605 patients with osteoarthritis (OA) of the knee and resultant chronic knee pain were recruited to the study. Participants were randomized to consume glucosamine, chondroitin, a combination of both, or a placebo once daily for 2 years. The purpose of the study was to assess the effect on the supplements on joint space narrowing (JSN), pain, and function. The trial found that groups were comparable in all outcomes, with the exception of the combination of glucosamine and chondroitin displaying significantly reduced JSN in comparison to the placebo group at 2 years.