Knee joint stiffness during walking in knee osteoarthritis

Area of Science:

• Biomechanics
• Orthopedics
• Kinetics

Background:

• Knee osteoarthritis (OA) is a prevalent condition characterized by joint pain and stiffness.
• Objective measures of knee stiffness during dynamic activities like walking are needed to understand OA pathophysiology.
• Existing research often relies on subjective patient reports of stiffness, which may not fully capture the mechanical properties of the joint.

Purpose of the Study:

• To determine if walking knee stiffness can differentiate between individuals with and without knee OA.
• To assess the construct validity of walking knee stiffness in relation to self-reported knee stiffness.
• To investigate factors contributing to walking knee stiffness, including knee range of motion, loading rate, and adduction moment.

Main Methods:

• Thirty-seven individuals diagnosed with knee OA and 11 asymptomatic controls were recruited.
• Knee stiffness during walking was calculated as the change in knee flexion-extension moment divided by the change in knee flexion angle.
• Forward-stepwise regression and Pearson's correlation coefficients were employed to analyze relationships between biomechanical and subjective measures.

Main Results:

• Walking knee stiffness was significantly greater in the knee OA group (10.1 Nm/degrees/kg x 100) compared to controls (5.6 Nm/degrees/kg x 100) (P < 0.001).
• Knee range of motion explained 39% of the variance in walking knee stiffness, with knee extensor moment contributing an additional 7%.
• In the OA group, walking knee stiffness showed no association with self-reported stiffness (r = 0.029; P = 0.863).

Conclusions:

• The study supports the construct validity of walking knee stiffness as an objective measure in knee OA.
• The dissociation between objective walking stiffness and subjective self-reported stiffness indicates they represent different aspects of the condition.
• Walking knee stiffness holds potential as a valuable clinical measure, warranting further research into its clinical significance.