Lower Extremity Stress Fractures in Athletes and Military Personnel: Risk Factors, Diagnosis, and Management

Bone stress injuries of the lower extremity are among the most consequential overuse conditions in sports medicine and military occupational health, arising when repetitive submaximal loading outpaces bone's capacity to repair and adapt. This review draws together contemporary evidence on the epidemiology, risk factors, diagnosis, and management of these injuries in athletes and physically active populations, with emphasis on work published since 2021, together with foundational earlier literature. Biomechanical exposures are prominent: in a four-year cohort of 1,772 military cadets, each additional movement error on the Landing Error Scoring System raised stress fracture incidence by 15% (IRR 1.15; 95% CI, 1.02-1.31), while flat-footed and asymmetric landings carried more than twofold higher incidence. Foot structure contributes independently, with a higher arch and reduced toe-off angle distinguishing injured recruits. Energy availability, menstrual function, and vitamin D status form a second, modifiable domain: female runners with repeated injuries showed higher cumulative Triad risk and more restrictive eating, and 74% of military trainees with stress fractures were vitamin D insufficient or deficient. Magnetic resonance imaging is the diagnostic reference standard, and MRI grade predicts time to return to sport. Management follows the distinction between low-risk sites, which respond to activity modification, and high-risk sites, where delayed union and progression to complete fracture justify a more aggressive approach. Among professional basketball players, return-to-play time after high-risk fractures did not differ significantly between operative and nonoperative treatment. Screening that combines movement quality, energy availability, and vitamin D status offers a practical route to reducing injury burden.