title: Magnetic resonance imaging parameters for assessing risk of recurrent hamstring injuries in elite athletes.
abstract: BACKGROUND
  Magnetic resonance (MR) imaging has established its usefulness in diagnosing hamstring muscle strain and identifying features correlating with the duration of rehabilitation in athletes; however, data are currently lacking that may predict which imaging parameters may be predictive of a repeat strain.
  
  
  OBJECTIVE
  This study was conducted to identify whether any MR imaging-identifiable parameters are predictive of athletes at risk of sustaining a recurrent hamstring strain in the same playing season.
  
  
  METHODS
  Cohort study; Level of evidence, 3.
  
  
  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 suffered a repeat injury. Of the 27 players sustaining a hamstring 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Medical Imaging, Victoria House Hospital, Prahran, Australia. drgeorgek@gmail.com
authors.forename: George
authors.initials: G
authors.lastname: Koulouris
authors.forename: David A
authors.initials: DA
authors.lastname: Connell
authors.forename: Peter
authors.initials: P
authors.lastname: Brukner
authors.forename: Michal
authors.initials: M
authors.lastname: Schneider-Kolsky
mesh_terms: D000328:Adult; D001265:Athletic Injuries / Q000175:diagnosis* / Q000503:physiopathology / Q000534:rehabilitation; D015331:Cohort Studies; D005538:Football / Q000293:injuries*; D006801:Humans; D016015:Logistic Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries* / Q000503:physiopathology; D011237:Predictive Value of Tests; D020127:Recovery of Function; D012008:Recurrence; D012016:Reference Values; D018570:Risk Assessment / Q000379:methods