A modular augmented arthroplasty system to manage larger bone defects in the ankle: a case series

R. Martin, M. Dean, R. Kakwani, A. Murty, I. Sharpe, D. Townshend

Introduction: Large bone defects such as those encountered after failed total ankle arthroplasty have previously been a relative contraindication to revision arthroplasty due to inadequate bone stock. We describe our early experience and patient reported outcomes with a novel modular ankle replacement system that includes tibial and talar augments.

Methods: This is a retrospective case series of patients who underwent a total ankle arthroplasty using the INVISION system across two centres between 2016 and 2022. Local approvals were granted. Patients completed the Manchester-Oxford Foot Questionnaire (MOXFQ), Ankle Osteoarthritis Scale (AOS) and EQ-5D-5L pre-operatively and then post-operatively at 6 months, 1 year, 2 years, 3 years and 5 years. Medical records were reviewed for complications and re-operations. Radiographs were reviewed for cysts or radio-lucencies and alignment.

Results: 17 patients were included in the study; 14 men and 3 women with an average age of 67.9 years (range 56 years to 80 years). The average follow up post operatively was 40.5 months (range 7 to 78) at the time of this study. The indication for surgery was revision of failed TAR in 16 and revision of failed ankle fusion in 1. An augmented tibia was used in 3, an augmented talus in 9, and both augmented tibia and talus in 5 cases. There was one post-operative medial malleolar fracture and one patient underwent debridement and implant retention for late deep infection. No implants have been revised. The average MOXFQ score improved by 19.3 points at most recent follow up. The average AOS score improved by 25.2 points.

Conclusion: The early results of a modular augmented ankle arthroplasty system have shown satisfactory patient outcomes with a low complication and re-operation rate and presents a viable option for patients with larger bone defects. Longer term follow up is required to determine implant survivorship.