Glucosamine chondroitin combo beneficial in knee osteoarthritis

Combining the commonly used supplements glucosamine and chondroitin reduces joint space narrowing in people with symptomatic knee osteoarthritis, new Australian data shows. The researchers, led by Dr Marlene Fransen from the Faculty of Health Sciences, University of Sydney, found patients who had two years of the daily combination treatment, had a reduction of 0.1mm in joint space narrowing (JSN) compared to placebo: (p=0.046) mean difference 0.10 mm (95% CI 0.002 mm to 0.20 mm).  Narrowing joint-space indicates cartilage loss and worsening osteoarthritis. The double-blind randomised placebo-controlled clinical trial included 605 participants, aged 45–75 years, reporting chronic knee pain and with evidence of medial tibio-femoral compartment narrowing (but retaining >2 mm medial joint space width). They were randomised to once daily: glucosamine sulfate 1500 mg (n=152), chondroitin sulfate 800 mg (n=151), a combination of both dietary supplements (n=151) or matching placebo capsules (n=151). JSN (mm) over 2 years was measured from digitised knee radiographs. Maximum knee pain (0–10) was self-reported in a participant diary for 7 days every 2 months over 1 year. The researchers found that the reduction in JSN only occurred in the group who had taken both supplements together, with no improvement detected in patients randomised to either of the supplements on its own. However, they hypothesised that as both glucosamine and chondroitin have similar effects on articular cartilage, it may be that the combination increased overall dosage to a therapeutic level. All four allocation groups demonstrated reduced knee pain over the first year, but no significant between-group differences (p=0.93) were detected. According to their findings the researchers worked out that 14 patients would need to take the glucosamine-chondroitin combination for two years to avoid one knee replacement surgery within the following 2-5 year period. That said, they concluded that allocation to the glucosamine–chondroitin combination resulted in “a statistically significant reduction in JSN at 2 years.  “The clinical significance of the study findings is highlighted by the demonstrated increased risk of knee joint replacement surgery with increased annual JSN or cartilage losses,” they wrote. Source: Annals of the Rheumatic Diseases 2013 doi:10.1136/annrheumdis-2013-203954

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