To identify changes in joint pain, stiffness, and functional ability in patients with knee osteoarthritis (OA) after use of a knee sleeve that prevents loss of body heat by the joint.
Subjects with symptomatic knee OA (n = 52) were randomized to 2 treatment groups: verum sleeve (specially fabricated to retain body heat) or placebo sleeve (standard cotton/elastane sleeve). Subjects wore the sleeve over the more painful OA knee for at least 12 hours daily for 4 weeks. Pain, stiffness, and functional impairment (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]) in the index knee were measured at baseline and after 4 weeks of wear, after which sleeve use was discontinued. Telephone followup interviews were conducted 2 and 4 weeks later.
After 4 weeks of sleeve wear, subjects in the active treatment group reported a 16% decrease in mean WOMAC pain score relative to baseline (P = 0.001). Those who wore the placebo sleeve reported a 9.7% decrease from baseline (P = 0.002). The difference between treatment groups was not statistically significant (P = 0.12). However, it was found that the 12 subjects who believed correctly that they had received the verum sleeve reported a highly significant decrease in WOMAC pain score (-27.5% relative to baseline, P = 0.0001). In comparison, subjects who received the verum sleeve but believed they had received the placebo sleeve exhibited only a marginally significant improvement in pain (-13.0% relative to baseline, P = 0.07). In the placebo group, the modest improvement in pain scores appeared unrelated to the subject's impression of the type of sleeve worn.
This pilot study was insufficiently powered to be a definitive trial of the heat-retaining sleeve. Given the magnitude of changes in knee pain in the active treatment group, heat retention merits further scientific investigation as a treatment modality for patients with knee OA.