Soft Tissue Reconstruction and Flap Coverage for Revision Total Knee Arthroplasty

The Journal of Arthroplasty xxx (2016) 1e10

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The Journal of Arthroplasty

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Soft Tissue Reconstruction and Flap Coverage for Revision Total Knee Arthroplasty

Allison J. Rao, MD a, Steven J. Kempton, MD b, Brandon J. Erickson, MD a, * Brett R. Levine, MD a, Venkat K. Rao, MD, MBA b, a Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois b Division of Plastic Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin article info abstract

Article history: Background: Total knee arthroplasty is a successful operation for treatment of arthritis. However, devas- Received 24 August 2015 tating wound complications and infections can compromise the knee joint, particularly in revision situations. Received in revised form Methods: Soft tissue loss associated with poor wound healing and multiple operations can necessitate 22 December 2015 the need for reconstruction for wound closure and protection of the prosthesis. Accepted 28 December 2015 Results: Coverage options range from simple closure methods to complex reconstruction, including Available online xxx delayed primary closure, healing by secondary intention, vacuum-assisted closure, skin grafting, local ﬂap coverage, and distant microsurgical tissue transfer. Keywords: total knee arthroplasty Conclusion: Understanding the advantages and pitfalls of each reconstructive option helps to guide revision arthroplasty treatment and avoid repeated operations and potentially devastating consequences such as knee ﬂap arthrodesis or amputation. gastrocnemius © 2016 Elsevier Inc. All rights reserved. reconstruction

Total knee arthroplasty (TKA) is a recognized procedure for the periprosthetic joint infection (PJI), however, 2-stage reimplantation management of disabling knee arthritis with successful outcomes is widely accepted to be the standard of care in the United States resulting in marked pain relief and improved patient functionality. [3,4,6,7]. The first stage involves the removal of all prosthetic ma- Studies have cited survivorship of TKA of over 90%, 80%, and 70% at terial and foreign material from the joint, followed by extensive 10, 15, and 20 years, respectively [1,2]. Complications after TKA debridement, irrigation, and reaming of the medullary canals [5]. include persistent pain, stiffness, instability, or infection and can The joint is then loaded with a static or articulating antibiotic necessitate a need for revision surgery [3]. In a large meta-analysis cement spacer followed by closure of the soft tissues. Provided a of 9879 TKA patients followed for an average of 4.1 years, 89.3% reaspiration of the joint is negative for persistent infection and achieved a good or excellent result, 10.7% were fair or poor, and 3.8% there are no additional complications, return to the operating room underwent revision [4]. Other authors have reported the incidence is usually planned within 6-12 weeks for reimplantation [5]. of deep infection associated with TKA to range from 1.0%- 12.4%, all Wound complications after revision TKA can present a signifi- requiring revision [5,6]. With an increasing elderly population, the cant problem for the surgeon and the patient including delay of number of primary TKAs is projected to increase 673% by 2030, and reimplantation due to persistent infection, additional surgery for revision total arthroplasty will likely mirror this trend, especially as debridement of skin necrosis and/or flap coverage, and a longer patients continue to live longer [7]. than expected recovery period. A retrospective study at the Mayo Revision TKA for instability, stiffness, or persistent pain can Clinic from 1981 to 2004 found that of the 17,000 primary TKAs, often be accomplished in a single stage [8]. In the setting of there was a 0.33% incidence of wound problems requiring surgery within 30 days of index surgery [9]. Despite a low incidence, the probability of further major surgery (removal of implants, muscle One or more of the authors of this paper have disclosed potential or pertinent fl conflicts of interest, which may include receipt of payment, either direct or indirect, ap rotation, and leg amputation) or diagnosis of deep infection in institutional support, or association with an entity in the biomedical field which these patients was 5.3% and 6.0%, respectively, within 2 years of may be perceived to have potential conflict of interest with this work. For full index surgery. In contrast, TKAs at 2 years with no postoperative disclosure statements refer to http://dx.doi.org/10.1016/j.arth.2015.12.054. wound complications had a 0.6% and 0.8% incidence of needing a * Reprint requests: Venkat K. Rao, MD, MBA, Division of Plastic Surgery, major operation or a diagnosis of a deep infection, respectively. University of Wisconsin Hospital and Clinics, 600 Highland Ave, G5/350, Madison, WI, 53792. Additional patient factors to consider include patient advanced age, http://dx.doi.org/10.1016/j.arth.2015.12.054 0883-5403/© 2016 Elsevier Inc. All rights reserved. 2 A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 diabetes mellitus, connective tissue disease, malnutrition, rheu- devascularization of skin or bone and when helping the plastic matoid arthritis, vascular insufficiency, smoking, and steroid use, surgeon in reconstructive planning (Fig. 1). which can further delay wound healing [10-13]. Ultimately, mea- The main blood supply to the knee arises from branches from sures that can be taken to minimize wound complications would the femoral artery, popliteal artery, and anterior tibial artery. The translate into improved patient outcomes and prevent potential skin surrounding the knee is perfused through an anastomosis of loss of the prosthesis or even of the limb [14]. vessels just superficial to the deep fascia, fed by underlying perfo- Wound complications and multiple reoperations may compro- rating vessels [14]. Perforators over the medial and anterior aspect mise the soft tissue coverage of the knee, requiring treatment to fill of the knee are supplied by the saphenous branch of the descending dead space, protect the prosthesis, and close the wound. Skin or genicular artery, with a small contribution anterior inferiorly from muscle flap coverage is often required in these situations, either as the anterior tibial recurrent artery. Perforators feeding the deep prophylactic treatment for anticipated wound complications or fascial plexus laterally include the superior and inferior lateral during revision. Markovich et al described 12 patients who were genicular branches of the popliteal artery [15]. The deep fascial treated with muscle flaps used for different treatment purposes: (1) vascular network sends vessels that penetrate the subcutaneous fat prophylactic soft tissue coverage before definitive reconstruction, to reach the epidermis; however, there is little communication (2) muscle flaps for treating infected prostheses with deficient soft between vessels at the superficial level. Therefore, wide dissection tissue coverage, and (3) salvage muscle flaps for wound dehiscence superficial to the deep fascia will compromise the blood supply to or necrosis in the immediate postoperative period. At an average the skin, whereas dissection deep to the fascia will maintain the 4.1-year follow-up, the wound was revascularized in 100% of knee, skin blood supply [16]. This illustrates the need for elevation of full- and the prosthesis preserved in 83% [11]. thickness skin flaps during dissection. Although complex wound coverage is often driven by the plastic The blood supply to the patella should be preserved to prevent surgeon, the orthopedic surgeon should be familiar with the patellar osteonecrosis and fragmentation, both of which can lead to reconstructive options and actively participate in decision making periprosthetic and wound infections [16]. The patellar blood supply to facilitate a collaborative effort toward the best possible patient arises from an anastomotic ring fed by the muscularearticular branch outcomes. In this review, the management of wound complications of the descending geniculate artery, the 4 genicular arteries (superior and soft tissue defects surrounding the knee will be discussed, with medial, inferior medial, superior lateral, and interior lateral), and the specific focus on skin grafts, local skin flaps, and free flap coverage. anterior tibial recurrent artery, from which the transverse infrapa- tellar artery and the oblique prepatellar arteries arise. Importantly, this vascular network does not contribute significantly to skin blood Vascular Considerations supply because of lack of communication through the prepatellar bursa. Intraosseous blood supply to the patella arises from pene- An extensive knowledge of knee vascular anatomy is essential to trating vessels from the inferior aspect of the patella and from the guide both the orthopedic approach to revision TKA to prevent middle third of the anterior surface of the patella [17].

Fig. 1. Vascular anatomy about the knee. A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 3

During initial arthroplasty using a standard parapatellar approach just medial to midline, contribution of the 3 medial blood vessels (saphenous, superior medial genicular, and inferior medial genicular) supplying the patella will be interrupted. In addition, the inferior lateral genicular artery will be interrupted during excision of the lateral meniscus, and branches of the anterior tibial artery may be removed during excision of the fat pad [16,18]. If not already divided, care should be taken during revision to preserve the superior lateral genicular artery, which can be found deep to the synovium in the plane of the vastus lateralis muscle [15]. During revision TKA, the posterior cruciate ligament is commonly removed or no longer functioning [16]. Care should be taken when removing the posterior cruciate ligament as it is possible to penetrate the posterior capsule and damage the popliteal contents, including the popliteal artery and vein, and tibial nerve. Branches of the popliteal artery may also be damaged including genicular arteries that could compromise skin and patellar blood ﬂow and sural arteries, which may impair blood supply to the gastrocnemius muscle, compromising an important option for reconstruction.

Approach to Wound Closure

Closure during revision TKA can present a challenging problem to the orthopedic surgeon. Adequate soft tissue coverage is essential to lower the rate of infection and careful consideration must be given for the potential for reoperation, especially in the setting of 2- stage reimplantation. Before closure, adequate debridement of nonviable tissue is of utmost importance. Selection of the appro- “ ” priate method of closure and coverage needed should be based on Fig. 2. The reconstructive elevator. careful assessment of the wound and associated risks, treatment morbidity, reoperation, recovery time, and long-term prognosis. tendons were exposed, and a musculocutaneous flap for covering The reconstructive ladder may be used as a general guide to stratify large defects, especially if the prosthesis is exposed [20]. reconstructive options. The simplest method of closure is denoted on the bottom rung, with progressive rungs representing sequen- tially more complex reconstructive techniques (Fig. 2) [19]. If suc- Primary and Secondary Closure cess rates of lower rung options are thought to be low, the concept of a reconstructive “elevator” allows the surgeon to jump directly to Primary closure is the preferred method of closure after revision the level of reconstructive complexity with a highest chance for TKA; however, it should not be done in the setting of high wound success. It is essential that the operation with the highest proba- tension or devascularized skin flaps due to scarring from prior bility of success be the first choice in the “reconstructive ladder” of surgeries. Delayed primary closure is not indicated in the setting of procedures. PJI or exposed prosthesis. However, in the setting of excessive skin Prophylactic measures can also be taken in cases of anticipated tension without infection, delayed closure could be considered to wound closure problems. Casey et al retrospectively reviewed 23 prevent more invasive reconstruction. Delayed closure takes patients who underwent prophylactic flap coverage before TKA for advantage of the viscoelastic creep inherent in the skin, giving time high risk of wound complications, mainly because of prior opera- for the skin to close small defects [21]. Such methods include use of tions and infections around the knee. They found that despite a vessel loop shoelace method, although this method requires return high rate of complications at the time of flap transfer, up to 48%, all visits to the operating room for tightening, progressive manual patients successfully underwent subsequent TKA with no wound tensioning of sutures at the bedside, or daily reapplication of complications. Conversely, they reviewed 18 patients who had a tensioned SteriStrip [21,22]. salvage procedure done with flap coverage after TKA implantation Healing by secondary intention is not recommended in the case and found that complications were similarly high; however, 3 pa- of arthroplasty with exposure of nonvascularized structures such as tients required above-the-knee amputation. In both prophylactic bone, hardware, and tendons [21]. As an alternative to secondary and salvage procedures, both the orthopedic and plastic surgeon closure, a vacuum-assisted closure (VAC) device may be applied to together should decide what treatment option has the best chance an open wound bed and can be used as a temporizing measure to for success based on individual patients risk and history. delay definitive closure or to assist in closure of small full thickness In cases of salvage reconstructive procedures, careful preoper- and partial thickness soft tissue defects, as long as there is no ative planning must be done, taking into account patient’s previous exposed bone or prosthetic material. Argenta et al [23] first surgical history, prior surgical incisions, and chance for further developed the VAC in the 1990s as a novel method for closure of wound complications. Menderes et al reviewed the results of 17 large, chronic wounds that could not be closed by another measure. patients with complex wounds after TKA and the impact of patient- Through use of negative-pressure dressings, the VAC facilitates specific factors, wound factors, choice of operation, and secondary movement of distensible soft tissue toward the center of the wound procedures on clinical outcomes. They reported 94% prosthesis and aids in the evacuation of interstitial fluids that may accumulate retention, with 30% reoperation rate. Menderes et al recommended [24]. These interstitial fluids are also thought to contain inhibitory using a fasciocutaneous flap when the defect was small or if bone or factors that suppress the formation of fibrous tissue which are 4 A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 crucial to wound healing [24-27]. When placing the VAC, it is (fasciocutaneous, muscle, musculocutaneous), blood supply important to debride nonviable bone and soft tissue. In addition, (random, axial), and method of transfer (pedicled, free flaps) [21]. although a VAC sponge may be placed over exposed hardware, it is For the knee, the location of the flap taken for transfer can be local recommended to limit exposure to the sponge to less than 72 hours, or regional from the gastrocnemius, tibialis anterior, or vastus lat- making it less useful in 2-stage revision arthroplasty [21]. The VAC eralis, or taken as distant or free from sources such as the latissimus is often set to a pressure of 100-125 mm Hg continuous suction dorsi, rectus abdominis, gracilis, serratus anterior, or the antero- [28]. Complications, although rare, include bleeding from the lateral thigh (ALT). wound, pain with changing of sponges, and excessive growth of Flap blood supply can be random, based on the subdermal granulation tissue into the sponge [21]. plexus, or axial, which is based on an inflow vessel or pedicle. In the lower extremity, the length-to-width ratio recommended when Skin Grafts using random pattern flaps is 2:1, where axial flaps allow for greater freedom in the length-to-width ratio and flap transposition. Skin grafts can be used in cases of skin loss due to necrosis or in The method of transfer is of significant importance in determining combination with flap harvest for coverage of the recipient site in surgical options [36]. Local and regional axial pattern flaps are the setting of flaps lacking a cutaneous component. In addition, based on preservation of an intact pedicle, which is used as the axis limited soft tissue coverage over the anteromedial aspect of the to transfer tissue by way of transposition, rotation, or advancement proximal tibia often requires skin grafting at the time of revision [37]. Regional flaps may also be taken in an island fashion where surgery to prevent wound problems [29,30]. Skin grafts can be the flap is only attached by the pedicle allowing for greater mobility harvested as both split-thickness and full-thickness skin grafts [31]. of flap placement. Skin grafts heal by way of oxygen diffusion from surrounding tis- Muscle flaps are most commonly used in reconstruction around sues (plasmadic imbibition) and lining up of graft and recipient the knee; however, they require a skin graft on the transposed blood vessels (inosculation) for the first 2-3 days followed by new muscle to complete closure of the defect. Muscle flaps can be vessel in-growth by angioneogenesis. As such, viable subcutaneous classified according the Mathes and Nahai classification based on tissue, muscle, fascia, periosteum, or paratenon is required at the their blood supply or pedicle: type I (single dominant vascular recipient site for graft survival [21]. Skin grafts should not be placed pedicle), type II (1 dominant and 1 minor pedicle), type III (2 on an infected wound bed. dominant pedicles), type IV (segmental branches), and type V (1 Full-thickness skin grafts include the entire thickness of the dominant and multiple minor pedicles; Table 1) [38,39]. epidermis and dermis (>0.6-mm thick) and require primary closure Free flaps (also known as microsurgical flaps) refer to the of the donor site [32]. Split-thickness grafts include the epidermis transfer of tissue with its vascular pedicle from a distant site to a and an only small portion of the dermis (between 0.15 and 0.6-mm recipient site, where the pedicle is anastomosed to local vessels thick) and do not require donor site closure due to re- with microsurgery. Although more technically demanding, they can epithelialization from the peripheral epidermal basal layer and provide greater surface area coverage, can be tailor fitted to a underlying deep dermal adnexal structures [32]. Although full- defect, and can rely on blood supply outside of the operative zone. thickness skin grafts tend to have less secondary contracture than Studies indicate that free flaps may have a greater antibiotic ca- split-thickness skin grafts, they are often not used in the lower pacity and ability to deliver humoral defense factors, potentially extremity because of donor site availability and an increased risk of reducing the risk of postoperative infection [14,40]. Disadvantages complete or partial loss. The thicker graft has an increased diffusion of free flaps include donor site morbidity, longer operative time, distance required in the early healing phases, making it more and delayed rehabilitation of the knee [14,41]. sensitive to shear forces, underlying fluid collection, excessive During preoperative planning, the orthopedic and plastic sur- electrocoagulation of the wound base, and vasoconstrictive effects geons should consider the type and volume of tissue deficiency, size of smoking [31]. Split-thickness skin grafts are more prone to of wound surface area, risk of infection, and need for future reop- contracture and scaring, which is an important aspect when eration to help guide selection of flap coverage. Local and random considering range of motion across a joint. The thinner split- based flaps are typically not used in coverage of wounds around the thickness skin grafts, however, offer the advantage of large donor knee because of poor local skin mobility, excessive scar tissue from site availability and improved graft take on wound beds with poor multiple operations, and nonreliable subdermal blood supply. vascular supply. In addition, split-thickness skin grafts can be Therefore, this review is focused on regional and free flap options. meshed to increase surface area, improve take over irregular wound bed contours, and prevention of graft failure from underlying hematoma and/or seroma formation. Surgical Technique and Progressive Options After harvest of a skin graft, the graft should be secured at the recipient site to promote incorporation. This can be done with Pedicle Flaps negative-pressure dressings, VAC use, or application of a bolster [21,33]. Vacuum pumps should be used with continuous suction, Pedicle flaps should be considered when regional options are which minimizes shearing. For management of the donor site, available and wound size permits. Typically, a pedicle flap is used potential dressings include use of occlusive cellophane on small sites, silver-impregnated gauze, or topical silver [21,34,35]. Table 1 Mathes and Nahai Classification of Reconstructive Flap Coverage. Principles of Flaps Mathes and Nahai Flap Classification

Tissue flaps differ from skin grafts in that they are transferred to Type Example Flap a wound bed with an intact blood supply, allowing for more robust Type I: single dominant vascular pedicle Tensor fascia lata coverage of larger defects with higher bacterial counts and wounds Type II: 1 dominant and 1 minor pedicle Gracilis with exposed hardware, exposed bone or tendon, and vital struc- Type III: 2 dominant pedicles Gluteus maximus tures such as blood vessels and nerves. Tissue flaps can be classified Type IV: segmental branches Sartorius Type V: 1 dominant and multiple minor pedicles Latissimus dorsi according to location (local, regional, or distant), type of tissue A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 5 for first option reconstruction as they do not prevent later free flap use if necessary. Careful attention to prior surgeries may uncover compromise to axial inflow to these flaps in which they should not be used in this setting.

Gastrocnemius

The gastrocnemius flap is the regional workhorse for reconstruction of the upper third of the leg and defects of the knee (Fig. 3). Its use for coverage of exposed knee prosthesis was first described by Barford and Pers in 1970 to aid in primary closure of compound injuries of the knee and further described by Sanders et al in 1981 [42,43]. Gastrocnemius flaps can provide excellent results during revision TKA for select patients. Preoperative planning for potential gastrocnemius flap must take into account the variable size of the muscle relative to the defect [38].

Anatomy The gastrocnemius muscle consists of medial and lateral heads, Fig. 4. Rotation of pedicled gastrocnemius flap about the knee. which originate from their respective femoral condyles and join just distal to the knee and are innervated by the tibial nerve. The the joint Achilles tendon. The medial portion of the gastrocnemius muscle becomes tendinous near the junction of the middle and contribution to the Achilles tendon is divided 1 cm distal to the distal thirds of the leg where it joins the soleus tendon to form the musculoaponeurotic junction to allow for easy suture tacking to the Achilles tendon. Each muscular head is supplied by a medial and recipient site. The median raphe separating the medial and lateral lateral sural artery branching directly off of the popliteal artery, heads can then be identified. Care is taken to preserve the sural making it a Mathes and Nahai class I circulation pattern. The sural nerve and lesser saphenous vein by gently retracting them laterally artery enters the muscle just beneath the level of the joint space before dividing the raphe. Care should be taken not to damage the and arborizes proximal in the muscle [38]. This artery serves as the sural vessels when approaching the knee joint. If the medial head pedicle about which either head is rotated for coverage of the does not reach the wound, the muscular fascia can be scored or the medial or lateral knee. The medial head is preferred for recon- muscle can be released from its origin on the medial femoral struction as it is larger and longer (3.0-4.0 cm) than the lateral head condyle adding 5-8 cm of rotation [38,44,45] (Fig. 4). The flap is and has a longer vascular pedicle allowing for greater arc of rotation then grafted with a meshed split-thickness skin graft. to reach the knee [14,38]. In addition, the common peroneal nerve crosses posterior to the lateral head of the gastrocnemius and may be injured intraoperatively when the lateral gastrocnemius is used. Lateral Gastrocnemius Flap Elevation To mobilize the lateral head of the gastrocnemius, a longitudinal Medial Gastrocnemius Flap Elevation incision is made either posterior midline or 2-3 cm posterior to the fi fi To reach the medial head of the gastrocnemius, a longitudinal bula. The common peroneal nerve should be identi ed and pre- fi incision can be made either posterior midline or parallel to the served at the neck of the bula. The lateral head is separated from medial border of the tibia, extending from the tibial plateau to 8-10 the medial head as previously described, and the muscle is then cm above the ankle. The saphenous vein is preserved and the transposed into position and skin-grafted [38]. muscle is separated from the overlying subcutaneous tissue. The plane between the soleus and medial portion of the gastrocnemius Results fl fl is developed by blunt finger dissection down to its attachment at The gastrocnemius ap is the most common muscle ap used for reconstruction after TKA. Nahabedian et al [11] reported an 84% prosthesis salvage rate using medial gastrocnemius transposition in 29 wound problems after TKA. Corten et al [46] reported on 24 patients treated with gastrocnemius muscle flap coverage during the first stage of 2-stage reimplantation for infected TKA and found that 22 patients (92%) obtained a satisfactory result, with Knee Society Score improvement from 53 preoperatively to 103 at 4.5- year follow-up. The gastrocnemius muscle may be less effective for treatment of more proximal defects, up to the level of the superior pole of the patella, because of the length of the vascular pedicle and the muscle itself. Ries et al reported on 12 patients who underwent medial gastrocnemius transposition flap after TKA. They found that for patients with defects over the tibial tubercle or patellar tendon, the flap healed and salvaged the TKA. However, if the defect extended proximally to the patella or quadriceps tendon, 3 of 4 patients required additional coverage with fasciocutaneous, lateral gastrocnemius, or free flap coverage and 1 patient required an above-knee amputation [47]. Overall, the gastrocnemius flap can help fill large soft tissue defects around the knee and has a high rate Fig. 3. Pedicle flap: gastrocnemius. of success of salvaging the prosthesis and limb. 6 A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10

Vastus Lateralis In contrast to a pedicled flap, survival of a free flap depends on early maintained patency of a microsurgical anastomosis between Failure of the gastrocnemius flap can present as a challenging the flap vascular pedicle and a recipient artery and vein [52]. The situation, however, the distally based vastus lateralis may be a first 24-48 hours after surgery is the period with the highest chance potential local solution for select patients. The vastus lateralis is less of vessel thrombosis and requires frequent clinical and external commonly used as it can be more challenging to use to fill medial Doppler monitoring by an experienced team trained in recognizing defects. vascular compromise. After 5 days, the anastomosis endothelializes and risk of thrombosis decreased substantially. Surgical technique Anatomy and inexperience are the most common causes of thrombosis, with The vastus lateralis is the largest of the quadriceps femoris factors such as inclusion of adventitial tissue, trauma to the intima, muscles and originates as a broad aponeurosis from the upper part or exposure to subintimal structures increasing the chances of of the intertrochanteric line and anterior and inferior borders of the microsurgical failure [52].Freeflaps can be harvested as pure greater trochanter. The muscle inserts via a thickened flat tendon muscle flaps with recipient site skin grafting, musculocutaneous into the lateral border of the patella, blending with 3 other tendons flaps, or fasciocutaneous flaps. Muscle flaps with skin grafting, to form the quadriceps tendon. The vastus lateralis demonstrates a however, are the best option for the complicated wound. Mathes and Nahai class I circulation pattern and receives its Recipient vessels for free flap transfer should be carefully dominant blood supply from the descending branch of the lateral selected to ensure success of the free flap transfer. Although there is femoral circumflex artery and a distal minor pedicle from the su- no clear consensus, the branches of the popliteal artery are most perior lateral geniculate artery. It receives its nervous supply from commonly used. However, the popliteal artery itself has limited the femoral nerve. The superior lateral geniculate artery gives rise utility in free flap transfer to the anterior surface of the knee [53]. to 3 branches that enter the muscle belly distal and posteriorly in The popliteal artery divides into the anterior and posterior tibial which at least 2 are needed to vascularize the vastus lateralis after arteries, which are better able to support flap transfer. The super- ligation of its dominant blood supply [48,49]. ficial femoral artery and genicular arteries can also be used, and an individual decision must be made based on the patient’s anatomy Surgical Technique and Results [53]. The patient is positioned supine or in the lateral decubitus position and a longitudinal incision is made along the lateral Latissimus Dorsi aspect of the thigh from the greater trochanter (10 cm below the anterior superior iliac spine) to the lateral patellar border. After The latissimus dorsi is a commonly used free flap for a variety of dissection to the deep fascia, the anterior and posterior borders of lower extremity reconstructive purposes and may be taken as the vastus lateralis are identified. The rectus femoris is then either a muscle or myocutaneous flap (Fig. 5). It has sufficient bulk retracted medially to identify the descending lateral femoral to fill large volumes of dead space and can cover a large surface circumflex artery, which passes under the rectus femoris and area; the muscle also shrinks with pressure garments, leaving a enters the vastus lateralis around the level of the greater good contour at the knee [21]. The latissimus dorsi flap has a long trochanter. This pedicle can be divided; however, a segment pedicle that allows for anastomosis outside the surgical site that should be preserved in case the flap needs to be supercharged if may have extensive scarring from prior operations. A major the minor pedicles are inadequate for flap perfusion. The origin of disadvantage of latissimus dorsi free flap is the common occurrence the muscle is then incised and the muscle is separated from the of donor site seroma, which can be managed with repeated aspi- biceps femoris and vastus intermedius until 5 cm proximal to the rations or excision [37]. lateral femoral condyle. Transposition of the flap is now possible fl [50]. This ap may also be harvested in a delayed fashion where Anatomy and Surgical Technique fl the main pedicle is cut in small operation and then the ap is The latissimus dorsi muscle, innervated by the thoracodorsal harvested 1-2 weeks later. nerve, has a broad origin extending from the thoracic spinous The vastus lateralis is not commonly used and often follows processes and posterior iliac crest and inserts into the medial side fl failure of a gastrocnemius ap, and there are limited reported cases of the intertubecular groove on the posterior humerus. The latis- on its use. Auregan et al reported on 4 patients, 3 of which were simus dorsi has a Mathes and Nahai type V circulation classification used around revision TKA. In all cases, skin closure was achieved; however, final joint mobility was poor at 45 on average [50].Itis important to note that the use of this flap will eliminate the pos- sibility of downstream use of an ALT free flap due to ligation of the descending branch of the lateral femoral circumflex.

Free Flaps

Free flaps represent the highest rung on the reconstructive ladder and may only be necessary in patients with persistent infection after prior failed reconstruction with regional options. As such, free flaps should only be considered for defects that cannot be covered by a pedicled flap. Benefits of free flaps include the pos- sibility for reoperation such as in a 2-stage implantation, prevention of postoperative knee stiffness, and a robust blood supply to allow for less complications in patients at high-risk for skin necrosis and wound dehiscence [51]. Disadvantages include donor site morbidity, high technical acumen, and a longer operative and recovery time. Fig. 5. Harvesting of a latissimus dorsi flap for grafting about the knee. A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 7 with the primary blood supply from the thoracodorsal vessels, inconspicuous scars and that the gracilis flap can be used as a which serve as the pedicle for transfer and minor segmental sensory flap when a nerve supply via a branch of the obturator branches from the lumbar and/or intercostal vessels. nerve is present [57]. When harvesting the latissimus dorsi flap, the patient is positioned in the lateral decubitus position. An oblique incision is made Anatomy and Surgical Technique along the anterior aspect of the muscle, and the anterior leading The gracilis muscle, innervated by the obturator nerve, origi- edge of the muscle is identified. The muscle is elevated off the nates as a thin aponeurosis from the anterior margins of the lower posterior thorax and its broad origin is divided. Care is taken when half of the symphysis pubis. Its tendinous insertion passes behind dissecting toward the axilla to protect the dominant pedicle. The the medial condyle of the femur, curving around the medial insertion is then divided before dividing the pedicle. During condyle of the tibia, and joins the pes anserinus. The gracilis muscle dissection, the serratus branch of the thoracodorsal artery is has a Mathes and Nahai type II circulation and receives its domi- identified and divided, which provides the longest vascular pedicle nant blood supply from the ascending branch of the medial for the latissimus flap [54]. circumflex femoral artery with a minor pedicle from 1 to 2 branches off the superficial femoral artery. Rectus Abdominis In harvesting a gracilis, the patient is positioned supine, with the thigh abducted. A line is drawn from the pubic symphysis to the The rectus abdominis muscle free flap can provide coverage for medial condyle in which the gracilis muscle is located 2-3 cm large lower extremity defects, has a long and consistent vascular posterior. The position of the gracilis muscle is also identified by pedicle, and low donor site morbidity. It can be harvested as either palpation in thinner patients, and the vascular pedicle may be a muscle only or a myocutaneous flap [55]. A major disadvantage of audible on Doppler examination. The dominant pedicle is harvest is the potential for herniation unless the rectus sheath is commonly 8-10 cm inferior from the pubic tubercle. When har- carefully closed [37]. Contraindications include patients who have vesting for free tissue transfer, a 10- to 15-cm sagittal incision is had previous abdominal or pelvic surgery that may compromise made from the pubis to the medial anterior knee [55,57]. The the flap vascular supply, patients with significant abdominal girth muscle is then disinserted and dissected from distal to proximal, who may be at higher risk for pulmonary and abdominal wall separating it from the sartorius and semimembranosus muscles. complications, and patients with previous vascular surgery on the Care is taken more proximally to preserve the dominant pedicle, iliac system [56]. before more superior dissection to release the muscle origin. To expose the pedicle, the adductor longus is retracted medially and Anatomy and Surgical Technique the pedicle traverses on top of adductor magnus. After superior The rectus abdominis muscle arises from the pubic symphysis release of the muscle, the pedicle is divided and ready for transfer. and pubic crest and inserts on the fifth, sixth, and seventh costal The gracilis can also be taken as a distally based pedicled flap cartilages. There are 3-5 fibrous bands (tendinous intersections) based on the minor pedicles from the superficial femoral artery. In that divide the muscle that are firmly adherent to the anterior this case, it is often recommended to delay the flap with an opera- sheath. The rectus abdominis is a Mathes and Nahai type III flap as it tion that ligates the dominant pedicle 2 weeks before flap transfer. is supplied by the inferior and superior epigastric artery. The free After skin incision, the muscle origin is divided and dissection is flap is most commonly based on the inferior epigastric artery, carried out proximal to distal until the minor pedicle(s) are which enters the lateral border of the rectus muscle just below the encountered in the lower third of the muscle. The muscle flap is then arcuate line, halfway between the pubis and umbilicus [54]. reversed 180 and tunneled under the skin of the anterior aspect of To harvest the muscle, a longitudinal incision is made down to the distal thigh to reach the exposed wound and/or prosthesis [55]. the level of the anterior rectus sheath. The skin and subcutaneous tissue are elevated off the rectus muscle. An incision is made in the Results anterior rectus sheath, with care to create a cuff of fascia with the Cetrulo et al reported on 11 patients with complex wounds and perforators that supply the skin if a myocutaneous flap is planned. exposed total knee prostheses with free tissue transfer, of which 3 The tendinous intersections at the linea alba and semilunaris are patients had failed previous local muscular rotation flap coverage. addressed first to free the most adherent portion of the muscle. The Five patients received latissimus dorsi muscle flaps and 6 patients rectus abdominis is then dissected off the posterior rectus sheath received rectus abdominis muscle flaps. All of the free flaps were above the arcuate line, with care taken to not injure the pedicle, successful (100%), the limb was salvaged in 100%, and the pros- which runs in the undersurface of the muscle belly [54]. At the level thesis salvaged in 10 patients (91%) [59]. Hierner et al reported on of the arcuate line, the deep inferior epigastric vessels can be the use of prophylactic latissimus dorsi free flap coverage with TKA. identified entering laterally and dissected down to its iliac origin. Fourteen patients were reviewed who had on average 10 previous The superior epigastric is then ligated and the muscle insertion surgeries and for whom gastrocnemius free flap was not an option. detached. The inferior epigastric artery is then ligated proximally to They found that primary wound healing occurred in 8 patients, skin preserve pedicle length and the flap is ready for transfer. The breakdown occurred in 5 patients requiring secondary skin graft- abdominal defect must be carefully closed to prevent herniation of ing, and 3 late recurrences of infection occurred. Overall, free la- the anterior abdominal wall. tissimus dorsi transfer made prosthesis implantation possible, prevented postoperative knee stiffness, and had a low rate of severe Gracilis complications in patients at high risk for wound-healing problems [51]. The gracilis free flap can be considered as an effective alternative for knee reconstruction in the case of failed gastrocnemius flaps or Anterolateral Thigh in addition to a medial or lateral gastrocnemius flap [57]. It can be harvested as either a muscle or myocutaneous flap. Functionally, The ALT flap is a free fasciocutaneous flap (no muscle) and is the gracilis muscle is of lesser importance in leg adduction, and most commonly used in patients with large, superficial skin loss therefore, donor site morbidity is uncommon [58]. Advantages to >4 cm, without joint or implant exposure and without deep the gracilis flap include primary direct donor site closure with infection [10,14]. Recent head-to-head studies comparing muscle 8 A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 to fasciocutaneous flaps are finding that infection is likely not a Postoperative Considerations contraindication for the use of fasciocutaneous flaps, however, Patients after flap and graft reconstruction need graduated muscle flaps tend to have a more robust blood supply [40]. The mobilization and weight bearing after their operation. Initially for main advantages are improved cosmetic outcomes, better about 7 days bed rest is needed for optimal healing of the flap and/ pliability, and easier revision, no need for skin grafting, and no or graft. During the next 2 weeks, progressively increasing mobi- donor site weakness [37]. However, there are limited studies lization and weight bearing is followed. For about 4-6 months regarding its use in periprosthetic infection [14]. Disadvantages postoperatively, patients should use compression stockings to include a more technical flap harvest and poor vascularity in the provide support to the skin graft to prevent breakdown. setting of the obese patient with a thick layer of subcutaneous fat During the postoperative period, because of prolonged immo- on the lateral thigh. bilization, patients should be on a standard protocol of subcutaneous heparin or enoxaparin. Anatomy and Surgical Technique The blood supply to the ALT flap is the descending branch of the Complications lateral femoral circumflex artery (LFCA), which traverses in the intermuscular septum between the rectus femoris and vastus lat- Vascular compromise is the most serious and potentially eralis [60]. Perforating vessels supplying the skin may course devastating complication of flaps, especially in the setting of free through the vastus lateralis muscle (type C: musculocutaneous) or tissue transfer (Table 2). Prompt surgical intervention is needed in pass directly between the muscles on the septum (type B: septo- these situations to restore blood flow and attempt to salvage the cutaneous). Kuo et al reported on the success and anatomic vari- flap. Venous compromise causing congestion is more common, as ability of 140 ALT flaps transferred for reconstruction of various soft the venous side of the flap is a low-flow system. Failure to tissue defects. They found that the blood supply to the skin re-establish effective perfusion within 2 hours usually results in came from the septocutaneous perforators only in 19 patients irreversible insult to the muscle flap [37]. After microsurgical (13.6%), from the descending or transverse branch of the LFCA or anastomosis in free flaps, a multitude of different monitoring de- directly from the LFCA. Other variations included supply by mus- vices and techniques have been used to aid in assessing free flap culocutaneous perforators that were elevated as a true perforator viability. Clinical examination remains the gold standard method of flap via intramuscular dissection (n ¼ 34, 24.3%) or used a cuff of flap assessment, and external Doppler examination is useful when vastus lateralis for added bulk (n ¼ 87, 62.1%) [44]. About one third a perforator or intramuscular vessel can be audibly identified. In of the population has an extra vessel in the ALT in the plane be- addition, use of implantable venous Doppler monitoring may tween the rectus femoris and vastus lateralis, known as the oblique shorten the time to the detection of vascular thrombosis, poten- branch of the lateral circumflex femoral artery, which can also be tially improving free flap salvage rates. Swartz et al reviewed 103 reliably used as the pedicle of the ALT flap [61,62]. patients with venous monitors implanted, which detected 16 of 16 For harvest, a line is first drawn from the anterior superior iliac thromboses, with 12 flaps salvaged. Overall, the implantable spine to the superlateral border of the patella, which represents the Doppler showed a higher level of detection of venous thrombosis muscular septum between the rectus femoris and vastus lateralis and helped to salvage a majority of flaps [66]. Early flap hematoma muscles. Cutaneous perforating vessels can then be identified using may also result in vessel compression leading to flap compromise a handheld Doppler centered over the midpoint of this line, and and should be addressed promptly. skin markings can be made to include these vessels. A skin flap can Donor site complications can include hematoma, seroma, sen- be designed in the middle third of this line, extending approxi- sory nerve dysfunction, and scar formation, which can be prob- mately 10 cm below the anterior superior iliac spine to 7 cm su- lematic for patients and potentially necessitate reoperation. Muscle perior to the lateral patella. An incision is made at the medial weakness is also common in the cases of muscle flaps, but this is border of the flap over the rectus femoris, through the deep fascia, often transient and compensation occurs quickly. Kramers-de so that the flap is raised laterally until the intermuscular septum is Quervain et al objectively evaluated donor site morbidity after reached. The pedicle is then identified in the groove between the harvest of the gastrocnemius or soleus for flap procedures. They rectus femoris and vastus lateralis muscles. If the perforators are evaluated 5 patients using comprehensive gait analysis during free through the vastus lateralis, a 2-cm cuff of muscle is harvested with level, fast level, and uphill walking. They found no relevant donor the flap to protect the vessels. The pedicle is then carefully site morbidity in free walking; in fast level walking, there was a dissected proximally to achieve a length of 12 cm. The lateral skin slight decrease in the second vertical peak force during push off. incision is made and the flap elevated [54]. During uphill walking, they found a compensatory strategy in all patients, reducing the demand on the posterior calf muscles. Pa- Results tients shortened the length of the step on the contralateral side, and The ALT flap can be used in select patients for reconstruction of also exhibited a calcaneal motion pattern, meaning increased ankle the knee. In a larger series, Kuo et al [63] reported on the success dorsiflexion, showing decreased function of the posterior calf rate at time of operation was 92%, and at 2-year follow-up, all flaps muscles [67]. had healed uneventfully with minimal morbidity. Lewis et al reported on 7 patients with exposed total knee prostheses that were Table 2 fl treated with a fasciocutaneous ap. One patient required Pearls to Achieve Success and Prevent Complications. concomitant reconstruction with a medial gastrocnemius flap and one patient experienced mild wound separation secondary to a Pearls for Successful Flap Coverage About the Knee severe spasm; however, no other complications occurred in 1-year Adequate and thorough debridement of vascular bed in host site and donor follow-up [64]. Townley et al prospectively followed 100 patients site fl Use of wound vac is contraindicated in the presence of a wound infection with ALT aps taken for various reconstructive procedures and Adequate and appropriate antibiotic therapy based on cultures followed them for 6 months for donor site complications. They A gastrocnemius flap will work for most patients. Its presence in the middle of found that tingling was the more common symptom (59%), the reconstructive ladder recommends consideration of a gastrocnemius flap whereas pain, itching, muscle herniation, and quadriceps muscle before other pedicled and free flaps. The operation with the highest probability of success is the best operation weakness were infrequent [65]. A.J. Rao et al. / The Journal of Arthroplasty xxx (2016) 1e10 9

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