well as patient-reported angulation of the subtalar joint potentially representing an outcomes following PCFD reconstructive surgery.12 important risk factor for progressive deformity. In addition, However, no direct correlation was found between postoper­ this finding serves as a potential tool to guide treatment by ative improvements of FAO and patient-reported outcomes. identifying patients who could possibly benefit from early Given the combined results of these studies, the expert reconstructive surgery. consensus opinion is to obtain WEIGHTBEARING CT The severity of PTS in PCFD patients has also being inves­ images of the foot and ankle if available for surgical plan­ tigated by direct assessment of the overlap/subluxation of the ning prior to PCFD reconstruction, especially to assess early articular facets using coronal plane WEIGHTBEARING CT and pronounced findings of hindfoot deformity and PTS, images. In a landmark study by Ananthakrisnan et al,1 the including increased FAO, presence of sinus tarsi impinge­ authors demonstrated significantly decreased overlap in the ment, subfibular impingement, increased valgus inclination anterior/middle and posterior facets of the subtalar joint when of the posterior facet of the subtalar joint, and subluxation of comparing PCFD and controls. The amount of subluxation was the subtalar joint at the posterior and/or middle facet. more pronounced in the anterior/middle facet than in the poste­ rior facet. Following that study, the literature mostly focused on Declaration of Conflicting Interests the severity of PTS measured at the posterior facet, with Ferri The author(s) declared no potential conflicts of interest with 20 et al reporting the amount of lateral subluxation of the calca­ respect to the research, authorship, and/or publication of this arti­ neus at the posterior facet of the subtalar joint in millimeters. cle. ICMJE forms for all authors are available online. They found that only patients with PCFD demonstrated signifi­ cant subluxation (26.6% of PCFD patients, with a mean dis­ Funding placement of 7 mm), with none of the control patients presenting The author(s) received no financial support for the research, with signs of PTS. More recently, de Cesar Netto et al14 empha­ authorship, and/or publication of this article. sized the role of the middle facet of the subtalar joint as possibly a more accurate indicator of PTS and symptomatic PCFD. The ORCID iD authors reported reliable assessment of PTS at the middle facet, showing that an incongruence angle greater than 8.4 degrees Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- and a subluxation of more than 17.9% are highly accurate diag­ 6037-0685 nostic tools in symptomatic PCFD and potentially represent Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042 early findings of PCFD. The assessment of PTS in PCFD Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 patients using the middle facet of the subtalar joint was also Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055- shown to demonstrate more severe deformity when compared 9998 de Cesar Netto et al 5

References 17. de Cesar Netto C, Shakoor D, Roberts L, et al. Hindfoot align­ ment of adult acquired flatfoot deformity: a comparison of 1. Ananthakrisnan D, Ching R, Tencer A, Hansen ST, Jr., Sangeorzan BJ. Subluxation of the talocalcaneal joint in clinical assessment and weightbearing cone beam CT exami­ adults who have symptomatic flatfoot. J Bone Joint Surg Am. nations. Foot Ankle Surg. 2019;25(6):790-797. 1999;81(8):1147-1154. 18. de Cesar Netto C, Silva T, Li S, et al. Assessment of posterior 2. Apostle KL, Coleman NW, Sangeorzan BJ. Subtalar joint axis and middle facet subluxation of the subtalar joint in progres­ in patients with symptomatic peritalar subluxation compared sive flatfoot deformity [published online June 26, 2020]. Foot to normal controls. Foot Ankle Int. 2014;35(11):1153-1158. Ankle Int. 3. Arangio GA, Wasser T, Rogman A. Radiographic comparison of 19. Ellis SJ, Deyer T, Williams BR, et al. Assessment of lat­ standing medial cuneiform arch height in adults with and without eral hindfoot pain in acquired flatfoot deformity using acquired flatfoot deformity. Foot Ankle Int. 2006;27(8):636-638. weightbearing multiplanar imaging. Foot Ankle Int. 4. Barg A, Amendola RL, Henninger HB, Kapron AL, Saltzman 2010;31(5):361-371. CL, Anderson AE. Influence of ankle position and radio­ 20. Ferri M, Scharfenberger AV, Goplen G, Daniels TR, Pearce graphic projection angle on measurement of supramalleo­ D. Weightbearing CT scan of severe flexible pes planus lar alignment on the anteroposterior and hindfoot alignment deformities. Foot Ankle Int. 2008;29(2):199-204. views. Foot Ankle Int. 2015;36(11):1352-1361. 21. Haleem AM, Pavlov H, Bogner E, Sofka C, Deland JT, Ellis 5. Baverel L, Brilhault J, Odri G, Boissard M, Lintz F. Influence SJ. Comparison of deformity with respect to the talus in of lower limb rotation on hindfoot alignment using a conven­ patients with posterior tibial tendon dysfunction and controls tional two-dimensional radiographic technique. Foot Ankle using multiplanar weight-bearing imaging or conventional Surg. 2017;23(1):44-49. radiography. J Bone Joint Surg Am. 2014;96(8):e63. 6. Chadha H, Pomeroy G, Manoli A II. Radiologic signs of uni­ 22. Kunas GC, Probasco W, Haleem AM, Burket JC, Williamson lateral pes planus. Foot Ankle Int. 1997;18(9):603-604. ERC, Ellis SJ. Evaluation of peritalar subluxation in adult 7. Cody EA, Williamson ER, Burket JC, Deland JT, Ellis SJ. acquired flatfoot deformity using computed tomography Correlation of talar anatomy and subtalar joint alignment on and weightbearing multiplanar imaging. Foot Ankle Surg. weightbearing computed tomography with radiographic flat­ 2018;24(6):495-500. foot parameters. Foot Ankle Int. 2016;37(8):874-881 23. Lintz F, Welck M, Bernasconi A, et al. 3D biometrics for 8. Colin F, Horn Lang T, Zwicky L, Hintermann B, Knupp M. hindfoot alignment using weightbearing CT. Foot Ankle Int. Subtalar joint configuration on weightbearing CT scan. Foot 2017;38(6):684-689. Ankle Int. 2014;35(10):1057-1062. 24. Malicky ES, Crary JL, Houghton MJ, Agel J, Hansen ST Jr, 9. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal posi­ Sangeorzan BJ. Talocalcaneal and subfibular impingement tion of the heel following reconstruction of the stage II adult- in symptomatic flatfoot in adults. J Bone Joint Surg Am. acquired flatfoot deformity. Foot Ankle Int. 2015;36(8):919-927. 2002;84(11):2005-2009. 10. Conti MS, Garfinkel JH, Kunas GC, Deland JT, Ellis SJ. 25. Probasco W, Haleem AM, Yu J, Sangeorzan BJ, Deland JT, Postoperative medial cuneiform position correlation with Ellis SJ. Assessment of coronal plane subtalar joint alignment patient-reported outcomes following cotton osteotomy for in peritalar subluxation via weight-bearing multiplanar imag­ reconstruction of the stage II adult-acquired flatfoot defor­ ing. Foot Ankle Int. 2015;36(3):302-309. mity. Foot Ankle Int. 2019;40(5):491-498. 26. Saltzman CL, Brandser EA, Berbaum KS, et al. Reliability 11. Dagneaux L, Moroney P, Maestro M. Reliability of hind­ of standard foot radiographic measurements. Foot Ankle Int. foot alignment measurements from standard radiographs 1994;15(12):661-665. using the methods of Meary and Saltzman. Foot Ankle Surg. 27. Sangeorzan BJ, Mosca V, Hansen ST Jr. Effect of calcaneal 2019;25(2):237-241. lengthening on relationships among the hindfoot, midfoot, 12. Day J, de Cesar Netto C, Nishikawa DRC, et al. Three- and forefoot. Foot Ankle. 1993;14(3):136-141. dimensional biometric weightbearing CT evaluation of the 28. Sensiba PR, Coffey MJ, Williams NE, Mariscalco M, operative treatment of adult-acquired flatfoot deformity. Foot Laughlin RT. Inter- and intraobserver reliability in the radio­ Ankle Int. 2020;41(8):930-936. graphic evaluation of adult flatfoot deformity. Foot Ankle Int. 13. de Cesar Netto C, Bang K, Mansur NS, et al. Multiplanar semi­ 2010;31(2):141-145. automatic assessment of foot and ankle offset in adult acquired 29. Toolan BC, Sangeorzan BJ, Hansen ST Jr. Complex recon­ flatfoot deformity. Foot Ankle Int. 2020;41(7):839-848. struction for the treatment of dorsolateral peritalar sublux­ 14. de Cesar Netto C, Godoy-Santos AL, Saito GH, et al. Subluxation ation of the foot: early results after distraction arthrodesis of of the middle facet of the subtalar joint as a marker of peritalar the calcaneocuboid joint in conjunction with stabilization of, subluxation in adult acquired flatfoot deformity: a case-control and transfer of the flexor digitorum longus tendon to, the mid­ study. J Bone Joint Surg Am. 2019;101(20):1838-1844. foot to treat acquired pes planovalgus in adults. J Bone Joint 15. de Cesar Netto C, Schon LC, Thawait GK, et al. Flexible adult Surg Am. 1999;81(11):1545-1560. acquired flatfoot deformity: comparison between weight-bear­ 30. Younger AS, Sawatzky B, Dryden P. Radiographic assess­ ing and non-weight-bearing measurements using cone-beam ment of adult flatfoot. Foot Ankle Int. 2005;26(10):820- computed tomography. J Bone Joint Surg Am. 2017;99(18):e98. 825. 16. de Cesar Netto C, Shakoor D, Dein EJ, et al. Influence of 31. Zhang Y, Xu J, Wang X, et al. An in vivo study of hindfoot investigator experience on reliability of adult acquired flat­ 3D kinetics in stage II posterior tibial tendon dysfunction foot deformity measurements using weightbearing computed (PTTD) flatfoot based on weight-bearing CT scan. Bone Joint tomography. Foot Ankle Surg. 2019;25(4):495-502. Res. 2013;2(12):255-263. FAIXXX10.1177/1071100720950738Foot & Ankle InternationalHintermann et al 950738research-article2020

Topical Review

Foot & Ankle International® 4–­1 Consensus on Indications for Isolated © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Subtalar Joint Fusion and Naviculocuneiform DOI:https://doi.org/10.1177/1071100720950738 10.1177/1071100720950738 Fusions for Progressive Collapsing Foot journals.sagepub.com/home/fai Deformity

Beat Hintermann, MD1, Jonathan T. Deland, MD2, Cesar de Cesar Netto, MD, PhD3 , Scott J. Ellis, MD2 , Jeffrey E. Johnson, MD4 , Mark S. Myerson, MD5, Bruce J. Sangeorzan, MD6, David Thordarson, MD7, and Lew C. Schon, MD8,9,10,11

Abstract Recommendation: Peritalar subluxation represents an important hindfoot component of progressive collapsing foot deformity, which can be associated with a breakdown of the medial longitudinal arch. It results in a complex 3-dimensional deformity with varying degrees of hindfoot valgus, forefoot abduction, and pronation. Loss of peritalar stability allows the talus to rotate and translate on the calcaneal and navicular bone surfaces, typically moving medially and anteriorly, which may result in sinus tarsi and subfibular impingement. The onset of degenerative disease can manifest with stiffening of the subtalar (ST) joint and subsequent fixed and possibly arthritic deformity. While ST joint fusion may permit repositioning and stabilization of the talus on top of the calcaneus, it may not fully correct forefoot abduction and it does not correct forefoot varus. Such varus may be addressed by a talonavicular (TN) fusion or a plantar flexion osteotomy of the first ray, but, if too pronounced, it may be more effectively corrected with a naviculocuneiform (NC) fusion. The NC joint has a curvature in the sagittal plane. Thus, preserving the shape of the joint is the key to permitting plantarflexion correction by rotating the midfoot along the debrided surfaces and to fix it. Intraoperatively, care must be also taken to not overcorrect the talocalcaneal angle in the horizontal plane during the ST fusion (eg, to exceed the external rotation of the talus and inadvertently put the midfoot in a supinated position). Such overcorrection can lead to lateral column overload with persistent lateral midfoot pain and discomfort. A contraindication for an isolated ST fusion may be a rupture of posterior tibial tendon because of the resultant loss of the internal rotation force at the TN joint. In these cases, a flexor digitorum longus tendon transfer is added to the procedure. Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, peritalar instability, subtalar fusion, naviculocuneiform fusion, subfibular impingement, progressive collapsing foot deformity, PCFD

Consensus Statements Voted 1Kantonspital Baselland, Liestal, Switzerland 2Hospital for Special Surgery, New York, NY, USA 1. CONSENSUS STATEMENT—Subtalar joint 3Department of Orthopaedics and Rehabilitation, University of Iowa, fusion should be considered in the treatment of Iowa City, IA, USA deformities where the subtalar joint is arthritic and 4Washington University School of Medicine, St. Louis, MO, USA stiff or where there is severe peritalar subluxation/ 5Department of Orthopedic Surgery, University of Colorado School of dislocation (subtalar joint subluxation/dislocation, Medicine, Aurora, CO, USA 6University of Washington, Seattle, WA, USA subfibular impingement). 7Cedars-Sinai Medical Center, Los Angeles, CA, USA Delegate Vote: Agree: 100% (9/9); Disagree: 0%; 8Mercy Medical Center, Baltimore, MD, USA Abstain: 0% 9New York University Grossman School of Medicine, New York, NY, (Unanimous, Strongest Consensus) USA 10 2. CONSENSUS STATEMENT—In the correction of Johns Hopkins School of Medicine, Baltimore, MD, USA 11Georgetown School of Medicine, Washington, DC, USA the forefoot varus component of progressive collaps- ing foot deformity (PCFD), naviculocuneiform (NC) Corresponding Author: Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and joint fusion should be considered when the NC joint Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon is arthritic and symptomatic and/or when there is sig- Pavilion, Room 01066, Iowa City, IA 52242, USA. nificant sagittal plane sagging of the NC joint. Email: [email protected] 2 Foot & Ankle International 00(0)

Delegate Vote: Agree: 89% (8/9), Disagree: 0%; Abstain foot is unloaded, the valgus and pronation deformity of the 11% (1/9) hindfoot may be or may be not correctable. (Strong Consensus) In general, while the severity of the deformity and amount of breakdown of the medial arch are evident on Rationale clinical exam, most surgeons use radiographic parameters to help guide their decision making. Many different radio- Subtalar (ST) fusion has been used in PCFD surgery in graphic measures have been described.39 The consensus of advanced stages of deformity, mostly including the talona- our group was that the talar–first metatarsal angle, in both vicular (TN) and the calcaneocuboid (CC) joints (eg, triple lateral and anteroposterior (AP) views, and the talonavicu- arthrodesis).12,21,23,24,32 More recently, to preserve motion lar uncoverage angle on an AP view of the foot are most in the lateral column, double arthrodesis has been advo- helpful. Other measures of a PCFD that have been discussed cated for the operative treatment of more advanced stages regarding the necessity for reconstruction of the medial of PCFD.4,26,31,38 The rationale in both the triple and dou- arch include the AP lateral incongruency angle15,37,39 and ble fusion is that the ST fusion provides hindfoot correc- the talocalcaneal overlap on lateral WEIGHTBEARING tion and stability, whereas the TN fusion corrects the radiographs of the foot.3 The lateral view also serves for forefoot supination and abduction. However, there is little assessing the degree of sagging of the TN, NC, and first evidence in the literature whether TN fusion does suffi- tarsometatarsal (TMT) joints, which may have an impact ciently address the breakdown of the medial arch and the regarding the necessity and the location of medial column forefoot supination associated with hindfoot peritalar sub- stabilization and ST fusion procedures. While the Saltzman luxation (PTS) in PCFD. In cadaveric studies, a double axial heel views and ankle radiographs are important for arthrodesis (ST and TN fusion) was able to fully correct fully assessing PCFD, they do not influence the decision to the deformity, but no indications were made regarding res- perform a ST and NC fusion. toration of the medial arch.29 By assessing the dynamic With the introduction of WEIGHTBEARING computed plantar pressure distribution in 16 feet after ST and TN tomography (WBCT) scans, a more detailed analysis of the fusion, force transmission of the midfoot was increased, subtalar joint and hindfoot positioning during loading has whereas push-off force was decreased, as compared with become possible, and thus it has a significant role in evalu- healthy feet.33 Apparently, a fusion at the TN joint in addi- ating PCFD, especially with respect to decision making for tion to ST fusion may work if the main pathology is PTS, a ST fusion. An increased subluxation among the patients but it may have a limited effect on restoration of the medial with PCFD of 56% was reported vs 13% among the con- longitudinal arch and forefoot pronation when the defor- trols at the anterior and middle facets and 30% vs 11% at the mity is mainly caused by collapse of the medial column posterior facet.1 Currently, the middle facet is used as an structures of the midfoot associated with PTS. With stiff- isolated marker for PTS, with a mean subluxation (uncover- ening of the hindfoot, the breakdown of medial arch may age) of approximately 45% in symptomatic patients with even increase as a result of subsequent overload due to PCFD and 5% among controls.8 Measurement of the amount stress transfer to the adjacent nonfused joints. Theoretically, of linear subluxation of the subtalar joint at the posterior an extension of the ST and TN fusion to the naviculocu- facet in the coronal plane has also been proposed to indicate neiform (NC) joint may be the solution to correct the over- PTS,7,9,30 but it was found to be less reliable.9 Lateral sub- all deformity.2 However, extensive surgical exposure is luxation was reported to cause sinus tarsi and subfibular required, and debridement of navicular bone carries with it impingement.27 The consensus of our group was that PCFD fear of devascularization. Fixation is also very challenging patients with severe PTS (marked subtalar joint subluxation for this rather small joint. and subfibular impingement) should be considered for ST In PCFD, a controversial concept is the notion that its fusion. Pain secondary to degenerative disease and stiffness origin of the deformity can be distal to the hindfoot joints at the subtalar joint are also an indication for ST fusion. due to breakdown of the medial longitudinal arch.14 There is a consensus of our group that there is need for a ST Posterior tibial tendon (PTT) function may be preserved or fusion as the primary measure to address severe PTS as well not. Therefore, a careful clinical evaluation with appropri- as rigid/arthritic subtalar joints. ate history and physical exam is an important starting point. Isolated ST repositional arthrodesis for moderate to Clinically, the visible severity of flattening of the medial severe PCFD was found to produce excellent correction of longitudinal arch and the forefoot abduction in combination the hindfoot.22,25,36 It is generally accepted that, with an with hindfoot valgus are hallmarks of this disorder.10 The incompetent medial arch, an additional medial column sta- diagnosis can further be confirmed by the first-ray raise bilizing procedure will be necessary to address the com- sign when the hindfoot pronation and valgus position are plex deformity.2,3,16,35 To date, most surgeons rely on passively corrected.16 While in most instances, the medial fusion at the TN site or even include the CC joint in the longitudinal arch can easily be corrected manually if the belief that this is mandatory for correction of significant Hintermann et al 3 forefoot abduction and uncoverage of the talar head. surgical technique, union of both joints was found in 32 of However, the concept of using an NC fusion instead TN 34 cases; a nonunion occurred in only 1 case at the ST fusion was reported to be successful in correcting and sta- joint and in 1 case at the NC fusion site, but the patient bilizing the forefoot.34,35 With the hypothesis that attenua- remained asymptomatic.35 The low nonunion rate could tion of the medial supporting structures of the foot results potentially be explained by a protective effect of the ST in the progression of the PCFD, Miller28 was the first to fusion stability to the fusion site at the NC joint, possibly propose correction of the medial alignment of the foot by decreasing the mechanical overload in this joint, even with fusion of the medial column, specifically, a fusion of the early weightbearing as tolerated being allowed immedi- NC and first TMT joints. In addition to the medial column ately postoperatively. In 15 cases (44%), an additional fusion, he performed an advancement of the PTT complex medial sliding osteotomy of the calcaneus was performed as an osteoperiosteal flap. His theory that progression of to achieve the required correction of hindfoot alignment, PCFD results from extreme flexibility of the midtarsal and in 5 cases (14.7%), an FDL tendon transfer was done. joints was supported by others,5,6,11,17,20 all of whom have Radiographically, all angles of interest were found to be used an NC fusion as the key procedure. Although the corrected significantly, and there was no loss of correction above procedures were described primarily for use in the observed after 2 years. pediatric or adolescent flatfoot, similar principles can be used in PCFD. Declaration of Conflicting Interests While many studies have been published on the surgical The author(s) declared no potential conflicts of interest with management of PCFD, almost all of them appropriately respect to the research, authorship, and/or publication of this arti- report on combinations of procedures used to correct this cle. ICMJE forms for all authors are available online. complex deformity. This feature of the PCFD literature makes it difficult to separate the contributions of the various Funding components of each surgery to the final outcome. However, the literature does provide evidence that the best results are The author(s) received no financial support for the research, achieved when the deformity is fully corrected.18,19 authorship, and/or publication of this article. Although the literature is still sparse, the concept of adding an NC fusion to the ST fusion has apparently the capability ORCID iDs to correct and stabilize the complex deformity in advanced Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- stages of PCFD in both the flexible or fixed condi- 6037-0685 tion.5,11,17,20,28 Thus, there was a consensus of our group that Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 NC joint fusion should be considered in the arthritic and Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998 symptomatic joints, as well as when significant sagittal plane sagging of the NC joints is present. References Because PTS results in greater subluxation in the ante- rior than in the posterior ST joint,1 a medial approach to 1. Ananthakrisnan D, Ching R, Tencer A, Hansen ST Jr, Sangeorzan BJ. Subluxation of the talocalcaneal joint in the ST joint makes it easier and more effective for the sur- 2,13 adults who have symptomatic flatfoot. J Bone Joint Surg Am. geon to reposition the talus on the top of calcaneus. It 1999;81(8):1147-1154. also allows for the tightening of the medial capsule and 2. Barg A, Brunner S, Zwicky L, Hintermann B. Subtalar and deltoid ligament complex and to debride and/or tighten the naviculocuneiform fusion for extended breakdown of the PTT or, if incompetent, to do a flexor digitorum longus medial arch. Foot Ankle Clin. 2011;16(1):69-81. (FDL) tendon transfer. Two to 3 screws are usually neces- 3. Benink RJ. The constraint-mechanism of the human tarsus: sary to provide the stability needed at the ST fusion site a roentgenological experimental study. Acta Orthop Scand against translational and rotational forces.13 While pre- Suppl. 1985;215:1-135. serving the TN joint with its capsule, the NC joint can be 4. Berlet GC, Hyer CF, Scott RT, Galli MM. Medial double exposed by lengthening the medial incision distally. The arthrodesis with lateral column sparing and arthrodiastasis: a NC joint can be distracted over 2 K-wires, and after radiographic and medical record review. J Foot Ankle Surg. 2015;54(3):441-444. debridement to subchondral bone, the K-wires can be used 5. Butte FL. Navicular-cuneiform arthrodesis for flat-foot: an as joysticks to plantarflex the first ray and to apply com- end-result study. J Bone Joint Surg. 1937;19(2):496-502. 13 pression force at the fusion site. Beside screw fixation, a 6. Caldwell GD. Surgical correction of relaxed flatfoot by the medioplantar tension band plate can ensure optimal stabil- Durham flatfoot plasty. Clin Orthop. 1953;2:221-226. ity.2,13 Even though prior literature has reported important 7. Cody EA, Williamson ER, Burket JC, Deland JT, Ellis SJ. nonunion rates of NC joint fusions,20,28,34 using this Correlation of talar anatomy and subtalar joint alignment on 4 Foot & Ankle International 00(0)

weightbearing computed tomography with radiographic flat- 24. Kelly IP, Easley ME. Treatment of stage 3 adult acquired foot parameters. Foot Ankle Int. 2016;37(8):874-881. flatfoot. Foot Ankle Clin. 2001;6(1):153-166. 8. de Cesar Netto C, Godoy-Santos AL, Saito GH, et al. 25. Kitaoka HB, Patzer GL. Subtalar arthrodesis for posterior Subluxation of the middle facet of the subtalar joint as a tibial tendon dysfunction and pes planus. Clin Orthop Relat marker of peritalar subluxation in adult acquired flatfoot Res. 1997;345:187-194. deformity: a case-control study. J Bone Joint Surg Am. 26. Knupp M, Schuh R, Stufkens SA, Bolliger L, Hintermann B. 2019;101(20):1838-1844. Subtalar and talonavicular arthrodesis through a single medial 9. de Cesar Netto C, Schon LC, Thawait GK, et al. Flexible approach for the correction of severe planovalgus deformity. adult acquired flatfoot deformity: comparison between J Bone Joint Surg Br. 2009;91(5):612-625. weight-bearing and non-weight-bearing measurements using 27. Malicky ES, Crary JL, Houghton MJ, Agel J, Hansen ST Jr, cone-beam computed tomography. J Bone Joint Surg Am. Sangeorzan BJ. Talocalcaneal and subfibular impingement 2017;99(18):e98. in symptomatic flatfoot in adults. J Bone Joint Surg Am. 10. Deland JT. Adult-acquired flatfoot deformity. J Am Acad 2002;84(11):2005-2009. Orthop Surg. 2008;16(7):399-406. 28. Miller OL. A plastic flat foot operation. J Bone Joint Surg. 11. Duncan JW, Lovell WW. Modified Hoke-Miller flatfoot pro- 1927;9(1):84-91. cedure. Clin Orthop Relat Res. 1983(181):24-27. 29. O’Malley MJ, Deland JT, Lee KT. Selective hindfoot arthrod- 12. Francisco R, Chiodo CP, Wilson MG. Management of the esis for the treatment of adult acquired flatfoot deformity: an rigid adult acquired flatfoot deformity. Foot Ankle Clin. in vitro study. Foot Ankle Int. 1995;16(7):411-417. 2007;12(2):317-327, vii. 30. Probasco W, Haleem AM, Yu J, Sangeorzan BJ, Deland JT, 13. Gilgen A, Knupp M, Hintermann B. Subtalar and navicu- Ellis SJ. Assessment of coronal plane subtalar joint alignment locuneiform arthrodesis for the treatment of hindfoot valgus in peritalar subluxation via weight-bearing multiplanar imag- with collapse of the medial arch. Techn Foot Ankle Surg. ing. Foot Ankle Int. 2015;36(3):302-309. 2013;12(4):190-195. 31. Rohm J, Zwicky L, Horn Lang T, Salentiny Y, Hintermann 14. Greisberg J, Assal M, Hansen ST Jr, Sangeorzan BJ. Isolated B, Knupp M. Mid- to long-term outcome of 96 corrective medial column stabilization improves alignment in adult- hindfoot fusions in 84 patients with rigid flatfoot deformity. acquired flatfoot. Clin Orthop Relat Res. 2005(435):197-202. Bone Joint J. 2015;97B(5):668-674. 15. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis 32. Sangeorzan BJ, Smith D, Veith R, Hansen ST Jr. Triple WH, Manoli A II. Symposium: adult acquired flatfoot defor- arthrodesis using internal fixation in treatment of adult foot mity. Foot Ankle Int. 2011;32(1):95-111. disorders. Clin Orthop Relat Res. 1993;294:299-307. 16. Hintermann B, Gachter A. The first metatarsal rise sign: a 33. Schuh R, Salzberger F, Wanivenhaus AH, Funovics PT, simple, sensitive sign of tibialis posterior tendon dysfunction. Windhager R, Trnka HJ. Kinematic changes in patients with Foot Ankle Int. 1996;17(4):236-241. double arthrodesis of the hindfoot for realignment of pla- 17. Hoke M. An operation for the correction of extremely relaxed novalgus deformity. J Orthop Res. 2013;31(4):517-524. flat feet. J Bone Joint Surg. 1931;13(4):773-783. 34. Seymour N. The late results of naviculo-cuneiform fusion. J 18. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc- Bone Joint Surg Br. 1967;49(3):558-559. tion. Foot Ankle Clin. 2017;22(3):613-624. 35. Steiner CS, Gilgen A, Zwicky L, Schweizer C, Ruiz R, 19. Iossi M, Johnson JE, McCormick JJ, Klein SE. Short-term Hintermann B. Combined subtalar and naviculocuneiform radiographic analysis of operative correction of adult acquired fusion for treating adult acquired flatfoot deformity with flatfoot deformity. Foot Ankle Int. 2013;34(6):781-791. medial arch collapse at the level of the naviculocuneiform 20. Jack EA. Naviculo-cuneiform fusion in the treatment of flat joint. Foot Ankle Int. 2019;40(1):42-47. foot. J Bone Joint Surg Br. 1953;35(1):75-82. 36. Stephens HM, Walling AK, Solmen JD, Tankson CJ. 21. Jeng CL, Vora AM, Myerson MS. The medial approach to Subtalar repositional arthrodesis for adult acquired flatfoot. triple arthrodesis: indications and technique for management Clin Orthop Relat Res. 1999;365:69-73. of rigid valgus deformities in high-risk patients. Foot Ankle 37. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of Clin. 2005;10(3):515-521, vi-vii. the adult acquired flatfoot deformity. Curr Rev Musculoskelet 22. Johnson JE, Cohen BE, DiGiovanni BF, Lamdan R. Subtalar Med. 2013;6(4):294-303. arthrodesis with flexor digitorum longus transfer and spring 38. Wachter JD, Knupp M, Beat H. Double-hindfoot arthrodesis ligament repair for treatment of posterior tibial tendon insuf- through a single medial approach. Techn Foot Ankle Surg. ficiency. Foot Ankle Int. 2000;21(9):722-729. 2007;6(4):237-242. 23. Kadakia AR, Haddad SL. Hindfoot arthrodesis for the adult 39. Younger AS, Sawatzky B, Dryden P. Radiographic assess- acquired flat foot. Foot Ankle Clin. 2003;8(3):569-594, x. ment of adult flatfoot. Foot Ankle Int. 2005;26(10):820-825. FAIXXX10.1177/1071100720950739Foot & Ankle InternationalJohnson et al 950739research-article2020

Topical Review

Foot & Ankle International® 3–­1 Consensus on Indications for Medial © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Cuneiform Opening Wedge (Cotton) DOI:https://doi.org/10.1177/1071100720950739 10.1177/1071100720950739 Osteotomy in the Treatment of journals.sagepub.com/home/fai Progressive Collapsing Foot Deformity

Jeffrey E. Johnson, MD1 , Bruce J. Sangeorzan, MD2, Cesar de Cesar Netto, MD, PhD3 , Jonathan T. Deland, MD4, Scott J. Ellis, MD4 , Beat Hintermann, MD5, Lew C. Schon, MD6,7,8,9, David Thordarson, MD10, and Mark S. Myerson, MD11

Abstract Recommendation: Forefoot varus is a physical and radiographic examination finding associated with the Progressive Collapsing Foot Deformity (PCFD). Varus position of the forefoot relative to the hindfoot is caused by medial midfoot collapse with apex plantar angulation of the medial column. Some surgeons use the term forefoot supination to describe this same deformity (see Introduction section with nomenclature). Correction of this deformity is important to restore the weightbearing tripod of the foot and help resist a recurrence of foot collapse. When the forefoot varus deformity is isolated to the medial metatarsal and medial cuneiform, correction is indicated with an opening wedge medial cuneiform (Cotton) osteotomy, typically with interposition of an allograft bone wedge from 5 to 11 mm in width at the base. When the forefoot varus is global, involving varus angulation of the entire forefoot and midfoot relative to the hindfoot, other procedures are needed to adequately correct the deformity. Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, forefoot varus, Cotton osteotomy, cuneiform osteotomy, progressive collapsing foot deformity, PCFD

Consensus Statements Voted: Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. CONSENSUS STATEMENT ONE: A stable medial (Unanimous, strongest consensus) longitudinal column is critical for restoration of a bal- anced foot tripod. Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. 1Washington University School of Medicine, St. Louis, MO, USA (Unanimous, strongest consensus) 2University of Washington, Seattle, WA, USA CONSENSUS STATEMENT TWO: Indications for per- 3University of Iowa, Department of Orthopaedics and Rehabilitation, forming a Cotton osteotomy for residual forefoot varus Iowa City, IA, USA should be determined clinically, not radiographically, after 4Hospital for Special Surgery, New York, NY, USA 5 hindfoot deformity correction. By pushing up on the bot- Kantonspital Baselland, Liestal, Switzerland 6Mercy Medical Center, Baltimore, MD, USA tom of the forefoot, the surgeon can feel the head of the 7New York University Grossman School of Medicine, New York, first metatarsal in relation to the fifth metatarsal head. This NY, USA maneuver will indicate if correction is needed and help 8Johns Hopkins School of Medicine, Baltimore, MD, USA determine when adequate correction has been obtained. 9Georgetown School of Medicine, Washington, DC, USA 10 Delegate vote: agree, 100% (9/9); disagree, 0%; Cedars-Sinai Medical Center, Los Angeles, CA, USA 11Department of Orthopedic Surgery, University of Colorado School of abstain, 0%. Medicine, Aurora, CO, USA (Unanimous, strongest consensus) CONSENSUS STATEMENT THREE: The typical Corresponding Author: Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and wedge size needed for correction using a medial cunei- Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon form dorsal opening wedge (Cotton) osteotomy ranges Pavilion, Room 01066, Iowa City, IA 52242, USA. from 5 to 11 mm. Email: [email protected] 2 Foot & Ankle International 00(0)

CONSENSUS STATEMENT FOUR: Presence of joint-preserving osteotomies, especially lateral column some clinical instability of the first ray does not preclude lengthening (LCL) procedures, and noted that residual fore- the use of a Cotton osteotomy. foot varus was limiting the complete correction of many Delegate vote: agree, 89% (8/9); disagree, 0%; abstain, feet with PCFD.5 Currently, osteotomy of the medial cunei- 11% (1/9). form is a commonly used technique to correct forefoot CONSENSUS STATEMENT FIVE: The presence of varus, with the concept that restoring the weightbearing tri- gross clinical instability of the first ray and/or radio- pod of the foot will help resist recurrent foot collapse. graphic plantar gapping of the first tarsometatarsal joint Benthien et al, in a cadaveric biomechanical study, demon- are indications for first tarsometatarsal joint fusion. strated that LCL increased lateral forefoot pressures in a Delegate vote: agree, 100% (9/9); disagree, 0%; severe PCFD model.2 The authors demonstrated that an abstain, 0%. added Cotton osteotomy provided increased deformity cor- rection and decreased pressure under the lateral forefoot, Rationale thereby suggesting that the Cotton osteotomy could help restore a more normal loading pattern of the foot. Forefoot varus is a component of the multiplanar Progressive Collapsing Foot Deformity (PCFD), as well as in some Alternative Technique cases of developmental pes planovalgus and osteoarthritis of the medial column of the foot. This deformity is not cor- A closing wedge osteotomy for correction of forefoot varus rected by hindfoot procedures such as a lateral column performed from a plantar approach to the medial cuneiform lengthening, medial displacement calcaneal osteotomy, or has been described and has the advantage of direct bone heal- repositional subtalar arthrodesis. ing without a need for graft, no implant interposition, ability Forefoot varus is characterized by a spectrum of physical to perform the procedure through a single plantar incision examination findings from elevation of the first ray (only in used for the medial soft tissue repair, and the ability to slightly the sagittal plane) or rotation of the entire forefoot around the adduct the foot through the osteotomy.10 However, the central longitudinal axis of the foot toward the midline in the amount of correction is more difficult to titrate for a given coronal plane with deformity at the talonavicular joint, mid- deformity, and closing a significant wedge resection to tarsal joints, or tarsometatarsal joints. The deformity may be achieve apposition of the cuneiform can be challenging. fixed or flexible and the diagnosis is made by physical exami- Multiple fixation techniques for Cotton osteotomies have nation in the nonweightbearing position, with the hindfoot been described, using specialized wedge plates, screws,5,11 corrected to a neutral hindfoot alignment reference position. Kirschner wires,11 and no fixation.3,11,15 Alternatives to This examination will indicate the location, magnitude, and allograft or autografting methods include use of trabecular flexibility of the deformity as well as indicate when the defor- metal wedges,13,14 or metal wedges attached to thin dorsal mity has been adequately corrected intraoperatively. First-ray plates. A dorsal wedge plate has been found to be as effective elevation is typically related to dorsal instability of the first as a bone graft wedge in a cadaver model.9 Potential advan- tarsometatarsal (TMT) or first-second intercuneiform joint tages include no donor site morbidity seen with autograft, no with dorsal angulation at the naviculocuneiform joint. potential risk of disease transmission with allograft and eas- A lateral weightbearing radiograph will help determine the ier availability for outpatient surgical centers. In a series of presence of dorsal instability, plantar first TMT joint gapping, patients that received trabecular metal wedges, 2 nonunions osteoarthritis, as well as location of the apex of the deformity were identified, but only 1 was found to be symptomatic at along the medial column as being at the talonavicular, navicu- 35.4 months postoperation.14 locuneiform, or TMT joints.6,12 Reconstruction of the PCFD The disadvantage of plates and screws is that they may cre- begins in the proximal aspect of the foot and ankle and pro- ate a painful prominence on the dorsum of the foot requiring ceeds distally because each level of correction is determined an additional surgical procedure for hardware removal,5,11,15 by aligning it to the next most proximal segment. Therefore, and metal wedges may confound any future revision surgery. forefoot varus is often the last portion of the deformity to be The metallic wedges need to be removed with a saw if revi- corrected during the bony realignment portion of the proce- sion of the osteotomy is needed and they are difficult to drill dure. Occasionally, once the hindfoot deformity correction has across or place a screw through them if an extended medial been performed, the apparent forefoot varus that was present column fusion is required later. Long-term studies evaluating preoperatively has been improved sufficiently that osteotomy the durability of these nonbiologic implants are lacking. of the medial cuneiform is not required. Extraosseous and intraosseous blood supply to the medial Correction of this deformity with an opening wedge, cuneiform is robust and does not exhibit consistent watershed plantarflexion, medial cuneiform osteotomy was described areas of hypovascularity.7 Predictable osteotomy healing by Cotton in 1936 to restore the “static triangle of support.”4 rates using allograft wedges, of up to a 100%, has been However, the Cotton osteotomy did not gain widespread reported by many authors, and they do not seem to be related use until decades later, when surgeons began using to type of fixation or whether any fixation is utilized.1,3,5,11,15 Johnson et al 3

Quantifying the contribution of the Cotton osteotomy to References the overall radiographic changes from preoperative to post- 1. Aiyer A, Dall GF, Shub J, Myerson MS. Radiographic cor- operative is difficult given that multiple procedures are usu- rection following reconstruction of adult acquired flat foot ally preformed at the time of surgery. Numerous radiographic deformity using the cotton medial cuneiform osteotomy. Foot measurements have been used to describe the correction Ankle Int. 2016;37(5):508-513. that is observed following Cotton osteotomy including the 2. Benthien RA, Parks BG, Guyton GP, Schon LC. Lateral lateral talus-first metatarsal angle, lateral medial cuneiform column calcaneal lengthening, flexor digitorum longus metatarsal angle, calcaneal pitch, medial cuneiform dis- transfer, and opening wedge medial cuneiform osteotomy tance,5 medial arch sag angle (MASA),1 and cuneiform for flexible flatfoot: a biomechanical study. Foot Ankle Int. articular angle (CAA).3 Using a multivariate linear regres- 2007;28(1):70-77. sion model, Kunas et al demonstrated that the Cotton oste- 3. Castaneda D, Thordarson DB, Charlton TP. Radiographic otomy graft size was significantly associated with changes assessment of medial cuneiform opening wedge osteotomy in the CAA, calcaneal pitch, lateral talonavicular Cobb for flatfoot correction. Foot Ankle Int. 2012;33(6):498-500. 4. Cotton FJ. Foot statics and surgery. N Engl J Med. angle, and lateral naviculomedial cuneiform angle.8 1936;214(8):353-362. However, the authors emphasized that the Cotton graft size 5. Hirose CB, Johnson JE. Plantarflexion opening wedge was the only factor found to significantly predict a change medial cuneiform osteotomy for correction of fixed fore- in the CAA. Therefore, preoperative measurement of the foot varus associated with flatfoot deformity. Foot Ankle Int. cuneiform articular angle (CAA) can help predict the graft 2004;25(8):568-574. size intraoperatively. Each millimeter of the width of the 6. Johnson JE, Yu JR. Arthrodesis techniques in the manage- base of the wedge-shaped graft corresponds to an approxi- ment of stage II and III acquired adult flatfoot deformity. Instr mately 2.1-degree decrease of the CAA.8 However, intraop- Course Lect. 2006;55:531-542. erative clinical examination is best used to confirm the 7. Kraus JC, McKeon KE, Johnson JE, McCormick JJ, Klein proper graft size that provides satisfactory correction of the SE. Intraosseous and extraosseous blood supply to the medial deformity. Typically, a graft size of 5-11 mm width at the cuneiform: implications for dorsal opening wedge plan- tarflexion osteotomy. Foot Ankle Int. 2014;35(4):394-400. base of the wedge is needed to correct most deformities. 8. Kunas GC, Do HT, Aiyer A, Deland JT, Ellis SJ. Contribution The indication for performing a Cotton osteotomy should of medial cuneiform osteotomy to correction of longitudinal be determined clinically, not radiographically, and is depen- arch collapse in stage IIb adult-acquired flatfoot deformity. dent on the presence of residual forefoot varus after hind- Foot Ankle Int. 2018;39(8):885-893. foot deformity correction.6,12 By pushing up on the bottom 9. League AC, Parks BG, Schon LC. Radiographic and of the forefoot, the surgeon can feel the balance of the first pedobarographic comparison of femoral head allograft ray in relation to the lateral rays by placing one thumb of versus block plate with dorsal opening wedge medial cunei- each hand on the first and fifth metatarsal heads, respec- form osteotomy: a biomechanical study. Foot Ankle Int. tively. This maneuver will indicate which metatarsals are 2008;29(9):922-926. elevated relative to the fifth metatarsal and help determine 10. Ling JS, Ross KA, Hannon CP, et al. A plantar closing whether a Cotton osteotomy, alone, is indicated or whether wedge osteotomy of the medial cuneiform for residual fore- foot supination in flatfoot reconstruction. Foot Ankle Int. a more global correction of the midfoot is needed. 2013;34(9):1221-1226. 11. Lutz M, Myerson M. Radiographic analysis of an opening Declaration of Conflicting Interests wedge osteotomy of the medial cuneiform. Foot Ankle Int. The author(s) declared no potential conflicts of interest with 2011;32(3):278-287. respect to the research, authorship, and/or publication of this arti- 12. McCormick JJ, Johnson JE. Medial column procedures in cle. ICMJE forms for all authors are available online. the correction of adult acquired flatfoot deformity. Foot Ankle Clin. 2012;17(2):283-298. 13. Romeo G, Bianchi A, Cerbone V, Parrini MM, Malerba F, Funding Martinelli N. Medial cuneiform opening wedge osteotomy for The author(s) received no financial support for the research, correction of flexible flatfoot deformity: trabecular titanium vs. authorship, and/or publication of this article. bone allograft wedges. Biomed Res Int. 2019;2019:1472471. 14. Tsai J, McDonald E, Sutton R, Raikin SM. Severe flexible ORCID iDs pes planovalgus deformity correction using trabecular metal- lic wedges. Foot Ankle Int. 2019;40(4):402-407. Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998 15. Wang CS, Tzeng YH, Lin CC, Chang MC, Chiang CC. Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- Comparison of screw fixation versus non-fixation in dorsal 6037-0685 opening wedge medial cuneiform osteotomy of adult acquired Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 flatfoot. Foot Ankle Surg. 2020;26(2):193-197. FAIXXX10.1177/1071100720950741Foot & Ankle InternationalEllis et al 950741research-article2020

Topical Review

Foot & Ankle International® 4–­1 Titrating the Amount of Bony Correction © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions in Progressive Collapsing Foot Deformity DOI:https://doi.org/10.1177/1071100720950741 10.1177/1071100720950741 journals.sagepub.com/home/fai

Scott J. Ellis, MD1 , Jeffrey E. Johnson, MD2 , Jonathan Day, MS1 , Cesar de Cesar Netto, MD, PhD3 , Jonathan T. Deland, MD1, Beat Hintermann, MD4, Mark S. Myerson, MD5, Lew C. Schon, MD6,7,8,9, David Thordarson, MD10, Bruce J. Sangeorzan, MD11

Abstract Recommendation: There is evidence indicating that the amount of bony correction performed in the setting of progressive collapsing foot deformity reconstructive surgery can be titrated within a recommended range for a variety of procedures. The typical range when performing a medial displacement calcaneal osteotomy should be 7 to 15 mm of medialization of the tuberosity. The typical range when performing an Evans lateral column lengthening should be 5 to 10 mm of a laterally based wedge in the anterior calcaneus. The typical range when performing a plantarflexion opening wedge osteotomy of the medial cuneiform (Cotton) osteotomy should be 5 to 10 mm of a dorsal wedge. Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, adult acquired flatfoot deformity, AAFD, reconstruction, osteotomy, titration, progressive collapsing foot deformity, PCFD

Consensus Statements Voted: CONSENSUS STATEMENT FOUR: The typical range when performing a lateral column lengthening is 5 CONSENSUS STATEMENT ONE: We recommend to 10 mm of correction. performing a medializing calcaneal displacement osteot- Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. omy (MDCO) as isolated bony procedure when there is (Unanimous, strongest consensus) an isolated hindfoot valgus, with adequate talonavicular CONSENSUS STATETMENT FIVE: Indications for joint coverage (less than 35%-40% uncoverage), and lack performing a cotton osteotomy should be determined of significant forefoot supination, varus, or abduction. clinically, not radiographically, related to residual fore- Delegate vote: agree, 100% (9/9); disagree, 0%; foot supination after hindfoot deformity correction. Feel abstain, 0%. the balance of first ray in relation to the lateral ones, pal- (Unanimous, strongest consensus) pating the plantar aspect of the metatarsal heads. CONSENSUS STATEMENT TWO: The typical range when performing a MDCO, while considering the loca- 1Hospital for Special Surgery, New York, NY, USA tion and rotation of the osteotomy, is 7 to 15 mm of 2Washington University School of Medicine, St. Louis, MO, USA correction. 3Department of Orthopaedics and Rehabilitation, University of Iowa, Delegate vote: agree, 100% (9/9); disagree, 0%; Iowa City, IA, USA abstain, 0%. 4Kantonspital Baselland, Liestal, Switzerland 5 (Unanimous, strongest consensus) Department of Orthopedic Surgery, University of Colorado School of Medicine, Aurora, CO, USA CONSENSUS STATEMENT THREE: Lateral col- 6Mercy Medical Center, Baltimore, MD, USA umn lengthening (LCL) procedure is recommended 7New York University Grossman School of Medicine, New York, NY, USA when the amount of talonavicular joint uncoverage is 8Johns Hopkins School of Medicine, Baltimore, MD, USA above 40%. The amount of coverage needed should be 9Georgetown School of Medicine, Washington, DC, USA 10 judged intraoperatively by the amount of correction of Cedars-Sinai Medical Center, Los Angeles, CA, USA 11University of Washington, Seattle, WA, USA the uncoverage and by adequate residual passive ever- sion range of motion of the subtalar joint. Corresponding Author: Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon abstain, 11% (1/9). Pavilion, Room 01066, Iowa City, IA 52242, USA. (Strong consensus) Email: [email protected] 2 Foot & Ankle International 00(0)

Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 0%. of correction of approximately 10 mm,1,11,12,20,21 the use of (Unanimous, strongest consensus) a recommended range is more appropriate given the vary- CONSENSUS STATETMENT SIX: We report a typi- ing degrees of preoperative hindfoot valgus alignment is cal range of 5 to 11 mm opening dorsal wedges of the more appropriate. Given the results of these studies and the medial cuneiform (Cotton) to be used for correction. end goal of achieving a clinically straight heel, the expert Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, consensus is that the typical range of MDCO performed is 0%. 7 to 15 mm of correction. (Unanimous, strongest consensus) LCL with either an Evans-type,16 Central CONSENSUS STATETMENT SEVEN: Presence of (Hintermann),13 or Van der Griend (step-cut)26 osteotomy some clinical instability of the first ray does not preclude is commonly used to correct forefoot and midfoot abduc- the use of Cotton osteotomies. tion at the talonavicular (TN) joint, which can be evalu- Delegate vote: agree, 89% (8/9); disagree, 0%; abstain, ated using the lateral incongruency angle, TN coverage 11% (1/9). angle, and talo–first metatarsal angle on anteroposterior (Strong consensus) radiograph.12,24,27 Because LCL is a powerful procedure in correcting abduction and there is a risk for overcorrection, Rationale studies have cited a TN uncoverage of greater than 40% as an indication for LCL.9,24 Previous work has also derived The purpose of bony procedures such as the medial dis- a linear equation relating the change in lateral incongru- placement calcaneal osteotomy (MDCO), lateral column ency angle (LIA) with the amount of LCL correction,3 lengthening (LCL), and Cotton osteotomy is to correct which allows for preoperative planning and titration of symptomatic progressive collapsing foot deformity (PCFD) operative correction.6 Proper titration and correction are by restoring normal alignment and the medial longitudinal integral to the success of the procedure as multiple studies arch. To date, there has been no general consensus regard- have shown that overcorrection (adduction of the TN ing a recommended range of correction for such bony pro- joint) is associated with inferior patient-reported outcomes cedures, nor has there been a general consensus on methods in addition to lateral column overload, increased risk for to titrate them. Such guidelines are essential to help achieve stress fractures of the fifth metatarsal, increased lateral optimal operative correction and theoretically maximize plantar pressure, and pain.5,10,22 One such study demon- patient-reported outcomes. strated that overcorrection to an LIA of less than 5 degrees MDCO is commonly performed to correct the valgus (adduction) was associated with significantly lower hindfoot, with studies highlighting its efficacy as the most improvement in patient-reported outcomes compared to significant contributor to hindfoot alignment correction.4 patients with residual midfoot abduction at mean 1.9 years Using the validated hindfoot moment arm (HMA) mea- following PCFD reconstruction with LCL.5 Another study surement on the hindfoot alignment view,23 Chan et al demonstrated that 2-mm increments of LCL correction derived a linear equation relating the change in preopera- from 6 to 10 mm resulted in significant improvement of tive and postoperative HMA with the amount of MDCO TN abduction as well as increased lateral plantar pres- correction, demonstrating that a medial translation of 1 mm sures, emphasizing that further overcorrection can result corresponds to approximately 1.5 mm change in radio- in substantially increased overload to the lateral column.22 graphic HMA.4 This aids in preoperative titration of the In order to mitigate the risk for overcorrection, emphasis amount of MDCO needed in order to correct the hindfoot should be made to not overload the lateral column by valgus deformity and achieve a clinically straight heel (ie, maintaining passive eversion potential and passive range physiologically valgus hindfoot). A study by Conti et al of motion.10 On the other hand, undercorrection of the lat- compared postoperative outcomes in 3 groups of patients eral column in the setting of abduction can increase the based on postoperative HMA: those with residual valgus risk for failure of reconstruction due to excess stress on alignment, mild varus overcorrection of 0 to 5 mm, and medial soft tissues.15 Therefore, it is crucial that surgeons moderate varus overcorrection of greater than 5 mm.7 The carefully titrate the amount of LCL correction. In a study authors not only determined that mild radiographic over- investigating the use of trial wedges in LCL, investigators correction of 0 to 5 mm resulted in a clinically straight found that the average wedge size for adequate correction heel, but also that this range of correction was associated was 6.8 mm (range, 4-10). Given the overall results of with superior patient-reported outcomes.7 In both afore- these studies, the expert consensus is that the typical range mentioned studies, the amount of MDCO performed varied of LCL performed is 5 to 10 mm of correction. between patients based on severity of the deformity, with A Cotton osteotomy is performed to correct residual Chan et al noting that the mean amount of MDCO correc- forefoot supination along the medial longitudinal arch tion was 10.4 mm (SD 1.9).4 Although previous studies in after correction of the hindfoot valgus deformity.9,27 the literature have attempted to provide specific amounts Traditionally, graft size is determined intraoperatively Ellis et al 3 based on a combination of clinical judgement, trial grafts, ORCID iDs 19 and fluoroscopic assessment, with an average graft size Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 reported in the literature ranging from 4 to 8 mm.14,28 Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055- Because undercorrection can increase risk for deformity 9998 recurrence and increased valgus thrust to the ankle and hindfoot, and overcorrection can cause excess loading of Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042 the medial column, with overpressure of the first metatar- Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- sal head and sesamoids,8,18 methods to titrate the amount 6037-0685 of correction have been studied. Previous work by Castaneda et al has defined a cuneiform articular angle as References a reliable measurement of the effects of the Cotton oste- 1. Arangio GA, Salathe EP. A biomechanical analysis of posterior otomy at the medial cuneiform.2 A study performed by tibial tendon dysfunction, medial displacement calcaneal oste- Kunas et al17 identified a linear correlation between graft otomy and flexor digitorum longus transfer in adult acquired size and degree of plantarflexion, in which an increase in flat foot. Clin Biomech (Bristol, Avon). 2009;24(4):385-390. graft size of 1 mm equates to 2 degrees’ increase in plan- 2. Castaneda D, Thordarson DB, Charlton TP. Radiographic assessment of medial cuneiform opening wedge osteotomy tarflexion of the cuneiform articular angle. The authors for flatfoot correction. Foot Ankle Int. 2012;33(6):498-500. also noted that the average amount of Cotton osteotomy 3. Chan JY, Greenfield ST, Soukup DS, Do HT, Deland JT, performed in their cohort of 79 feet was 5.6 mm (SD Ellis SJ. Contribution of lateral column lengthening to correc- 17 0.9). A subsequent study highlighted the importance of tion of forefoot abduction in stage IIb adult acquired flatfoot titration of the Cotton osteotomy, as excess plantarflexion deformity reconstruction. Foot Ankle Int. 2015;36(12):1400- defined as a cuneiform articular angle of less than negative 1411. 2 degrees has been associated with inferior patient- 4. Chan JY, Williams BR, Nair P, Young E, Sofka C, Deland JT, reported outcomes.8 Although the authors of this study Ellis SJ. The contribution of medializing calcaneal osteotomy noted an average graft size of 5.5 mm (range 4-10, SD 0.9) on hindfoot alignment in the reconstruction of the stage II in their cohort of 63 feet, they also concluded that graft adult acquired flatfoot deformity. Foot Ankle Int. 2013;34(2): size alone did not correlate with changes in patient- 159-166. 5. Conti MS, Chan JY, Do HT, Ellis SJ, Deland JT. Correlation reported outcomes, but rather the final postoperative posi- 8 of postoperative midfoot position with outcome following tion of the medial cuneiform. reconstruction of the stage II adult acquired flatfoot defor- Although some studies have shown that instability of the mity. Foot Ankle Int. 2015;36(3):239-247. first ray at the tarsometatarsal joint should be indicated for 6. Conti MS, Deland JT, Ellis SJ. Stage IIB flatfoot reconstruction arthrodesis, there is no definitive contraindication for per- using literature-based equations for heel slide and lateral column forming a Cotton osteotomy.25 Cotton osteotomy is a tech- lengthening. Tech Foot Ankle Surg. 2017;16(4):153-166. nically easy operative option that has the advantage of 7. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal preserving motion at the medial column.19 The combined position of the heel following reconstruction of the stage expert experience of the authors suggest that clinical insta- II adult-acquired flatfoot deformity. Foot Ankle Int. bility of the first ray is not a clear contraindication and that 2015;36(8):919-927. careful patient selection should be made when considering 8. Conti MS, Garfinkel JH, Kunas GC, Deland JT, Ellis SJ. Postoperative medial cuneiform position correlation with a Cotton osteotomy in the setting of medial ray instability. patient-reported outcomes following cotton osteotomy for Given the averages reported and the titration methods for reconstruction of the stage II adult-acquired flatfoot defor- correcting forefoot supination, the expert consensus for the mity. Foot Ankle Int. 2019;40(5):491-498. typical range of Cotton osteotomy performed is 5 to 11 mm 9. Deland JT. Adult-acquired flatfoot deformity. J Am Acad of correction. The experts also agreed that mild/moderate Orthop Surg. 2008;16(7):399-406. clinical instability of the first ray would not preclude the use 10. Ellis SJ, Yu JC, Johnson AH, Elliott A, O’Malley M, Deland of a Cotton osteotomy. J. Plantar pressures in patients with and without lateral foot pain after lateral column lengthening. J Bone Joint Surg Am. Declaration of Conflicting Interests 2010;92(1):81-91. 11. Guha AR, Perera AM. Calcaneal osteotomy in the treat- The author(s) declared no potential conflicts of interest with ment of adult acquired flatfoot deformity. Foot Ankle Clin. respect to the research, authorship, and/or publication of this arti- 2012;17(2):247-258. cle. ICMJE forms for all authors are available online. 12. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis WH, Manoli A. Adult acquired flatfoot deformity. Foot Funding Ankle Int. 2011;32(1):95-101. The author(s) received no financial support for the research, 13. Hintermann B, Valderrabano V, Kundert HP. Lateral column authorship, and/or publication of this article. lengthening by calcaneal osteotomy combined with soft tissue 4 Foot & Ankle International 00(0)

reconstruction for treatment of severe posterior tibial tendon 21. Myerson MS, Badekas A, Schon LC. Treatment of stage II dysfunction. Technique and preliminary results. Orthopade. posterior tibial tendon deficiency with flexor digitorum lon- 1999;28(9):760-769. gus tendon transfer and calcaneal osteotomy. Foot Ankle Int. 14. Hirose CB, Johnson JE. Plantarflexion opening wedge 2004;25(7):445-450. medial cuneiform osteotomy for correction of fixed fore- 22. Oh I, Imhauser C, Choi D, Williams B, Ellis S, Deland J. foot varus associated with flatfoot deformity. Foot Ankle Int. Sensitivity of plantar pressure and talonavicular alignment to 2004;25(8):568-574. lateral column lengthening in flatfoot reconstruction. J Bone 15. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc- Joint Surg Am. 2013;95:1094-1100. tion. Foot Ankle Clin. 2017;22(3):613-624. 23. Saltzman CL, El-Khoury GY. The hindfoot alignment view. 16. Kitaoka HB, Kura H, Luo ZP. Calcaneocuboid distraction Foot Ankle Int. 1995;16(9):572-576. arthrodesis for posterior tibial tendon dysfunction and flatfoot: 24. Saunders SM, Ellis SJ, Demetracopoulos CA, Marinescu A, a cadaveric study. Clin Orthop Relat Res. 2000;381:241-247. Burkett J, Deland JT. Comparative outcomes between step- 17. Kunas GC, Do HT, Aiyer A, Deland JT, Ellis SJ. Contribution cut lengthening calcaneal osteotomy vs traditional Evans of medial cuneiform osteotomy to correction of longitudinal osteotomy for stage IIB adult-acquired flatfoot deformity. arch collapse in stage IIb adult-acquired flatfoot deformity. Foot Ankle Int. 2018;39(1):18-27. Foot Ankle Int. 2018;39(8):885-893. 25. Tankson CJ. The Cotton osteotomy: indications and tech- 18. Lutz M, Myerson M. Radiographic analysis of an opening niques. Foot Ankle Clin. 2007;12(2):309-315. wedge osteotomy of the medial cuneiform. Foot Ankle Int. 26. Vander Griend R. Lateral column lengthening using a 2011;32(3):278-287. “Z” osteotomy of the calcaneus. Tech Foot Ankle Surg. 19. McCormick JJ, Johnson JE. Medial column procedures in 2008;7(4):257-263. the correction of adult acquired flatfoot deformity. Foot Ankle 27. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of Clin. 2012;17(2):283-298. the adult acquired flatfoot deformity. Curr Rev Musculoskelet 20. Mosier-Laclair S, Pomeroy G, Manoli A. Operative treat- Med. 2013;6:294-303. ment of the difficult stage 2 adult acquired flatfoot deformity. 28. Yarmel D, Mote G, Treaster A. The Cotton osteotomy: a Foot Ankle Clin. 2001;6(1):95-119. technical guide. J Foot Ankle Surg. 2009;48(4):506-512. FAIXXX10.1177/1071100720950742Foot & Ankle InternationalDeland et al 950742research-article2020

Topical Review

Foot & Ankle International® 5–­1 Indications for Deltoid and Spring © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Ligament Reconstruction in Progressive DOI:https://doi.org/10.1177/1071100720950742 10.1177/1071100720950742 Collapsing Foot Deformity journals.sagepub.com/home/fai

Jonathan T. Deland, MD1, Scott J. Ellis, MD1 , Jonathan Day, MS1 , Cesar de Cesar Netto, MD, PhD2 , Beat Hintermann, MD3, Mark S. Myerson, MD4, Bruce J. Sangeorzan, MD5, Lew C. Schon, MD6,7,8,9, David Thordarson, MD10, and Jeffrey E. Johnson, MD11

Abstract Recommendation: There is evidence supporting medial soft tissue reconstruction, such as spring and deltoid ligament reconstructions, in the treatment of severe progressive collapsing foot deformity (PCFD). We recommend spring ligament reconstruction to be considered in addition to lateral column lengthening or subtalar fusion at the initial operation when those procedures have given at least 50% correction but inadequate correction of the severe flexible subluxation of the talonavicular and subtalar joints. We also recommend combined flatfoot reconstruction and deltoid reconstruction be considered as a joint sparing alternative in the presence of PCFD with valgus deformity of the ankle joint if there is 50% or more of the lateral joint space remaining. Level of Evidence: Level V, expert opinion.

Keywords: flatfoot, adult-acquired flatfoot deformity, AAFD, spring ligament, progressive collapsing foot disorder, PCFD

Consensus Statements Voted Rationale CONSENSUS STATEMENT ONE: Even though Progressive collapsing flatfoot deformity (PCFD) is a com- there is still a great deal of uncertainty in soft tissue plex disorder that is secondary to degeneration of the medi- reconstruction for severe progressive collapsing foot ally positioned soft tissue structures that include multiple deformity, if lateral column lengthening does not fully ligaments of the foot and ankle, as well as the posterior correct the abduction deformity, we recommend consid- tibial tendon (PTT). This soft tissue failure leads to valgus ering medial soft tissue procedures (Spring ligament/ and abduction deformity of the hindfoot and midfoot Superficial and Deep Deltoid repair/reconstruction) or a resulting in progressive collapse of the medial longitudinal talonavicular fusion. arch, and less commonly, valgus talar tilt at the ankle.6,9,10,11,15 Delegate vote: agree, 100% (9/9); disagree, 0% (0/9); abstain, 0% (0/9). 1Hospital for Special Surgery, New York, NY, USA (Unanimous, strongest consensus) 2Department of Orthopaedics and Rehabilitation, University of Iowa, CONSENSUS STATEMENT TWO: Even though the Iowa City, IA, USA 3Kantonspital Baselland results and efficacy of medial soft tissue reconstruction 4Department of Orthopedic Surgery, University of Colorado School of procedures (Spring ligament/Deep and Superficial Medicine, Aurora, CO, USA Deltoid) are currently unknown (anecdotal), they 5University of Washington, Seattle, WA, USA 6 should be considered as a joint-sparing alternative in Mercy Medical Center, Baltimore, MD, USA 7New York University Grossman School of Medicine, New York, NY, USA the presence of valgus deformity of the ankle joint if 8Johns Hopkins School of Medicine, Baltimore, MD, USA there is less than 50% cartilage loss on the joint’s lat- 9Georgetown School of Medicine, Washington, DC, USA 10Cedars-Sinai Medical Center, Los Angeles, CA, USA eral side. Deformities with more than 50% of lateral 11 cartilage loss should be considered for ankle fusion/ Washington University School of Medicine, St. Louis, MO, USA replacement. Corresponding Author: Delegate vote: agree, 89% (8/9); disagree, 0% (0/9); Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon abstain, 11% (1/9). Pavilion, Room 01066, Iowa City, IA 52242, USA. (Strong consensus) Email: [email protected] 2 Foot & Ankle International 00(0)

The ligament pathology is as prevalent or even more impor- and radiographic correction.6,8,16,20,30,32 One such study by tant than the posterior tibial tendinopathy.12 The ligament Williams et al32 demonstrated such results at a mean of failure indeed creates the biggest problem, the progressive 8.9 years’ follow-up. These patients underwent spring collapse of the foot and possible involvement of the ankle. ligament reconstruction with peroneus longus autograft In the severe deformities of this condition, joint-sparing tendon transfer and maintained long-term improvement corrective procedures may be inadequate and necessitate in multiple patient-reported outcomes measures fusion of critical joints to allow adequate deformity correc- (American Orthopaedic Foot & Ankle Society hindfoot tion and to provide proper stability. Ligament reconstruc- score, Foot and Ankle Outcome Score, 36-Item Short tion procedures, rather than repair and tightening of Form Health Survey) as well as radiographic correction degenerated weak ligaments, may allow for preservation of and eversion strength.32 In this study, none of the patients critical joints when there is adequate remaining motion in went on to need additional joint fusions. those joints. The bony procedures at the time of the opera- In a more recent study of 14 feet by Brodell et al,5 tion must give 50% or more correction of these joints. In spring ligament reconstruction was indicated in the cor- order to consider ligament reconstruction, preoperative rection of flexible PCFD after lateral column lengthening, stress radiographs must demonstrate full correction of the medial displacement calcaneal osteotomy, and first ray deformity at that joint. There is some evidence that recon- procedures resulted in inadequate intraoperative correc- struction of the ligaments of these joints in addition to bony tion of the TN joint. Using similar intraoperative operative realignment procedures can give adequate correction of algorithm utilized by Williams et al,32 the surgeon was alignment and good functional outcomes in the severe flex- prepared for in the setting of a severe flexible deformity to ible deformities.8,13,14,32 This allows for the avoidance of proceed in properly selected patients with spring ligament fusions of critical joints in properly selected patients. reconstruction. Such patients were identified intraopera- tively when the bony procedures can correct up to 50% the Spring Ligament bony realignment of the TN joint, but inadequate correc- tion would still remain. Patients achieved good correction Anatomically, the spring ligament spans from the susten- in anteroposterior talonavicular and sagittal alignment taculum tali of the calcaneus to the navicular bone and is measurements as well as good functional outcomes.5,32 composed mainly of the superomedial and inferior calca- The technique of the spring ligament reconstruction was neonavicular ligaments.2 Functionally, the spring ligament somewhat different and used allograft tendon rather than acts as a main stabilizer of the medial arch and the primary autograft. All but one patient were satisfied. That patient static support of the talonavicular (TN) joint.3,7,9,10,15,30 developed a medial navicular stress fracture with loss of Biomechanical studies have demonstrated that releasing correction, indicating the need in the technique to preserve the spring ligament and cyclically loading the foot creates adequate bone stock of the medial wall of the navicular, to PCFD.9 The integral role played by the spring ligament is avoid stress reaction/fractures and loss of correction. evident as it is the most commonly and severely affected Patients can have more TN deformity in the anteroposte- ligament in PCFD, with almost all patients having some rior plane than sagittal plane of the foot, or vice versa. This degree of spring ligament degeneration.12 Biomechanically, stems most likely from involvement of one part of the spring this degeneration leads to combined plantar sag, abduction, ligament more than the other. In the opinion of the senior and valgus through the TN and subtalar (ST) joints, with author of this consensus article, the TN joint must be cor- flattening of the medial longitudinal arch as the foot dis- rected by 50% in all planes for a spring ligament reconstruc- places from underneath the talus (peritalar subluxation).31 tion to be successful. In the most common method of the Studies have demonstrated various techniques in senior author’s version of spring ligament reconstruction, the addressing dysfunction of the spring ligament.1 Direct tendon graft goes from the plantar navicular to the medial repair has been tried but with poor deformity correction malleolus of the tibia. Adequate correction should be con- clinically and radiographically.2,15,26 Spring ligament firmed intraoperatively. If plantar TN sag is the worst defor- reconstruction allows for the use of strong nondegener- mity, reconstruction may need to be done primarily from the ated tendon graft. Tendon autograft or allograft has supe- plantar navicular to the calcaneus with a smaller graft to the rior biomechanical properties compared with simple tibia. For a severe plantar sag deformity noted preoperatively, repair and can better withstand stress forces across the TN ST fusion may be chosen, and spring ligament reconstruction joint and therefore can maintain correction with the help can be added with either of the 2 techniques, aiming to obtain of bony procedures.9 Reconstruction has been tried using good alignment of the TN joint in all planes. Subluxation of the superficial deltoid ligament,10 peroneus longus,6,30,32 the ST joint in the coronal plane, usually associated with sub- flexor hallucis longus autografts,22 and Achilles tendon fibular impingement of the calcaneus against the fibula, may allograft.13 Overall, previous studies have demonstrated be secondary to insufficiency of the talocalcaneal interosseus efficacious results, including both good clinical outcomes ligament. This should be checked for on preoperative Deland et al 3

WEIGHTBEARING imaging, intraoperative inspection at the superficial and deep.4 Because it provides rotatory and valgus level of the distal tip of the fibula, and checking for an intact stability of the ankle,18,28 failure of both components of the interosseus ligament. Often the ligament cannot be fully seen deltoid ligament results in medial ankle instability and intra- intraoperatively. However, it can be palpated with an elevator articular ankle valgus tilt as seen in late-stage PCFD. and good tension confirmed. Also, the ligament can be evalu- According to the new classification system by Myerson in the ated preoperatively with a magnetic resonance imaging scan. present consensus group, the valgus ankle tilt patients can be Certainly, clear subfibular impingent is not likely to be IE, ankle instability (flexible deformity), or rigid ankle val- reduced by spring ligament reconstruction. With the use of gus, IIE. The ankle valgus tilt can be identified on a WEIGHTBEARING computed tomographic (CT) scans for WEIGHTBEARING anteroposterior conventional radio- preoperative evaluation, such impingement or severe anterior graphs of the ankle.25,31 The IE patients correspond to the subluxation of the talus on the calcaneus can be easily Bluman et al IVA, supple tibiotalar valgus, category. The assessed and if present a subtalar fusion would be the most treatment of PCFD IE patients is widely recognized as chal- reliable option. At this time, it is not known if mild cases of lenging. However, there is evidence in the literature to sup- subfibular impingement or cases of severe sinus tarsi port that improvement of the talar tilt and good function can impingement with the tip of the lateral process of the talus be gained from combined deltoid ligament reconstruction and migrating up the anterior process of the calcaneus, can be correction of the foot deformity. Unfortunately, there are only treated with spring ligament reconstruction. This will require a few articles with talar tilt measurements pre- and postopera- studies with pre- and postoperative WEIGHTBEARING tively. The number of patients in each study is small.11,14,19 CTs. It is not expected that a spring ligament reconstruction The challenging nature of this operation should be will be a satisfactory reconstruction of the interosseous liga- acknowledged. The operation requires good correction of ment. It is more likely that certain amounts of sinus tarsi (sub- the bony realignment in the hindfoot, midfoot, and forefoot talar) impingement can be corrected. Documentation of these as well as reconstruction of the deltoid ligament. The results amounts await studies with postoperative WEIGHTBEARING reported in the literature are not uniformly good. For exam- CTs. A primary reason for spring ligament reconstruction is to ple, one article described all patients who had hindfoot avoid TN fusion. If such a fusion is done, there is loss of all fusions ended up with an increased valgus talar tilt postop- TN motion and nearly all ST motion, resulting in loss of func- eratively.27 In the same study, patients who did not have tion and stress on the ankle joint.2,29 The senior author hindfoot fusions, but had other bony realignment proce- acknowledges that not all TN joint motion is preserved with dures, did not have improvement of talar tilt. However, they spring ligament reconstruction, but with experience approxi- also did not have progression of talar tilt deformity with mately half of this key motion can be preserved. The tension short-term follow-up.27 of the reconstruction should be adjusted to just slight over- Different techniques of deep and superficial deltoid correction, to avoid both overcorrection and inadequate cor- reconstructions are described in the literature.5,11,14,17,21,23,24,27 rection, thereby preserving motion of the joint and avoiding There is likely to be variability in how authors correct the stiffness. Indications when a TN fusion should be performed accompanying foot deformity in stage IE patients PCFD. are fixed deformity on preoperative inversion stress conven- This makes comparison of outcomes related to combined tional radiographic imaging showing that the TN joint cannot deltoid and reconstruction problematic. be inverted, severe arthritis of the TN joint, and failure for the The following is a summary of the literature. Two arti- reconstruction to correct the TN abduction and/or plantar sag cles have given technique descriptions but no clinical out- intraoperatively. come data.21,23 Another article described good biomechanical Despite good results, with a total of only 28 feet from 2 testing of a technique as well as including conventional institutions, a high level of recommendation cannot yet be radiographic findings of 2 patients with good deformity given for spring ligament reconstruction. Recommendation of correction postoperatively.17 An addendum to the article Level C is reasonable because additional studies are needed. A mentioned that the author had performed 8 such procedures long-term follow-up study with more patients is in progress. and has a clinical trial underway.17 Two other articles pre- However, the present studies do demonstrate that preservation sented a tibionavicular-calcaneal ligament reconstruction of the TN joint, and sometimes the ST joint, can be achieved for PCFD, a combined spring-deltoid ligament reconstruc- in very severe flexible deformities when the bony realignment tion, but did not report ankle joint measurements.5,24 procedures do not give adequate correction. It requires proper Aside from the articles mentioned above, there are 3 intraoperative assessment as mentioned above. articles in the literature that report pre-and postoperative talar tilt measurements as well as clinical outcomes. All 3 11,14,19 Deltoid Ligament articles are Level IV studies. The first 2 articles have the same series of 5 patients, one with early and the other Anatomically, the deltoid ligament complex is a broad strong with longer term follow-up. The 5 patients were first structure that can be divided into 2 main components: reported in 2004 with minimum 2-year follow-up of a deep 4 Foot & Ankle International 00(0) deltoid reconstruction using peroneus longus autograft and ORCID iDs 11 flatfoot correction. There was one failure, defined by a Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 patient with 9 degrees of valgus talar tilt remaining, rather Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042 than the 4 degrees required for success. The second article by Ellis et al14 reported on the same patient cohort but with Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- an average of 8.9-year follow-up. The failure patient had 6037-0685 progressed from mild to moderate pain but with no increase Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998 in the tilt. All patients in the study were satisfied with the procedure. Except for the failure patient, the patients had References either no or mild pain at the average 8.9-year follow-up. 1. Acevedo J, Vora A. Anatomical reconstruction of the spring Conventional WEIGHTBEARING radiographs showed all ligament complex: “Internal brace” augmentation. Foot Ankle patients had maintained their correction. The third article Spec. 2013;6(6):441-445. by Jeng et al was from a different institution and had 8 2. Astion DJ, Deland JT, Otis JC, Kenneally S. Motion of 19 patients with an average 3-year follow-up. Three of the 8 the hindfoot after simulated arthrodesis. J Bone Joint Surg. patients were considered a failure for not having met the 1997;79(2):241-246. criteria of success, defined as 3 degrees or less postopera- 3. Bastias GF, Dalmau-Pastor M, Astudillo C, Pellegrini MJ. tive talar tilt with greater than 2 mm lateral joint space Spring ligament instability. Foot Ankle Clin. 2018;23(4): remaining. Five patients met the criteria for success. The 3 659-678. patients who failed were found to have more severe ankle 4. Boss AP, Hintermann B. Anatomical study of the medial deformity preoperatively when compared to the patients ankle ligament complex. Foot Ankle Int. 2002;23(6):547- who gained successful correction. 553. The senior author is presently working on a review of a 5. Brodell JD Jr, MacDonald A, Perkins JA, Deland JT, Oh I. much larger series of patients with longer follow-up. The find- Deltoid-spring ligament reconstruction in adult acquired flat- ings so far strongly suggest maintenance of correction and foot deformity with medial peritalar instability. Foot Ankle Int. 2019;40(7):753-761. improved function. A good candidate for the procedure is 6. Choi K, Lee S, Otis JC, Deland JT. Anatomical reconstruc- defined as a patient with 50% or more of ankle lateral joint tion of the spring ligament using peroneus longus tendon space remaining on WEIGHTBEARING conventional radio- graft. Foot Ankle Int. 2003;24(5):430-436. graph. It should be emphasized that a clinically straight heel (no 7. Chu I, Myerson MS, Nyska M, Parks BG. Experimental flat- residual clinical heel valgus), good alignment of the TN joint, foot model: the contribution of dynamic loading. Foot Ankle and a stable first ray with the metatarsal head slightly prominent Int. 2001;22(3):220-225. in comparison to the second metatarsal are prerequisite for a 8. Deland JT. Spring ligament complex and flatfoot deformity: successful deltoid reconstruction. It should be achieved either curse or blessing? Foot Ankle Int. 2012;33(3):239-243. before or at the time of the deltoid reconstruction. 9. Deland JT. The adult acquired flatfoot and spring ligament A high level of recommendation for deltoid reconstruction complex. pathology and implications for treatment. Foot combined with PCFD reconstruction cannot be given based Ankle Clin. 2001;6(1):129-135, vii. on the present literature. There are only 3 published studies 10. Deland JT, Arnoczky SP, Thompson FM. Adult acquired with tilt measurements, 2 of which have the same patients. flatfoot deformity at the talonavicular joint: reconstruc- All 3 studies have very few patients, for a total of 13.11,14,19 tion of the spring ligament in an in vitro model. Foot Ankle. 1992;13(6):327-332. Therefore, the level of recommendation is I (insufficient). 11. Deland JT, de Asla RJ, Segal A. Reconstruction of the chron- The paucity of data to support this combined procedure ically failed deltoid ligament: a new technique. Foot Ankle should be explained to patients. Although there is insufficient Int. 2004;25(11):795-799. data to date to give even a fair recommendation, the literature 12. Deland JT, de Asla RJ, Sung I, Ernberg LA, Potter HG. shows that talar tilt correction to good alignment and good Posterior tibial tendon insufficiency: which ligaments are function is possible. More studies are needed. involved? Foot Ankle Int. 2005;26(6):427-435. 13. Ellis SJ, Williams BR, Joseph CY, Deland JT. Spring Declaration of Conflicting Interests ligament reconstruction for advanced flatfoot deformity with the use of an Achilles allograft. Oper Tech Orthop. The author(s) declared no potential conflicts of interest with 2010;20(3):175-182. respect to the research, authorship, and/or publication of this arti- 14. Ellis SJ, Williams BR, Wagshul AD, Pavlov H, Deland cle. ICMJE forms for all authors are available online. JT. Deltoid ligament reconstruction with peroneus longus autograft in flatfoot deformity. Foot Ankle Int. 2010;31(9): Funding 781-789. The author(s) received no financial support for the research, 15. Gazdag AR, Cracchiolo A III. Rupture of the posterior tibial authorship, and/or publication of this article. tendon. evaluation of injury of the spring ligament and clinical Deland et al 5

assessment of tendon transfer and ligament repair. J Bone Joint 25. Oburu E, Myerson MS. Deltoid ligament repair in flatfoot Surg. 1997;79(5):675-681. deformity. Foot Ankle Clin. 2017;22(3):503-514. 16. Grunfeld R, Oh I, Flemister S, Ketz J. Reconstruction of 26. Palmanovich E, Shabat S, Brin YS, Feldman V, Kish B, the deltoid-spring ligament: tibiocalcaneonavicular ligament Nyska M. Anatomic reconstruction technique for a plantar complex. Tech Foot Ankle Surg. 2016;15(1):39-46. calcaneonavicular (spring) ligament tear. J Foot Ankle Surg. 17. Haddad SL, Dedhia S, Ren Y, Rotstein J, Zhang L. Deltoid 2015;54(6):1124-1126. ligament reconstruction: a novel technique with biomechani- 27. Patel MS, Barbosa MP, Kadakia AR. Role of spring and del- cal analysis. Foot Ankle Int. 2010;31(7):639-651. toid ligament reconstruction for adult acquired flatfoot defor- 18. Harper MC. Deltoid ligament: an anatomical evaluation of mity. Tech Foot Ankle Surg. 2017;16(3):124-135. function. Foot Ankle. 1987;8(1):19-22. 28. Rasmussen O, Kromann-Andersen C, Boe S. Deltoid 19. Jeng CL, Bluman EM, Myerson MS. Minimally invasive del- ligament: functional analysis of the medial collateral liga- toid ligament reconstruction for stage IV flatfoot deformity. mentous apparatus of the ankle joint. Acta Orthop Scand. Foot Ankle Int. 2011;32(1):21-30. 1983;54(1):36-44. 20. Kelly M, Masqoodi N, Vasconcellos D, et al. Spring ligament 29. Saltzman CL, Fehrle MJ, Cooper RR, Spencer EC, Ponseti tear decreases static stability of the ankle joint. Clin Biomech. IV. Triple arthrodesis: twenty-five and forty-four-year 2019;61:79-83. average follow-up of the same patients. J Bone Joint Surg. 21. Lack W, Phisitkul P, Femino JE. Anatomic deltoid ligament 1999;81(10):1391-1402. repair with anchor-to-post suture reinforcement: Technique 30. Thordarson DB, Schmotzer H, Chon J. Reconstruction with tip. Iowa Orthop J. 2012;32:227-230. tenodesis in an adult flatfoot model. A biomechanical evalu- 22. Lee WC, Yi Y. Spring ligament reconstruction using the ation of four methods. J Bone Joint Surg Am. 1995;77(10): autogenous flexor hallucis longus tendon. Orthopedics. 2014; 1557-1564. 37(7):467-471. 31. Vulcano E, Deland JT, Ellis SJ. Approach and treatment of 23. Lui TH. Endoscopic repair of the superficial deltoid ligament the adult acquired flatfoot deformity. Curr Rev Musculoskelet and spring ligament. Arthrosc Tech. 2016;5(3):e621-e625. Med. 2013;6(4):294-303. 24. Nery C, Lemos, André Vitor Kerber C, Raduan F, Mansur NSB, 32. Williams BR, Ellis SJ, Deyer TW, Pavlov H, Deland JT. Baumfeld D. Combined spring and deltoid ligament repair in Reconstruction of the spring ligament using a peroneus longus adult-acquired flatfoot. Foot Ankle Int. 2018;39(8):903-907. autograft tendon transfer. Foot Ankle Int. 2010;31(7):567-577. FAIXXX10.1177/1071100720950747Foot & Ankle InternationalSchon et al 950747research-article2020

Topical Review

Foot & Ankle International® 4–­1 Consensus for the Indication of a © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Medializing Displacement Calcaneal DOI:https://doi.org/10.1177/1071100720950747 10.1177/1071100720950747 Osteotomy in the Treatment of journals.sagepub.com/home/fai Progressive Collapsing Foot Deformity

Lew C. Schon, MD1,2,3,4, Cesar de Cesar Netto, MD, PhD5 , Jonathan Day, MS6 , Jonathan T. Deland, MD6, Beat Hintermann, MD7, Jeffrey E. Johnson, MD8 , Mark S. Myerson, MD9, Bruce J. Sangeorzan, MD10, David Thordarson, MD11, and Scott J. Ellis, MD6

Abstract Recommendation: There is evidence that the medial displacement calcaneal osteotomy (MDCO) can be effective in treating the progressive collapsing foot deformity (PCFD). This juxta-articular osteotomy of the tuberosity shifts the mechanical axis of the calcaneus from a more lateral position to a more medial position, which provides mechanical advantage in the reconstruction for this condition. This also shifts the action of the Achilles tendon medially, which minimizes the everting deforming effect and improves the inversion forces. When isolated hindfoot valgus exists with adequate talonavicular joint coverage (less than 35%-40% uncoverage) and a lack of significant forefoot supination, varus, or abduction, we recommend performing this osteotomy as an isolated bony procedure, with or without additional soft tissue procedures. The clinical goal of the hindfoot valgus correction is to achieve a clinically neutral heel, as defined by a vertical axis from the heel up the longitudinal axis of the Achilles tendon and distal aspect of the leg. The typical range when performing a MDCO, while considering the location and rotation of the osteotomy, is 7 to 15 mm of correction. Level of Evidence: Level V, consensus, expert opinion.

Keywords: flatfoot, adult-acquired flatfoot deformity, AAFD, hindfoot valgus, medial displacement calcaneal osteotomy, MDCO, medial slide, calcaneal osteotomy, progressive collapsing foot deformity, PCFD

Consensus Statements Voted 1Mercy Medical Center, Baltimore, MD, USA 2 1. CONSENSUS STATEMENT 1—We recommend New York University Grossman School of Medicine, New York, NY, performing a medializing displacement calcaneal USA 3Johns Hopkins School of Medicine, Baltimore, MD, USA osteotomy (MDCO) as an isolated bony procedure 4Georgetown School of Medicine, Washington, DC, USA when there is an isolated hindfoot valgus, with ade- 5Department of Orthopaedics and Rehabilitation, University of Iowa, quate talonavicular joint coverage (less than 35%- Iowa City, IA, USA 40% uncoverage) and lack of significant forefoot 6Hospital for Special Surgery, New York, NY, USA 7 supination, varus, or abduction. Kantonspital Baselland, Liestal, Switzerland 8 Delegate Vote: Agree: 100% (9/9); Disagree: 0%; Washington University School of Medicine, St. Louis, MO, USA 9Department of Orthopedic Surgery, University of Colorado School of Abstain: 0% Medicine, Aurora, CO, USA (Unanimous, Strongest Consensus) 10University of Washington, Seattle, WA, USA 2. CONSENSUS STATEMENT 2—The clinical goal 11Cedars-Sinai Medical Center, Los Angeles, CA, USA of hindfoot valgus correction with a medial displace- ment calcaneal osteotomy (MDCO) is to achieve a Corresponding Author: Cesar de Cear Netto, MD, PhD, Department of Orthopaedics and clinically neutral heel, as defined by a vertical axis Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon from the heel up the longitudinal axis of the Achilles Pavilion, Room 01066, Iowa City, IA 52242, USA. tendon and distal aspect of the leg. Email: [email protected] 2 Foot & Ankle International 00(0)

Delegate Vote: Agree: 100% (9/9); Disagree: 0%; as the posterior tibial tendon (PTT).24 It has also been shown Abstain: 0% to restore foot alignment,21,27 stabilize forces at the talona- (Unanimous, Strongest Consensus) vicular joint,1 and improve patient outcomes.3,7,11,18 Studies 3. CONSENSUS STATEMENT 3—The typical range have demonstrated that tendon transfers alone, such as a when performing a medializing calcaneal osteotomy, flexor digitorum longus (FDL) tendon transfer to the navicu- while considering the location and rotation of the lar tuberosity, do not result in acceptable biomechanical or osteotomy, is 7 to 15 mm of correction. clinical outcomes following PCFD reconstruction and that Delegate Vote: Agree: 100% (9/9); Disagree: 0%; the foot remains deformed and prone to failure with Abstain: 0% time.8,15-17 Therefore, osseous correction of the deformity is (Unanimous, Strongest Consensus) necessary for long-term maintenance of correction and clini- 4. CONSENSUS STATEMENT 4—The following cal outcomes.20 WEIGHTBEARING conventional radiographic In a study of 129 patients with flexible PCFD, correc- incidences are considered mandatory by the consen- tion with tendon transfer and MDCO resulted in significant sus group in the assessment of progressive collaps- improvement in surgical outcomes at a mean 5.2 years fol- ing foot deformity (PCFD) patients: anteroposterior lowing reconstruction. Specifically, the authors noted sig- (AP) foot, AP or mortise ankle, lateral foot. The nificant and sustained improvement in patient-reported consensus group also strongly recommends a hind- outcomes (American Orthopaedic Foot & Ankle Society, foot alignment view when available. Short Form–36), clinical strength, radiographic and clini- Delegate Vote: Agree: 100% (9/9); Disagree: 0%; cal deformity correction, and pain relief, with 92% of Abstain: 0% patients entirely satisfied at final follow-up.20 Improvements (Unanimous, Strongest Consensus) in objective and subjective clinical outcomes correlated with improvements in radiographic correction, therefore Rationale suggesting that by correcting the heel malalignment defor- mity, MDCO improves upon the benefits of tendon transfer The purpose of the medial displacement calcaneal osteot- alone. It is important to note that patients with more than omy (MDCO) is to restore normal hindfoot alignment in the 15 degrees of fixed forefoot varus deformity were excluded surgical treatment of progressive collapsing foot deformity from this study.20 (PCFD). To date, there has been no general consensus Indeed, the specific clinical indication for an isolated regarding when to perform the MDCO. In addition, there is MDCO is a PCFD patient with an increased valgus hind- no general consensus on the goals of this osteotomy or on foot alignment and a flexible, nonarthritic foot that can be the range of correction possible. Such guidelines are essen- passively manipulated into good alignment. If there is sig- tial to help achieve optimal surgical correction and maxi- nificant forefoot varus or abduction, additional bony cor- mize patient outcomes. rective procedures would be needed to fully correct the The MDCO is performed to correct mainly the valgus deformity.9,10 Contraindications include rigid PCFD and hindfoot deformity, specifically as a key mechanical element significant hindfoot arthritis.20 In a study by Niki et al,22 to improving the alignment of the leg with respect to the heel the authors noted that preoperative conventional radio- during weightbearing. It also shifts the moment arm of the graphic findings of a lateral talus–first metatarsal angle Achilles tendon in a medial direction, which changes the exceeding 25 degrees and a hindfoot alignment view tibio- leverage about the axis of rotation of the subtalar joint, con- calcaneal angle greater than 15 degrees would be associ- verting it from an eversion deforming force,10,20,23 alleviat- ated with failure to maintain adequate correction following ing the contribution of Achilles tension to worsening FDL transfer and MDCO, with an average 5.6 years of deformity progression.9 Nyska et al23 demonstrated that fol- follow-up. Also, from a conventional WEIGHTBEARING lowing MDCO, Achilles loading contributed less to arch radiographic perspective, it is the opinion of the consensus collapse, suggesting the powerful role of MDCO in not only experts that the use of MDCO as an isolated bony proce- correcting the existing deformity but also preventing further dure should only be considered when the talonavicular progression. Restoration of hindfoot alignment is critical to (TN) joint uncoverage, assessed on anteroposterior foot prevent failure of the reconstruction and to correct the abnor- views, is less than 35% to 40%. If there is over 35% to 40% mal gait kinematics that can accompany hindfoot valgus TN uncoverage, the authors have suggested performing deformity.26 In addition, MDCO redistributes plantar pres- additional realignment procedures such as lateral column sures of the collapsed foot by shifting medial pressures more lengthening (LCL) and/or joint fusions.14,20 laterally.13 Numerous studies have demonstrated the utility The clinical goal of hindfoot valgus correction is to of MDCO to decrease the strain on the medial soft tissue achieve a clinically neutral heel, as defined by a vertical structures such as the spring and deltoid ligaments, as well axis from the heel up the longitudinal axis of the Achilles Schon et al 3 tendon and distal aspect of the leg. This is achieved in the the deformity. Again, given the results of these studies and operating room and is appreciated by visual and tactile the end goal of achieving a clinically straight heel, the expert means. Oftentimes during the surgery, the leg can be held consensus is that the typical range of MDCO displacement up from the operating table and viewed from the posterior is 7 to 15 mm. perspective. Studies have shown that a clinically neutral heel is in fact radiographically in a neutral alignment or Declaration of Conflicting Interests mild varus, as measured by the hindfoot moment arm (HMA) in the hindfoot alignment view.3,25 A previous The author(s) declared no potential conflicts of interest with study by Conti et al3 in a cohort of 55 patients with flexible respect to the research, authorship, and/or publication of this PCFD not only showed that a neutral or mild radiographic article. ICMJE forms for all authors are available online. varus alignment, defined as an HMA of 0 to 5 mm, is equivalent to a clinically neutral heel but that this was also Funding associated with superior patient-reported outcomes com- The author(s) received no financial support for the research, pared to patients with a residual valgus alignment or authorship, and/or publication of this article. increased moderate varus overcorrection. In addition, the authors found no correlation between the amount of ORCID iDs MDCO displacement and improvement in patient-reported outcomes, suggesting that successful surgical outcomes Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- may be influenced by the final position of the heel rather 6037-0685 than the actual amount corrected. Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042 Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055- Preoperative planning should include a detailed clinical 9998 and radiographic assessment of the hindfoot alignment, Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 keeping in mind that the clinical assessment has been shown to underestimate the bony hindfoot valgus deformity by an average of 11 to 12.8 degrees.4 The expert consensus is for References WEIGHTBEARING conventional radiographic assess- 1. Arangio GA, Salathe EP. A biomechanical analysis of pos- ment to be performed via the hindfoot alignment view, terior tibial tendon dysfunction, medial displacement cal- when available, with the HMA representing an accurate caneal osteotomy and flexor digitorum longus transfer in and reliable parameter in quantifying deformity.25 Use of adult acquired flat foot. Clin Biomech (Bristol, Avon). 2009; WEIGHTBEARING computed tomography (WBCT) is 24(4):385-390. also advocated for preoperative planning, when available.5,6 2. Chan JY, Williams BR, Nair P, et al. The contribution of While the literature attempts to provide guidance that the medializing calcaneal osteotomy on hindfoot alignment in shift should be around 10 mm,1,2,10,12,19,20 what occurs prac- the reconstruction of the stage II adult acquired flatfoot defor- tically is that the surgeon shifts the heel based on the degree mity. Foot Ankle Int. 2013;34(2):159-166. 3. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal of the deformity, their sense of what the optimal alignment position of the heel following reconstruction of the stage II should be in each given case, and also according to what the adult-acquired flatfoot deformity. Foot Ankle Int. 2015;36(8): soft tissue tensioning allows. The consensus expert opinion 919-927. is that the typical range when performing a MDCO, aiming 4. de Cesar Netto C, Kunas GC, Soukup D, Marinescu A, Ellis to achieve a neutrally aligned heel, is 7 to 15 mm of medial SJ. Correlation of clinical evaluation and radiographic hind- displacement correction, depending on the severity of the foot alignment in stage II adult-acquired flatfoot deformity. deformity. The literature supports that when pursuing ade- Foot Ankle Int. 2018;39(7):771-779. quate hindfoot alignment correction, the use of validated 5. de Cesar Netto C, Schon LC, Thawait GK, et al. Flexible adult HMA measurements on the hindfoot alignment view repre- acquired flatfoot deformity: comparison between weight- sents an attractive surgical planning tool.25 Chan et al2 bearing and non-weight-bearing measurements using cone- derived a linear equation relating the change between preop- beam computed tomography. J Bone Joint Surg Am. 2017; erative and postoperative HMA with the amount of intraop- 99(18):e98. 6. de Cesar Netto C, Shakoor D, Roberts L, et al. Hindfoot align- eratively measured MDCO, demonstrating that a medial ment of adult acquired flatfoot deformity: a comparison of translation of 1 mm corresponds to approximately a 1.5-mm clinical assessment and weightbearing cone beam CT exami- change in radiographic HMA. As mentioned earlier, mild nations. Foot Ankle Surg. 2019;25(6):790-797. radiographic overcorrection of 0 to 5 mm varus resulted 7. Fayazi AH, Nguyen HV, Juliano PJ. Intermediate term fol- in a clinically straight heel and superior patient-reported low-up of calcaneal osteotomy and flexor digitorum longus outcomes.3 In these 2 latter studies,2,3 the magnitude of the transfer for treatment of posterior tibial tendon dysfunction. MDCO shift varied between patients based on severity of Foot Ankle Int. 2002;23(12):1107-1111. 4 Foot & Ankle International 00(0)

8. Funk DA, Cass J, Johnson K. Acquired adult flat foot second- procedure for stage II posterior tibial tendon insufficiency. ary to posterior tibial-tendon pathology. J Bone Joint Surg Foot Ankle Int. 2001;22(4):283-291. Am. 1986;68(1):95-102. 19. Mosier-LaClair S, Pomeroy G, Manoli A. Operative treat- 9. Greenfield S, Cohen B. Calcaneal osteotomies: pearls and ment of the difficult stage 2 adult acquired flatfoot deformity. pitfalls. Foot Ankle Clin. 2017;22(3):563-571. Foot Ankle Clin. 2001;6(1):95-119. 10. Guha AR, Perera AM. Calcaneal osteotomy in the treat- 20. Myerson MS, Badekas A, Schon LC. Treatment of stage II ment of adult acquired flatfoot deformity. Foot Ankle Clin. posterior tibial tendon deficiency with flexor digitorum 2012;17(2):247-258. longus tendon transfer and calcaneal osteotomy. Foot Ankle 11. Guyton GP, Jeng C, Krieger LE, Mann RA. Flexor digitorum Int. 2004;25(7):445-450. longus transfer and medial displacement calcaneal osteotomy 21. Myerson MS, Corrigan J, Thompson F, Schon LC. Tendon for posterior tibial tendon dysfunction: a middle-term clinical transfer combined with calcaneal osteotomy for treatment of follow-up. Foot Ankle Int. 2001;22(8):627-632. posterior tibial tendon insufficiency: a radiological investiga- 12. Haddad SL, Myerson MS, Younger A, Anderson RB, Davis tion. Foot Ankle Int. 1995;16(11):712-718. WH, Manoli A. Adult acquired flatfoot deformity. Los 22. Niki H, Hirano T, Okada H, Beppu M. Outcome of medial Angeles, CA: Sage; 2011. displacement calcaneal osteotomy for correction of adult- 13. Hadfield MH, Snyder JW, Liacouras PC, Owen JR, Wayne acquired flatfoot. Foot Ankle Int. 2012;33(11):940-946. JS, Adelaar RS. Effects of medializing calcaneal osteotomy 23. Nyska M, Parks BG, Chu IT, Myerson MS. The contribution on Achilles tendon lengthening and plantar foot pressures. of the medial calcaneal osteotomy to the correction of flatfoot Foot Ankle Int. 2003;24(7):523-529. deformities. Foot Ankle Int. 2001;22(4):278-282. 14. Hunt KJ, Farmer RP. The undercorrected flatfoot reconstruc- 24. Otis JC, Deland JT, Kenneally S, Chang V. Medial arch tion. Foot Ankle Clin. 2017;22(3):613-624. strain after medial displacement calcaneal osteotomy: an in 15. Johnson KA. Tibialis posterior tendon rupture. Clin Orthop vitro study. Foot Ankle Int. 1999;20(4):222-226. Relat Res. 1983(177):140-147. 25. Saltzman CL, El-Khoury GY. The hindfoot alignment view. 16. Kitaoka HB, Luo Z-P, An K-N. Reconstruction operations Foot Ankle Int. 1995;16(9):572-576. for acquired flatfoot: biomechanical evaluation. Foot Ankle 26. Svoboda Z, Honzikova L, Jaroszczuk S, Vidal T, Martinaskova Int. 1998;19(4):203-207. E. Kinematic gait analysis in children with valgus deformity 17. Mann RA, Thompson F. Rupture of the posterior tibial ten- of the hindfoot. Acta Bioeng Biomech. 2014;16(3):89-93. don causing flat foot: surgical treatment. J Bone Joint Surg 27. Vora AM, Tien TR, Parks BG, Schon LC. Correction of mod- Am. 1985;67(4):556-561. erate and severe acquired flexible flatfoot with medializing 18. Moseir-LaClair S, Pomeroy G, Manoli A II. Intermediate calcaneal osteotomy and flexor digitorum longus transfer. follow-up on the double osteotomy and tendon transfer J Bone Joint Surg Am. 2006;88(8):1726-1734. FAIXXX10.1177/1071100720950759Foot & Ankle InternationalSangeorzan et al 950759review-article2020

Topical Review

Foot & Ankle International® 4–­1 Progressive Collapsing Foot © The Author(s) 2020 Article reuse guidelines: sagepub.com/journals-permissions Deformity: Consensus on Goals DOI:https://doi.org/10.1177/1071100720950759 10.1177/1071100720950759 for Operative Correction journals.sagepub.com/home/fai

Bruce J. Sangeorzan, MD1, Beat Hintermann, MD2, Cesar de Cesar Netto, MD, PhD3 , Jonathan Day, MS4 , Jonathan T. Deland, MD4, Scott J. Ellis, MD4 , Jeffrey E. Johnson, MD5 , Mark S. Myerson, MD6, Lew C. Schon, MD7,8,9,10, and David Thordarson, MD11

Abstract Recommendation: In the treatment of progressive collapsing foot deformity (PCFD), the combination of bone shape, soft tissue failure, and host factors create a complex algorithm that may confound choices for operative treatment. Realignment and balancing are primary goals. There was consensus that preservation of joint motion is preferred when possible. This choice needs to be balanced with the need for performing joint-sacrificing procedures such as fusions to obtain and maintain correction. In addition, a patient’s age and health status such as body mass index is important to consider. Although preservation of motion is important, it is secondary to a stable and properly aligned foot. Level of Evidence: Level V, consensus, expert opinion.

Keywords: adult acquired flatfoot deformity, AAFD, flatfoot, range of motion, ROM, mobility, talonavicular, fusion, progressive collapsing foot deformity, PCFD.

Consensus Statements Voted: younger patients, attempts should be made for joint pres- ervation procedures. CONSENSUS STATEMENT ONE: In general, we Delegate vote: agree, 78% (7/9); disagree, 11% (1/9); aim to maximize preservation of joint range of motion abstain, 11% (1/9). and mobility. When given the choice of surgical proce- (Strong consensus) dures, we recommend preserving joint motion. Delegate vote: agree, 100% (9/9); disagree, 0%; abstain, 1University of Washington, Seattle, WA, USA 0%. 2Kantonspital Baselland, Liestal, Switzerland (Unanimous, strongest consensus) 3Department of Orthopaedics and Rehabilitation, University of Iowa, CONSENSUS STATEMENT TWO: Talonavicular Iowa City, IA, USA (TN) joint fusion should be considered in the arthritic 4Hospital for Special Surgery, New York, NY, USA 5 and stiff joints, important sagittal plane sagging of the Washington University School of Medicine, St. Louis, MO, USA 6Department of Orthopedic Surgery, University of Colorado School of TN joint, severe deformities, as well as in cases where Medicine, Aurora, CO, USA inadequate correction of the TN abduction deformity is 7Mercy Medical Center, Baltimore, MD, USA achieved intraoperatively. 8New York University Grossman School of Medicine, New York, NY, USA Delegate vote: agree, 89% (8/9); disagree, 0%; abstain, 9Johns Hopkins School of Medicine, Baltimore, MD, USA 10 11% (1/9). Georgetown School of Medicine, Washington, DC, USA 11Cedars-Sinai Medical Center, Los Angeles, CA, USA (Strong consensus) CONSENSUS STATEMENT THREE: Patients with Corresponding Author: high BMI, defined as a BMI equal to or higher than 30, Cesar de Cesar Netto, MD, PhD, Department of Orthopaedics and Rehabilitation, University of Iowa, 200 Hawkins Drive John Pappajon will generally do worse with reconstructive surgery Pavilion, Room 01066, Iowa City, IA 52242, USA. when compared to hindfoot fusions. However, in Email: [email protected] 2 Foot & Ankle International 00(0)

Rationale information of the severity of forefoot abduction deformity and may guide treatment.13,17 Goals of Progressive Collapsing Foot Disorder In its simplest form, the structural mechanical goals of Operative Correction PCFD treatment are twofold. First, coronal plane deformity correction of the hindfoot, realigning the calcaneus colinear Although 100% of our expert opinion panel agreed that with the mechanical plumb line at heel strike.8 When the preservation of joint motion in treatment of progressive col- center of gravity of the body weight is medial to the calca- lapsing foot deformity (PCFD) is a goal and 89% agreed neus at heel strike phase of the gait, there will be strain on that this standard should be especially applied to the talona- the medial soft tissue structures such as the spring and del- vicular (TN) joint, only 78% agreed that obesity is a predic- toid ligaments, PTT, and plantar intertarsal ligaments. tor of worse outcomes. The general nature of these Second, that same mechanical plumb line should stay in line consensus statements points out knowledge gaps in our with the second metatarsal during heel rise for the same rea- understanding and treatment of the disorder. The study of sons. This is done by correcting the forefoot abduction. PCFD is relatively new. Kettelkamp and Alexander,27 in During heel rise, body weight multiplied by the length of the 1969, alluded to a connection between the posterior tibial foot creates a large vector upward and laterally if the fore- tendon (PTT) and deformity of the foot. But very few papers foot is not aligned with the center of gravity of the body addressed treatment in the adult prior to 1995. The early weight.21 Similar to a valgus hindfoot, this mechanical situ- association of PTT disruption with PCFD,27 and the poten- ation places significant strain on the medial plantar liga- tial causal relationship,20 may have slowed our mechanistic ments. When combined with contracture of triceps surae, a understanding of the interplay between malalignment and significant resultant valgus strain occurs in the hindfoot of degeneration of multiple medial soft tissue structures, that PCFD patients. Although triceps contracture is accepted in would include but not be restricted to the PTT, and the over- the adolescent flatfoot literature,3 it is controversial in adults. all progression of the deformity.12 Dilwyn Evans himself Operative treatment of equinus should be based on examina- suggested that his osteotomy should be applied only to chil- tion of the surgeon. Note that neither of these important dren. The treatment of this diverse, multifaceted disorder is mechanical issues are happening in the sagittal plane and are still changing and evolving. not related to the height and collapse of the arch. The general goals of treatment are to relieve pain, restore Although preservation of native joint motion and stabil- alignment and mechanics, facilitate shoe fitting, and pre- ity is a consensus goal, alignment is the highest priority. vent further mechanical consequences of the progressed When joints are arthritic, unstable, or severely subluxed, deformity such as joint degeneration, medial knee pain, or arthrodesis may be needed.11,24 Patients tend to tolerate fibular stress fractures. These broad goals, however, do not fusion of the TN joint, with studies demonstrating improved guide us completely during the treatment process. To select outcomes in pain and function with minimal complica- a specific treatment, we need to identify the cause and loca- tion.9,18,22 However, TN fusion has been shown to result in tion of the pain symptoms, as well as understand and man- up to 80% decrease in hindfoot motion.32 In more severe age the mechanical disorder.31 PCFD when the deformity is uncorrectable and there is In a symptomatic PCFD early symptoms are typically degeneration in the triple joint complex, TN and ST fusion somewhat vague in nature. The premorbid mechanical con- may be indicated. Studies have shown that combined TN ditions that will eventually lead to collapse, such as hind- and ST fusion in these patients results in improved pain, foot valgus,10 an intrinsic altered bone morphology,2,7,34 and functional, and clinical outcomes.5 triceps surae contracture,14 may contribute to the nonspe- Another example is a chronically subluxated or dislo- cific symptoms that can include fatigue and strain and are cated subtalar joint, with the calcaneus rotating externally difficult to locate and categorize.11 With further use of and translating laterally, with progressive development of WEIGHTBEARING computed tomographic, there has impingement between the talus and calcaneus at the sinus been additional focus placed on subluxation of the talona- tarsi area (sinus tarsi impingement) and finally impacting vicular and subtalar joints that contributes to the forefoot into and eroding the fibula (subfibular impingement) as a abduction and hindfoot valgus deformities, respectively, nontraumatic subtalar dislocation.16,30 The goals of stability that are classically seen in PCFD.1,26 and alignment have a higher priority than preservation of Clinical and radiographic assessment help to character- motion under these circumstances because the primary ize the location of the deformity that drives operative plan- alignment goals cannot be achieved without it and there are ning. This is most easily assessed with evaluation of clear signs of joint instability and degeneration. uncoverage of the medial talar head on standing anteropos- There are other factors that affect mechanics such as terior view of the foot.11 The TN coverage angle35 and talar obesity.19,25,37 Hindfoot arthrodesis may be more effective incongruency angle17 are 2 reliable and validated radio- in achieving and maintaining correction in this patient pop- graphic measurements used to assess severity of forefoot ulation.19,23,37,36 A subtalar fusion is known to impact hind- abduction. Both radiographic parameters provide valuable foot motion, and has been shown to decrease adjacent joint Sangeorzan et al 3 motion as well in the talonavicular and CC.6,32,33 With References greater impairment of hindfoot motion, there is a more sig- 1. Abousayed MM, Tartaglione JP, Rosenbaum AJ, Dipreta nificant risk of progressive adjacent joint degeneration in JA. Classifications in brief: Johnson and Strom classification the long-term.23 Although this may have less impact in an of adult-acquired flatfoot deformity. Clin Orthop Relat Res. elderly, low-demand, and/or obese patient, this option is 2016;474(2):588-593. less attractive as the primary procedure in younger, more 2. Apostle KL, Coleman NW, Sangeorzan BJ. Subtalar joint axis active individuals.23 in patients with symptomatic peritalar subluxation compared The causes of symptoms of PCFD are not scientifically to normal controls. Foot Ankle Int. 2014;35(11):1153-1158. established. Nearly a quarter of the population has a foot 3. Carr JB 2nd, Yang S, Lather LA. Pediatric pes planus: a state- that can be defined as flat by clinical and radiographic of-the-art review. Pediatrics. 2016;137(3):e20151230. 4. Cody EA, Williamson ER, Burket JC, Deland JT, Ellis SJ. parameters, but the vast majority of them are not symp- 15,28,29 Correlation of talar anatomy and subtalar joint alignment on tomatic and will never require operative intervention. weightbearing computed tomography with radiographic flat- Many elite professional basketball players have severe foot parameters. Foot Ankle Int. 2016;37(8):874-881. arch collapse. Some of those also have a tight triceps surae 5. Coetzee JC, Hansen ST. Surgical management of severe mechanism that can be dramatically helpful with jumping deformity resulting from posterior tibial tendon dysfunction. activities. It is very possible to have a flatfoot with no Foot Ankle Int. 2001;22(12):944-949. symptoms if the underlying morphology does not create 6. Cohen BE, Johnson JE. Subtalar arthrodesis for treatment mechanical strain. A great deal of the orthopedic literature of posterior tibial tendon insufficiency. Foot Ankle Clin. describes ruptured posterior tibial tendon as a cause of 2001;6(1):121-128. PCFD, but the consensus group feels it is more likely a 7. Colin F, Horn Lang T, Zwicky L, Hintermann B, Knupp M. result of the deformity.15 Multiple studies more recently Subtalar joint configuration on weightbearing CT scan. Foot Ankle Int. 2014;35(10):1057-1062. have documented changes in the shape of the tarsal bones 8. Conti MS, Ellis SJ, Chan JY, Do HT, Deland JT. Optimal posi- and possible changes in the slope of the posterior facet as tion of the heel following reconstruction of the stage II adult- 2,4,7,34 risk factors for PCFD. It is unknown what role such acquired flatfoot deformity. Foot Ankle Int. 2015;36(8):919-927. things as level of activity and body weight play in the 9. Crevoisier X. The isolated talonavicular arthrodesis. Foot development and progression of the deformity. Ankle Clin. 2011;16(1):49-59. In conclusion, the PCFD expert consensus group sup- 10. de Cesar Netto C, Kunas GC, Soukup D, Marinescu A, Ellis ports that the collapsing foot is more than an isolated tendon SJ. Correlation of clinical evaluation and radiographic hind- dysfunction and is influenced by intrinsic morphological foot alignment in stage II adult-acquired flatfoot deformity. (bony and soft tissue) and motor factors, as well as extrinsic Foot Ankle Int. 2018;39(7):771-779. elements, all contributing to the development of progres- 11. Deland JT. Adult-acquired flatfoot deformity. J Am Acad sive collapsing deformity. The general goals of treatment Orthop Surg. 2008;16(7):399-406. 12. Deland JT, de Asla RJ, Sung IH, Ernberg LA, Potter HG. are to improve function and reduce pain by restoring fixed Posterior tibial tendon insufficiency: which ligaments are and dynamic mechanical alignment while minimizing loss involved? Foot Ankle Int. 2005;26(6):427-435. of motion. Treatment should prioritize coronal plane defor- 13. Deland JT, Page A, Sung I-H, O’Malley MJ, Inda D, Choung mity restoration in all phases of gait. S. Posterior tibial tendon insufficiency results at different stages. HSS J. 2006;2(2):157-160. Declaration of Conflicting Interests 14. DiGiovanni CW, Langer P. The role of isolated gastrocne- The author(s) declared no potential conflicts of interest with mius and combined Achilles contractures in the flatfoot. Foot respect to the research, authorship, and/or publication of this arti- Ankle Clin. 2007;12(2):363-379, viii. cle. ICMJE forms for all authors are available online. 15. Dyal CM, Feder J, Deland JT, Thompson FM. Pes planus in patients with posterior tibial tendon insufficiency: asymptom- Funding atic versus symptomatic foot. Foot Ankle Int. 1997;18(2):85- 88. The author(s) received no financial support for the research, 16. Ellis SJ, Deyer T, Williams BR, et al. Assessment of lateral authorship, and/or publication of this article. hindfoot pain in acquired flatfoot deformity using weightbear- ing multiplanar imaging. Foot Ankle Int. 2010;31(5):361-371. ORCID iDs 17. Ellis SJ, Yu JC, Williams BR, Lee C, Chiu YL, Deland Cesar de Cesar Netto, MD, PhD, https://orcid.org/0000-0001- JT. New radiographic parameters assessing forefoot abduc- 6037-0685 tion in the adult acquired flatfoot deformity. Foot Ankle Int. 2009;30(12):1168-1176. Jonathan Day, MS, https://orcid.org/0000-0003-1106-3042 18. Fortin PT. Posterior tibial tendon insufficiency. Isolated fusion Scott J. Ellis, MD, https://orcid.org/0000-0002-4304-7445 of the talonavicular joint. Foot Ankle Clin. 2001;6(1):137-151, Jeffrey E. Johnson, MD, https://orcid.org/0000-0003-2055-9998 vii-viii. 4 Foot & Ankle International 00(0)

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