Time to Achieve the Minimal Clinically Important Difference in Primary Total Hip Arthroplasty: Comparison of Anterior and Posterior Surgical Approaches

Abstract

Introduction: There is an ongoing debate about whether there are differences in outcomes between anterior and posterior total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) provide insight into the patient’s perspective, which has proven valuable in assessing postoperative outcomes.

Objective: This study aimed to compare the time to achieve the minimal clinically important difference (MCID) for the Hip Disability and Osteoarthritis Outcome Score-Physical Function Short Form (HOOS-PS) and the Patient-Reported Outcomes Measurement Information System (PROMIS) Global-Physical for patients who underwent anterior and posterior surgical approaches in primary THA.

Methodology: Patients who completed HOOS-PS or PROMIS Global-Physical questionnaires between January 2018 and January 2021 in a single, large hospital system were identified and separated into anterior and posterior approach groups. Demographic and MCID achievement rates were compared using Pearson chi-squared and Wilcoxon rank-sum tests. Survival curves with and without interval censoring were used to assess the time to achieve the MCID by approach. Log-rank tests were used to analyze data without interval censoring, and weighted log-rank tests were used for interval-censored data. Weibull regression analysis with hazard functions was performed to assess potential covariates.

Results: A total of 2,725 patients (1,054 anterior/1,671 posterior) were analyzed. Anterior THA patients had a lower Charlson Comorbidity Index than posterior THA patients (6.1±2.8 vs. 6.6±3.1, p<0.001). There were no significant differences in the median time to achieve MCID for either the HOOS-PS (anterior: 5.9 months, 95% CI: 4.6-6.4 months; posterior: 4.4 months, 95% CI: 4.1-5.1 months, p=0.65) or the PROMIS Global-Physical (anterior: 4.2 months, 95% CI: 3.5-5.3 months; posterior: 3.5 months, 95% CI: 3.4-3.8 months, p=0.08) between the two surgical approaches. Interval censoring revealed earlier times of achieving the MCID for both the HOOS-PS (anterior: 1.509-1.511 months; posterior: 1.7-2.3 months, p=0.874) and the PROMIS Global-Physical (anterior: 3.0-3.1 weeks; posterior: 2.7-3.3 weeks, p=0.180) for both surgical approaches.

Conclusion: The time to achieve MCID did not differ by surgical approach. Most patients will achieve clinically meaningful improvements in physical function much earlier than previously believed. Choosing which surgical approach should be based on the patient’s specific condition and the surgeon’s expertise and preferences.

Aris Paschalidis

Medical Student

My research interests include health analytics, infectious diseases, and artificial intelligence.