194 patients with knee osteoarthritis were randomized to undergo treatment once a day for 24 months with either 1200mg chondroitin sulfate or 200mg celecoxib. The study was conducted in order to investigate suggestions in prior studies that chondroitin sulfate provides benefits in preserving the integrity of cartilage and slowing its progressive deterioration. The findings of this study displayed significantly reduced cartilage volume loss in the chondroitin sulfate group in the medial tibiofemoral compartment and global knee at 12 months and in the medial tibiofemoral compartment at 24 months. Changes in synovial thickness, bone marrow lesion size, joint swelling and effusion, and clinical outcomes were comparable between groups, as were the occurrence of adverse events.