Indications for Supramalleolar Osteotomy in Patients with Ankle Osteoarthritis and Varus Deformity

Background: Osteotomies are reported to be effective for the treatment of most cases of primary and traumatic moderate osteoarthritis of the ankle joint. Because of unsatisfactory results following supramalleolar tibial osteotomy in several of our patients, we investigated the cause of the unsatisfactory results and the indications for this surgical procedure. Methods: Supramalleolar tibial osteotomy combined with fibular osteotomy was performed in sixteen ankles (sixteen patients) to treat moderate medial ankle osteoarthritis. The median duration of follow-up was 2.3 years (range, one to 6.5 years). Clinical assessment was performed with use of the American Orthopaedic Foot & Ankle Society (AOFAS) scale, and the osteoarthritis stage was determined radiographically with use of the modified Takakura classification system. Clinical and radiographic results were compared among groups defined by high (>= 9.5 degrees) or low (<= 4 degrees) postoperative talar tilt and by the presence or absence of postoperative lateral subfibular pain. The optimal threshold of preoperative talar tilt for predicting high postoperative talar tilt was determined with use of receiver operating characteristic curve analysis. Results: The mean AOFAS score, mean Takakura stage, and mean values of all radiographic parameters were improved significantly after surgery. The preoperative talar tilt was correlated with the postoperative talar tilt (Spearman rho = 0.75, p < 0.01). The mean AOFAS score was higher (p = 0.02) and the mean radiographic stage was lower (p = 0.03) in the group with low postoperative talar tilt than in the group with high talar tilt. The optimal threshold for predicting high postoperative talar tilt was 7.3 degrees of preoperative talar tilt, with a sensitivity of 100% and a specificity of 91.7%. The patients with lateral subfibular pain had a lower mean AOFAS score, a greater angle between the tibia and the ankle surface postoperatively, and greater postoperative heel valgus than those without lateral subfibular pain. Conclusions: Supramalleolar osteotomy is indicated for the treatment of ankle osteoarthritis in patients with minimal talar tilt and neutral or varus heel alignment.