Ground reaction torque and pathway of point of application of ground reaction force during gait of intoeing children.

One hundred twenty-four children with intoeing and 80 age-matched controls were investigated with the Kistler force plate. Tr2, reflecting the maximum external rotational ground reaction torque, is reduced by 30% to 40% in all intoeing children. There also is an appreciably shorter pathway of the point of application of the ground reaction force in the Y-direction (from 20% to 25%) and an obvious medial shift of the point of application of the ground reaction force in the X-direction (from 105% to 290%), from heel strike to toe-off as compared with controls. In spontaneous correction of intoeing, point of application of the ground reaction force in the X-direction becomes more close to normal. The "foot progression angle," which can easily be calculated from the force plate measurements to judge the degree of intoeing, is different from the values in the literature.