SLR - January 2022 - Devrie Stellar

Three-Year Rates of Reoperation and Revision Following Mobile Versus Fixed-Bearing Total Ankle Arthroplasty: A Cohort of 302 Patients with 2 Implants of Similar Design

Reference: Assal M, Kutaish H, Acker A, Hattendorf J, Lübbeke A, Crevoisier X. Three-Year Rates of Reoperation and Revision Following Mobile Versus Fixed-Bearing Total Ankle Arthroplasty: A Cohort of 302 Patients with 2 Implants of Similar Design. J Bone Joint Surg Am. 2021 Nov 17;103(22):2080-2088. doi: 10.2106/JBJS.20.02172. PMID: 34424866.

Level of Evidence: III

Scientific Literature Review

Reviewed By: Devrie Stellar, DPM
Residency Program: Inova Fairfax Medical Campus – Falls Church, VA

Podiatric Relevance: The gold standard surgical treatment for ankle arthritis has traditionally been arthrodesis, but total ankle arthroplasty (TAA) has gained popularity as advancements in implant design have improved outcomes and implant survival rates. Most current designs are usually separated into mobile-bearing three-component implants or fixed-bearing two-component implants. Despite the overall increase in literature regarding outcomes of TAA, there is still debate on which construct is superior. The purpose of this study was to compare the short-term survival and evaluate the frequency, cause and type of reoperation of mobile-bearing versus fixed-bearing implants of similar design from the same manufacturer, implanted by the same surgeons at three years after implantation.
   
Methods: Three hundred two (302) patients included underwent TAA with either the mobile-bearing Salto (171 patients) or fixed-bearing Salto Talaris (131 patients) implant by two surgeons together from 2004-2018 through an anterior approach. All patients who underwent TAA after April 2013 received the fixed-bearing implant. The surgeons stated they were adequately experienced with the procedure by the time the study began as they had been implanting the mobile-bearing TAA since 2000. The primary outcome was time to first all-cause reoperation or revision, defined as any procedure on the ankle and/or any adjacent joints following the initial surgery within three years post-operatively. Secondary outcomes included the frequency, cause and type of reoperation.

Results: Regarding patient demographics, the fixed-bearing group was found to have a higher proportion of valgus-aligned ankles and a higher mean age. Twenty-two patients (12.9 percent) in the mobile-bearing group underwent at least one reoperation with a total of 31 reoperations compared with 11 patients (8.4 percent) with a total of 14 reoperations in the fixed-bearing group. Fourteen patients in the mobile-bearing group underwent revision of any component of the implant for a three-year component survivorship of 91.8 percent compared with three in the fixed-bearing group for a survivorship of 97.7 percent. In the mobile-bearing group the most common reoperation procedures were cyst debridement, gutter debridement, salvage arthrodesis, wound debridement and polyethylene exchange compared to wound debridement, salvage arthrodesis and ligamentoplasty in the fixed-bearing group.

Conclusions: The debate about usage of mobile-bearing vs fixed-bearing implants is ongoing. The authors concluded that their results support the use of a fixed-bearing implant model for TAA due to the three times higher rate of revision of the mobile-bearing construct compared to the fixed-bearing group. Although limited by its retrospective design, strengths of this study include the large patient cohorts and the utilization of two implants of similar designs and from the same manufacturer implanted by the same surgeons. By eliminating the bias that can be found in using different manufacturers or different surgeons, this study gives a more accurate view into if fixed vs mobile-bearing design plays a role in the development of short-term complications. Future literature should target why mobile-bearing implants appear to have higher complication rates than the fixed-bearing designs, particularly regarding cyst formation and polyethylene wear. 

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