Analysis of the lower extremity muscle activity depending on the use of a knee aid in elderly people with osteoarthritis

This study analysed the lower extremity muscle activity depending on the use of the Power Leg, a wearable knee aid, in elderly people with osteoarthritis. Eight participants who had osteoarthritis were asked to repeat sit-to-stand from a chair first without the knee aid, following which they were asked to repeat the same movement with the knee aid. Surface electromyography (EMG) was used to analyse muscle activities of the vastus medialis, rectus femoris, and vastus lateralis on the quadriceps femoris of the right leg while performing sit-to-stand motion. The result showed an 11.25% decrease in muscle activity of the vastus medialis, from 50.43% without the knee aid to 39.18% with the knee aid, which was significant (p < .05). Muscle activity of the rectus femoris decreased by 5.17%, from 29.49% without the knee aid down to 24.32% with the knee aid. However, the difference was not significant. The vastus lateralis had reduced muscle activity by 16.22%, from 57.15% without the knee aid to 40.93% with the knee aid, which was significant (p < .05). The results of this study showed that the Power Leg knee aid may decrease muscle activity by assisting lower extremity muscles during the sit-to-stand motion and effectively support the knee extensor during knee extension. Given these findings, as well as the ease of wearing and using the Power Leg knee aid, it is concluded that the wearable knee aid is very useful for the elderly with knee osteoarthritis.