The relationship between lower-extremity stress fractures and the ground reaction force: a systematic review.
BACKGROUND Stress fractures are common in athletics and are more prevalent in women. The current literature has not identified a reason for this gender difference. HYPOTHESIS Women with a history of a second/third metatarsal stress fracture will demonstrate differences in loading in the middle forefoot. STUDY DESIGN Controlled laboratory study. METHODS Fifteen men, 15 control women, and 9 women with a history of a second/third metatarsal stress fracture were asked to run at 3.3 m/s +/- 5% along a 10-m runway. Plantar loading parameters were recorded using a Pedar-X system. RESULTS The women with fractures demonstrated a decrease in contact area and maximum force beneath the middle forefoot when compared with the female controls. Men demonstrated a decreased contact area in the medial and middle forefoot when compared with the control women. In addition, the women with fractures had decreased maximum force in the middle forefoot when compared with the control women. CONCLUSIONS The decrease in maximum force in the middle forefoot in patients with a previous stress fracture could have resulted from gait alterations after the fracture. Therefore, prospective studies need to be completed to better understand the loading differences that could be used to predict stress-fracture injury risk. CLINICAL RELEVANCE It is unclear whether plantar loading can be used as a predictor of stress-fracture injury risk as these patients were tested after a stress fracture.