Biomechanical + anthropometric measures in stress fractures
Stress fractures have long been known as a musculoskeletal pitfall due to the difficulties in both clinical and radiological diagnosis, as well as the inevitable realities of treatment and their ability to disrupt training and/ or competition. This prospective study set out to identify variables that may influence the development of stress fractures through analysis of gait and anthropometric data. The authors concluded lower body mass index, narrow bimalleolar width, high heel peak pressures and low tibial rotation were associated with increased incidence of tibial stress fractures (TSF).
Among lower extremity injuries, stress fractures pose a real threat in elite and endurance sports due to the arduous training needed. The authors hypothesized that the primary pathological mechanisms at work were 1) reduced ability to withstand load; and 2) reduced impact attenuation.
In the current population, lower bone mineral density has been linked with lower BMI and lower lean muscle mass found in the stress fracture group. This has led the authors to deduce the possibility that decreased bone strength and a reduced calf size support the argument for the above hypothesis. The decreased bimalleolar width found in the stress fracture group structurally reflects a reduced potential to withstand bending, thus a predisposition to stress fracture reflective of poor load bearing ability. Tibial rotation was described as one of the mechanisms at work to reduce impact while running, therefore the increased incidence of lower tibial rotation in the stress fracture group was seen as a contributing factor of reduced impact attenuation. Lastly, higher heel impact pressure was pressumed to be reflective of an inefficient ability to identify or reduce impact in this sub-group.
Although the current analysis awaits further validation studies before the identified variables can be used in a predictive tool, the research presented provides some interesting insight and provides noteworthy step toward pre-screening individuals at risk for TSF.
> From: Nunns et al., Br J Sports Med 50 (2017) 1206-1210. All rights reserved to BMJ Publishing Group Ltd. Click here for the online summary.