Michel D. Crema MD, Presenter: Shareholder, Boston Imaging Core Lab, LLC

Ali Guermazi MD, PhD, Abstract Co-Author: President, Boston Imaging Core Lab, LLC Research Consultant, Merck KgaA Research Consultant, Sanofi-Aventis Group Research Consultant, TissueGene, Inc

Johannes Tol MD, PhD, Abstract Co-Author: Nothing to Disclose

Jingbo Niu, Abstract Co-Author: Nothing to Disclose

Bruce Hamilton, Abstract Co-Author: Nothing to Disclose

Frank W. Roemer MD, Abstract Co-Author: Chief Medical Officer, Boston Imaging Core Lab LLC Research Director, Boston Imaging Core Lab LLC Shareholder, Boston Imaging Core Lab LLC

To describe in detail the anatomic distribution of acute hamstring injuries in soccer players, including which muscles are affected and the locations of the injuries within each muscle, and to assess the relationship between location and extent of edema and tears (fiber disruption), all based on findings from MRI.

We included 275 consecutive male soccer players who had sustained acute hamstring injuries and had positive findings on MRI. For each subject, lesions were recorded according to the presence of typical MRI features in specific locations (and groups of locations) of the hamstring muscles, which were divided into proximal or distal: Free tendon, myotendinous junction locations, muscle belly locations, and myofascial junction locations. For each lesion, we assessed the largest cross-sectional area of edema and/or tears (when present). We calculated the prevalence of injuries by location. The average value of edema and tears for each hamstring muscle was determined, considering the whole sample, and used as the reference standard. The relationships between locations and extent of edema and tears were assessed using a one-sample t-test, with significance set at p<0.05.

The sample included 393 lesions. The long head of biceps femoris (LHBF) was the most commonly affected muscle (56.5%). Overall, injuries were most common in the myotendinous junction and in proximal locations. The proximal myotendinous junction was associated with a greater extent of edema in the LHBF and semitendinosus muscles (p<0.05). Proximal locations in the LHBF had larger edema than distal locations (p<0.05). Distal locations in the semitendinosus muscle had larger tears than proximal locations (p<0.05).

The proximal myotendinous junction and proximal locations in general are more commonly affected and are associated with a greater extent of edema in acute hamstring muscle injury. Distal locations, however, seem to be associated more with larger tears.

Knowledge of the findings and relationships between hamstring muscle injury location and extent of edema and tears could potentially give useful prognostic information and guide physicians in the management of the injured athletes, since previous studies have shown that the extent of injury is associated with important clinical features such as time of recovery and risk of re-injury.

Crema, M, Guermazi, A, Tol, J, Niu, J, Hamilton, B, Roemer, F, Acute Hamstring Injury in Soccer Players: Distribution of Locations and Association between Location and Extent of Injury – A Large Single-center Magnetic Resonance Imaging (MRI) Report.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011768.html