Background Hamstring injury with intramuscular tendon involvement is regarded as a serious injury with a delay in return to play (RTP) of more than 50 days and reinjury rates up to 63%. However, this reputation is based on retrospective case series with high risk of bias.
Objective Determine whether intramuscular tendon involvement is associated with delayed RTP and elevated rates of reinjury.
Methods MRI of male athletes with an acute hamstring injury was obtained within 5 days of injury. Evaluation included standardised MRI scoring and scoring of intramuscular tendon involvement. Time to RTP and reinjury rate were prospectively recorded.
Results Out of 70 included participants, intramuscular tendon disruption was present in 29 (41.4%) injuries. Injuries without intramuscular tendon disruption had a mean time to RTP of 22.2±7.4 days. Injuries with <50%, 50%–99% and 100% disruption of tendon cross-sectional area had a mean time to RTP of 24.0±9.7, 25.3±8.6 and 31.6±10.9 days, respectively. Injuries with full-thickness disruption took longer to RTP compared with injuries without disruption (p=0.025). Longitudinal intramuscular tendon disruption was not significantly associated with time to RTP. Waviness was present in 17 (24.3%) injuries. Mean time to RTP for injuries without and with waviness was 22.6±7.5 and 30.2±10.8 days (p=0.014). There were 11 (15.7%) reinjuries within 12 months, five (17.2%) in the group with intramuscular tendon disruption and six (14.6%) in the group without intramuscular tendon disruption.
Conclusion Time to RTP for injuries with full-thickness disruption of the intramuscular tendon and waviness is significantly longer (by slightly more than 1 week) compared with injuries without intramuscular tendon involvement. However, due to the considerable overlap in time to RTP between groups with and without intramuscular tendon involvement, its clinical significance for the individual athlete is limited.
- muscle Injury
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Contributors AM was involved in study design, data collection, data analysis, data interpretation and drafting. EA was involved for radiological expertise, evaluation of MRI scans and drafting. RW, BH, CE and FH were involved in data collection and drafting. JT was involved in study design, data interpretation and drafting.
Funding Internally funded by Aspetar.
Competing interests None declared.
Patient consent Obtained.
Ethics approval Ethical Committee of Aspetar, Orthopaedic and Sports Medicine Hospital.
Provenance and peer review Not commissioned; externally peer reviewed.