OBJECTIVE: To investigate the effects of short-term light therapy with 890-nm radiation on pain, physical activity, and postural stability in patients with knee osteoarthritis (OA). DESIGN: A double-blind, randomized, placebo-controlled study. SETTING: Rehabilitation clinic. PARTICIPANTS: Women (n = 62) and men (n = 10) with a mean age of 61.2 years (range 40 to 88y). All patients fulfilled the combined clinical and radiographic criteria for knee OA as established by the American College of Rheumatology, and all had obtained a Kellgren-Lawrence score of 2 or more. INTERVENTIONS: Participants received 6 sessions, lasting 40 minutes each, of active or placebo radiation treatment over the knee joints for 2 weeks (wavelength, 890nm; radiant power output, 6.24W; power density, 34.7mW/cm2 for 40 minutes; total energy, 41.6J/cm2 per knee per session). MAIN OUTCOME MEASURES: Participants were assessed weekly over 4 weeks using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for pain, stiffness, and physical function. Physical activity (timed stair climbing, 10-m fast-speed walking, and chair-rising time) and postural stability (using the postural stability evaluation system) were also assessed. The pain score on WOMAC was the primary outcome variable. Data were analyzed by repeated-measures analysis of covariance. RESULTS: Compared with baseline, no significant improvement was observed between groups for pain (p = 0.546), stiffness (p = 0.573), or physical function (p = 0.904). No significant improvement was noted for physical activity including the 10-m fast-speed walking time (p = 0.284), stair-climbing time (p = 0.202), stair-descending time (p = 0.468), chair-rising time (p = 0.499), or postural stability (p = 0.986) at the 4 follow-up assessments. Follow-up assessments were conducted after 1 week of treatment (thus, after 3 treatments); after 2 weeks of treatment (thus, after 6 treatments); and 1 and 2 weeks, respectively, after treatment was terminated. Although we found a significant time effect for the 10-m fast-speed walking time (p < 0.001) in the 2 groups, and a significant group effect in the improvement of stair-climbing time in the treatment group (p = 0.032), the group x time interaction effects were not significant. CONCLUSIONS: Short-term 890-nm radiation therapy for patients with knee OA provided no beneficial effect in improving pain, physical activity, and postural stability.

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