Glucosamine Preserves Cartilage in Knee OA
Written by Editor   
Wednesday, May 04, 2016 12:00 AM

The use of combined glucosamine and chondroitin sulfate significantly decreased the loss of cartilage volume in knee osteoarthritis (OA) over a 6-year period, Canadian researchers have found.

Compared with individuals who had never taken the supplements and whose cartilage loss in the lateral compartment at 6 years was -8.85%, those with 1 year of exposure to medications had a loss of -8.21%.  In addition, patients with 2 to 3 years of exposure had a loss of -6.66%, while those with 4 to 6 years of exposure showed a loss in the lateral compartment of -6.90%.

In a double-blind, NIH-sponsored study known as GAIT, more than 1,500 patients with painful knee OA were randomized to receive glucosamine, chondroitin, both, celecoxib (Celebrex), or placebo for 6 months.

In that study, neither of the supplements, alone or in combination, led to significant reductions in pain, although a subgroup analysis suggested the possibility of benefits for those with moderate-to-severe pain at baseline.

However, in a systematic review of randomized studies evaluating chondroitin with or without glucosamine, the medication was associated with greater improvements in pain than placebo. A second meta-analysis of glucosamine and chondroitin found "moderate to large effects," but the quality of the studies was a concern, as was the likelihood of publication bias.

Yet another meta-analysis found no improvements in pain and "minute" changes in joint space, and the Swiss authors concluded that health authorities and payers should not cover the costs of the treatment, and patients should be discouraged from taking them.

But some of the studies thus far have suggested that the effects on disease progression might be clearer with a longer intervention, so researchers sought longer-term outcomes, analyzing data from the longitudinal Osteoarthritis Initiative.

Patients included in the analysis had at least 6 years' follow-up, had at least 1 mm of joint space width at baseline, and also had MRI evidence of medial meniscal extrusion, indicating that structural changes were already present.

A total of 96 patients had taken glucosamine/chondroitin for 1 year, 38 for 2 to 3 years, and 112 for 4 to 6 years. The "not exposed" (control) group included 183 individuals.

In addition to the decreased cartilage loss in the lateral compartment, there also was significantly less loss for the global knee among patients with 4 to 6 years of exposure to glucosamine/chondroitin compared with no exposure.

The researchers concluded, "These data are consistent with the hypothesis that individuals with knee OA, at a moderate stage of the disease, could benefit from long-term structure modifying agents such as glucosamine/chondroitin."