Effect of magnetic knee wrap on quadriceps strength in patients with symptomatic knee osteoarthritis

To determine the effects of magnetic knee wrap on isokinetic quadriceps strength in patients with painful knee osteoarthritis (OA).

Randomized, double-blinded, placebo-controlled and before-after trial.

Rehabilitation clinic in a tertiary hospital.

Eligible patients (N=50) (mean age+/-SD, 66.0+/-8.6 y) with mild to moderate knee OA were recruited from the outpatient department and 37 (74%) completed the trial. Only 3 (6%) withdrew due to study-related adverse effects.

Wearing the active (n=24) or sham (n=26) magnetic knee wrap for 12 weeks.

The primary outcome measure was isokinetic quadriceps strength. Secondary outcome measures included the Health Assessment Questionnaire Disability Index (HAQ-DI) and the Health Assessment Questionnaire (HAQ) Pain Scale.

Using intention-to-treat analyses, the peak isokinetic quadriceps strength increased significantly in the treated leg at 30 degrees/s (P=.007) and 60 degrees/s (P=.022) after wearing the magnetic knee wrap. Compared with baseline, the median strength increase for the treated leg in the study group significantly exceeded that in the control group at week 4 (.05 Nm/kg vs -.09 Nm/kg at 60 degrees/s, P=.038) and week 12 (30 degrees/s, .09 Nm/kg vs .04 Nm/kg, P=.044; 60 degrees/s, .17 Nm/kg vs .02 Nm/kg, P=.031). The HAQ-DI and HAQ Pain Scales improved significantly in both groups. Compared with baseline, the improvement at week 12 in terms of the HAQ-DI in the study group significantly exceeded that in the control group.

Magnetic knee wrap may significantly facilitate isokinetic quadriceps strength in patients with mild to moderate knee OA.