Keywords: Total Ankle Arthroplasty, Ankle Arthroplasty, Outcomes Measures
Introduction/Purpose: Total ankle arthroplasty (TAA) preserves motion compared to arthrodesis and has been associated with improved patient-reported outcomes. However, postoperative stiffness remains a common complication and is linked to poorer function and satisfaction. Limited adequately powered data exist on patient- or surgery-specific predictors of final ankle motion after TAA. The purpose of this study was to identify risk factors associated with postoperative stiffness following TAA.
Methods: We retrospectively reviewed 379 consecutive primary TAAs performed by a single surgeon between 2010 and 2023 with minimum 2-year follow-up. Patients were identified through CPT code search, and 165 met inclusion criteria of ≥1-year postoperative follow-up radiographs and documented preoperative ROM. Data collected included demographics (age, sex, BMI), comorbidities (diabetes, smoking, alcohol use, Charlson comorbidity index), surgical history, and adjuvant procedures such as gastrocnemius recession (GR) or tendo Achilles lengthening (TAL). Weight-bearing lateral radiographs in maximal dorsiflexion and plantarflexion were used to calculate total ROM. Preoperative ROM was classified as full (≥20° dorsiflexion) or limited. Comparisons were made between pre-op full vs. limited ROM groups and final follow-up full vs. limited ROM groups. T-tests or Mann-Whitney U tests were used for continuous variables and chi-square or Fisher’s exact tests for categorical data. Multivariable logistic regression was performed to identify independent predictors of final stiffness.
Results: The cohort included 168 patients with a mean age of 64 and BMI 30.7. Preoperatively, 64 patients (38.8%) demonstrated full ROM, and 101 (61.2%) had limited ROM. Patients with prior ankle surgery were more likely to have limited pre-op ROM (57% vs. 34.4%, p=0.009). At final follow-up of a mean 3 years (range 365-3410 days), 63 patients (38.2%) achieved full ROM, while 102 (61.8%) were limited. Patients with full preop ROM were more likely to achieve greater dorsiflexion (19.5 vs 16.5, p = 0.001) and full ROM at final follow up (52.4% vs. 30.4%, p=0.008). Adjuvant procedures were less common in patients who achieved full ROM (24.5% vs. 9.5%, p=0.029). In the regression model, preoperative ROM was the only significant predictor of achieving full final ROM.
Conclusion: Preoperative ROM was the strongest predictor of final postoperative stiffness following TAA. Patients with limited pre-op motion were significantly less likely to regain full ROM, while traditional comorbidities such as diabetes, BMI, and smoking were not associated with stiffness. These findings emphasize the importance of preoperative motion assessment and patient counseling. Future work should evaluate targeted surgical and rehabilitation strategies to improve motion recovery in high-risk patients.
