RESECTION ARTHRODESIS BY TRIANGULAR EXTERNAL FIXATION FOR POSTTRAUMATIC ARTHROSIS OF THE ANKLE – CLINICAL RESULTS IN 95 CASES

Abstract

Introduction: In the last ten years there is a clear favour toward internal fixation. We evaluated the technique and the clinical long term results of external fixation in a triangular frame.

Patients and Methods: From 1994 to 2001 a consecutive series of 95 patients with end stage arthritis of the ankle joint were treated. Retrospectively the case notes were evaluated. Mean age at the index procedure was 45.4 years (18–82), 67 patients were male (70.5%). In all cases the arthritic deformity was due to a posttraumatic condition. The index procedure took place on average 129 months (6–516 months) after trauma. Preoperatively 43 patients had a relevant mal-alignment. In 41 patients the range of motion (ROM) was decreased with a remaining ROM of < 20°, in further 37 cases the remaining ROM was < 10° ROM. Via a bilateral approach the malleoli and the joint surfaces were resected. An AO fixator was applied with four Steinmann-nails inserted. Follow up examination at mean 4.4 years included a standardised questionnaire and a clinical examination including the criteria of the AOFAS-Score and radiographs.

Results: In all cases the index procedure was possible although in 2 cases soft tissue contracture meant that a pes equinus position of approximately 15° was required. After mean 12.3 (8–16) weeks radiographs confirmed satisfactory union and the fixator was removed. There were no cases of DVT or PE detected in the postoperative period. In 9 cases (10.1%) we saw a reversible irritation of the dorsal cutaneous nerve. In 18 cases a pin tract infection developed (20.2%) which healed under conservative measures. In one case (1.1%) a bony infection around a pin site developed, one patient suffered a fracture of the tibia at the site of the former proximal tibial pin site due to a minor trauma. In 4 patients a non-union of the ankle arthrodesis developed (4.5%). The mean AOFAS score improved from 20.8 (Std. dev.16.2) to 69.3 at F/U (Std.dev. 21.5, p = 0,004–30, T-test). The largest improvements were found regarding to pain and walking distance. Whilst preoperatively only one patient had mild pain, at follow up 54 patients had no or only mild pain. The maximal walking distance improved from mean 675 metres to mean 3245 m (T-test, p < 0,025 –18). Analysis of the insurance status showed patients that patients insured under a workers injury compensation scheme had a mean score of 63.6 compared to 75.1 for the remaining (T-test, p=0,027).

Discussion: Non-union rates and clinical results of arthrodesis by triangular external fixation of the ankle joint do not differ to internal fixation

Methods: The complication rate and the reduced patient comfort reserve this method mainly for infected arthritis and complicated soft tissue situations.