Restoration of Talar Height using a Modular Revision Prosthesis after Failed Total Ankle Arthroplasty

CATEGORY: Ankle INTRODUCTION/PURPOSE: Talar component subsidence is the most common indication for revision total ankle replacement. The management of talar bone loss and alteration in the ankle joint center of rotation is challenging following component subsidence. Unfortunately, ankle arthrodesis as a salvage procedure for failed ankle arthroplasty has been associated with high rates of nonunion and collapse. Equally unfortunate, there is paucity in the literature on revision total ankle arthroplasty. The purpose of this study was to report the early outcomes of revision total ankle replacement using a modular prosthesis and metal/cement augmentation to reconstitute talar height following catastrophic failure of the index total ankle arthroplasty. METHODS: Retrospective review was performed on sixteen patients who underwent revision total ankle replacement for failed arthroplasty associated with talar component subsidence and subsequent talar bone loss. All patients underwent revision arthroplasty using a revision modular ankle prosthesis and had a minimum of one-year follow-up. Demographic data, postoperative complications, original prosthesis, and concomitant procedures were recorded. Radiographic measurements were performed at three time-points (preoperative, immediately after surgery, and at most recent follow-up) to evaluate alignment of the prosthesis, talar height, and ankle range of motion. Implant survivorship was determined. Failure was defined as >2 mm of talar subsidence, conversion to ankle arthrodesis or below the knee amputation, and/or revision of the prosthesis. Ankle Osteoarthritis Score (AOS), Foot Function Index (FFI), and visual analog score (VAS) were collected at the most recent postoperative visit. RESULTS: Patient follow-up ranged from 12.1 –20.6 months, with a mean follow-up of 15.0 months. The mean preoperative and immediate postoperative talar height was 28.7 mm and 33.4 mm, respectively. There was a significant improvement in talar height of 4.7 mm after revision total ankle replacement (P<0.001). Talar height was maintained at most recent follow-up. The mean preoperative and postoperative radiographic arc of motion was 19.5° and 24.0°, respectively. Two patients, with a mean BMI of 43.5, developed >2 mm of talar subsidence (one patient required revision surgery). The mean postoperative AOS and FFI was 25.0 and 28.8, respectively. The majority of patients (84%) were satisfied with their outcome, and all patients would choose to undergo the same procedure again (vs. arthrodesis or amputation). CONCLUSION: Revision ankle replacement using a modular prosthesis with metal/cement augmentation allows restoration of talar height. Though we recognize this data constitutes a very early follow up, this cohort has utilized the revision ankle implant with significant repetitive load after which older generation implants underwent secondary subsidence due to poor talar bone stock. Early outcomes demonstrate a predictable method to salvage catastrophic prosthesis failure associated with severe talar subsidence and deformity. The risk of postoperative complications, although moderate, is an acceptable alternative to lower limb amputation/arthrodesis. Further follow-up is warranted to determine functional outcomes and longevity of revision implant systems.