KNEE JOINT PRESSURE STIMULATION IMPROVES QUADRICEPS STRENGTH AND NEUROMUSCULAR ACTIVITY IN PATIENTS WITH END-STAGE KNEE OSTEOARTHRITIS

F. Temporiti^1,2, S. Moro¹, P. Adamo¹, R. Gatti^1,2

¹IRCCS Humanitas Clinical and Research Center, Physiotherapy Unit, Milano, Italy, ²Humanitas University, Department of Biomedical Sciences, Milano, Italy

Background: Weakness of the quadriceps muscle represent a common symptom in patients with knee osteoarthritis, leading to impaired knee function and disability during daily activities. In these patients, quadriceps weakness has been described as partially related to arthrogenic muscle inhibition, defined as the inability to fully activate a muscle in the absence of a nerve damage. This phenomenon has been mainly explained through spinal excitability modifications deriving from a mechanoreceptors damage, which leads to an alteration of sensory feedbacks from the knee joint. The result is an inhibition of the quadriceps alpha-motoneuron pool and a decrease in quadriceps muscle recruitment. In this scenario, the stimulation of the knee joint mechanoreceptors, such as through a periarticular pressure stimulation, may modify quadriceps neuromuscular activity and force.

Purpose: To investigate the effects of a periarticular pressure stimulation of the knee joint on quadriceps strength and neuromuscular activity in patients with end-stage knee osteoarthritis.

Methods: Twenty-five patients with end-stage knee osteoarthritis and and twenty-five age-matched healthy subjects were enrolled. Participants were seated on a dynamometer chair (BAR, OTBioelettronica, Italy) with hips and knees at 90 degrees and 30 degrees of flexion, respectively. The dynamometer rotational axis was aligned with the lateral condyle of the femur and the lever arm was fixed 2 cm above the lateral malleolus. After a familiarization trial, participants performed 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 were performed for each pressure level, and the peak force (kg) was 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 was recorded using bipolar surface electromyography electrodes (FREEEMG, BTS, Italy). The RMS-peak of each muscle was normalized for its highest value among the three conditions (nRMS-peak) and used as index of neuromuscular activity.

Results: A 3 x 2 General Linear Model revealed higher quadriceps peak force with 60 mmHg (p<0.001) and 120 mmHg (p<0.001) of periarticular pressure compared to the absence of periarticular pressure patients, whereas different pressure levels did not modify quadriceps strength in healthy subjects. Patients showed lower normalized peak force of the quadriceps in the absence of pressure (p=0.002), whereas no between-group differences were detected after the application of 60 mmHg and 120 mmHg pressure stimuli. Moreover, higher rectus femoris nRMS-peak was found with 60 mmHg (p=0.022) and 120 mmHg (p<0.001) of periarticular pressure compared to the absence of periarticular pressure patients, whereas different pressure levels did not modify neuromuscular activity in healthy subjects. No interaction between pressure levels and group was found for vastus medialis and vastus lateralis muscles.

Conclusions: The application of a periarticular pressure stimulation around the knee joint increased quadriceps strength and neuromuscular activity in patients with end-stage knee osteoarthritis.

Implications: This approach may be adopted in rehabilitative interventions aimed at increase quadriceps strength in patients with disability for knee osteoarthritis.

Funding acknowledgements: The authors did not receive any funding.

Keywords:
Knee osteoarthritis
Quadriceps strength
Pressure stimulation

Topics:
Musculoskeletal: lower limb
Musculoskeletal

Did this work require ethics approval? Yes

Institution: IRCCS Humanitas Clinical and Research Center

Committee: Internal Ethical Committee of the Humanitas Clinical and Research Center

Ethics number: CLF22/05