Clinical Question: Is chondroitin sulfate effective in relieving pain or preventing the progression of osteoarthritis of the knee in patients with severe disease?

Setting: Outpatient (specialty)

Study Design: Randomized controlled trial (double-blinded)

Allocation: Concealed

Synopsis: Patients 40 to 85 years of age with clinically symptomatic osteoarthritis of the knee (according to American College of Rheumatology criteria) were eligible to participate in this study unless they had severe changes on radiography (i.e., severely narrowed joint space with sclerosis of the subchondral bone). Those who had secondary osteoarthritis or the most severe symptoms were excluded. Patients were assigned randomly to receive 800 mg of chondroitins 4 and 6 sulfate (n = 150) or placebo (n = 150) daily for two years.

The main outcomes, assessed via intention to treat, were radiographic progression and symptom relief as measured by the Western Ontario and McMaster Universities Osteoarthritis Index. Participants and study personnel did not know to which group the patients were assigned until the conclusion of the study.

Although only 219 patients (73 percent) completed the two-year study, the researchers carried forward the final observation and performed radiography at the time each patient dropped out. At the end of two years, patients taking chondroitin experienced no change in joint space width from baseline; in the patients taking placebo, joint space narrowed by an average of 0.14 mm (± 0.57 mm; P = .04). It appears that chondroitin protected the joint from further deterioration. However, it had no effect on pain.

Bottom Line: After two years of treatment, chondroitin sulfate has no effect on comfort in patients with severe degenerative arthritis of the knee. Compared with placebo, however, it appears that chondroitin may have a small protective effect on the joint. The clinical relevance of this effect is not known. (Level of Evidence: 1b)