Simulated Increase in Monoarticular Hip Muscle Strength Reduces the First Peak of Knee Compression Forces During Walking

Abstract

Reducing compressive knee contact forces (KCF) during walking could slow the progression of knee osteoarthritis. A previous study has shown that compensating for the hip flexion/extension moment could reduce the KCF peak occurring during early-stance (KCFp1). Therefore, this study aimed to identify if monoarticular hip muscle could allow this compensation while considering different walking strategies. Gait trials from 24 healthy participants were used to make musculoskeletal models. Five load-cases were examined: (I) Normal, (II) with an applied external moment compensating for the hip flexion/extension moment, (III-V) three conditions with isolated/combined 30% increase of isometric strength of gluteus medius and maximus. KCF, hip muscle forces, and joint moments were computed. A cluster analysis of the Normal condition was performed with hip and knee flexion/extension moment during KCFp1 as input to examine the influence of walking strategies. The cluster analysis revealed two groups having different hip and knee moments in early-stance [p<0.01]. The reduction in KCFp1 from the normal condition, although present in both groups, was greater for the group with the highest hip and lowest knee flexion/extension moments for all conditions (II: -6.03% versus -21.82% [p<0.001], III: -3.21% versus -1.59%, IV: -3.00% versus -1.76%, V: -6.12 versus -3.09%). This reduction in KCFp1 occurred through a shift in force developed by the hamstrings to the gluteus medius and maximus. Differences between groups suggest that this reduction depends on the walking strategy.