Effective Index of Talar Dome Articular Surface as a Predictor of Clinical Outcomes for Supramalleolar Osteotomy for Takakura 3B Ankle Osteoarthritis

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: The supramalleolar osteotomy (SMOT) procedure may delay the need for ankle arthroplasty or arthrodesis in stage 3B varus ankle arthritis. For the surgeon, determining which patients would benefit from SMOT is the challenge. The purpose of this study was to determine the relationship between effective index of talar dome articular surface (EITDAS) and clinical outcomes after the SMOT as a preliminary predictor. Methods: Outcomes of 44 SMOT patients with stage 3B were reviewed at an average of 43.5 months. The clinical outcomes and radiologic parameters were collected at the preoperative and last follow-up. The correlation between preoperative radiologic parameters and postoperative outcomes was analyzed to determine predictor variables for outcomes after SMOT. And subgroup analyses for predictor variables were performed. The receiver operating characteristic (ROC) curve analysis determined the cut-off value for the predictor variable. The patients were divided into two groups according to the cut-off value, and outcomes with both groups were compared. Results: EITDAS was the only preoperative radiologic variable that demonstrated a significant correlation with AOFAS-AH (r=0.64, P<.001), VAS (r=-0.74, P<.001), SF-12 MCS (r=0.44, P=.003), and SF-12 PCS (r=0.72, P<.001), but not associated with radiologic parameters and stage postoperatively (ALL, P>.05). And the significant correlations remained after performing subgroup analyses (ALL, P<.05). Among them, with the highest linear correlation with VAS (R2=0.60, P<.001). Optimal cut-off of EITDAS for predicting postoperative pain (VAS>3) derived from the ROC curves were 0.544 (sensitivity=100%, specificity= 65.5%).The improvement of VAS, AOFAS-AH, and SF-12 PCS were better in the EITDAS>0.544 group as compared to the<0.544 group (P <.05). Conclusion: The preoperative EITDAS was a valuable predictor of clinical outcomes after SMOT in stage 3B ankle arthritis. Patients of EITDAS < 0.544 may have lower benefits from the SMOT procedure, and the risk of potential pain may have to be considered when preoperative counseling and surgery. (A) The ratio of red to yellow is for EITDAS value. (B)<a, tibial articular surface angle (TAS); <b, talar tilt (TT) angle; d1, tibial medial displacement (TMD). (C)<c, tibial lateral surface (TLS) angle; <e, Meary angle; <f, calcaneal incline angle (CIA). (D)<g, hindfoot alignment angle (HAA).