What Factors Are Associated With Clinically Meaningful Improvements After Bernese Periacetabular Osteotomy?

Abstract

Background: Patient-reported outcome measures (PROMs) quantify symptoms and function, but the degree to which a patient considers an improvement or outcome after surgery to be meaningful can be difficult to quantify. Benchmarking improvement using metrics like the minimum clinically important difference (MCID), patient acceptable symptom state (PASS), and substantial clinical benefit (SCB) can help clinicians know what outcome or how large of an improvement is large enough to matter clinically and to their patients. Yet, procedure-specific thresholds for Bernese periacetabular osteotomy (PAO) remain poorly defined, and factors associated with clinically meaningful outcome achievement have yet to be identified.

Questions/purposes: For patients who underwent PAO, we sought to: (1) determine the MCID, PASS, and SCB absolute thresholds for the Hip Disability and Osteoarthritis Outcome Score (HOOS) and the 12-Item International Hip Outcome Tool (iHOT-12); (2) determine the proportion of patients achieving the MCID, PASS, and SCB across individual PROMs as well as for any PROM (that is, ≥ 1 PROM); and (3) identify patient factors that are independently associated with clinically meaningful outcome achievement.

Methods: Patients who underwent a Bernese PAO between June 2020 and December 2024 performed by a single surgeon were identified through a longitudinally maintained institutional hip preservation repository. During the study period, 162 patients had a PAO. A total of 7% of those (12 of 162) were excluded because they underwent unplanned reoperation; of the 150 who remained, 11% (17 of 150) were lost to follow-up before 1 year, leaving 82% (133 of 162) for final analysis with ≥ 1 postoperative PROM at a minimum of 1-year follow-up. The included patient population had a mean ± SD age of 24 ± 8 years, 94% (125 of 133) were women, most reported being physically active (51% [68 of 133]), and most underwent the PAO with a concomitant procedure, with staged hip arthroscopy being the most common (67% [89 of 133]). The MCID thresholds were established using the distribution method, whereas PASS and SCB absolute thresholds were calculated using the anchor question-based method. The proportion of patients achieving the MCID, PASS, and SCB for individual PROMs as well as for any PROM (that is, ≥ 1 PROM) was recorded. Stepwise multivariate logistic regression was used to identify factors independently associated with achieving the MCID, PASS, and SCB for any PROM. To determine the MCID, PASS, and SCB absolute thresholds for the HOOS and iHOT-12, thresholds were calculated as follows, respectively: HOOS symptoms (12, 62, 78), HOOS pain (12, 79, 80), HOOS activities of daily living (12, 83, 92), HOOS sports and recreation (16, 57, 72), HOOS quality of life (14, 61, 65), and iHOT-12 (16, 75, 77).

Results: When evaluating the proportion of patients achieving these thresholds across individual and combined metrics, we found that the MCID was achieved by 61% (62 of 102) to 73% (74 of 102) of patients for individual PROMs, with 83% (101 of 122) achieving it for at least one measure. The proportion of PASS achievement ranged from 52% (65 of 125) to 73% (85 of 117) across PROMs, with 77% (103 of 133) overall. The SCB achievement proportion was 47% (55 of 117) to 55% (64 of 117) per PROM and 70% (93 of 133) overall. With respect to identifying independent patient factors associated with clinically meaningful outcome achievement, a preoperative pathologic gait was independently associated with MCID achievement (OR 5 [95% confidence interval (CI) 1.3 to 33.6]; p = 0.046). Preoperative symptom duration > 2 years (OR 0.3 [95% CI 0.1 to 0.9]; p = 0.048) and femoral antetorsion > 25° (OR 0.2 [95% CI 0.1 to 0.9]; p = 0.03) were associated with lower odds of PASS achievement. Preoperative symptom duration > 2 years also was associated with lower odds of SCB achievement in a negative fashion (OR 0.4 [95% CI 0.2 to 0.9]; p = 0.04).

Conclusion: The present study defined MCID, PASS, and SCB thresholds for the HOOS and iHOT-12 after Bernese PAO, demonstrating that while the majority of patients achieve these benchmarks, a notable subset fall short of a satisfactory outcome. We identified specific patient factors, including preoperative symptom duration > 2 years and femoral antetorsion > 25°, that negatively impact clinically meaningful outcome achievement. These findings highlight chronicity and complex structural anatomy as markers of more advanced condition that may limit the efficacy of Bernese PAO. Surgeons should be cognizant of these factors and utilize them during preoperative counseling. Ultimately, these procedure-specific thresholds offer a more practical approach than raw outcome scores alone to improve risk stratification and track clinical success. Future studies are needed to validate these thresholds across larger, diverse populations, evaluate additional PROMs, establish anchor question-based thresholds for MCID, and determine the long-term durability of achieving these clinically meaningful outcomes.

Level of evidence: Level III, therapeutic study.