Structural Allograft Reconstruction for Chronic Proximal Hamstring Avulsion Yields Significant Functional Improvement, Acceptable Satisfaction, but Limited Return to Preinjury Sport Levels.

PURPOSE: To evaluate midterm outcomes of structural allograft reconstruction in patients with chronic proximal hamstring avulsion injuries. METHODS: This was a retrospective cohort study (minimum 2-year follow-up) including patients who underwent allograft surgical reconstruction for proximal hamstring avulsion injuries between 2016 and 2023. The primary outcome was the Parisian Hamstring Avulsion Score (PHAS). Secondary outcomes included the Tegner Activity Scale, University of California, Los Angeles Activity Scale, return to sport rates, postoperative patient satisfaction, and complication rates. A cohort-specific minimal clinically important difference analysis was performed using the distribution-based method (½ standard deviation of the change in PHAS score). In addition, substantial clinical benefit and patient acceptable symptom state thresholds were determined using anchor-based methods. RESULTS: A total of 42 patients were included, with 39 having complete functional follow-up (mean follow-up: 3.4 ± 1.6 years). The PHAS score improved significantly from a median of 56.3 (interquartile range [IQR]: 49.0-64.0) preoperatively to 84.5 (IQR: 73.8-94.8) at the final follow-up (P < .001). The Tegner score increased from 2.0 (IQR: 1.0-3.0) to 3.0 (IQR: 3.0-5.0) and the University of California, Los Angeles from 4.0 (IQR: 3.0-5.0) to 6.0 (IQR: 5.0-9.0) (both P < .001). Compared with preinjury levels, both scores remained significantly lower (P = .005 and P = .007, respectively). Regarding return to sport, 48.7% returned to sport, but only 15.4% resumed at the same or higher level. The overall complication rate was 16.7%, including 5 reruptures (11.9%), occurring at a median of 40 days (IQR: 35.0-73.0). The minimal clinically important difference for PHAS was reached by 97.4% of patients, the substantial clinical benefit by 43.6%, and the patient acceptable symptom state threshold (PHAS > 82.3) by 56.4%. CONCLUSIONS: Allograft reconstruction is a viable option for chronic proximal hamstring avulsion injuries when direct repair is not feasible, yielding significant functional gains and acceptable satisfaction. LEVEL OF EVIDENCE: Level IV, retrospective case series.