Severe Ankle Varus Malalignment Management with a Fix-Bearing Total Ankle Replacement Implant

Abstract

Category:Ankle Arthritis; AnkleIntroduction/Purpose:Despite Total ankle replacement (TAR) is currently considered a safe procedure and an optimal alternative to ankle fusion in end-stage ankle arthritis, still the precise indications and the limits of TAR are a highly controversial topic. Coronal malalignment correction with TAR is also a widely debated point. Purpose of this work was to confront two patient groups undergoing Total Ankle Replacement (a group of patients with a pre-operative ankle varus misalignment on coronal plane, versus a group of patients with neutral pre-operative ankle alignment) comparing clinical and radiographic results, complications and survival rate of the implant.Methods:171 patients, all affected by end-stage ankle arthritis and all treated with total ankle replacement with fix-bearing Trabecular Metal Total Ankle System (Zimmer-Biomet, Warsaw IN, USA), were divided in two groups. Group ‘A’ included 159 patients having a normal alignment or a slight valgus or valgus misalignment within 10°. Group ‘B’ included 12 patients with a pre- operative varus malalignment >10°. Each patient of the study was evaluated, clinically and radiologically, before and after surgery, and subsequently at 6 and 12 months follow-up, then once every year. Clinical evaluation comprised some score: visual analogue scale (VAS); American Foot and Ankle Society Score (AOFAS); and the Short Form (SF)-12 Quality of Life, in both of its ‘physical’ (PCS) and ‘mental’ (MCS) components. Radiological evaluated parameters were: tibio-talar surface angle (TTS), lateral distal tibial angle (LDTA-α), and anterior distal tibial angle (ADTA-β). Complications and implant survival rate were evaluated for both groups.Results:At a mean follow up of 2,75 years (range 2.09-5.66 years), improvement was found in all clinical and radiological evaluated parameters of two groups, without statistically significant differences between two groups at last follow-up. In group A most frequent reported complication was the presence of a fibular symptomatic hardware. Major complication were a deep arthroplasty infection and a 3 months post-operative ankle fracture-dislocation/periprostethic fracture. In group B there were 2 delayed wound healing, and one case of loosening of correction. No significant difference in complication and revision rate comparison between two groups was founded.Conclusion:Mid-term results reported in the present show that in patients with varus greater than 10 ° it is possible to obtain a post-operative alignment similar to pre-operative neutral ankles and that the complication rate is not greater. Despite this, is Authors opinion that major and complex misalignment should be approached by skilled surgeons, with an adequate learning curve experience, with a wide range of cases and in highly specialized centers.