Gender differences of sagittal knee and ankle biomechanics during stair-to-ground descent transition

• Women had a significantly lower peak knee extension moment than men.
• Women had a significantly higher ground-toe-trochanter angle at the peak knee extension moment than men.
• The peak knee extension moment was correlated with ground-toe-trochanter angle.
• Women seem to increase the risk of falls and reduce the demand of the knee muscle function.

BackgroundFalls on stairs often result in severe injury and occur twice as frequently in women. However, gender differences in kinetics and kinematics during stair descent are unknown. Thus, this study aimed to determine whether gender differences of knee and ankle biomechanics exist in the sagittal plane during the stair-to-ground descending transition. It was hypothesized that 1) women would reveal higher ground-toe-trochanter angle and lower ground-toe length during stair-to-ground descent transition than men; and 2) women would reveal lower peak knee extension moment during stair-to-ground descent transition than men.MethodsFifteen men and fifteen women were recruited and performed a stair descent activity. Kinetic and kinematic data were obtained using a force plate and motion capture system.FindingsThe women performed the stair descent with a lower peak knee extension moment and a peak knee power at the early weight acceptance phase. The women also revealed a higher ground-toe-trochanter angle and a lower ground-toe length, which indicated a more forward position of the lower extremity relative to the toe contact point at both the initial contact and at the time of peak kinematic and kinetic events.InterpretationThis study found that knee and ankle kinematics and kinetics differed significantly between the genders due to differences in ground-toe-trochanter angle. Women have a different stair descending strategy that reduces the demand of the lower extremity muscle function, but this strategy seems to increase the risk of falls.