Intermittent treatment of knee osteoarthritis with oral chondroitin sulfate: a one-year, randomized, double-blind, multicenter study versus placebo

OBJECTIVE: To investigate the efficacy and tolerability of a 3-month duration, twice a-year, intermittent treatment with oral chondroitin sulfate (CS) in knee osteoarthritis (OA) patients. DESIGN: A total of 120 patients with symptomatic knee OA were randomized into two groups receiving either 800mg CS or placebo (PBO) per day for two periods of 3 months during 1 year. Primary efficacy outcome was Lequesne's algo-functional index (AFI); secondary outcome parameters included VAS, walking time, global judgment, and paracetamol consumption. Radiological progression was assessed by automatic measurement of medial femoro-tibial joint space width on weight-bearing X-rays of both knees. Clinical and biological tolerability was assessed. RESULTS: One hundred and ten of 120 patients were included in the ITT analysis. AFI decreased significantly by 36% in the CS group after 1 year as compared to 23% in the PBO group. Similar results were found for the secondary outcomes parameters. Radiological progression at month 12 showed significantly decreased joint space width in the PBO group with no change in the CS group. Tolerability was good with only minor adverse events identically observed in both groups. CONCLUSION: This study provides evidences that oral CS decreased pain and improved knee function. The 3-month intermittent administration of 800mg/day of oral CS twice a year does support the prolonged effect known with symptom-modifying agents for OA. The inhibitory effect of CS on the radiological progression of the medial femoro-tibial joint space narrowing could suggest further evidence of its structure-modifying properties in knee OA.