Diagnosis and Management of Intraoperative Fractures in Primary

1 7 The prevalence of intra- 7 Overall, appropriate recognition, Hence, the demand for primary THA 8 3 – 1 This is especially relevant because complications 6 – 4 s overall quality of life. ’ otal hip arthroplasty (THA) is oneprocedures of in the reducing most effective pain, and restoringtient successful function, and improving a pa- Periprosthetic fractures (PPFx) are devastating complications related with has increased over the past 20the years and upcoming is projected decade. to exponentially grow in including mindfulness of preoperativecritical patient to and the surgical successfultraoperative risk management fractures. factors, of This is incidence, both comprehensive patient acetabular and review and surgical risk article femoral factors, in- focuses diagnosis, management, on clinical the operative PPFx (IPPFx)utilization has increased of in recent cementless years with implants. the increasing after THA areprocedural expected volume. Most to complicationsmon, concomitantly associated preventable increase if with anticipated, THA with and are the managed uncom- when increase recognized. in an increase inclinical other outcomes postoperative and complications increased that mortality may rates. lead to worse T ABSTRACT Intraoperative periprosthetic fractures are challenging complications that may affect implant stability andacetabular survivorship. fractures Periprosthetic are uncommon and infrequentlystudies. are Acetabular the fractures are focus occasionally of recognized after patients report unremitting groin pain weeks postoperatively.use The of widespread cementless acetabular cups mightfractures lead than to is higher clinically number detectable. of Conversely,intraoperative the periprosthetic incidence femoral of fractures are moreencompass common a and broad spectrum, ranging from a small cortical perforation to displaced fractures with an unstablerecognition, prosthesis. including Appropriate mindfulness of preoperative patient and surgical risk factors, is critical to the successful managementfemoral of complications. acetabular This and comprehensive review articlethe focuses incidence, on patient and surgical riskmanagement, factors, and diagnosis, clinical outcomes associated withacetabular intraoperative and femur fractures in primary total hip arthroplasty.

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JAAOS From the Department ofClinic Orthopedics, Cleveland Foundation, Cleveland, OHPiuzzi), (Siddiqi, the Department ofOrthoCarolina Orthopedics Hip Atrium, and KneeMusculoskeletal Center, Institute, Charlotte, NC (Springer), and the DepartmentBrigham of and Orthopedics, Women’s Hospital,(Chen). Boston, MA Siddiqi or an immediate familyan member serves unpaid as consultant tostock AZ or Solutions, stock LLC; options has serves held as in a ROMTech paid and Piuzzi consultant or to an Zimmer-Biomet. immediateas family a board member member, serves owner, officer,member or of committee ISCT; servesowner, as officer, a or board committee member, of member Knee of Surgery, Journal JournalOrthopaedic of Research Hip Society. Surgery Piuzzi and immediate or family an member has receivedor research institutional support fromZimmer-Biomet. RegenLab Springer and serves asmember, a owner, officer, board or committee memberKnee of Society, AJRR, AAHKS, Arthroplasty Today and Journal of Arthroplasty;Ceramtec, paid Convatec, Joint consultant purifications for systems, osteoremedies; receives royalties fromChen Stryker. serves as a boardor member, committee owner, member officer, ofAnnals AAOS, of AJRR, AAHKS, Joint, CORR,Association, European Healthcare Knee Transformation ICJR, JOA, JBJI, JBJS, JOR,received KSSTA, royalties MSIS; and paid has consultant fromConvatec, AMA, Ethicon, GLG, Graftworx, Guidepoint, Heraeus, Hyalex, Irrimax, JointSystem, Purification Pfizer, PhagoMed, Recro,incorportated, SLACK Sonoran, Stryker, UpToDate. J Am Acad Orthop Surg DOI: 10.5435/JAAOS-D-20-00818 Copyright 2021 by the AmericanOrthopaedic Academy Surgeons. of Nicolas S. Piuzzi, MD Bryan D. Springer, MD Antonia F. Chen, MD, MBA Fractures in Primary Total Hip Arthroplasty Ahmed Siddiqi, DO, MBA Diagnosis and Management of Intraoperative Review Article

Downloaded from http://journals.lww.com/jaaos by k38zdtHxkv6vYCpY6eTuHAvjaBKfkiBvTDlT9UnCurpiFF0LpmGCRtZciWbnx/5o97dLVS/w6H4UBNoIdbWSMFPfrDRrgELMxjRi3nLPvlA5oKaJ+Q9/ELdcC+W3OaGdzSaoRM9vgAY= on 01/21/2021 Downloaded from http://journals.lww.com/jaaos by k38zdtHxkv6vYCpY6eTuHAvjaBKfkiBvTDlT9UnCurpiFF0LpmGCRtZciWbnx/5o97dLVS/w6H4UBNoIdbWSMFPfrDRrgELMxjRi3nLPvlA5oKaJ+Q9/ELdcC+W3OaGdzSaoRM9vgAY= on 01/21/2021 Intraoperative Fractures in Primary THA outcomes, and cost associated with intraoperative acetabular IPPFx; therefore, the true incidence and preva- tabular and femur fractures in primary THA. lence remain unknown. Because implant survivorship relies on stable bone- prosthesis interfaces, vigilant fracture identification that disrupt the femoral-implant or acetabular-prosthesis Incidence interface is critical because failure to recognize may The incidence of femoral IPPFx has been reported to be have serious implications on component function and between 0.1% and 1% for cemented and nearly 5% for survival.9 cementless primary THA.9 Other studies have reported the incidence of femur IPPFx to be as high as 27.8%.8 The discrepancy in the prevalence of this complication may be accounted for by diverse demographic data, Risk Factors multitude of femoral implant types, surgical history, and Patient Factors surgeon proficiency.10 Several patient characteristics are associated with an By contrast, periprosthetic acetabular fractures are increased IPPFx risk. Female sex and increased age are more uncommon, with reported rates as low as 0.4%.9 independent and nonmodifiable risk factors.12 Lindberg- Although cementless acetabular components in primary Larsen et al 13 found women, osteoporosis, and poor THA have become more common over the past few bone quality to have reduced cortical thickness indices decades, most fractures are unrecognized intra- leading to an increased risk of fracture. Canal bone ratio operatively. Recently, Hasegawa et al 11 reported an (CBR), or the ratio between the inner and outer diam- 8.4% prevalence of occult acetabular fracture con- eters of the proximal femur 10 cm below the less tro- firmed on postoperative computed tomography (CT) chanter, is a validated method to assess bone quality on imaging; however, these fractures were unrecognized plain radiographs with CBR $0.49 in the proximal intraoperatively or through postoperative radiographs. femur as a threshold for osteoporosis (Figure 1).14 Currently, limited population-based data exist on ace- Zhang et al 10 found that patients with CBR $0.49,

Figure 1

Radiographs demonstrating the (A) canal-calcar ratio (CCR) = E/C, canal flare index (CFI) = A/E, morphological cortical index (MCI) = B/D, canal bone ratio (CBR) = E/F. (B) Anteroposterior (AP) radiograph of femur with a relatively wide canal and thin cortices suggestive of osteoporosis. CBR = 0.68 with a T score = 25.34. (C) Anteroposterior (AP) radiograph of femur with a relatively narrow canal and thick cortices. CBR = 0.34 with a T score = 22.02. (Adapted from Yeung Y, Chiu KY, Yau WP, Tang WM, Cheung WY, Ng TP. Assessment of the proximal femoral morphology using plain radiograph-can it predict the bone quality? J Arthroplasty. 2006; 21(4):508-13.)

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Radiographs demonstrating the Dorr classification serving as a descriptor of femoral morphology and bone quality. Type A femurs have a narrow canal with thick cortical walls (champagne flute canal). Type B femurs have moderate cortical walls. Type C femurs have a wide canal with thin cortical walls (stove-pipe canal). (Adapted from Ponzio DY, Shahi A, Park AG, Purtill JJ. Intraoperative Proximal Femoral Fracture in Primary Cementless Total Hip Arthroplasty. J Arthroplasty. 2015; 30(8):1418-22.) decreased bone mineral density, and women to be of intraoperative femur fractures during its learning associated with both intraoperative and postoperative curve.17,18 Masonis et al 17 reported three intraoperative PPFx. Dorr et al 15 classified the proximal femur mor- calcar fractures in the first 62 of 300 (4.8%) DAA THA. phology according to the CBR (Figure 2). Dorr-C Similarly, Jewitt et al 19 found that most IPPFx occur in femurs represent a lower CBR and have a 2-fold to 5- the first 200 DAA procedures (20/200 cases, 10%). The fold higher risk of intraoperative and undiagnosed learning curve is related to intrinsic femoral exposure postoperative PPFx.13 difficulty and orientation while broaching.20 In a retrospective review of 793,823 primary THA The impact of minimally invasive techniques with patients, Lamb et al 16 found a bimodal age distribution other anterior-based approaches, including the modified of older than 50 years and younger than 80 years to anterolateral (AL) and direct lateral (DL) approaches, have increased IPPFx risk along with patients with has also been reported as risk factors for IPPFx. Asayama American Society of Anesthesiologists grade 3 to 5. et al 21 reported intraoperative fractures in 3.8% pa- Medical comorbidities—such as vitamin D and calcium tients (2/52) who underwent minimally invasive DL deficiency, inflammatory arthritis, and metabolic bone THA. Similarly, Lamb et al 16 found a 1.09 relative risk disease, and conditions with aberrant acetabular or (RR) of femoral IPPFx for AL approach versus DL or proximal femur anatomy, such as protrusio, dysplasia, posterior approach. Anterior-based approaches place or Paget disease—have also been reported to have substantial forces on trochanteric muscle attachments higher IPPFx risk.10,12,16 and the femur, which are often under tension during femoral canal preparation and stem impaction.16 The Surgical Approach medial gluteal muscles may direct broaches and final Several studies have reported the direct anterior implant positions in the medial and anterior directions, approach (DAA) to be associated with an increased rate introducing stress forces to the medial cortex and

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Figure 3

Figure demonstrating theAcetabular component designs of hemispherical, peripheral self-locking, and elliptical cups. Elliptical cups have a peripheral flare 2 mm larger than a cup diameter and peripheral self-locking cups have a rim that is 1.8 mm larger than the cup diameter. (Adapted from Hasegawa K, Kabata T, Kajino Y, Inoue D, Tsuchiya H. Periprosthetic Occult Fractures of the Acetabulum Occur Frequently During Primary THA. Clin Orthop Relat Res. 2017; 475(2):484-494.) predisposing to calcar fracture.22 Increased rotational types, elliptical peripheral self-locking cups have been trochanter and femoral shaft loading may explain the reported to with the highest risk of IPPFx.12 increased risk of IPPFx.16 However, no studies exist, to our knowledge, reporting surgical approach risk factors Femur on acetabular IPPFx. Regardless of the surgical Cementless femoral stems have grown in popularity approach, adequate acetabular and femoral exposure because of their relative ease and implantation efficiency. with appropriate retractor placement is necessary before Various cementless stem designs exist as noted in the reaming and broaching, respectively. review article by Khanuja et al 24 However, certain stem designs are associated with a higher risk of IPPFx. Implant Factors Overall, 90% of IPPFxs occur in “fit-and-fill” stems Acetabulum (type-2), whereas the remaining 10% are in anatomic Most THAs in the United States use cementless acetab- stems (type-6), likely attributed to the substantial prox- ular components. Acetabular preparation techniques imal femoral geometry variability that can affect include line-to-line reaming and under-reaming mechanical stress distribution (Figure 4).25 Although (1–2 mm) for interference fit, often depending on the first-generation cementless, tapered wedge designs have implant. Under-reaming and press-fit impaction with or excellent long-term outcomes, they are also associated without adjuvant screws has been the most prevalent with higher rates of intraoperative and postoperative acetabular reconstruction method.11 However, Sharkey femur fractures.26 Studies have also reported an increased et al 23 reported that acetabular IPPFx commonly occur rate of occult femoral IPPFx with double-tapered stems from oversized acetabular component insertion in an with a proximal and distal trapezoidal and quadrangular under-reamed cup or excessive medialization with poor cross-section, respectively.27 However, shorter cement- bone quality. less reduced femoral geometry stems have been shown to Acetabular component designs are classified as hemi- decrease fracture risk.26 spherical, peripheral self-locking, and elliptical (Figure 3). Femoral IPPFx can occur during both stem broaching Elliptical cups have a peripheral flare, whereas peripheral and final component impaction. During broaching, self-locking cups are structured with a rim that is 1.8 mm femoral fracture can be predisposed by the broach larger than the true cup diameter.11 Of all the design geometry, the cutting or compaction tooth broach

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Schematic drawings illustrating the classification of the cementless femoral stem designs. Type 1 is a single wedge, type 2 is a double wedge, type 3A is tapered and round, Type 3B is tapered and splined, Type 3C is tapered and rectangular, type 4 is cylindrical and fully coated, type 5 is modular, and type 6 is anatomic. P = posterior and A = anterior. (Adapted from Khanuja HS, Vakil JJ, Goddard MS, Mont MA. Cementless femoral fixation in total hip arthroplasty. J Bone Joint Surg Am. 2011; 93(5):500-9.) pattern, and surgical technique.28 Berend and Lombar- roversion placement of the stem.28 During insertion, the di8 compared the incidence of IPPFx between 439 stem should move distally with each mallet impaction tapered-wedge stems with a single low-profile cutting with the same impaction intensity. If the stem starts to blade calcar mill with 18 proximally modular tapered- advance at a notably increased rate during impaction, wedge design stems with a calcar mill with multiple deep an intraoperative fracture should be suspected, and the cutting teeth. The authors found an 11% IPPFx rate in proximal femur should be meticulously inspected. patients in whom a multiple-toothed stem broach was used compared with 0% using the comparison broach. During the final femoral implant impaction, fracture Prevention can be caused by implant geometry, correlation of the Because IPPFxs may be associated with poor clinical out- broach to the implant, broach canal preparation, and comes and high mortality rates, prevention of intraoperative surgical techniques such as excessive anteversion or ret- fractures is pivotal. Prevention of periprosthetic fractures

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Figure 5 hip. Orthogonal Judet views and CT scan may be ob- tained in the presence of any bone deformity or bone loss that may increase the likelihood of IPPFx. Acetabular and femoral components should be carefully planned with the use of conventional or digital templating on preoperative radiographs to anticipate component sizing. A different femoral stem may need to be used, or at least should be available as backup, if mismatch exists between the femoral stem and the patient’s proximal femoral anatomy. If the templated component is unstable by multiple sizes, careful acetabular and femoral inspection is needed to confirm a lack of fracture that can cause instability and fixation failure.12 During surgical exposure, adequate soft-tissue releases and exposure is needed before procedural parts that are at highest risk for fracture such as hip dislocation, acetabular reaming and implant impaction, and femoral canal preparation and stem insertion. Eccentric acetabular reaming should be avoided, although bone loss regions should be carefully protected from errant Figure demonstrating the modified anatomic classification for retractor placement. Temptation to ream to a larger cup — intraoperative acetabular fractures includes five areas the (1) to gain a larger femoral head size should be avoided, medial wall, (2) posterior wall, (3) superolateral wall, (4) anterior wall, and (5) other locations. (Adapted from Hasegawa K, particularly in elderly and female patients, because this Kabata T, Kajino Y, Inoue D, Tsuchiya H. Periprosthetic Occult can notably thin the acetabular bone and increase the risk Fractures of the Acetabulum Occur Frequently During Primary of insertional fracture. THA. Clin Orthop Relat Res. 2017; 475(2):484-494.) The utilization of suction, normal saline irrigation, and drying allows for clear bone visualization, especially during requires careful preoperative planning with comprehensive femoral broaching. Careful attention is needed for femoral assessment of risk factors. A detailed history and physical alignment and the direction of instruments during the prep- examination should focus on the assessment and optimiza- aration and insertion of the femoral broach and stem. Special tion of patient comorbidities and overall nutrition. Thor- care should be taken so as to not to impact the femoral ough preoperative screening and management of broach or definitive stem until it has been fully seated by the osteopenia/osteoporosis is critical. Current guidelines rec- hand. Intraoperative imaging may be used to ensure central ommend all women older than 65 years be screened with placement of implants in the medullary canal in complex dual energy x-ray absorptiometry.29 Women, older than 65 primaries with femoral deformity or obese individuals where years, warrant screening if the estimated 10-year fracture exposure may be challenging. If the final femoral implant risk equals or surpasses a 65-year-old Caucasian woman advances beyond where the trial broach was seated, there without risks.29 The US Preventative Services Task Force should be a high suspicion for an intraoperative fracture. An reports inconclusive data to recommend routine osteopo- in-vitro finite element analysis study demonstrated that 2 rosisscreeningformen.29 Bisphosphonates are recom- “high-average” mallet strikes were sufficient for femoral mended as first-line pharmacologic treatment.29 The stem seating with subsequent similar forces having minimal optimal intake of calcium and vitamin D is uncertain. seating effect while substantially increasing the risk of Postmenopausal women are recommended 1200 mg of microfracture from greater stress concentration in the calcium (total blood calcium 8.5 to 10.3 mg/dL; ionized medial calcar region.30 Prophylactic cerclage with either a calcium 4.4 to 5.4 mg/dL) and 800 international units (IU) metallic cable or braided suture can reduce strain and of vitamin D daily (target range 40-80 ng/mL).29 Although increased hoop stress resistance to reduce the risk of IPPFx guidelines for premenopausal women or men with osteo- in higher-risk patients.25 A recent cadaveric biomechanical porosis are more variable, 1000 mg of calcium and 600IU study found that collared cementless stems to offer a pro- of vitamin D daily are generally suggested.29 tective effect in torsional loading which can cause early Preoperative radiographs should include an ante- PPFx from missed IPPFx or trauma that occur before roposterior pelvis and cross-table lateral of the surgical implant osseointegration.31,32

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Table 1. Periprosthetic Acetabular Fracture Classification in Primary Total Hip Arthroplasty Study Classification Subclassification Description Peterson et al.34 Type I—Stable cup — Postoperative fractures only — Type II—Unstable cup —— Callaghan Anterior wall transverse — Based on in-vitro investigation et al.35 — Inferior lip —— — Posterior wall —— Della Valle Type 1—intraoperative component 1A: Nondisplaced fracture, Complex classification and et al.36 insertion recognized, stable component difficult to implement clinically —— 1B: Displaced fracture, recognized, — cup unstable —— 1C: Not recognized intraoperatively — — Type 2—Intraoperative during cup 2A: , 50% bone stock loss — removal —— 2B: .50% bone stock loss — — Type 3—Traumatic 3A: Stable component — —— 3B: Unstable component — — Type 4—Spontaneous 4A: ,50% bone stock loss — —— 4B: .50% bone stock loss — — Type 5—Pelvic discontinuity 5A: ,50% bone stock loss — —— 5B: .50% bone stock loss — —— 5C: Associated with pelvic radiation — Davidson et al.12 Type I—nondisplaced with implant — Vancouver classification stability modification; type 2 fractures may include transverse acetabular fractures that may occur with acute pelvic discontinuity or an oblique fracture that separates the anterior column and posterior column acetabular dome. — Type II—nondisplaced fracture that —— may compromise implant stability — Type III—displaced fracture that —— requires surgical fixation

Other studies have also shown a large cumulative sidered in patients with abnormal, dysplastic anatomy. fracture reduction risk with the use of cemented implants, Cementing femoral stems should strongly be considered in posterior approach, and computer-assisted surgery. It is patients with abnormal anatomy, especially in elderly critical to identify femoral geometry preoperatively that patients with Dorr C bone, because of immediate fixation may predispose to fracture such as Dorr C femurs. In concerns and the occurrence of intraoperative and post- addition, femurs with high valgus necks, as seen in dys- operative fractures around cementless designs. Although plasia, are difficult to match with modern broach only registry studies have shown a decreased risk of revision for stem designs that further predisposes patients for fracture fracture with cemented constructs, few studies within the risk. Cemented stems, proximally fitting monoblock PPFx literature provide detailed implant information30 splined tapered stems, proximal modular stems, or Within cemented stems, loaded-taper (Exeter) stems have diaphyseal engaging stems that allow anteversion man- been associated with more PPFx than composite-beam agement to be independently addressed should be con- (Charnley) stems.

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Figure 6

Figures demonstrating the Mallory Classification of intraoperative femur fractures in primary total hip arthroplasty. (Adapted from Mallory TH, Kraus TJ, Vaughn BK. Intraoperative femoral fractures associated with cementless total hip arthroplasty. Orthopedics. 1989; 12(2):231-9.)

implant stability and may require implant removal to Diagnosis fully assess the extent of the fracture morphology and Acetabulum acetabulum. This is done to determine whether a pri- A high-index of suspicion for acetabular IPPFx is mary hemispherical cup is still a viable option for doing important because recognition is often challenging. Pre- primary THA or whether a revision component is operative radiograph templating is helpful for providing needed for additional screw or plate fixation. Undiag- an idea of the anticipated implant sizing. A fracture may nosed acetabular IPPFx are often identified postopera- be suspected if the acetabular reamer size and implant is tively when patients continue to report groin pain weeks notably larger than preoperative templating or if the after surgery. Advanced imaging, such as a CT scan, implant is unable to be implanted with stability. When may be used to confirm the diagnosis. Postoperative concern of a possible fracture exists, a full clinical and management of intraoperative acetabular fracture usu- radiographic assessment is warranted. Although diffi- ally consists of protected weight-bearing with gradual cult, obtaining intraoperative Judet-views may help progression after 6 to 8 weeks to allow for bone healing. demonstrate acetabular column and wall integrity. Careful determination of component stability with the Femur utilization of manual pelvis and acetabular implant stress Similar to acetabular IPPFx, a high-index of suspicion is testing is required. If a fracture is identified after final cup needed for diagnosing iatrogenic femur fractures. It is impaction, it must be thoroughly exposed so that the critical to do adequate soft-tissue releases before hip dis- entire fracture is visualized. Often times, small (“episi- location and maintain adequate visualization, especially otomy like”) cracks are noted that may not affect the by the calcar, before broaching and femoral stem inser- stability of the implant. However, a fracture that tion.33 During broach and femoral stem insertion, a propagates near or into the sciatic notch can affect sudden change in resistance with a previous interference

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Figures demonstrating the Vancouver classification of intraoperative femoral periprosthetic fractures. A: type A1; B: type A2; C: type A3; D: type B1; E: type B2; F: type B3; and G: type C1. (Adapted from Davidson D, Pike J, Garbuz D, Duncan CP, Masri BA. Intraoperative periprosthetic fractures during total hip arthroplasty. Evaluation and management. J Bone Joint Surg Am. 2008; 90(9):2000-12.) fit is highly suggestive of a femur fracture. Intraoperative pattern and only categorized postoperative injuries. In radiographs and further surgical dissection are critical to an in-vitro study, Callaghan35 et al classified acetabular further evaluate the presence and extent of the fracture. IPPFx into four types based on the anatomic location. Importantly, nondisplaced fractures are not readily rec- Hasegawa et al 11 expanded the anatomic classification ognized in plain radiographs, further highlighting the of Callaghan into five areas after conducting a CT-based need to combine intraoperative clinical findings in con- study evaluating occult acetabular fracture (Figure 5). junction with advanced imaging for prompt fracture Della Valle et al 36 further categorized acetabular diagnosis. Implant stability has to be carefully assessed fracture into intraoperative and postoperative types; before final reduction and wound closure to mitigate however, the classification has not routinely been used, catastrophic postoperative complications and instability. given the difficulty to implement clinically. Davidson et al 12 revised the Vancouver periprosthetic fracture classification system to include intraoperative acetabular fractures. Although this revised classification has not Classification been validated, it provides clinical assessment that helps Acetabulum guide intraoperative management (Table 1). Periprosthetic acetabular fractures were first classified by Peterson et al 34 into type-I and type-II fractures with Femur stable and unstable acetabular cups, respectively. Mallory et al 37 first classified femoral IPPFx in the early However, the authors did not account for fracture 1980s as type-I, type-II, and type-III depending on the

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Table 2. Vancouver Classification for Intraoperative Periprosthetic Femur Fracture in Primary Total Hip Arthroplasty

Classification Fracture Site Subclassification Description Type A Proximal metaphysis Subtype 1 Cortical perforation Type B Diaphysis Subtype 2 Nondisplaced fracture Type C Distal to stem Subtype 3 Displaced fracture Unstable stem

femoral shaft location (Figure 6). However, the Van- weight-bearing (FFWB) with gradual progression after couver classification is most commonly used for intra- signs of fracture healing and bone consolidation. Our operative and postoperative periprosthetic femur algorithm for the management of acetabular IPPFx is fractures. The intraoperative fracture classification is summarized in Figure 9. based on the fracture location, pattern, and femoral stem stability, whereas the postoperative categorization Femur accounts for fracture location, implant stability, and Similar to acetabular fractures, the principles of femur residual bone stock.10 Unlike the postoperative Van- IPPFx focus on fracture stabilization, prevention of couver classification, the intraoperative categorization fracture propagation, protection of component align- has not been validated (Figure 7 and Table 2).10,12 ment, and stability.12 Although lack of comparative studies providing standardized treatment exists, accurate fracture classification helps guide appropriate Management management options. Although the intraoperative Acetabulum Vancouver classification has not been validated, it is The principles of acetabular IPPFx management focus most commonly used to guide definitive fracture on fracture stabilization, mitigation of fracture propa- management. gation, preservation of component alignment and stability, and ultimate fracture union.12 When discovered Adjuvant Fixation Constructs intraoperatively, nondisplaced fractures with stable Biomechanical studies have compared strengths of dif- components can be left in situ with additional ace- ferent fixation constructs. Allograft strut fixation with tabular screw fixation and conventional postoperative cerclage wires do not provide adequate strength and rehabilitation protocols with potential modification of stability compared with cerclage cables.38 Cerclage ca- weight-bearing. If the component is unstable, anterior bles resulted in increased strut compression and and posterior column integrity evaluation should be enhanced frictional resistance between allograft and done to determine further stabilization options. Utili- host cortical bone.38 Fixation with a limited contact zation of a large revision cup with multiple multidi- dynamic compression plate and unicortical screws for rectional screw fixation, morselized allografts, and distal intraoperative fractures has comparable strength acetabular reamings for local bone graft should be with allograft struts and cerclage cables.38 Other bio- considered. If substantial fracture instability or pres- mechanical studies have shown that plate constructs ence of acute pelvic discontinuity exists, the posterior with screws only or screws combined with cables pro- column should be stabilized with a column recon- vide optimal stability.11 Although dual plating along the struction plate. After the pelvis is stabilized, the ace- lateral and anterior femoral cortex provides greater tabulum can be reconstructed with a traditional rigid fixation of unstable intraoperative fractures com- surgical technique (Figure 8). pared with a single lateral plate with screws/cables, If posterior column fixation does not provide ade- studies report notable disadvantages of additional soft- quate stabilization, revision reconstructive options tissue dissection and disruption for the dual-plating with a cup-cage and bone grafting can allow for tempo- strategy.11 Wilson et al 39 demonstrated that the optimal rary fixation until fracture union and bony acetabular method of fracture fixation with a stable stem was a implant ingrowth are achieved. If fracture fixation with plate with an anterior allograft cortical strut. Although revision component reconstruction is needed, postoper- achieving optimal implant and fracture stability are the ative protocols can be modified to protected flatfoot goals, the minimal stability needed for successful

Radiographs demonstrating the (A) intraoperative acetabular fracture of the floor, anterior and posterior columns. (B) Postoperative radiographs after open reduction and internal fixation of the acetabulum with an anterior column screw and a posterior column plate, followed by acetabular reconstruction and implantation of a standard femoral component. (Adapted from Davidson D, Pike J, Garbuz D, Duncan CP, Masri BA. Intraoperative periprosthetic fractures during total hip arthroplasty. Evaluation and management. J Bone Joint Surg Am. 2008; 90(9):2000-12.) fracture union and implant longevity after intra- management consists of augmenting fixation with cerc- operative injury is unknown. Furthermore, considerable lage cables if the implant is stable. If stem stability is risk has been associated with femoral wiring or cabling, compromised, a longer diaphysis engaging component is including nerve and vascular injury.8 needed to bypass the defect and distal fracture extent similar to the management of unstable type-A fractures Femur Management by Fracture Type (proximal metaphysis and calcar). Cortical allograft may Type-A1 fractures (proximal metaphysis and cortical be used adjunctively in patients with poor bone quality or perforation) can often be treated with bone graft alone when a stem is unable to bypass the defect for a stable fit. from either morselized allograft or autograft from ace- However, these injuries can often be missed intra- tabular reaming or from a longer metaphyseal fit stem operatively and are usually recognized on postoperative 12 (Figure 10). Type-A2 fractures (nondisplaced and cal- radiographs. If nondisplaced diaphyseal femur IPPFx car) should be closely inspected to determine the distal are diagnosed postoperatively, patients should maintain extent of the fracture. If a fracture is recognized after FFWB for 6 to 8 weeks with serial radiographs and close final stem insertion, the stem should be removed for observation. better metaphyseal and diaphyseal evaluation. Cerclage Type-C fractures (distal to stem) are uncommon dur- stabilization with either metal or polymer cables along ing primary THA and are more common in revision THA the fracture site and distal to the fracture can help sta- procedures; however, they can occur from increased bilize and prevent further propagation.12 Bypassing rotational torque during native hip dislocation or after unstable fractures beyond 2 to 3 cortical diameters distal trialing. Our algorithm for the management of femur to the defect and fracture extent is considered effective in IPPFx is summarized in Figure 11. preventing subsequent fracture.40 Isolated greater trochanteric fractures may generally be managed with trochanteric fixation methods, including cables and/or Clinical Outcomes claw plates, to reduce trochanteric escape and antalgic Acetabulum gait postoperatively. Proximal femur IPPFx do not Because intraoperative periprosthetic acetabular frac- impede the utilization of stem cementation in elderly tures are uncommon, a paucity of literature reporting patients. However, it is critical to prevent cement clinical outcomes after different management options extrusion into surrounding soft tissues through bone exists. In a retrospective review of 13 acetabular IPPFx, defects and the fracture site during pressurization to Sharkey et al 23 reported that 6 patients were treated optimize the cement mantle and allow for appropriate with additional acetabular screw fixation, two patients fracture healing.12 did not receive additional fixation or alteration in Type-B fractures (diaphyseal) commonly occur from postoperative rehabilitation, and one patient was trea- increased hoop stresses during broaching or stem ted with protected non–weight-bearing without any impaction. If the diagnosis is made intraoperatively, additional fixation support. The authors reported

Figure 9

Algorithm demonstrating the acetabular periprosthetic fracture management. fracture union in 9 patients, although 4 patients who Femur were identified to have acetabular IPPFx postoperatively Similar to acetabular fractures, the treatment outcomes had progressive implant loosening during the short-term of intraoperative femur fracture are also difficult to follow-up. Two of the four patients underwent revision compare because of different fixation strategies without arthroplasty. comparative cohorts. Hasegawa et al 11 reported 43 occult acetabular fractures in 585 primary THA patients with only in- Calcar Fractures traoperative identification of 2 peripheral rim fractures. Treatment of intraoperative calcar fractures is generally The patients were managed with additional screw fix- managed with cable or wire fixation at the level of the ation and non–weight-bearing for 3 weeks. Although lesser trochanter. Berend et al 41 retrospectively reviewed the authors did not report weight-bearing modification 1,320-primary THAs with 58 intraoperative calcar for undiagnosed intraoperative injuries, all occult fractures (4.4%) managed with cerclage wires or cables fractures achieved fracture union with superolateral or without postoperative rehabilitation modification. At a inferomedial bone ingrowth without component mean of the 7.5-year follow-up, all patients achieved radiographic alignment change or migration at the 12- fracture union without revision arthroplasty. Duwelius month follow-up.11 However, 24/43 patients (56%) et al 42 also reported two femoral IPPFx that extended were followed for more than 5 years and maintained beyond the lesser trochanter that were managed with component stability without failure. Although all two cerclage wires without complications. Cerclage occult acetabular fractures did not demonstrate any wires have shown to reduce the risk of fracture prop- clinical failure, the authors suggest that missed injuries agation and achieve satisfactory initial implant stability may be sources of unexplained pain during the early without compromising clinical outcomes.43 postoperative period after primary THA. Although future prospective studies with larger sample size may Greater Trochanter help provide definitive treatment guidelines, compar- The greater trochanter may fracture during extension, espe- ative studies may be challenging because of the rarity of cially during DAA, in patients with osteoporotic/osteopenic this intraoperative complication. bone or during broach extraction. If the soft-tissue sleeve of

Figures demonstrating the (A) intraoperative fluoroscopic anteroposterior (AP) view of the hip. (B) Immediate postoperative AP and (C) cross-table lateral radiographs reveal medial cortex perforation by the femoral stem. (D) The patient returned to the operating room the following day for revision total hip arthroplasty with a cementless metaphyseal fit and fill femoral. (Adapted from Cohen EM, Vaughn JJ, Ritterman SA, Eisenson DL, Rubin LE. Intraoperative Femur Fracture Risk During Primary Direct Anterior Approach Cementless Total Hip Arthroplasty With and Without a Fracture Table. J Arthroplasty. 2017; 32(9):2847-2851.) the bone is preserved without fragment escape, the fracture residual limp and continued pain at the short-term can be left without fixation because healing often occurs with follow-up (,1-year). The utilization of trochanteric the bone or fibrous union without notable effect on clinical claw plates, tension band wiring, or suture fixation have outcomes.44 Postoperative abduction exercises are often been described mostly in the context of extended tro- avoided. However, Rüdiger et al 44 demonstrated that pa- chanteric osteotomies or unstable intertrochanteric tients who sustained calcar fractures managed with cerclage fractures rather than IPPFx of the greater trochanter. cabling (n = 5) or greater trochanter fractures managed Pritchett et al 46 concluded that intraoperative tro- conservatively (n = 8) had worse WOMAC scores at 1 year chanteric fractures do not require fixation unless postoperatively, compared with patients without fractures implant instability or notable fracture displacement (n = 471). exists, both of which are uncommon during primary Yassin et al 45 retrospectively reviewed 688 THA THA. using a DL approach and reported 28 intraoperative greater trochanter fractures with 54% (15/28) of frac- Diaphyseal Perforations/Fractures tures identified intraoperatively and managed with wire Other studies of intraoperative fractures have reported fixation. The missed fractures were diagnosed within the less successful outcomes. ElSerwi et al 47 reported their first 3 months postoperatively with two patients pre- case series on femoral IPPFx with one B1 (diaphyseal senting with prosthesis dislocation. The authors perforation), three B2 (nondisplaced diaphyseal) frac- reported that all 15 fractures identified intraoperatively tures, and three B3 (displaced diaphyseal) fractures. The healed without complications. Missed fractures had B1 fracture patient was treated with cerclage wire

Figure 11

Algorithm demonstrating the femoral periprosthetic fracture management. fixation with fracture consolidation seen on radiographs provements in functional outcome contributed to lower at 7 months. B2 fracture patients were managed with patient satisfaction among IPPFx patients.48 longer stems and cerclage wiring with fracture consol- Nishihara et al 49 compared a series of patients who idation seen at a mean of 8.5 months. In B3 fractures, were hand-rasped for femoral preparation (n = 78) with two of the three patients were managed with plate fix- patients who were robotically milled (n = 78). In the ation with fracture union seen at 8 months. One missed robotically milled group, no intraoperative femoral B3 fracture was revised within 4 weeks postoperatively perforations/diaphyseal fractures were found compared to a diaphyseal engaging stem with cerclage wiring with with 6.4% (5/78) fractures in the conventional broach fracture union seen at 10 months. All patients had cohort. Patients with femur IPPFx had notably lower improved, yet lower, Harris Hip Scores (HHS) (range: walking ability with an assisted device within 2 weeks 74.6 to 89.5). after THA compared with the group without IPPFx (P , Similarly, Ferbert et al 48 retrospectively compared 50 0.05). Patients with IPPFx were also found to require IPPFx (21 calcar, 6 proximal metaphysis, five diaphyseal, higher postacute care with higher percent (41.7% versus and 18 greater trochanter) with a control group of patients 30.8%) of utilization and days of service at skilled receiving primary THA without complications matched nursing facilities (SNF) (13.3 days versus 6.8 days) and according to sex, age, BMI, and surgical indications. The inpatient rehab facility (IRF) (17.7% versus 10.1%; authors found that despite comparable stem survival at the 2.2 days versus 1.1 days) compared with patients midterm follow-up (mean 5.6-years), both the change in without IPPFx. HHS and patient satisfaction were collectively worse in the Similarly, in a retrospective observational cohort IPPFx cohort. Although both cohorts demonstrated HHS study using Medicare claims data, Chitnis et al 7 pro- improvement, the fracture cohort improved below pensity score matched 4,460 intraoperative fracture the minimally clinical important difference (MCID, .40 patients with 2,658 postoperative PPFx patients. points). The authors attributed the lower score to the However, 90-day postacute service usage was notably potentially greater soft-tissue trauma and subsequent higher among patients in both PPFx groups versus those abductor muscle impairment.48 Furthermore, delayed without fracture.7 The 90-day total all-cause payments mobilization, weight-bearing restrictions, and poorer im- were higher in both intraoperative ($30,114 versus

$21,229) and postoperative ($53,669 versus $ 19,817; medicare population: A retrospective cohort study. Medicine P , 0.0001) PPFx groups compared with those without (Baltimore) 2019;98:e15986. fracture. The cost differences during the 90-day global 8. Berend KR, Lombardi AV. Intraoperative femur fracture is associated with stem and instrument design in primary total hip arthroplasty. In: period were continued over 1 year. Clinical Orthopaedics and Related Research; 2010. doi: 10. 1007/s11999-010-1314-8. 9. Dammerer D, Putzer D, Glodny B, et al: Occult intra-operative periprosthetic fractures of the acetabulum may affect implant Summary survival. Int Orthop 2019;43:1583-1590. IPPFx are challenging complications that may affect implant 10. Zhang Z, Zhuo Q, Chai W, Ni M, Li H, Chen J. Clinical stability and survivorship. Periprosthetic acetabular frac- characteristics and risk factors of periprosthetic femoral fractures associated with hip arthroplasty A retrospective study. Med (United tures are uncommon and infrequently the focus of studies. States) 2016;95:e4751. Acetabular fractures are occasionally recognized after pa- 11. Hasegawa K, Kabata T, Kajino Y, Inoue D, Tsuchiya H: tients report unremitting groin pain weeks postoperatively. Periprosthetic occult fractures of the acetabulum occur frequently The widespread use of cementless acetabular cups might lead during primary THA. Clin Orthop Relat Res 2017;475:484-494. to higher number of fractures than is clinically detectable. 12. Davidson D, Pike J, Garbuz D, Duncan CP, Masri BA: Intraoperative Conversely, the incidence of intraoperative periprosthetic periprosthetic fractures during total hip arthroplasty: Evaluation and management. J Bone Joint Surg Ser A 2008;90:2000-2012. femoral fractures are more common and encompass a broad 13. 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