Fredericson et al [71] retrospectively correlated return to activity with an MRI grading system based on the pattern of periosteal and marrow edema on T1-weighted and fat-suppressed T2-weighted sequences. Similar findings were confirmed in other studies [13,72,73], including that the finding of abnormal cortical signal intensity or a fracture line was of prognostic value [73] and that MRI performed better in predicting return to activity than radiographs, bone scintigraphy, or CT [72,74]. A recent prospective study in university athletes found that MRI grading severity, total-body bone mineral density evaluated by dual-energy X-ray absorptiometry, and location of injury (ie, cortical or trabecular bone) were important variables for predicting time to full return to sport [42]. In this study, periosteal edema as described by Fredericson et al [71] was not associated with return to sport. Using the modified grading scale and a multiple regression model, for every 1-unit increase in MRI grade, the time to full return to sport increased by approximately 48 days [42]. Furthermore, trabecular stress injuries (eg, femur neck and pubic bone) were associated with a longer time to return to sport than cortical bone stress injuries. In addition, decreased bone mineral density leads to increased time to return to sport. Therefore, bone mineral density provides additional diagnostic and prognostic information [42]. The model of MRI grade, trabecular versus cortical bone site, and total-body bone mineral density accounted for 68% of the variation in time to return to sport [42]. Although further studies are needed, optimization of bone mass may reduce risk of sustaining stress injuries or possibly reduce recovery time in athletes with these injuries.
Stress Fatigue Insufficiency Fracture Including Sacrum Excluding Other Vertebrae PCAs. Fredericson et al [71] retrospectively correlated return to activity with an MRI grading system based on the pattern of periosteal and marrow edema on T1-weighted and fat-suppressed T2-weighted sequences. Similar findings were confirmed in other studies [13,72,73], including that the finding of abnormal cortical signal intensity or a fracture line was of prognostic value [73] and that MRI performed better in predicting return to activity than radiographs, bone scintigraphy, or CT [72,74]. A recent prospective study in university athletes found that MRI grading severity, total-body bone mineral density evaluated by dual-energy X-ray absorptiometry, and location of injury (ie, cortical or trabecular bone) were important variables for predicting time to full return to sport [42]. In this study, periosteal edema as described by Fredericson et al [71] was not associated with return to sport. Using the modified grading scale and a multiple regression model, for every 1-unit increase in MRI grade, the time to full return to sport increased by approximately 48 days [42]. Furthermore, trabecular stress injuries (eg, femur neck and pubic bone) were associated with a longer time to return to sport than cortical bone stress injuries. In addition, decreased bone mineral density leads to increased time to return to sport. Therefore, bone mineral density provides additional diagnostic and prognostic information [42]. The model of MRI grade, trabecular versus cortical bone site, and total-body bone mineral density accounted for 68% of the variation in time to return to sport [42]. Although further studies are needed, optimization of bone mass may reduce risk of sustaining stress injuries or possibly reduce recovery time in athletes with these injuries.