Subchondral Bone Cysts Remodel after Correction of Varus Deformity in Ankle Arthritis

Category: Ankle Arthritis; Ankle Introduction/Purpose: Subchondral bone cysts (SBCs) of the talus are frequently observed in ankle osteoarthritis (OA). It is unclear whether the cysts need an additional operation after correction of the varus deformity in ankle OA. The purpose of this study is to investigate the incidence of SBCs and the change after supramalleolar osteotomy (SMOT). Methods: Thirty-one patients treated by SMOT were retrospectively reviewed, 11 ankles with pre-operative cysts. After SMOT, the evolution of cysts was evaluated on weightbearing computerized tomography (WBCT) without management of cysts. The preoperative and postoperative tibial articular surface angle (TAS), tibio-talar surface angle (TTS), Foot and Ankle Offset (FAO), and hindfoot alignment calcaneal moment arm (HA) were compared. Results: At baseline, 11 (35.5%) of these 31 ankles had the SBCs, and the average maximum cyst volume was 65.86±60.53 mm 3 . By comparison with the pre and postoperative parameters, the TAS, TTS, FAO and HA were significantly corrected (P＜0.001). The number and volume of cysts were reduced dramatically (P＜0.05). Conclusion: Supramalleolar osteotomy can effectively correct the varus alignment and remodel the SBCs of talus in varus ankle arthritis. The regression of SBCs was observed after SMOT, additional intervention for the SBCs of the talus may not be necessary.