Risk Factors for Complications After Proximal Hamstring Avulsion Injury: Analysis of 757 Patients From the PHAS Cohort

Background: Proximal hamstring avulsion injuries (PHAIs) are significant but rare injuries that might require surgical repair. However, limited data exist on postoperative complication rates, associated risk factors, and long-term musculoskeletal outcomes. Purpose: To analyze the complication rate following PHAI surgery, identify risk factors for non-rerupture complications, and investigate the incidence of associated musculoskeletal conditions. Study Design: Cohort study; Level of evidence, 3. Methods: This prospective cohort study included 757 patients (mean age, 47.3 years) surgically treated for PHAI between 2002 and 2023. Patients with revision surgery or bony avulsions were excluded. Primary outcomes were complication rates and associated risk factors. Secondary outcomes included the functional outcomes of patients with or without complications, assessed through the Parisian Hamstring Avulsion Score (PHAS), Tegner Activity Scale, and UCLA score (University of California, Los Angeles). Results: The overall complication rate was 10.4% (79/757), including a 5.6% rerupture rate and 4.7% non-rerupture complication rate. Most complications (75%) occurred within 5.5 months postsurgery. Significant risk factors for non-rerupture complications included work-related accidents (odds ratio, 5.59; 95% CI, 1.43-37.0; P = .029) and isolated semimembranosus injuries (odds ratio, 12.1; 95% CI, 2.13–227; P = .020). Moderate to severe sitting discomfort was reported in 5% of the cohort but was not associated with postoperative complications. Functional outcomes were worse in the complication group, with lower PHAS ( P = .0053) and reduced return-to-sport rates at the preoperative level (31.3% vs 65.0%; P = .0137). Conclusion: PHAI surgery has a 4.7% complication rate excluding reruptures and 10.4% including them. These complications notably impair functional outcomes. Work-related accidents and isolated semimembranosus injuries are risk factors for non-rerupture complications. Moderate to severe sitting discomfort occurs in a minority of patients (~5%) and does not appear directly linked to postoperative complications. Registration: NCT02906865 (ClinicalTrials.gov identifier).