Nogah Shabshin MD, Presenter: Nothing to Disclose

Rachel K. Evans PhD, Abstract Co-Author: Nothing to Disclose

Yael Arbel BSc, Abstract Co-Author: Nothing to Disclose

Mark E. Schweitzer MD, Abstract Co-Author: Nothing to Disclose

Dani Moran PhD, Abstract Co-Author: Nothing to Disclose

MR imaging is considered the most sensitive technique for diagnosing early stress fractures (SF). However, its high sensitivity can be confusing when abnormal MR stress findings are demonstrated in asymptomatic patients. Such findings become more significant when found in elite combat recruits, as a diagnosis of bone overuse injury can interrupt their training program. This has brought us to investigate the clinical outcome of asymptomatic MR stress findings in elite combat recruits.

MR images of the legs of 58 asymptomatic male elite combat recruits were prospectively obtained upon entry into a vigorous training program. Forty nine had a follow-up scan at 4 months, and 40 at 9 months. In addition, the patients were monitored clinically for evidence of SF. 0.5T and 3T MR systems were used to take coronal and axial T2 fat sat images (TR/TE=2430/34). The images were evaluated for the presence of stress findings that included abnormal bone marrow signal, periosteal/endosteal reaction, and fracture lines. Correlation was obtained between the following: Negative MRIs in recruits that developed SF; Positive MRIs in recruits who did not develop SF; and positive MRIs in individuals who developed SF. SF were diagnosed clinically, radiographically, and on bone scans.

50 abnormal MR findings were observed in 27 asymptomatic recruits. 46 exhibited hyperintense T2 signal in the tibia. Of those 31 presented with endosteal hyperintensity in the proximal-middle third junction of the tibia or middle-distal thirds; 10 showed patchy hyperintensity in the proximal meta-epiphysis; and 4 exhibited periosteal reactions. Five showed hyperintense T2 signal in the proximal fibula. Ten individuals who developed tibial sf during training had negative MRI of the tibia at baseline. Five had positive MRIs and developed sf, and 3 had abnormal MR findings  that did not progress to SF. On MR follow-up 3 showed progression however only one of them developed a tibial SF.  

MRI with stress findings in legs of asymptomatic elite combat recruits do not correlate with pain, nor predict the development of SF. Negative MRIs do not indicate a lower risk of developing SF. Some of these findings can possibly represent normal bone remodeling.

In elite combat recruits, leg MRIs does not correlate with pain, nor predict development of SF thus asymptomatic findings might not require interuption of training.

Shabshin, N, Evans, R, Arbel, Y, Schweitzer, M, Moran, D, Can MRIs of the Legs of Elite Combat Recruits Predict the Development of Stress Fractures?.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6022061.html