To determine whether chondroitin sulfate (CS) is effective in inhibiting cartilage loss in knee osteoarthritis (OA).
In this randomized, double-blind, placebo-controlled trial, 300 patients with knee OA were recruited from an outpatient clinic, from private practices, and through advertisements. Study patients were randomly assigned to receive either 800 mg CS or placebo once daily for 2 years. The primary outcome was joint space loss over 2 years as assessed by a posteroanterior radiograph of the knee in flexion; secondary outcomes included pain and function.
Of 341 patients screened, 300 entered the study and were included in the intent-to-treat analysis. The 150 patients receiving placebo had progressive joint space narrowing, with a mean +/- SD joint space loss of 0.14 +/- 0.61 mm after 2 years (P = 0.001 compared with baseline). In contrast, there was no change in mean joint space width for the 150 patients receiving CS (0.00 +/- 0.53 mm; P not significant compared with baseline). Similar results were found for minimum joint space narrowing. The differences in loss of joint space between the two groups were significant for mean joint space width (0.14 +/- 0.57 mm; P = 0.04) and for minimum joint space width (0.12 +/- 0.52 mm; P = 0.05). CS was well tolerated, with no significant differences in rates of adverse events between the two groups.
While there was no significant symptomatic effect in this study, long-term treatment with CS may retard radiographic progression in patients with OA of the knee. However, the clinical relevance of the observed structural results has to be further evaluated, and further studies are needed to confirm the structural effects of CS.