The increase of joint contact forces in foot joints with simulated subtalar fusion in healthy subjects

Abstract

Background: Subtalar fusion usually leads to a satisfactory clinical outcome by eliminating the motion of the subtalar joint but can cause an aggravation of osteoarthritis after the subtalar fusion. Previous studies have investigated the effect of subtalar fusion in static testing using cadaver limbs, but there was no evidence of an aggravation of osteoarthritis. Research question: The objective was to investigate the differences in foot joint kinematics and kinetics during a standing pose and walking with and without subtalar fusion, using a musculoskeletal simulation. Methods: Full-body joint kinematics, ground reaction force, and foot pressure of the healthy subjects were recorded during walking using an optical motion capture system. The models with and without subtalar fusion were constructed using the AnyBody Modeling System (AnyBody Technology, Aalborg, Denmark). The range of motion and contact forces in the individual foot joints with and without simulated subtalar fusion in healthy subjects were estimated using computational simulation and compared using the Wilcoxon signed-rank test. The change of motion in the Chopart's joint was observed. Results: Normalized to the subject's body weight (BW), the average maximum contact forces in the tibiotalar and Lisfranc joints during walking were significantly increased by 2.6 and 0.9 BW with the simulated subtalar joint fusion, respectively. The simulated subtalar joint fusion increased joint contact forces significantly during walking, which can increase the risks of secondary arthritis in the adjacent joints. Significance: The subtalar joint fusion increased the joint contact forces in adjacent joints during walking implying that the fusion can increase the risk of secondary injuries in adjacent joints in the foot.