Strong thigh muscles could be protected from osteoarthritis of the knee, a new US study suggests.

A new study by researchers at the University of Iowa Hospitals and Clinics found that thigh muscle strength does not predict the occurrence of knee osteoarthritis uncovered in x-rays, but does predict incidence of painful or stiff knee osteoarthritis.

Women & Osteoarthritis

Women with the strongest quadriceps muscles appeared to be protected against the development of knee osteoarthritis symptoms. Details of this study appear in the September issue of Arthritis Care & Research, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology.

Osteoarthritis: The Knee

The knee is the most common weight-bearing joint affected by osteoarthritis or degenerative joint disease. The Centers for Disease Control and Prevention (CDC) estimate that 26.9 million U.S. adults are affected by osteoarthritis with 16% (aged 45+ years) of those cases occurring in the knee.

Approximately 18.7 % of symptomatic knee osteoarthritis patients are female and 13.5% are male. A Medical Expenditure Panel Survey estimates that total out-of-pocket expenditures for treatment of arthritis was $32 billion in 2005.

Neil Segal and colleagues in a study funded by the National Institute on Aging followed 3,026 men and women ages 50-79 over a 30-month period in the Multicenter Knee Osteoarthritis Study (MOST) to assess whether knee extensor strength would predict incident radiographic (osteoarthritis that can be determined through X-ray) or symptomatic knee osteoarthritis.

Of those enrolled, a total of 2,519 knees were included in the study of radiographic knee osteoarthritis and 3,392 knees were evaluated for the combination of radiographic osteoarthritis and symptoms of osteoarthritis that include pain, aching or stiffness on most days of the month.

Osteoarthritis: Scientific Research

By the conclusion of the study 48 of 680 men and 93 of 937 women developed osteoarthritis detected by x-ray. At the end of the 30-month period 10.1% of women and 7.8% of men displayed signs of symptomatic knee OA.

Women in the top third of peak knee extensor strength had a lower incidence of symptomatic knee osteoarthritis, while men with strong thigh muscles had only slightly better odds of developing osteoarthritis symptoms compared to men with weaker knee extensor strength.