The use of surface electromyography in rehabilitating rheumatic patients after knee arthroplasty (pilot study)

OBJECTIVES: The aim of the conducted research was to assess muscle performance in rheumatic patients qualified for knee arthroplasty before and after surgical treatment. MATERIAL AND METHODS: Patients with the diagnosis of rheumatoid arthritis or a degenerative joint disease qualified for surgical treatment were examined. Three groups were analysed: 1) a control group, 2) a group of patients qualified for knee arthroplasty (G1), 3) a group of patients with one knee joint endoprosthesis qualified for the second surgery (G2). The study was carried out through a portable surface electromyography system from Noraxon U.S.A. INC., Clinical DTS and using surface electrodes. The surface electromyography (sEMG) examination was conducted twice: before and on the 10th day after the surgery. The study concerned the quadriceps femoris muscle, i.e. its straight and medial head in both lower limbs during isometric tension and active movement. RESULTS: The comparison of the examined muscles’ activity in the control group revealed greatly increased activity during isometric tension than during active movement in both muscles. In the G1 group, the comparison of the average values of isometric tension of the examined muscles before the surgery showed slight differences between the healthy limb and the one qualified for the surgical treatment. After the surgery, significant asymmetry between the average values achieved by the healthy and the operated limb could be identified in both muscles. In the G2 group, muscle activity within the currently operated limb revealed only slight differences between the limbs before the surgery. After the surgery, there was an increase in muscle activity within the previously operated limb. CONCLUSIONS: Considerably higher average values of muscle activity during the isometric tension, when compared to the active movement in a sitting position, indicate the necessity of more widespread use of isometric tension in rehabilitating patients after knee arthroplasty.