CONSEQUENCE OF TIBIOTALAR ARTHRODESIS ON FOOT KINEMATICS AND KINETICS WHEN WALKING

Abstract

Purpose: The purpose of this study was to analyse changes in foot dynamics secondary to tibiotalar arthrodesis and examine the adaptation mechanisms induced by wearing shoes.

Material and methods: A 3D gait analysis was performed (Vicon 370) in ten patients with a tibiotalar arthrodesis fixed in a neutral position and in ten matched controls. Recordings were made in three conditions: walking barefooted, walking at a comfortable self-chosen speed wearing shoes, and walking at maximal speed wearing shoes. We measured tibial inclination in the sagittal plane, knee flexion, and the tibia-forefoot angle produced at heel lift-off. The distance of the ground reaction force (GRF) from the heel was measured during the weight-bearing phase and at lift-off. Statistical comparisons were made with the contralateral side and the control group.

Results: Heel lift-off came significantly earlier on the arthrodesis side compared with the contralateral side and with the control group. At heel lift-off, the knee was in complete extension in all three groups. The GRF moved forward more rapidly but remained more posterior on the arthodesis side at heel lift-off in comparison with the contralateral side and the control group. Wearing shoes enabled later heel lift-off on the arthrodesis side and increased tibial inclination at lift-off as well as decreased speed of the anterior displacement of the GRF. The GRF however remained more posterior than in the control group. At maximal walking speed, heelk lift-off came earlier on the arthrodesis side and at the same time a lesser anterior tibial inclination and a more posterior position of the GRF.

Discussion: Early heel lift-off on the arthrodesis side allows anterior inclination of the tibia to continue and to increase stride length. Heel lift-off however occurs when the GRF has not yet advanced to the metatarsophalangeal position, thus increasing stress on the rear and mid foot. Wearing shoes improves the kinematic parameters and decreases stress on the joints below the arthrodesis. Increased walking speed aggravates the perturbed foot dynamics when walking.