Triaxial motion of normal knee during walking, as measured by electrogoniometer. Flexion and extension are about 70 degrees during swing phase and 20 degrees during stance phase. About 10 degrees of abduction and adduction and 10 to 15 degrees of internal and external rotation occur during each gait cycle. FF, Flatfoot; HO, heel-off; HS, heel-strike; TO, toe-off.