Chapter 25 Revision Total Ankle Arthroplasty: Managing Osteolysis and Subsidence

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1 Chapter 25 Revision Total Ankle Arthroplasty: Managing Osteolysis and Subsidence James A. Nunley, MD Indications A review of 2,240 total ankle arthroplasties (TAAs) from multiple studies with adequate follow-up reveals implant survivorship rates ranging from 70% to 98% at 3 to 6 years and from 80% to 95% at 8 to 12 years. This finding implies that the surgeon who manages ankle arthroplasty must be familiar with revision arthroplasty as well as the conversion of failed TAA to ankle arthrodesis. All total joint arthroplasties have an increasing failure rate as the interval from implantation increases. The mode of failure varies with the duration of implantation; infection and malalignment predominate early on, whereas aseptic loosening dominates in the later stages. Aseptic loosening occurs as a result of osteolysis, which is characterized by a chronic granulomatous inflammatory response that is stimulated and maintained by implant-derived wear debris. Symptoms generally do not occur before osteolysis has progressed to the point of implant loosening. Overwhelming data in the arthroplasty literature indicate that implant wear particles are the initiator of osteolysis. Any particulate wear debris, including polyethylene, polymethyl methacrylate, or metallic particles, can initiate an osteolytic reaction. The choice of prosthesis and bearing surface affects the composition, size, shape, and concentration of the generated particulate matter. Polyethylene, the predominant particulate debris, is dispersed with joint motion and then occupies the effective joint space. The authors of a 2012 study documented between 100,000 and 500,000 particles released for each step taken by a patient with a polyethylene acetabular cup and a metallic femoral head. The risk factors for osteolysis are male sex, younger age, obesity, polyarthritis, genetic predispositions, and some metallic hypersensitivity. Revision arthroplasties are performed for malalignment, infection, and other reasons, but this chapter reviews only osteolysis and subsidence as the reasons for revision. Several studies have described implant migration, subsidence, and radiolucencies. However, all these studies are based on serial radiographs, and radiographic changes in the position of the prosthesis or radiolucencies do not necessarily indicate potential implant failure. Several studies have indicated that progressive lucencies or cysts Dr. Nunley or an immediate family member has received royalties from Wright Medical Technology; is a member of a speakers bureau or has made paid presentations on behalf of Orthofi x; serves as a paid consultant to Small Bone Innovations, Exactech, Integra LifeSciences, Tornier, Wright Medical Technology, and DT MedSurg; has stock or stock options held in Bristol-Myers Squibb, Merck, and Johnson & Johnson; and has received research or institutional support from the Orthopaedic Research and Education Foundation, Synthes, Integra LifeSciences, Berg, and Tornier. may be managed with bone grafting with successful implant retention provided that the original implant is well fixed. The authors of one study, in an attempt to categorize the complications after TAA, published an algorithm based on a review of 2,386 ankles from 20 separate studies. High-grade complications included aseptic loosening, deep infection, and implant failure, all of which were associated with failure of the TAA. Medium-grade complications included technical errors in alignment, subsidence of the prosthesis, and postoperative fracture and were associated with a moderate failure rate. Low-grade complications included intraoperative fractures and wound healing problems; these complications had a negligible effect on outcome. Not all prosthetic failures require arthrodesis of the ankle. In a metaanalysis of 13 studies comprising 801 mobile-bearing and 304 fixed-bearing ankle arthroplasties, implant failure was reported in 108 patients (9.8%) at an average of 5.2 years postoperatively. Sixty-seven (62%) of the failed arthroplasties were managed with revision arthroplasty, and only 39% required conversion to arthrodesis. Contraindications Inadequate motor innervation or muscle strength to power the ankle joint may 2015 American Academy of Orthopaedic Surgeons Advanced Reconstruction: Foot and Ankle 2 213

2 Degenerative Conditions of the Ankle preclude revision surgery. In addition, if inadequate talar bone remains, then revision is contraindicated. Alternative Treatments Osteolysis with areas of extremely small cystic change do not require revision. In these patients, long-term observation can be used to see if these areas enlarge. In addition, the author of this chapter has on occasion used bisphosphonate therapy to slow down and, in one case, reverse, osteolysis. If osteolysis and cyst formation occur in the setting of a well fixed and stable prosthesis, then the cyst may be grafted with or without revision of the metallic components of the ankle prosthesis. Techniques Setup/Exposure Typically, the location of the osteolysis dictates the exposure. The surgeon should use an approach that allows the most direct access to the area or areas of osteolysis in a safe manner. For nearly all revision arthroplasties, the author of this chapter performs a second anterior arthrotomy using the original approach. If the patient has previously had wound healing problems, preoperative consultation with a plastic surgeon can be extremely helpful. Occasionally, the author has sent the patient to have a free flap created before the revision arthroplasty procedure to provide adequate skin coverage and decrease the chances of postoperative infection or skin slough. Instruments/Equipment/ Implants Required For implant removal, the equipment is critical. A thin reciprocal saw allows precision cuts around the barrels of the STAR (Scandinavian Total Ankle Replacement; Stryker) prosthesis as well as the Agility (now available as Agility LP; DePuy) tibial component and the baseplate for the INBONE (Wright Medical Technology) and Salto Talaris (Tornier) implants. Straight and curved thin osteotomes can be used to get under the tibial component of the STAR and Salto Talaris prostheses. A standard set of impactors can be used to remove the stem of the INBONE prosthesis. A pin distractor is nearly always needed to create enough space to remove the polyethylene in a manner that minimizes bone resection. An oscillating saw is necessary to create a cortical window in the anterior tibia to allow removal of the tibial stem of the INBONE prosthesis. Implants are necessary for revision of an Agility prosthesis. Generally, this involves an INBONE II (Wright Medical Technology) prosthesis with a long tibial stem. Revision of the STAR prosthesis can be accomplished with standard instrumentation when only the tibial component requires removal; however, if the talar component is revised, it is probably best to use an ankle with a flat-top talar revision component, such as in the Salto XT or the INBONE prosthesis. Revision of a Salto talar component can be easily accomplished with the use of a Salto XT, which is a flat-top talar component. In addition, bone graft mixed with vancomycin or bone graft substitutes is necessary to fill any defects in the tibia or talus. On occasion, methyl methacrylate may be indicated if the bone is sufficiently weak. Procedure REVISION WITH RETENTION OF THE ORIGINAL METAL IMPLANT Preoperative planning for revision TAA should include a thorough physical examination, with particular attention paid to any previous skin problems or wound healing problems. The patient s neurovascular status must be carefully assessed, and adequate motor units to power a revision arthroplasty must be available. Weight-bearing AP, lateral, and Saltzman radiographs are critical for the overall assessment of the alignment. In addition, if excessive knee varus or valgus or overall lower extremity malalignment is a concern, fulllength standing radiographs that include the hip, knee, and ankle are necessary. Radiographic changes indicating osteolysis are generally more easily seen around the tibial component than around the talar component because most talar components are fixed with fin, barrel, or stemmed devices and the talar component therefore frequently obscures the bony anatomy beneath the talar cap. For this reason, the author of this chapter obtains thin-cut CT scans of all patients who are considered for revision arthroplasty. The CT scan allows for the detection of cysts in both the tibia and the talus (Figure 1). Assessing the amount of osteolysis and the potential subsidence of the prosthesis can help the surgeon decide whether revision surgery or arthrodesis is a better option. In patients with some older prostheses, such as the Agility prosthesis, 214 Advanced Reconstruction: Foot and Ankle American Academy of Orthopaedic Surgeons

3 Revision Total Ankle Arthroplasty: Managing Osteolysis and Subsidence Figure 1 Prerevision AP radiograph (A), coronal CT scan (B), and sagittal CT scan (C) demonstrate a cyst under the medial talus (arrows) in a patient with an 8-year-old STAR (Scandinavian Total Ankle Replacement) prosthesis. so much resorption may have occurred under the talus that the remaining bone stock is inadequate to allow revision arthroplasty. This type of subsidence can be seen with any prosthesis, especially if the initial arthroplasty was performed on a flat-top talus and the talar cut removed a significant portion of the superior dome of the talus. Other prostheses (eg, Buechel- Pappas; formerly manufactured by Endotec), unless they were recently implanted, may be heavily ingrown, such that removing the talar prosthesis is impossible without a flat cut that would further remove talar bone. This scenario, too, may make revision surgery nearly impossible. After the CT scan and physical examination are complete and the surgeon has verified that the patient s pain is originating from the ankle and not from the subtalar joint or potentially from medial or lateral gutter impingement, the next step is planning for the revision arthroplasty. The revision is performed through the same incision, which in most patients is the anterior retinaculum over the extensor hallucis longus tendon. Adequate exposure medially and laterally to allow visualization of the medial and lateral gutters and the medial and lateral malleoli is critically important. In most patients, the anterior ankle capsule is extremely thick and frequently has been invaded with granulomatous material that may necessitate its complete excision (Figure 2). Ideally, the capsule would be preserved, but preservation is rarely possible. As in any revision arthroplasty, obtaining intraoperative cultures and frozen tissue for pathology is important (Figure 3). In patients with mobile-bearing prostheses, the polyethylene component can generally be easily Figure 2 Intraoperative photograph from the same patient in Figure 1. Forceps hold the granulomatous material that must be completely excised during revision. Figure 3 Photomicrograph demonstrates polyethylene crystals within granulomatous material and fibrous tissue (hematoxylin-eosin). The arrow points to polyethylene crystal. removed unless it is fractured. If difficulty is encountered or the polyethylene has fractured, using a pin distractor will allow separation of the joint so that the posterior portion of the polyethylene can be easily removed. In patients with the fixed-bearing Salto Talaris prosthesis, the polyethylene can generally be removed using a small osteotome to lever the polyethylene off the rails on the tibial side (Figure 4). A specially designed clamp is available for polyethylene removal, but the author of this chapter does not find it useful. In patients with the INBONE or Agility prosthesis, drilling out the insertional ridges on the tibial 2015 American Academy of Orthopaedic Surgeons Advanced Reconstruction: Foot and Ankle 2 215

4 Degenerative Conditions of the Ankle component may be necessary. A cortical screw can then be placed in the anterior center of the polyethylene component, and with strong traction, the polyethylene can be removed without damaging the tibial component (Figure 5). At this point, the stability of the tibial and talar components must be assessed. This assessment is best done by using probes and small Figure 4 Intraoperative photograph shows removal of polyethylene from a Salto Talaris prosthesis without damaging the tibial component. osteotomes placed on the edge of the prosthesis (Figure 6). Despite the fact that the CT scan may show significant osteolysis, in the author s experience, many of the components are well fi xed and can be left in place as long as the granulation tissue that is invading the bone and producing the osteolysis can be removed and the defect can be filled (Figure 7). On the tibial side, the cysts tend to occur in the medial malleolus and laterally above the tibial Figure 5 Intraoperative photograph shows drilling along the rails of the polyethylene insert of an INBONE prosthesis, which allows for polyethylene removal without explanting of the tibial stem. component. Frequently, a cortical window must be made above the tibial component to remove the granulation tissue. In patients with stemmed prostheses, a cortical window in the tibia is almost always necessary to expose the intramedullary component (Figure 8). If the talar component seems to be well fixed and large lytic areas beneath the talar cap are seen on the CT scan, a bone trephine can be used to create a cortical window either anteromedially or anterolaterally (Figure 9). This method provides access to the posterior surface of the components that cap the talus. From this approach, granulomatous material can be excised using a curet and rongeurs. In addition to removing all granulomatous material from around the tibia and the talus, any granulomatous material that is in the posterior aspect of the joint or on the posterior capsule must be removed. To access the posterior capsule, pin distractors to provide greater access within the ankle and curved curets to get around the corners of the Figure 6 Intraoperative photographs show a probe used to assess the stability of the tibial (A) and talar (B) components in the revision of a total ankle arthroscopy with a STAR (Scandinavian Total Ankle Replacement) prosthesis. Figure 7 Intraoperative photograph shows a pin distractor applied to both the tibia and the talus; this allows a curet to be placed through the tibial cyst from the anterolateral tibia down to the tibial component. Note the bone strands that extend to the porous cylinder on the tibial component, maintaining tibial prosthesis stability. 216 Advanced Reconstruction: Foot and Ankle American Academy of Orthopaedic Surgeons

5 Revision Total Ankle Arthroplasty: Managing Osteolysis and Subsidence Figure 9 Intraoperative photographs show the revision procedure for the patient shown in Figures 1 and 2. A, A bone trephine is inserted to create an entrance to remove the granulomatous material from beneath the talus. B, Bone loss can be seen in the anterior distal tibia after a curet has been used to remove granulation tissue from beneath the tibial component. Figure 8 Intraoperative photograph shows a bone window created over the distal anterolateral tibia for revision of a total ankle arthroplasty with an INBONE prosthesis. A curet is used to push granulomatous material from around the prosthesis. The blue plastic protector between the tibia and the talus prevents scratching of the metallic component. prosthesis are frequently necessary (Figure 10). If both the tibial and talar components are well fixed, the resorbed area of bone must be replaced with either crushed cancellous bone graft or a bone substitute that will provide and help maintain structural integrity around the prosthesis. Calcium phosphate products, injected as a liquid and allowed to harden, have been successfully used to provide support in areas of osteolysis (Figure 11). REVISION ARTHROPLASTY WITH A POORLY FIXED COMPONENT If both components are loose, removal of the prosthesis is required, and the type of revision arthroplasty must be chosen. In patients with a failed Agility prosthesis, the author of this chapter has used only the INBONE Figure 10 Intraoperative photograph shows the posterior ankle capsule with granulomatous material after the polyethylene has been removed. The granulomatous material must be removed to minimize the recurrence of osteolysis. prosthesis for revision. The author believes that the incorporation of a stem onto the tibia can provide good stability (Figure 12). Furthermore, most patients who require revision of TAA with an Agility prosthesis have significant talar bone loss. A minimal flat-top cut as is made with the INBONE prosthesis will often leave enough bone remaining that the short (10-mm) talar stem can be easily accommodated. This fi xation, together with the Figure 11 Intraoperative photograph of the same patient shown in Figures 1, 2, and 9. Bone substitute is injected into the cyst at the posteromedial aspect of the talus beneath the talar component. new INBONE II anterior prong talar fixation and the deep sulcus polyethylene, can provide excellent stability. Other options are to use just anterior prong fixation, omitting the stem, or a longer (14-mm) talar stem and perform arthrodesis of the subtalar joint. For the Salto Talaris prosthesis, custom tibial stems have been available from the manufacturer in 30- and 40-mm segments with a tibial base plate increased by a thickness of 4 mm. These stems allow the surgeon to accomplish revision of a loose tibial component by 2015 American Academy of Orthopaedic Surgeons Advanced Reconstruction: Foot and Ankle 2 217

6 Degenerative Conditions of the Ankle Figure 12 Radiographs demonstrate revision of a total ankle arthroplasty with osteolysis through the use of a stemmed prosthesis. A, Prerevision AP radiograph demonstrates a painful, loose, and malaligned Agility prosthesis. Note the osteolytic lesions at the medial tibial metaphysis and the distal fibula. AP (B) and lateral (C) radiographs demonstrate the same ankle 3 years after revision with a flattop cut on the talus and insertion of a standard INBONE prosthesis. this width, revision surgery with implantation of an INBONE prosthesis must be considered. In the author s experience, revision of TAA in patients with an INBONE prosthesis can generally be accomplished only through revision to another INBONE prosthesis with a longer tibial stem and thicker polyethylene components. Figure 13 Revision of a total ankle arthroplasty (TAA) using a nonstemmed prosthesis is shown. A, Lateral radiograph demonstrates a STAR (Scandinavian Total Ankle Replacement) TAA with malalignment of the tibial component. B, Lateral weight-bearing radiograph demonstrates the same patient 8 years after revision, which involved recutting the distal tibia and inserting a new tibial component. freshening up the distal surface of the tibia, cutting an anterior window, and inserting the custom prosthesis with a standard polyethylene insert. For revision of TAA in patients with a STAR prosthesis, if the tibial component is loose, the tibia can be recut using regular instrumentation, and the tibial component can be moved superiorly (Figure 13). However, the thickest revision polyethylene insert available is only 14 mm. If the defect exceeds Wound Closure A layered closure is paramount to avoid catastrophic wound complications. If an anterior approach is used, special attention should be paid to closure of the retinaculum. This closure may be challenging because of scarring and diminished tissue compliance resulting from previous surgery. Postoperative Regimen Revision arthroplasties are treated the same as primary ankle replacements. The procedure is generally done under a popliteal catheter block, which 218 Advanced Reconstruction: Foot and Ankle American Academy of Orthopaedic Surgeons

7 Revision Total Ankle Arthroplasty: Managing Osteolysis and Subsidence allows for postoperative pain relief. A suction drain is used for the first 24 hours after the procedure. The author of this chapter places the patient in a short leg cast immediately postoperatively. Patients are discharged the day after revision arthroplasty and are seen in the clinic 3 weeks postoperatively. At that time, the cast is removed, and the wound is inspected. If only polyethylene exchange or bone grafting of the cyst was performed, partial weight bearing is allowed at 3 weeks postoperatively, and full weight bearing is allowed at approximately 6 weeks. If the tibial or talar components needed revision or other procedures were performed, the patient is generally kept in a cast for 6 weeks, and partial weight bearing is initiated at 6 weeks, with full weight bearing at 12 weeks. Avoiding Pitfalls and Complications The foremost concern during revision arthroplasty is to do no harm. Care of the soft tissues is of critical importance. The initial surgical exposure for all ankle arthroplasties has resulted in substantial wound problems. These anterior incisions can be troublesome for a revision arthroplasty and may require special techniques, such as the use of a preoperative free flap or consultation with a plastic surgeon. In addition, at the time of revision, the surgeon must handle the soft tissues with great care and not allow continuous retraction on the skin, which may result in necrosis. It is critically important that the surgeon exercise great care when removing the implanted prosthesis so as to not sacrifice tibial or talar bone. Removal is best accomplished by using a very thin reciprocal saw to cut around the metallic components and thin osteotomes and gentle distraction techniques. Finally, as with primary insertion of a prosthesis, overall alignment of the revised component is critical. Malpositioning of the components allows for premature wear and failure of the revision. Bibliography Barg A, Zwicky L, Knupp M, Henninger HB, Hintermann B: HINTEGRA total ankle replacement: Survivorship analysis in 684 patients. J Bone Joint Surg Am 2013;95(13): Beck RT, Illingworth KD, Saleh KJ: Review of periprosthetic osteolysis in total joint arthroplasty: An emphasis on host factors and future directions. J Orthop Res 2012;30(4): Bonnin M, Gaudot F, Laurent JR, Ellis S, Colombier JA, Judet T: The Salto total ankle arthroplasty: Survivorship and analysis of failures at 7 to 11 years. Clin Orthop Relat Res 2011;469(1): Buechel FF Sr, Buechel FF Jr, Pappas MJ: Twenty-year evaluation of cementless mobile-bearing total ankle replacements. Clin Orthop Relat Res 2004;(424): Easley ME, Adams SB Jr, Hembree WC, DeOrio JK: Results of total ankle arthroplasty. J Bone Joint Surg Am 2011;93(15): Glazebrook MA, Arsenault K, Dunbar M: Evidence-based classification of complications in total ankle arthroplasty. Foot Ankle Int 2009;30(10): Gougoulias N, Khanna A, Maffulli N: How successful are current ankle replacements? A systematic review of the literature. Clin Orthop Relat Res 2010;468(1): Holt G, Murnaghan C, Reilly J, Meek RM: The biology of aseptic osteolysis. Clin Orthop Relat Res 2007;460: Karantana A, Hobson S, Dhar S: The Scandinavian Total Ankle Replacement: Survivorship at 5 and 8 years comparable to other series. Clin Orthop Relat Res 2010;468(4): American Academy of Orthopaedic Surgeons Advanced Reconstruction: Foot and Ankle 2 219

8 Degenerative Conditions of the Ankle Knecht SI, Estin M, Callaghan JJ, et al: The Agility total ankle arthroplasty: Seven to sixteen-year follow-up. J Bone Joint Surg Am 2004;86(6): Kofoed H: Scandinavian Total Ankle Replacement (STAR). Clin Orthop Relat Res 2004;(424): Mann JA, Mann RA, Horton E: STAR ankle: Long-term results. Foot Ankle Int 2011;32(5):S473-S484. Nunley JA, Caputo AM, Easley ME, Cook C: Intermediate to long-term outcomes of the STAR Total Ankle Replacement: The patient perspective. J Bone Joint Surg Am 2012;94(1): Ollivere B, Wimhurst JA, Clark IM, Donell ST: Current concepts in osteolysis. J Bone Joint Surg Br 2012;94(1): Pyevich MT, Saltzman CL, Callaghan JJ, Alvine FG: Total ankle arthroplasty: A unique design. Two to twelve-year follow-up. J Bone Joint Surg Am 1998;80(10): San Giovanni TP, Keblish DJ, Thomas WH, Wilson MG: Eight-year results of a minimally constrained total ankle arthroplasty. Foot Ankle Int 2006;27(6): Takakura Y, Tanaka Y, Kumai T, Sugimoto K, Ohgushi H: Ankle arthroplasty using three generations of metal and ceramic prostheses. Clin Orthop Relat Res 2004;(424): Valderrabano V, Hintermann B, Dick W: Scandinavian total ankle replacement: A 3.7-year average followup of 65 patients. Clin Orthop Relat Res 2004;(424): Wood PL, Karski MT, Watmough P: Total ankle replacement: The results of 100 Mobility total ankle replacements. J Bone Joint Surg Br 2010;92(7): Wood PL, Prem H, Sutton C: Total ankle replacement: Medium-term results in 200 Scandinavian Total Ankle Replacements. J Bone Joint Surg Br 2008;90(5): Advanced Reconstruction: Foot and Ankle American Academy of Orthopaedic Surgeons