• Posted November 27, 2023

Want to Avoid Knee Replacement? Build Up Your Thighs

Squats and lunges aren't the most fun exercises, but a new study says they'll help save your knees.

Folks with strong quads building up their thighs appear to be less likely to require a total knee replacement, according to a presentation scheduled for Monday at a meeting of the Radiological Society of North America (RSNA) in Chicago.

Stronger muscles are generally associated with a lower rate of total knee replacement, researchers said in background notes.

However, it's been unclear whether people benefit more from stronger extensor muscles like the quadriceps, which extend the leg, or stronger flexor muscles like hamstrings that bend the leg.

“Our study shows that in addition to strong muscles individually, larger extensor muscle groups -- relative to hamstring muscle groups -- are significantly associated with lower odds of total knee replacement surgery in two to four years,” said Dr. Upasana Upadhyay Bharadwaj, a research fellow in radiology at the University of California-San Francisco School of Medicine.

About 14 million U.S. adults have knee arthritis, and more than half will eventually require knee replacement surgery, researchers said.

The quads and the hamstrings are of particular interest because they're the two most important muscle groups to the knee.

The quads are located on the front of the thigh. They are the strongest muscle group in the body and are essential to a person's gait, researchers said.

The hamstrings are on the back of the thigh and are equally essential for physical activity.

“The two muscle groups act as counter forces, and the balance between them enables a wide range of activities while protecting the knee joint,” Upadhyay Bharadwaj said in an RSNA news release. “An imbalance, in addition to other factors, leads to a change in the biomechanics resulting in the progression of osteoarthritis.”

For the study, Upadhyay Bharadwaj and her colleagues evaluated the thigh muscles of 134 participants in the Osteoarthritis Initiative, a nationwide study sponsored by the National Institutes of Health.

They compared 67 patients who underwent total replacement of a single knee with 67 other people who hadn't had a knee replacement, all matched for variables including age and gender.

AI analysis of knee MRIs from the participants revealed that a higher ratio of quadriceps to hamstring volume was significantly associated with lower odds of total knee replacement, results show.

Higher volumes of hamstrings and gracilis -- a long, thin muscle on the inside of the thigh -- also were linked to lower odds of knee replacement.

The results suggest that training programs that focus on quad strength in relation to the hamstrings could be beneficial, researchers said.

“Although we presume that overall muscle volume is important as a surrogate marker for muscle strength, the ratio, hence the balance, between extensor and hamstring muscles may be more important and significantly associated with lower odds of total knee replacement,” Upadhyay Bharadwaj said.

The findings may also help inform strength training for a wider segment of the population, she added.

“While these results are essential for targeted therapy in a population at risk for osteoarthritis, even the general public can benefit from our results to preventively incorporate appropriate strengthening exercises,” Upadhyay Bharadwaj said.

Findings presented at medical meetings are typically considered preliminary until published in a peer-reviewed journal.

More information

The Cleveland Clinic has more about quad exercises for knee arthritis.

SOURCE: Radiological Society of North America, news release, Nov. 27, 2023