3.0-Tesla MRI Observation at Return to Play After Hamstring Injuries

To describe 3.0-Tesla (T) magnetic resonance imaging (MRI) findings of hamstring muscles in clinically recovered athletes who were cleared for return to play (RTP).

Prospective observational study.

Hospital.

Athletes (amateur and professional) who were cleared for RTP after hamstring injury. Fifty-eight participants were included in the analysis.

3-T MRI at baseline (within 7 days from initial injury) and MRI at RTP (within 10 days of RTP).

Injury location, grade of injury (modified Peetrons and British Athletics Muscle Injury Classification/BAMIC), presence and the extent of intramuscular signal abnormality, intramuscular tendon disruption, and thickness. Reinjuries within 1 year of RTP were recorded.

Magnetic resonance images at RTP showed that 55 (95%) participants had intramuscular increased signal intensity (edema) and 44 (76%) participants had intramuscular abnormal low-signal intensity (suggesting fibrosis) on MRI. There was an overall reduction of injury grades according to the modified Peetrons and BAMIC classification at initial injury to RTP. Three (5%) participants had no abnormal signal intensities (grade 0 or grade 0A) on MRI at RTP. Intramuscular tendon disruption, waviness, and tendon thickening were present at RTP in, respectively, 22 (38%), 15 (26%), and 36 (62%). We recorded 3 (5%) reinjuries.

At RTP, 3.0-T MRI shows high percentages of MRI abnormalities (edema, fibrosis, and intramuscular tendon disruption and thickening). We conclude that complete normalization of 3.0-T MRI is not expected for RTP decision after a hamstring injury. Its possible association with reinjury risk has to be determined in larger cohorts.