Smoking may worsen knee arthritis

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NEW YORK, Dec 12 (Reuters) Smokers with knee arthritis suffer quicker joint deterioration than non-smokers with the condition, a new study suggests.

Researchers found that among 159 men with knee arthritis, smokers reported more pain and were more than twice as likely to show significant cartilage loss in the joint.

Cartilage is the elastic tissue that cushions the ends of the bones; in osteoarthritis -- the common ''wear-and-tear'' form of arthritis -- this cartilage gradually breaks down, leading to inflammation, pain and deformity in the bones.

Some past studies, though not all, have suggested that smokers might be at greater risk of osteoarthritis. The current one, published online by the Annals of the Rheumatic Diseases, suggests that when smokers do develop the condition, it may be more severe.

The findings are ''provocative'' and should spur further research, write the study authors, led by Dr Shreyasee Amin of the Mayo Clinic College of Medicine in Rochester, Minnesota.

The 159 men with knee osteoarthritis in the study were followed for 2.5 years. The researchers used MRI scans to measure cartilage loss in the knee at the beginning, midpoint and end of the study.

The men also rated their knee pain at each follow-up visit.

In general, Amin's team found, the 12 per cent of men who were smoking at the study's outset showed greater cartilage loss over time and reported more pain than their non-smoking counterparts. This was despite the fact that the smokers tended to be younger and weigh less, which might be expected to delay progression of their arthritis.

There are a number of reasons smoking could exacerbate arthritis, according to the researchers. For one, they note, smoking can deprive tissue of oxygen, which might hinder normal cartilage repair. In addition, since cartilage itself has no pain fibers, it's possible that smokers' greater pain comes from damage to other structures in the arthritic joint.