Defining the minimal clinically important difference, substantial clinical benefit, and patient-acceptable symptom state for femoral derotation osteotomy

Abstract To determine whether surgical intervention is effective from the patient’s perspective, clinically meaningful thresholds must be established to contextualize and interpret patient-reported change and postoperative status. The minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) have become widely used metrics in orthopedic surgery for providers to translate raw numerical values of patient-reported outcome measures into benchmarks of therapeutic relevance. These scores have yet to be defined for patients undergoing femoral derotation osteotomy (FDO) for the treatment of excessive femoral anteversion or retroversion. The MCID, SCB, and PASS for the modified Harris Hip Score (mHHS) were calculated through an anchor-based approach, according to subjective anchor questions assessing overall status and satisfaction. Minimal detectable change (MDC) was calculated to determine the smallest change in mHHS scores that can be considered above the level of measurement error. The validity of MCID and SCB estimates were assessed against MDC values. Of the 61 included patients (89% women, mean age 29 ± 9 years, mean 3 ± 2 year follow-up), 38 were treated for excessive femoral anteversion, and 23 were treated for excessive femoral retroversion. The MCID, SCB, and PASS thresholds for the mHHS were 8, 18, and 75, respectively. The MDC ranged from 5 to 7. The proportion of patients achieving MCID, SCB, and PASS for the mHHS were 85%, 72%, and 75%, respectively. As our scores are procedure-specific and derived directly from patient perceptions of change, they should be used preferentially in the postoperative assessment of FDO.