Abstract
Category:
Ankle Arthritis; Ankle
Introduction/Purpose:
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 early revision rate.
Methods:
This IRB approved retrospectivelreviewed 202 patients who underwent TAA with either mobile-bearing or fixed-bearing implants 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. Age, gender, ASA score, smoking status, BMI and eciology of the arthritis were reported from patients' record. Preoperative weight bearing x-ray were assessed for COFAS classification and intra-articular deformity. Non-concentric ankles were defined by a talar tilt angle greater than 4 degrees. The primary outcome was the rate of revision and reoperation within three years following the index procedure. Revision was defined as implants removal or exchange. Reoperation was defined as any additional surgery post-index surgery. The data underwent normality testing with the Shapiro-Wilk test, and comparisons were made via Kruskal-Wallis test and Chi square test. A p-value threshold of 0.05 or below was deemed significant.
Results:
All groups were not statistically different for age, gender, ASA score, BMI, and smoking status. 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. In the non-concentric group revision rate was significantly higher (p< 0.05) for the mobile-bearing implant (15.2%) compared to the fixed-bearing implant (0%) . In the concentric group, no significant difference in revision rates between the fixed-bearing (6.2%) and mobile-bearing designs (7%) was observed. Reoperation rates were similar across all groups.
Conclusion:
The study suggested 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. Preoperative intra-articular deformity seems to be a predictor of early revision rate after total ankle arthroplasty.
