Risk Factors for Rerupture After Proximal Hamstring Avulsion Injury Including the Optimal Timing for Surgery

Background: Despite the prevalence of proximal hamstring avulsion injuries (PHAIs), the understanding of rerupture risk factors and the influence of injury chronicity on these rates remain limited.

Purpose: To investigate the rerupture rate after PHAI repair and identify its associated risk factors and the optimal time to primary surgery.

Study Design: Case-control study; Level of evidence, 3.

Method: This is a retrospective analysis of prospectively collected data from the French Proximal Hamstring Avulsion Surgery Cohort Study targeting patients surgically treated for PHAI between 2002 and 2022. The primary outcome measure of this study was the rerupture rate of PHAI repair. The secondary outcome measures included the assessment of the potential risk factors for rerupture as well as the investigation of the incidence rate of rerupture for 100 person-years depending on various injury-surgery delay definitions.

Results: This study analyzed 740 patients with a mean age of 45.9 years (SD, 13.6 years) and followed up for a mean of 4.9 years (SD, 3.9 years). The rerupture rate was 4.59% (34/740). Most reruptures (75%) occurred within the first 6 months after surgery (median, 88.5 days; interquartile range, 39.5-182 days), and 74% were atraumatic. Univariate analysis identified potential risk factors: longer initial surgery delay (hazard ratio [HR], 1.03; 95% CI, 1.01-1.04; = .04) and initial complete ruptures (HR, 4.47; 95% CI, 1.07-18.7; = .04). Receiver operating characteristic curve analysis found the optimal injury-surgery delay cutoff predicting rerupture to be 32 days (area under the curve, 0.62; 95% CI, 0.53-0.71). The relative Youden index was calculated at 0.24, corresponding to a sensitivity of 65% and a specificity of 59%. Surpassing this cutoff showed the highest HR (2.56), narrowest 95% CI (1.27-5.17), and highest incidence of rerupture (1.42 per 100 person-years) ( = .01). In the multivariate analysis, an injury-surgery delay of >32 days (HR, 2.5; 95% CI, 1.24-5.06; = .01) and initial complete ruptures (HR, 4.33; 95% CI, 1.04-18.08; = .04) emerged as significant risk factors for rerupture.

Conclusion: This study found a 4.59% rerupture risk after PHAI repair. Most reruptures (75%) occurred within the first 6 months after surgery. Risk factors for rerupture included chronicity and initial complete injury. The optimal threshold for chronicity of PHAI lesions, based on rerupture rate, was marked by an injury-surgery delay of >32 days.