Predisposing Characteristics for Tibial Stress Fracture

Tibial stress fractures (TSF) increasingly affect athletes and military recruits, and are challenging to manage. There is a need to identify the characteristics most associated with the incidence of TSF in order for preventative strategies to be developed, and/or screening to be implemented where appropriate. PURPOSE To identify physical and behavioural characteristics related to incidence of tibial stress fracture in men and women. METHODS Twenty-seven patients (13 M, 14 F) with TSF and 27 age-, sex-, height-, weight-, and activity-matched subjects with no history of stress fracture were recruited. Physical (height, weight, menstrual history, bone parameters, lower limb alignment anomaly) and behavioural (diet, meds, oral contraceptives, training) characteristics were recorded from all subjects via anthropometry, questionnaire, dual-energy x-ray absorptiometry and quantitative ultrasound. Between group differences were examined via one-way ANOVA. RESULTS Stress fracture subjects exhibited shorter femoral necks (FN) with smaller FN area and thinner cortices, but greater lumbar spine (LS) bone mineral density (BMD), bone mineral apparent density (BMAD), stiffness (E) and strength index (IBS). Foot type also differed between groups with 70% of controls having normal feet versus 40% of fractured subjects. There were no other between group differences in any other anthropometric or behavioural variable. Split file analyses revealed subtle sex-specific characteristics. Only foot type differed between groups for men; the control group exhibiting fewer anomalies. All the aforementioned differences in bone parameters were apparent between female groups, with greater FN bone mineral content (BMC) and lower LS BMC in controls also becoming significant. CONCLUSION Foot anomalies appear to be the characteristic most associated with TSF for men; whereas women suffering TSF appear to have smaller bones of the lower extremity, but stronger lumbar spines than those who have never fractured. Supported by US Army MRMC, DAMD17-98-1-8519, and BIOLECTRON, Inc. now EBI, Parsippany, NJ.