gms | German Medical Science

Objectives: Literature trends indicate a generally lower rate of reoperation and revision associated with the fixed-bearing two-component design implant compared to the mobile-bearing three-component design for total ankle arthroplasty (TAA). Coronal deformity is also linked to poorer outcomes following TAA. The aim of this study was to assess the impact of intra-articular coronal deformity (non-concentric ankle arthritis) on both fixed and mobile implant designs. We hypothesized that non-concentric ankle arthritis and mobile bearings would be associated with a higher revision rate.

Methods: This study retrospectively reviewed 202 patients who underwent TAA with either mobile-bearing or fixed-bearing implants at three centers in Switzerland by two surgeons between 2007 and 2018. Patients who underwent TAA from 2007 to 2013 received the mobile-bearing implant, while those who underwent TAA after November 2012 received the fixed-bearing implant. The primary outcomes were the rates of revision and reoperation within three years following the initial procedure. Reoperation was defined as any additional surgery post-index surgery, excluding revisions. Non-concentric ankles were identified by a talar tilt angle greater than 4 degrees on preoperative X-rays.

Results: Of the 76 patients who received a mobile-bearing implant, 33 had non-concentric arthritis, and 43 had concentric arthritis. Of the 126 patients who received a fixed-bearing implant, 61 had non-concentric arthritis, and 65 had concentric arthritis. In the mobile-bearing group, 8 patients underwent revision and 9 underwent reoperation. In the fixed-bearing group, 4 patients underwent revision and 10 underwent reoperation. The revision rate was significantly higher (p<0.05) for the mobile-bearing implant (15.2%) compared to the fixed-bearing implant (0%) in the non-concentric group. In the concentric group, there was no significant difference in revision rates between the fixed-bearing (6.2%) and mobile-bearing designs (7%).

Conclusion: The study demonstrated that the use of mobile-bearing implants in patients with non-concentric arthritis is associated with a significantly higher revision rate compared to fixed-bearing implants. In patients with concentric arthritis, there was no significant difference in revision rates between the two implant designs. Additionally, the study found no significant difference in the reoperation rates across all groups.