Stiff knee gait in patients with knee osteoarthritis is associated with disturbed body perception.

This study aimed to clarify the factors related to knee flexion during the swing phase of gait in patients with knee OA.

The subjects were 89 patients with knee OA (18 males and 71 females, mean age 73.4 ± 6.6 years). The joint movement of the lower limbs during walking was measured using a three-dimensional motion analysis device equipped with an inertial sensor, and the maximum knee joint flexion angle during the swing phase of the affected side was calculated. Muscle activity of the medial muscles (vastus medialis and semitendinosus) and lateral muscles (vastus lateralis and biceps femoris) during walking was measured using a surface electromyograph, and co-contraction (co-contraction ratios; CCR) during the stance and swing phases were calculated. In addition, we assessed knee flexion range of motion, knee extension strength, pain during walking (visual analogue scale; VAS), and disturbed body perception (Fremantle Knee Awareness Questionnaire: FreKAQ). For statistical analysis, a hierarchical multiple regression analysis was performed with the maximum knee flexion angle during the swing phase as the dependent variable: basic attributes (age, BMI) were entered in step 1, physical function (CCR, knee flexion range of motion, knee extension strength) in step 2, and pain factors (VAS, FreKAQ) in step 3.

The maximum knee joint flexion angle during the swing phase was 43.5 ± 14.9°. Hierarchical multiple regression analysis showed that the regression model in step 3 was significant (adjusted R² = 0.30, p 0.01). Knee joint flexion range (β = 0.33, p 0.01), CCR during the stance phase (β = -0.30, p = 0.05), VAS (β = -0.24, p = 0.01), and FreKAQ (β = -0.28, p 0.01) were each significantly associated with maximum knee joint flexion angle during the swing phase.

These results suggest that the maximum knee flexion angle during the swing phase in patients with knee OA is related to the knee flexion range of motion, co-contraction during stance, pain during walking, and disturbed body perception.

When assessing and intervening for stiff knee gait in patients with knee OA, it is necessary to consider not only knee joint range of motion and co-contraction but also disturbed body perception.