Stronger quadriceps muscles, relative to the hamstrings, may lower the risk of total knee replacement, according to research presented November 27 at the annual meeting of the Radiological Society of North America in Chicago Researchers said the findings could inform strength-training programs for people with advanced arthritis in the knee.

While stronger muscle groups are generally understood to be associated with a lower rate of total knee replacement, their relative importance is not well established. Of particular interest is the relationship between the extensors and the hamstrings, the two most important muscle groups in the knee.

The extensors, the muscles on the front of the thigh commonly referred to as the quadriceps, are the strongest muscle group in the body and have essential influence on gait, other activities and biomechanics. The muscles around the back of the thigh, the hamstrings, are responsible for extension of the hip and flexion of the knee, making them equally essential for physical activity.

The researchers evaluated thigh muscle volume in 134 adults (mean age, 62; about half, women), comparing 67 patients who underwent total knee replacement of a single knee with 67 control participants who had not undergone knee replacement. The cases and controls were matched for variables including age and gender.

The researchers also evaluated MRI findings of the knee from two years and four years before the surgery.

Comparing patients who had total knee replacement with the control group, a higher ratio of quadriceps to hamstring volume was significantly associated with lower odds of total knee replacement. Higher volumes of hamstrings and gracilis, a long, thin muscle on the inside of the thigh, were also linked with lower odds of total knee replacement.

The results suggest that training programs that strengthen the quadriceps in relation to the hamstrings may be beneficial.

The authors note that while the results are "essential for targeted therapy in a population at risk for osteoarthritis, even the general public can benefit" from the results to preventively incorporate appropriate strengthening exercises.

To read the study presentation abstract, click here