Redistribution of joint moments during walking in patients with drop-foot

Abstract

Background: The purpose of the study was to analyze the distribution of net joint moments in the lower extremities in patients walking with a drop-foot compared to a group of healthy subjects. A drop-foot causes the patient to walk with a characteristic limp and it was hypothesized that the drop-foot could lead to increased loadings of one or more joints.

Methods: Six patients and fourteen healthy subjects walked at a fixed speed over two recessed force platforms while the movements were recorded by six infrared cameras. Net joint moments were calculated by inverse dynamics.

Findings: The patients showed an almost doubled peak knee extensor moment during the stance phase compared to healthy subjects. This was accompanied by an increased knee joint flexion. The increased extensor moment about the knee joint was found in both the affected and unaffected leg of the patients. This was accompanied by increased maximal knee joint flexion in both legs of the patients compared to the healthy subjects. Several additional differences were observed in joint moments and joint angles between the two groups and between the two legs of the patients.

Interpretation: The increased knee joint extensor moment leads to increased joint loading, which potentially may lead to development of osteo-arthritis over the years. It is recommended that patients with a drop-foot are offered an ankle joint orthosis in an attempt to restore normal function of the ankle joint, which will most likely reduce the knee joint loadings.