Rochester: Smokers risk more painful and progressive osteoarthritis, according to new research carried out by the Mayo Clinic in the US.

In a new study to be published in the Annals of the Rheumatic Diseases 159 men who had osteoarthritis of the knees were monitored for up to 30 months. The affected knees were scanned and the severity of pain scored. The men were monitored and again at 15 and 30 months.

Of the total, 12% (19) were active smokers at the start of the study. They smoked an average of 20 cigarettes a day and had done so for around 40 years.

Smokers tended to be younger and thinner, both factors that normally protect against osteoarthritis.

But the smokers were more than twice as likely to have a significant degree of cartilage loss compared with the non-smokers. Cartilage is the rubbery tissue that cushions bones at the joint.

Smokers were also significantly more likely to report greater pain severity.

Osteoarthritis is a degenerative joint condition, which commonly affects the knees and fingers. Knee osteoarthritis is one of the leading causes of disability among elderly people.

The authors suggest that smoking may alter the pain threshold. It also increases the levels of toxic substances in the blood and starves tissues of oxygen, which may hasten the loss of cartilage.