ARTHROSCOPIC ANKLE FUSION: TECHNIQUE AND THE LEARNING CURVE.

Abstract

The outcome of arthroscopic ankle fusion has been favourably reported in the literature. The technique allows for early weight-bearing and results in fusion earlier than that of open techniques. All authors state that it a demanding procedure that has a significant learning curve. The purpose of this presentation is to report on that learning curve by analysing the first two years experience of one surgeon. Technical details, difficulties encountered and outcomes are described.

We analysed the results of arthroscopic ankle fusion in 14 consecutive ankles in 13 patients over a two-year period. Average age at fusion was 59 years. There were 12 male patients and one female. Indication for surgery was osteoarthritis in all patients. All were non-smokers at the time of surgery. Anti-inflammatory drugs were not prescribed on discharge, All patients underwent pre-operative sciatic nerve block using a nerve stimulator. Fixation of the fusion was performed with two screws in 13 ankles and a single screw in one. Mean tourniquet time was 117 minutes (first 4 cases averaged 124 minutes; last 4 averaged 105 minutes). Mean hospital stay was a single night. All patients were treated post-operatively with plaster cast immobilisation for two weeks (non-weight bearing). Subsequently, they were instructed to fully weight bearing as tolerated in a removable walking boot.

Radiological union was achieved in 11 ankles within 3 months. One ankle fused at between 9–12 months post-operatively. One ankle failed to unite due to inadequate joint access and preparation and underwent later open revision with bone grafting. One case of superficial portal wound infection treated successfully with antibiotics. No thrombo-embolic events. All patients had excellent or good clinical results at last follow up.

Patient selection issues and intra-operative learning points are discussed. With adequate training, arthroscopic ankle fusion is a safe and reliable technique.

The level of accuracy and precision required for consistently good surgical results will vary depending upon the characteristics of surgical task being undertaken. Training surgeons to achieve these results rapidly and effectively is a continuing challenge. Resurfacing arthroplasty for cam type deformity (a common cause of early osteoarthritis) is a technically demanding operation. We considered it desirable that the operation should be performed within +/− 10¡ of the desired angular orientation, and +/− 6mm of entry point translation in 95% of cases. To achieve that level of accuracy, without learning slowly on real patients, technological aids are now available. Using 3 models of varying severity of cam, we assessed the efficacy of 3 systems of instrumentation in delivering the level of accuracy and precision that is needed to ensure the excellent results that this surgeon and patient group expects.