Sex difference in effect of ankle landing biomechanics in sagittal plane on knee valgus moment during single-leg landing.

Ankle landing strategies affects the biomechanical characteristics of the knee joint, especially knee frontal plane loading. However, no studies have investigated whether the association between ankle landing biomechanics in sagittal plane and the knee frontal plane loading differs between sexes. The purpose of this study was to examine whether there is a sex difference in the effect of ankle plantar flexion at the contact angle, ankle range of motion (ROM), and ankle plantar flexion moment on knee valgus loading during single-leg landing. Twenty-five females and twenty-four males performed a single-leg landing. Joint kinematics and kinetics of the lower extremities were measured. The relationship between ankle biomechanics in the sagittal plane (ankle plantar flexion angle at contact, ROM, and peak ankle plantar flexion moment) and peak knee valgus moment were analyzed. In males, the larger ankle plantarflexion angle at contact and ROM were significantly associated with lower peak knee valgus moment. In addition, in males only, a greater peak ankle plantar flexion moment was significantly associated with a lower peak knee valgus moment and greater peak ankle inversion moment. Altering ankle landing strategies in the sagittal plane during single-leg landing may reduce the knee valgus moment, which is one of risk factors for anterior cruciate ligament injury, in males only.