Magnetic resonance imaging parameters for assessing risk of recurrent hamstring injuries in elite athletes

METHODS: Forty-one players of the Australian Football League who sustained a hamstring injury underwent MR examination within 3 days of injury between February and August 2002. The imaging parameters measured were the length of injury, cross-sectional area, the specific muscle involved, and the location of the injury within the muscle-tendon unit. Players who suffered a repeat injury during the same season were reimaged, and baseline and repeat injury measurements were compared. Comparison was also made between this group and those who sustained a single strain. RESULTS: Forty-one players sustained hamstring strains that were positive on MR imaging, with 31 injured once and 10 suffering a second injury. The mean length of hamstring muscle injury for the isolated group was 83.4 mm, compared with 98.7 mm for the reinjury group (P =.35). In the reinjury group, the second strain was also of greater length than the original (mean, 107.5 mm; P =.07). Ninety percent of players sustaining a repeat injury demonstrated an injury length greater than 60 mm, compared with only 58 in the single strain group (P =.01). Only 7 of players (1 of 14) with a strain 60 mm, 33 (9 of 27) suffered a repeat injury. Of all the parameters assessed, only a history of anterior cruciate ligament sprain was a statistically significant predictor for suffering a second strain during the same season of competition. CONCLUSION: A history of anterior cruciate ligament injury was the only statistically significant risk factor for a recurrent hamstring strain in our study. Of the imaging parameters, the MR length of a strain had the strongest correlation association with a repeat hamstring strain and therefore may assist in identifying which athletes are more likely to suffer further reinjury.