Effects of Joint Pressure Stimuli on Quadriceps Strength and Neuromuscular Activity in Patients With Knee Ostearthritis

The study aimed at assessing the effects of a periarticular pressure stimulation of the knee joint on quadriceps strength and neuromuscular activity in patients with end-stage knee osteoarthritis.

Twenty-five patients with end-stage knee osteoarthritis and and twenty-five age-matched healthy subjects will be enrolled. Participants will seat on a dynamometer chair (BAR, OTBioelettronica, Italy) with hips and knees at 90 degrees and 30 degrees of flexion, respectively. Participants will perform six maximal voluntary knee extension tasks with three different pressure stimuli in terms of intensity (0 mmHg, 60 mmHg, 120 mmHg) around the knee using a sphygmomanometer. Two maximum voluntary contractions interspaced by 3 minutes of rest will be performed for each pressure level, and the peak force (N) will be collected and normalized for the highest value during the three conditions. Moreover, root-mean-square peak (RMS-peak) of rectus femoris, vastus medialis, and vastus lateralis will be recorded using bipolar surface electromyography electrodes (FREEEMG, BTS, Italy). The RMS-peak of each muscle will be normalized for its highest value among the three conditions (nRMS-peak) and used as index of neuromuscular activity.