MRI findings and return to play in football: a prospective analysis of 255 hamstring injuries in the UEFA Elite Club Injury Study

<jats:sec><jats:title>Aim</jats:title><jats:p>The present study evaluated whether the MRI parameters of hamstring injuries in male professional football players correlate with time to return to play (RTP).</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>46 elite European football teams were followed prospectively for hamstring injuries between 2007 and 2014. Club medical staff recorded individual player exposure and time-loss after hamstring injury. MRI parameters were evaluated by two independent radiologists and correlated with the RTP data.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>A total of 255 grade 1 and 2 injuries were evaluated in this study. RTP was longer for grade 2 than grade 1 injuries (24±13, 95% CI 21 to 26 days vs 18±15, 95% CI 16 to 20 days; mean difference: 6, 95% CI 2 to 9 days, p=0.004, d=0.39). 84% of injuries affected the biceps femoris (BF) muscle, whereas 12% and 4% affected the semimembranosus (SM) and semitendinosus (ST), respectively. No difference in lay-off time was found for injuries to the three different muscles (BF 20±15 days, SM 18±11 days, ST 23±14 days; p=0.83). The recurrence rate was higher for BF injuries than for SM and ST injuries combined (18% vs 2%, p=0.009). The size of the oedema weakly correlated with time to RTP (r<jats:sup>2</jats:sup>=6–12%). No correlation was found between location of injury and time to RTP. The majority of the intramuscular injuries affected the MT junction (56% in grade 1 and 2 injuries), but no difference in lay-off time was found between the different types of injuries.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>The radiological grade and size of the oedema correlate with time to RTP for both, grade 1 and 2 injuries. No correlations were found between time to RTP and the location and type of injury.</jats:p></jats:sec>