EP1.85 Identifying Independent Predictors of Clinically Significant Outcome Achievement following Bernese Periacetabular Osteotomy

Abstract Background Patient-reported outcome measures (PROMs) quantify post-surgical symptoms and function, but do not inherently indicate clinical significance. Clinically significant outcomes (CSOs), such as the minimal clinically important difference (MCID), patient acceptable symptom state (PASS), and substantial clinical benefit (SCB), help interpret meaningful changes. Procedure-specific thresholds for Bernese periacetabular osteotomy (PAO) remain sparsely defined and predictors of CSO achievement have yet to be identified. Methods Patients undergoing a Bernese PAO between 6/2020-12/2024 by a single surgeon were identified. Patients were administered HOOS and iHOT-12 preoperatively and at ≥1 year postoperatively. MCID thresholds were established using the distribution method, while PASS and SCB absolute thresholds were calculated using the anchor-question based method. The proportion of patients achieving MCID, PASS, and SCB for individual PROMs as well as for any PROM (i.e., ≥1 PROM) was recorded. Stepwise multivariate logistic regression was used to identify independent predictors of achieving the MCID, PASS, and SCB for any PROM. Results A total of 133 patients were included (age=24.0±8.0; female sex=94.0%). MCID, PASS, and SCB absolute thresholds were established across all PROMs, with receiver operating characteristic (ROC) curve performance ranging from good to excellent for PASS (AUROC=0.89-0.96) and SCB (AUROC=0.82-0.91). MCID was achieved by 60.8%-72.6% of patients for individual PROMs, with 82.8% achieving it for ≥1 measure. PASS rates ranged from 52.0%-72.7% across PROMs, with 77.4% overall. The SCB achievement rate was 47.0%-54.7% per PROM and 69.9% overall. A preoperative pathologic gait was independently predictive of MCID achievement (OR=5.04; P=0.043). Preoperative symptom duration >2 years (OR=0.33; P=0.048) and femoral antetorsion >25° (OR=0.23; P=0.031) were associated with lower PASS achievement. Preoperative symptom duration >2 years also independently predicted SCB achievement in a negative fashion (OR=0.39; P=0.041). Conclusion A high proportion of patients undergoing Bernese PAO achieve clinically meaningful improvement and satisfactory state. Preoperative pathologic gait was independently associated with increased likelihood of achieving MCID, whereas symptom duration >2 years and femoral antetorsion >25° were independently associated with decreased likelihood of achieving PASS, and symptom duration >2 years was also associated with decreased likelihood of achieving SCB.