Effect of Knee Orthosis Pressure Variation on Muscle Activities during Sit-to-Stand Motion in Patients with Knee Osteoarthritis

Abstract

It is yet not known whether the variation in knee orthotics pressure would lead to changes in muscle activity during-sit-to-stand postural transition in patients with knee osteoarthritis (OA). Participants in this analytical study were patients with knee OA. The research design was a cross-sectional study. They were enrolled in the study through a sample of convenience method. The primary outcome measure was surface electromyography for measuring muscle activity while changing knee orthotics pressure during sit-to-stand motion. Data were summarized with mean and standard deviation while Friedman's test was performed for multiple comparison of variables, at a significance level of p = 0.05. Seven elderly patients with knee osteoarthritis (mean age 71.4 ± 11.8 years) participated in the study. Moderate orthotics (7.3 mmHg) led to a significant increase in the percentage maximum voluntary contraction (MVC) of tibialis anterior compared to that obtained without orthotics. Rectus femoris, vastus medialis, vastus lateralis, and biceps femoris tended to increase the % MVC with an increase in wearing pressure. It was therefore concluded that the muscle activity during sit-to-stand motion could be increased in patients with knee osteoarthritis by wearing flexible orthotics with varying pressure.

Keywords: knee orthosis; knee osteoarthritis; muscle activity; sit-to-stand motion; wearing pressure.

Figure 1

Flexible knee orthosis.

Figure 2

Measurement of Femoral-tibial alignment by body surface image.

Figure 3

Palm Q sticking position.

Figure 4

Pasting position of surface electromyography (a) rectus femoris, (b) the vastus medialis, (c) vastus lateralis, (d) biceps femoris, (e) tibialis anterior, and (f) gastrocnemius.