Background Bone stress injuries are common in track and field athletes. Knowledge of risk factors and correlation of these to magnetic resonance imaging (MRI) grading could be helpful in determining recovery time. Purpose To examine the relationships between MRI grading of bone stress injury with clinical risk factors and time to return to sport in collegiate track and field athletes. Study Design Prospective cohort over 5 years. Methods Two hundred and eleven male and female collegiate track and field and cross-country athletes were followed prospectively through their competitive seasons. All athletes had a pre-participation history, physical exam, and anthropometric measurements obtained annually. An additional questionnaire was completed regarding nutritional behaviors, menstrual patterns and prior injuries, as well as a 3-day diet record. Dual energy X-ray absorptiometry was obtained at baseline and each year of participation in the study. Athletes with clinical evidence of bone stress injuries had plain radiographs. If radiographs were negative, MRI was obtained. Bone stress injuries were evaluated by two independent radiologists utilizing an MRI grading system. MRI grading and risk factors were evaluated to identify predictors of time to return to sport. Results Thirty-four (12 males, 22 females) of the 211 collegiate athletes sustained 61 bone stress injuries during the 5-year study period. The average prospective assessment for participants was 2.1 years. MRI grade and total body bone mineral density (BMD) emerged as significant and independent predictors of time to return to sport in the multiple regression model. Specifically, the higher the MRI grade, the longer the recovery time (p<0.002). Location of bone injury at predominantly trabecular sites of the femoral neck, pubic bone and sacrum (p<0.001), and lower total body BMD (p<0.029) independently predicted prolonged time to return to sport. Conclusions Higher MRI grade, lower BMD, and skeletal sites of predominant trabecular bone structure were independently associated with delayed recovery of bone stress injuries in track and field athletes. Knowledge of these risk factors, as well as nutritional and menstrual factors, can be clinically useful in determining time to return to sport.

We present new break-up and coherent data for h meson photoproduction on the deuteron, using a deuterium target and tagged bremsstrahlung photons up to 1 GeV. The differential cross sections for the coherent process were measured from threshold to 800 MeV. They are much smaller than those previously reported. The break-up channel provides a direct measurement of the neutron to proton differential cross section ratios. At the S 11 ͑1535͒ resonance peak, s n ͞s p 0.68 6 0.06 leading to an isoscalar to isovector amplitude ratio of A s ͞A y 0.096 6 0.02. [S0031-9007 (97)03324-3]

Nonpharmacologic intervention in college athletes with menstrual disturbances can restore regular menstrual cycles, although ROM may take more than 1 yr. Weight gain or an increase in BMI may be important predictors of ROM.