Flexural wave propagation velocity and bone mineral density in females with and without tibial bone stress injuries

Study Design: Case-control nonexperimental design. Objectives: To compare flexural wave propagation velocity (FWPV) and tibial bone mineral density (BMD) in women with and without tibial bone stress injuries (BSIs). Background: Physical therapists, particularly in military and sports medicine settings, routinely diagnose and manage stress fractures or bone stress injuries. Improved methods of preparticipation quantification of tibial strength may provide markers of BSI risk and thus potentially reduce morbidity. Methods and Measures: Bone mineral density, FWPV, bone geometry, and historical variables were collected from 14 subjects diagnosed with tibial BSIs and 14 age-matched controls; all 28 were undergoing military training. Results: No difference was found between groups in FWPV and tibial BMD when analyzed with t tests (post hoc power = 0.89 and 0.81, respectively). Furthermore, no difference was found in tibial length, tibial width, femoral neck BMD, and lumbar spine BMD among the groups. There were no differences between the 2 groups in smoking history, birth control pill use, and onset of menarche. Finally, sensitivity and positive likelihood ratios for FWPV (0.14 and 0.63), tibial BMD (0.0 and 0.0), and lumbar BMD (0.18 and 2.0) were low, while specificity was high (0.77, 0.93, and 0.91, respectively). Conclusion: Current bone analysis devices and methods may not be sensitive enough to detect differences in tibial material and structure; local stresses on bone may be more important in the development of BSIs than the overall structural stiffness.