Clinical and magnetic resonance imaging outcome after proximal hamstring tendon repair at mean 3 years follow-up

Purpose: The purpose of this study was to assess clinical and radiological outcome in patients after proximal hamstring tendon repair. We hypothesized that there is a significant correlation among subjective clinical outcome and interlimb asymmetries in muscle strength, fatty infiltration, and hamstring volume.

Methods: This retrospective monocentric case series included patients with surgical repair after proximal hamstring tendon rupture. Clinical outcome was assessed utilizing: Healthy Days Core Module (CDC HRQOL-4), numeric pain rating scale (NRS), modified Harris Hip Score (mHHS), Tegner Activity Scale (TAS), return to pre-injury activity level (RTPA), and patient satisfaction score. Postoperative hamstring strength was measured using a handheld dynamometer and radiological outcome was determined by postoperative magnetic resonance imaging (MRI).

Results: Twenty-seven patients with a mean age of 51.2 (± 12.6) years were available for follow-up at a mean of 41.11 (± 18.4) months. Patients state a mean of 10.6 (± 11.5) days in the unhealthy days (UHD) index and 88.9% show "good health" in the simple summary score (SSS). Mean subjective outcome scores were as follows: NRS 1.1 (± 2.4), mHHS 90.3 (± 14.8) and TAS 5.7 (± 2.2). A total of 59.3% RTPA and 88.9% state to be somewhat or very satisfied with their surgery. Mean interlimb strength ratio was 0.88 (± 0.21). MRI demonstrated a fully restored muscle-tendon unit, significantly greater fatty infiltration in the injured hamstrings (p = 0.009, d = 0.558), and a mean interlimb hamstring volume ratio of 0.94 (± 0.11). With respect to the 10% benchmark, patients had no significant asymmetries in muscle strength (p = 0.677, d = 0.084) or hamstring volume (p = 0.102, d = - 0.34). Correlation analysis revealed moderate correlation among asymmetries in strength and volume (p = 0.073, r = 0.373). In patients with the operated side inferior to the healthy side (n = 15), there was strong correlation among asymmetries in strength and volume (p = 0.002, r = 0.725). Statistically significant correlation was found between interlimb muscle volume atrophy and increase in fatty infiltration (p = 0.015, r = 0.481).

Conclusion: Proximal hamstring repair results in good clinical outcome with satisfactory recovery of hamstring strength and volume. Interlimb asymmetries, in terms of muscle strength, fatty infiltration, and hamstring volume do not correlate with clinical outcome.

Study type: Retrospective cohort study; Level of evidence, 3.