Impact of Stem Count on Clinical Outcomes Following INBONE I and II Revision Total Ankle Arthroplasty

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: INBONE I and INBONE II total ankle arthroplasty (TAA) systems utilize modular stemmed components, providing adaptability and enhanced stability in revision procedures. The determination of tibial stem count has remained guided by surgeon assessment. However, it remains unknown whether the number of stems used in revision cases influences implant survival and complication rates. This study evaluates the impact of stem count on clinical outcomes in revision TAA with INBONE I and INBONE II systems. Methods: A retrospective review of patients who underwent revision TAA using INBONE I or INBONE II at a single institution was conducted. Patients were categorized based on the number of stems used in the tibial component excluding the step top and base. Mechanical complication rates and subsequent reoperation were recorded. Cox proportional hazards model was preformed to assess the relationship between stem count and reoperation. Results: Seventy-seven patients underwent a revision TAA with INBONE I (18%) or II (82%) tibial component with average follow-up time of 4.0 ± 3.4 years. Mean age at the time of revision was 65.0 ± 9.8 years and mean BMI was 30.7 ± 6.1. The average number of stems was 3±1. Twenty patients (26.0%) sustained a complication resulting in reoperation. The metallic exchange rate after revision TAA was 15.6%, with infection being the most common reason for implant failure (n=3; 3.9%). There was no significant association between the number of stems and complication risk following revision TAA (p = 0.7, HR = 1.1, 95% CI: 0.71–1.72). Conclusion: Stem configuration in INBONE I and INBONE II revision TAA did not significantly impact complication rate. Future research should focus on understanding the balance between biomechanical stability and surgical complexity to guide implant selection and revision strategies, with an emphasis on longer-term follow-up to assess implant durability and patient outcomes over time.