Association between abductor tears and hip pathology: A nationwide large cohort study.

Introduction: Although gluteal tears have been observed in a substantial percentage of total hip arthroplasty (THA) patients and hip osteoarthritis (OA) has been shown to alter the function of the gluteal muscles, the association between gluteal tears and hip OA has not been characterized. Therefore, we evaluated (1) the overlap between hip OA and gluteal tears, (2) the relative risks of gluteal tears in patients who have hip OA, and (3) gluteal tear-free survival after diagnosis or treatment for hip osteoarthritis. Methods: This retrospective study sourced data from TriNetX, a research network that aggregates data from over 92 million patients. Relative risks for gluteal tears were calculated for known risk factors for gluteal tears, age ≥45 years, female sex, and obesity, as well as for hip OA, hip injections, and THA. A subgroup analysis was performed utilizing a Cox proportional hazard model for patients who were diagnosed with hip OA, received a hip injection, or underwent THA in 2015 to assess gluteal tear-free survival over a 9-year timeframe. Results: There was a large degree of overlap between patients with hip OA and gluteal tears, as 17.9% of patients with hip OA and 27.5% of patients with a gluteal tear also had the other pathology. Hip OA was associated with a markedly increased risk of a gluteal tear compared to healthy controls (Relative risk: 26.75, 95% CI: 26.64-26.86). Upon controlling for the established risk factors of gluteal tears, patients with hip OA had a markedly more likely to subsequently be diagnosed with an abductor tear (Hazard ratio: 12.46, 95% CI: 11.75-13.22). Conclusion: Overall, these findings suggest a strong association between hip OA and the development of gluteal tears, in which further investigation is merited to determine the biomechanical pathophysiology underlying this potential relationship to inform prevention and treatment strategies.