THURSDAY, Aug. 12 (HealthDayNews) -- Siblings of people with knee osteoarthritis have twice the risk of developing the problem themselves, which suggests a person's genes play a role in the condition.

The finding appears in the current issue of the Annals of Rheumatic Diseases.

The study included 490 people with severe knee osteoarthritis (OA), 773 of their siblings over age 40, and 1,729 people with knee pain. The researchers took X-rays of the knees of the siblings and the patients with knee pain to look for signs of OA.

The study found the siblings were more than twice as likely to have knee OA compared with the patients with knee pain. That was true even when the researchers factored in major risk factors such as smoking, being overweight, age and gender.

This genetic risk for OA among the siblings was spread across different ages, but brothers were more likely to have OA than sisters.

OA is a degenerative condition associated with aging that's characterized by inflammation and loss of joint cartilage. The knee is the joint most often affected by OA.

More information

The Arthritis Foundation has more about osteoarthritis.