Medium term follow-up of the Corin Zenith total ankle replacement in an independent non-inventor cohort

V. Sinclair, T. Millar, S. Garg

Introduction: Total ankle replacement (TAR) design has evolved greatly in recent years and offers a reasonable alternative to ankle arthrodesis in a select patient population with end-stage arthritis. Originator series' report good longevity and excellent patient reported outcomes (PROMs). We report our outcomes in an independent, non-inventor cohort.

Method: We collected prospective data on consecutive patients undergoing total ankle replacement between April 2008 and March 2012, under the care of one Consultant Orthopaedic surgeon. The primary outcome measure was time to revision. Secondary outcomes measures included American Orthopaedic Foot and Ankle Society (AOFAS) scores, Visual Analogue Score (VAS) for pain, and complications.

Results: 70 patients underwent TAR with a mean follow-up of 64 months (39-86). Three patients underwent revision of TAR to ankle arthrodesis, two for aseptic loosening and one for infection, equating to survivorship of 96%.
Three patients sustained intra-operative fractures, one of the lateral malleolus and two of the medial malleolus. The patient who sustained the lateral malleolus fracture later went on to develop aseptic loosening requiring revision. One patient developed a late stress fracture of the medial malleolus. Two patients underwent open exploration, grafting of bone cysts and fixation for ongoing pain at a mean time of 4.5 years following the primary TAR. At the most recent review all patients reported improved AOFAS scores from 39.55 (21-52) to 82.10 (57-100) and VAS from 9.11 (6-10) to 1.79 (0-6) respectively.

Conclusions: Longevity of the Zenith TAR in our non-inventor series is comparable to that of originator outcomes. Fractures are a recognized complication of TAR and when affecting the medial malleolus, do not appear to have an adverse effect on outcome. We feel that TAR offers an effective alternative solution to ankle arthrodesis with satisfactory relief of pain whilst preserving movement at the ankle joint.