The effects of medial soft tissue release for varus deformity during medial open wedge supramalleolar osteotomy: a cadaveric study

This study was performed to investigate the effects of fibular osteotomy and release of medial soft tissues including posterior tibial tendon (PTT), and deep deltoid ligaments, which act as medial stabilizing structures in medial open wedge SMO. Twelve fresh frozen human legs were obtained and disarticulated below the knee. Experiments were conducted in four steps. First, medial open wedge tibial osteotomy was performed. Second, fibular osteotomy was performed in an inferomedial direction at the same level as the tibial osteotomy. Third, the deep deltoid ligament was released from tibial attachments. Forth, total tenotomy of the PTT was performed behind the medial malleolus. After finishing each step, contact area and peak and mean pressures were measured in the tibiotalar and talofibular joints. Fibular osteotomy after medial open wedge SMO significantly decreased mean pressure in the tibiotalar joint, mean and peak pressures in the talofibular joint. Medial soft tissue release resulted in a remarkable lateral shift and decreased tibiotalar joint loading. However, no remarkable change was observed in the tibiotalar joint during releasing medial soft tissues. The overall peak pressure distribution tended to shift more laterally compared to the value of normal alignment. In conclusion, concomitant fibular osteotomy and release of the deltoid ligament and PTT provide a useful means of minimizing tibiotalar joint stress.