Minimum two year outcomes of a fixed bearing total ankle replacement in the United Kingdom

B. Drake, W. Reeve, P. Dearden, R. Kakwani, A. Murty, N. Talbot, A. Hughes, D. Townshend, I. Sharpe

Introduction: The Infinity (Wright Medical Group) total ankle replacement (TAR) has become the most implanted ankle replacement in the United Kingdom (UK) with a 30.1% share in the most recent 2016 England and Wales National Joint Registry 14th report. It is a fixed bearing implant utilising an anterior approach and radiological guidance to aid alignment, and is approved for use in the UK as an uncemented implant.

Methods: Since introducing the Infinity TAR in June 2014, all implants from two centres in the UK; The Royal Devon and Exeter Hospital National Health Service (NHS) Foundation Trust and Northumbria NHS Healthcare Trust, have been followed up prospectively. 113 implants are included with two year minimum follow-up, average follow-up being 33 months (24-52). Pre- and post-operative demographic, radiographic and functional outcomes were collected including Visual Analogue Score (VAS), Manchester Oxford Foot Questionnaire (MOxFQ; UK validated patient reported outcome score) and EQ5D (validated quality of life score). Complexity was assessed using the Canadian Orthopaedic Foot and Ankle Society classification pre-operative grade.

Results: Implant survivorship was 93.8% at two years minimum. Median age was 68 years (42-92), male:female ratio 72:41. Mean MOxFQ improved by 28, mean EQ5D by 1.4 and mean VAS by 7. 16 cases had planned additional procedures, five required intra-operative medial malleolar fixation. There have been two revisions for deep infection, two for tibial sided implant subsidence, one for instability and two for unexplained pain (6.2%). Five patients have required further surgery to the ankle and hindfoot with implant retention (4.4%). Three patients have asymptomatic tibial cysts (3.4%) and one patient has an asymptomatic talar cyst (0.9%), there is no evidence of progression or loosening.

Conclusions: We report favourable early functional, radiographic and survivorship outcomes of this implant in the UK population.