Individuals with knee osteoarthritis demonstrate increased passive stiffness of the hip flexor muscles

Preece, SJ; Alghamdi, W; Jones, R

Abstract

Background: People with knee osteoarthritis stand and walk with increased trunk flexion. This altered postural alignment will increase hamstring activation, elevating mechanical knee loads during walking. Increased hip flexor stiffness may lead to increased trunk flexion. Therefore, this study compared hip flexor stiffness between healthy individuals and individuals with knee osteoarthritis. This study also sought to understand the biomechanical effect of a simple instruction to reduce trunk flexion by 5° during walking.
Methods: Twenty individuals with confirmed knee osteoarthritis and twenty healthy individuals participated. The Thomas test was used to quantity passive stiffness of the hip flexor muscles and 3D motion analysis used to quantify trunk flexion during normal walking. Using a controlled biofeedback protocol, each participant was then instructed to decrease trunk flexion by 5°.
Results: Passive stiffness was larger in the group with knee osteoarthritis (effect size = 1.04). For both groups, there was relatively strong correlation between passive stiffness and trunk flexion in walking (r=0-61-0.72). The instruction to decrease trunk flexion produced only small, non-significant, reductions in hamstring activation during early stance.
Conclusions: This is the first study to demonstrate that individuals with knee osteoarthritis exhibit increased passive stiffness of the hip muscles. This increased stiffness appears to be linked to increased trunk flexion and may therefore underlie the increased hamstring activation which is associated with this disease. As simple postural instruction does not appear to reduce hamstring activity, interventions may be required which can improve postural alignment by reducing passive stiffness of the hip muscles.

Citation

Preece, S., Alghamdi, W., & Jones, R. (2023). Individuals with knee osteoarthritis demonstrate increased passive stiffness of the hip flexor muscles. ˜The œKnee (Amsterdam. Online), 41, 302-310. https://doi.org/10.1016/j.knee.2023.01.007

• Journal Article Type: Article
• Acceptance Date: Jan 5, 2023
• Publication Date: Feb 16, 2023
• Deposit Date: Mar 1, 2023
• Publicly Available Date: Feb 17, 2024
• Journal: The Knee
• Print ISSN: 0968-0160
• Publisher: Elsevier
• Volume: 41
• Pages: 302-310
• DOI: https://doi.org/10.1016/j.knee.2023.01.007
• Publisher URL: https://doi.org/10.1016/j.knee.2023.01.007