Correction Target of Supramalleolar Osteotomy for Early Varus Ankle Arthritis: Is Overcorrection Necessary?

Abstract

Background: The aim of this study was to investigate the clinical and radiologic outcomes following supramalleolar osteotomy for early varus ankle arthritis with the medial translation of the talus, wherein the lateral translation of the talus center to the tibial axis was used as a correction target. Another aim was to compare the results between the ankles with a normal range of medial distal tibial angle (MDTA) and overcorrected MDTA at the postoperative period to investigate the role of overcorrected MDTA after the supramalleolar osteotomy.

Methods: The study comprised 90 patients (93 ankles) with Takakura stage 2 or 3a varus ankle arthritis with the medial translation of the talus, which underwent medial opening supramalleolar osteotomy with fibular osteotomy, and the mean duration of follow-up was 50.7 (range, 24-84) months. Clinical assessments were done with a visual analog scale for pain and the Foot Function Index. The correction target was set at the lateral placement of the talus center to the tibial axis. Radiographic parameters, talus center migration (TCM) and tibial axis-talus ratio (TT ratio), were used to evaluate talus positioning related to the tibial axis. Two groups were established based on postoperative MDTA: a neutral group (MDTA < 94 degrees) and an overcorrected group (MDTA ≥ 94 degrees).

Results: Postoperatively, clinical and radiographic outcomes improved in all patients (P < .01). TCM and TT ratio showed a lateral shift of the talus (TCM: from 2.0 ± 1.7 mm to -1.3 ± 1.6 mm, TT ratio: from 55.5% ± 5.4% to 44.7% ± 5.0%, both P < .01). As expected, the overcorrected MDTA group had a larger MDTA than the neutral group preoperatively (P < .01). However, there were no differences in clinical outcomes or changes in various radiographic parameters between the groups.

Conclusion: Lateral translation of the talus center relative to the tibial axis can be used as a correction target for medial opening supramalleolar osteotomy to treat early varus ankle arthritis with medial translation of the talus. Overcorrection of the tibial plafond to valgus does not seem necessary.

Level of evidence: Level IV, retrospective case series study.