SLR - October 2018 - Danielle Yaros
Foot Kinematics Differ Between Runners with and without a History of Navicular Stress Fractures
Reference: Becker J, James S, Osternig L, Chou LS. Foot Kinematics Differ Between Runners with and without a History of Navicular Stress Fractures. Orthopaedic Journal of Sports Medicine. 2018 Apr; 6(4):2325967118767363.
Scientific Literature Review
Reviewed By: Danielle Yaros, DPM
Residency Program: SUNY Downstate Medical Center, Brooklyn, NY
Podiatric Relevance: Stress fractures are common injuries experienced by runners. In particular, navicular stress fractures (NSFs) may account for up to 35 percent of all stress fracture injuries. There is an ample amount of literature examining diagnoses, management protocols and clinical outcomes of NSF; however, there have been very few studies examining changes in foot structure and biomechanics after an NSF. The purpose of this study was to compare foot structure, range of motion and biomechanics between runners with a history of a unilateral NSF and runners who had never sustained this injury.
Methods: This was a level III cross-sectional study performed at the University of Oregon. Seven runners who had sustained an NSF were matched with seven controls without this injury history. They were matched based on their age, weekly running mileage and foot strike pattern. Previously, all seven participants with an NSF had the fracture surgically repaired, and at the time of this study, all seven had resumed their regular training program and were running without restriction. Participants underwent a clinical orthopaedic examination and a three-dimensional running gait analysis. Clinical examination variables, foot kinematics and ground-reaction forces were compared to determine differences between the involved and noninvolved feet of the NSF group, differences between the involved feet of the NSF group and control feet and differences between the noninvolved feet of the NSF group and control feet.
Results: Clinical examination demonstrated decreased ankle joint plantar flexion of both the involved and noninvolved feet of the NSF group versus the control group. No other clinical examination yielded statistically significant results. Three-dimensional running gait analysis demonstrated decreased forefoot abduction, increased rearfoot eversion and higher eversion velocity in the involved feet of the NSF group versus the noninvolved feet and control group. There were no statistically significant differences in forefoot abduction, rearfoot eversion and eversion velocity between the noninvolved feet of the NSF group and control group.
Conclusions: The authors concluded that there are differences in foot kinematics both between the involved and noninvolved feet of a runner who has sustained an NSF and between runners who have sustained an NSF and those who have not. The foot that sustained an NSF demonstrated greater rearfoot eversion, reduced forefoot abduction and higher peak rearfoot eversion velocities, all of which, if present prior to the NSF injury, could have led to increased shear stress across the navicular causing it to fracture. One major limitation of this study is that there are currently no studies documenting how the surgical repair of an NSF affects normal foot function. It follows, then, that since all of the participants had their NSF surgically repaired, the statistically significant kinematics could have developed secondary to surgical repair of the NSF and may not have been the factor causing the patient to sustain it. Thus, further studies are needed to determine if the altered kinematics are predictive of patients who might sustain an NSF or if they are a result of the NSF injury/surgical repair used to treat the injury.