Relationship between gait biomechanics and inversion sprains: a prospective study of risk factors.

This prospective study determined gait related risk factors for inversion sprains in 223 physical education students. Static lower leg alignment was determined, and 3D-kinematics combined with plantar pressure profiles were collected. After evaluation, the same sports physician registered all sports injuries during the next 6-18 months. During this period, 21 subjects had an inversion sprain, one of whom had a bilateral sprain. Twenty-two ankles, 12 left and 10 right comprised the inversion sprain group and both feet of 36 non-injured subjects acted as controls. Comparison of the two groups revealed that the gait of subjects who are at risk of sustaining an inversion sprain had a laterally situated centre of pressure at initial contact. These subjects also showed a mobile foot type at first metatarsal contact, forefoot flat and heel off. In this type the foot is more pronated over a prolonged period and accompanied by more pressure underneath the medial side of the foot and a delayed maximal knee flexion. Resupination is delayed and roll off does not occur across the hallux, but more laterally, probably because of the diminished support at the first metatarsophalangeal joint. Total foot contact time was also longer in the inversion sprain group compared with controls. The findings of this study suggest that effective prevention and rehabilitation of inversion sprains should include attention to gait patterns and adjustments of foot biomechanics.