Objective To compare the effectiveness of supramalleolar osteotomy (SMOT) and ankle arthrodesis (AA) in the treatment of inverted ankle osteoarthritis (OA) in Takakura 3A stage with talus tilt. Methods The clinical data of 41 patients with inverted ankle OA in Takakura 3A stage with talus tilt admitted between January 2016 to January 2020 and met the selection criteria were retrospectively analyzed, and they were divided into SMOT group (21 cases) and AA group (20 cases) according to the surgical method. There was no significant difference in baseline data such as gender, age, affected side, cause of injury, and preoperative talar tilt angle (TT), American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, visual analogue scale (VAS) score, short-form 36 health survey scale (SF-36) score, and sagittal range of motion (ROM) between the two groups (P>0.05). The operation time, intraoperative blood loss, partial weight-bearing time, and complications were recorded in the two groups. AOFAS ankle-hindfoot score, VAS score, SF-36 score, and sagittal ROM were used to evaluate the effectiveness. Bone healing was observed and the time of bony healing was recorded. In the SMOT group, the tibial lateral surface angle (TLS), TT, and the tibial articular surface angle (TAS) were measured on ankle joint weight-bearing anteroposterior and lateral X-ray films and compared with those before operation. And Takakura staging assessment was also performed. ResultsThe operation time and intraoperative blood loss in AA group were significantly less than those in SMOT group (P<0.05). Patients in both groups were followed up 24-36 months, with an average of 28.9 months. Incision infection occurred in 2 patients in SMOT group and 1 patient in AA group, respectively, and no vascular or nerve injury occurred in both groups. The partial weight-bearing time of SMOT group was significantly less than that of AA group (P<0.05), but there was no significant difference in bony healing time between the two groups (P>0.05). At last follow-up, the difference of VAS score and SF-36 score before and after operation of AA group were less than those of SMOT group, and the difference of sagittal ROM before and after operation in SMOT group was less than that of AA group, with significant differences (P<0.05). The difference of AOFAS ankle-hindfoot score before and after operation in AA group was slightly greater than that in SMOT group, but the difference was not significant (P>0.05). The above scores in both groups significantly improved when compared with those before operation (P<0.05). Sagittal ROM in AA group was significantly less than that before operation (P<0.05), while there was no significant difference in SMOT group (P>0.05). In the SMOT group, 17 patients (81.0%) showed improvement in imaging staging, 2 patients (9.5%) showed no improvement in staging, and 2 patients (9.5%) showed stage aggravation. TLS, TAS, and TT significantly improved when compared with those before operation (P<0.05). At last follow-up, 2 patients in SMOT group received AA due to pain and stage aggravation, and 1 patient with bone nonunion underwent bone graft. Subtalar joint fusion was performed in 1 case of subtalar arthritis in AA group.Conclusion For inverted ankle OA in Takakura 3A stage with talus tilt, both SMOT and AA can significantly releave pain, improve foot function and quality of life, but AA has more definite effectiveness and better patient satisfaction.