Supramalleolar Osteotomy Combined with Medial Malleolar Osteotomy for Varus Ankle Osteoarthritis with Varus Medial Malleolar Deformity

Abstract

Category: Ankle Arthritis; Ankle Introduction/Purpose: In some cases of varus ankle osteoarthritis (VAO), the varus medial malleolar deformity causes widening of the mortise and reduced conformity. In such cases, the angles of the medial distal tibial platform and the angle of the talar medial shoulder are different, so it is necessary to match the angles of both to improve the compatibility of the mortise. We performed lateral closing wedge supramalleolar osteotomy (LCWSMO) with opening wedge medial malleolar osteotomy (OWMMO) to achieve lateral shift of the load-bearing axis and mortise-plasty at the same time. The purpose of this study was to evaluate the therapeutic outcomes of this technique for VAO with the varus medial malleolar deformity. Methods: The subjects were 12 joints in 12 cases, two males and ten females, the mean age at the surgery was 58.2 years (36-76 years), and the mean follow-up period was 9 years and 1 month (1-20 years and 4 months). After LCWSMO was performed, OWMMO was made to fit the mortise, and autogenous bone grafting was performed in the gap. Additional surgery included two lateral ligament reconstructions, one osteochondral graft, and one high tibial osteotomy. Clinical evaluation was performed using the score of Takakura et al. For arthroscopic evaluation, we used our five grades classification, which is based on the percentage of eburnation areas on the articular surface. The radiographic assessments were the Takakura-Tanaka staging system, the tibial articular surface angle, the tibial lateral surface angle, the talar tilting angle, and the ratio of the medial distal tibial platform angle to the medial talar shoulder angle. Results: The clinical score improved from a preoperative average of 65.0±9.3 points to 82.8±9.8 points at the final follow-up. All arthroscopic grade improved at one year after surgery except one each of grade 2 and grade 3 joints which remained unchanged. According to the postoperative radiographic staging, 6 joints had improved, 3 had not changed, and 3 had progressed. The tibial articular surface angle increased from an average of 84.4 ± 2.1° preoperatively to 97.4 ± 3.6° at the last observation, the tibial lateral surface angle from 80.5 ± 2.5° to 83.7 ± 5.9°, the talar tilting angle increased 11.3 ± 4.7° to 7.9 ± 4.3°, and the ratio of the medial distal tibial platform angle to the medial talar shoulder angle from 112.3±4.9% to 103.6±5.8%. Conclusion: For VAO with varus medial malleolar deformity and large mortise opening, good results can be obtained by lateral shift the load-bearing axis with LCWSMO and improving the fit of the mortise with OWMMO.