Chondroitin sulfate slows the progression of knee osteoarthritis, according to findings from a pilot study that used magnetic resonance imaging to assess joint structural changes.
"It’s reassuring to see that the four major x-rays studies are now confirmed by high technology in the assessment of disease progression," said the study’s lead author Dr. Jean-Pierre Pelletier, in an interview. (Osteoarthr. Cartil. 1998;6:39-46), (Osteoarthr. Cartil. 2004;12:269-76), (Arthritis Rheum. 2005;52:779-86), (Arthritis Rheum. 2009;60:524-33).
The randomized, double-blind, placebo-controlled study showed that chondroitin sulfate reduced the cartilage loss volume in 69 patients with knee OA in as early as 6 months. (Ann. Rheum. Dis. 2011 March 1)
Dr. Roy D. Altman
The findings show that "[MRI] is a good quantitative technique to find answers in shorter period of time with smaller number of patients," said Dr. Roy D. Altman, professor of medicine at the University of California, Los Angeles, who is not involved with the study.
The effect of disease-modifying drug chondroitin sulfate on cartilage volume loss, bone marrow lesions (BML), and disease symptoms has been controversial (BMJ 2010;341:c4675). However, the authors of this study said that the MRI findings provided additional evidence on the joint structure protective effect of chondroitin sulfate.
Several studies have also shown that MRI can quantitatively and reliably assess the volume and cartilage thickness in addition to joint structural changes in subchondral bone, menisci, and synovium, the authors reported.
"MRI provides you with direct visualization of the cartilage," said Dr. Pelletier, director of the osteoarthritis research unit at the University of Montreal Hospital Research Centre. "And the beauty of MRI is that it not only it provides assessment of progression of change in cartilage, but also in many other tissues of the joint, like the subchondral bone and the synovium.
"In addition, the pronounced reduction in OA cartilage loss found in patients treated with chondroitin sulfate was also associated with a reduction in the size of BML. This finding is most interesting as BML are believed to be associated with the progression of OA cartilage lesions," according to a number of studies, said Dr. Pelletier.
The study also showed that patients who were being treated with NSAIDs in addition to chondroitin sulfate showed a significant reduction in synovial membrane thickness (1.3 plus or minus 0.3 mm in 6 months vs. 1.6 plus or minus 0.3 mm placebo) and a lower incidence of joint swelling, compared with the placebo group (0% in chondroitin sulfate vs. 11.4% in placebo). The finding "is interesting with practical clinical impact, and definitely needs future exploration," the authors wrote.
Researchers recruited 69 patients of both sexes between 40 and 80 years of age from rheumatology clinics in Quebec province. All patients had clinical signs of synovitis.
The study had two phases. For the double-blind phase, the patients were randomly assigned to once-daily placebo or 800 mg of chondroitin sulfate for 6 months. During the following 6 months, or the open-label phase, both groups received 800 mg of chondroitin sulfate daily.
Cartilage volume and BML were assessed by MRI at baseline, 6 months, and 12 months. Synovial membrane thickness was assessed at baseline and 6 months.
Patients who took a daily oral dose of chondroitin sulfate had a significant reduction in cartilage volume loss at 6 months (–2.87%) and 12 months (–3.71%) in the global knee compared to the placebo group (–4.67% at 6 months and -6.12% at 12 months).
There were no differences in BML during the first 6 months. But, at 12 months reduction in BML were observed in the chondroitin sulfate group (–0.57%), especially in the lateral compartment (–0.13%) and the lateral condyle (–0.43). The additional 6-months needed to see the change could suggest that "BML are consequential to cartilage degradation and thus reducing cartilage lesions could lead to fewer BML. Alternatively, BML were shown to be involved in an inflammatory/catabolic process on which chondroitin sulfate could act directly, leading to structural repair," according to the study.
No significant difference in disease symptoms were measured by visual analog scale and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaires. "The main aim of the study was not the symptoms. The main goal was to find out whether chondroitin sulfate can reduce progression of knee OA," said Dr. Pelletier.
The study had limitations, including a small sample size. In addition, the system used did not allow the detection of the cartilage in the patella, researchers reported. They added that long-term studies are needed to find the impact of CS in disease symptoms.
Whether the quantitive MRI technique will eventually replace X-ray technology in such studies is unclear, said Dr. Pelletier. "That’s for regulatory bodies to decide," he said. "But it’s quite clear that MRI is the technology of the future. It’s very helpful, because you can truly speed up drug development in the field of OA and with less expense, using smaller number of patients and in a shorter period of time."