Effectiveness of total hip arthroplasty versus non-surgery on patient-reported hip function at 3 months: a target trial emulation study of patients with osteoarthritis.

Background and purpose:  This study introduces an innovative research design in the field of orthopedics, using a target trial emulation approach. We aimed to assess the causal effects of total hip arthroplasty (THA) compared with nonoperative treatment in reducing patient-reported hip disability at 3 months in patients with osteoarthritis, using real-world data.

Methods:  We emulated a target trial using real-world data of 2 Dutch hospitals between April 2020 and January 2022. Patients diagnosed with hip osteoarthritis and eligible for primary THA were included in the study. During the COVID-19 pandemic, THA was often cancelled due to external factors (i.e., limited operating room capacity, or surgeon unavailable due to quarantine rules), resulting in an arbitrary allocation of patients to THA (n = 132) or non-THA (n = 60). We compared changes in hip disability, measured using the Hip disability and Osteoarthritis Outcome Score Physical function Short form (HOOS-PS), between the THA group at 3 months postoperatively and the non-THA group at ≥3 months post waiting-list. Linear regression analysis, adjusting for potential confounders, was used to compare between-group differences.

Results:  THA showed preferable outcomes compared with non-THA, indicated by a difference of -33 points (95% confidence interval [CI] -37 to -28) on the HOOS-PS. Patients in the THA group demonstrated a clinically significant improvement in hip function, with a mean change of -27 points (CI -31 to -24), while the control group showed no improvement with a mean change of 7 points (CI 3-11) on the HOOS-PS.

Conclusion:  THA significantly improves hip function in osteoarthritis patients, surpassing the outcomes observed in the non-surgery group.