Abstract
Category:
Ankle Arthritis; Ankle
Introduction/Purpose:
The Infinity (Wright Medical Group) Total Ankle Replacement (TAR) has been implanted in patients since 2014 and is now the most common primary ankle used in the National Joint Registry of England and Wales. We report a prospective series of 106 Infinity TARs, with 8-year survivorship data from two, non-designer centres in the UK. The primary aims were to assess survivorship and complications of the Infinity TAR. The secondary aims were to assess patient reported and radiological outcomes.
Methods:
Prospectively collected data between March 2014 to December 2016 was assessed from two specialist centres in the United Kingdom. All operations were performed, or supervised, by one of 5 surgeons with a minimum experience of 10 TAR per year. Inclusion criteria were any patient with end-stage tibiotalar arthritis, considered by the operating surgeon to be suitable for primary TAR. Revision TAR, or conversion from arthrodesis, were not included in this study. Implant survivorship, complications, patient reported outcome scores (PROMS) and radiological data were collected for each patient. PROMS data comprised the Manchester Oxford Foot Questionnaire (MOX-FQ) and the EuroQol-5 Dimension (EQ5D-5L) score. Pre-operatively, weight bearing radiographs were assessed for the degree of sagittal and coronal deformity. Post-operatively, weight bearing radiographs at 6 weeks were assessed for the degree of deformity correction. Cystic radiolucencies on the most recent follow up radiograph was assessed by using an established scoring system.
Results:
102 patients, comprising 106 TARs, were included. Mean age at implantation was 68 years (range 42 to 89 years). Mean follow up time was 98 months (range 83 to 113 months). 12 patients received further surgeries: 8 revision TARs, 3 debridement and grafting of talar cysts, and 1 capsular release. The reasons for revision surgery were unexplained pain (5 patients), proven deep infection (1 patient), tibial subsidence (1 patient) and instability (1 patient). Mean time to revision surgery was 43 months (range 15 to 82 months). Current survivorship of the cohort is 91%. Cystic radiolucencies were present in 35% of patients but the majority were small and asymptomatic. MOXFQ and EQ5D-5L PROMS showed significant and sustained post-operative improvements (p < 0.01).
Conclusion:
This series of 106 modern fixed bearing TAR shows an 8-year survivorship of 91%. 3 cases of talar cysts were grafted. The most common reason for revision surgery was unexplained pain and the deep infection rate was 1%. The fixed bearing Infinity TAR appears to be a safe, effective intervention in the treatment of end stage ankle osteoarthritis and gives significant improvement in disease specific and general health status outcomes.