Study: Strengthening Thighs Won't Always Slow Knee Osteoarthritis

Increasing the strength of the thigh muscle won't protect against the progression of knee osteoarthritis in certain patients, according to a study reported in the April 15 issue of the Annals of Internal Medicine.

The finding by Northwestern University researchers contradicts the current thinking among many clinicians that strengthening the thigh muscle helps delay the disease's progression.

The study involved 237 osteoarthritis sufferers whose average age was 64 years. The researchers tested the upper leg strength of the participants using a device that measures muscle force against resistance.

Besides measuring the looseness of the knee joints, the researchers also took x-rays to see whether the two bones that meet in the knee joint were misaligned. The researchers then followed the participants for 18 months to see whether their knee osteoarthritis stayed the same or worsened.

The predicted probability of osteoarthritic progression was 15 percent in high-strength thighs, compared to just 10 percent in low-strength thighs. In the misaligned knee group, the probability of progression was 40 percent among those with high-strength thighs versus 19 percent among those with low-strength thighs. Thigh strength was also associated with increased likelihood of progression in those with highly loose knee joints.

The researchers cautioned that the results do not mean that physical activity or exercise in general is harmful in adults with knee osteoarthritis. However, they suggested that special exercise programs be developed for osteoarthritis sufferers with misaligned or lax knees.

Other sources: Annals of Internal Medicine 2003;138:613-619