Knee arthritis: Stronger thigh muscles can lower the risk of surgery

Evan Walker
Evan Walker TheMediTary.Com |
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Experts say running is one way to strengthen your leg muscles. Stefania Pelfini, La Waziya Photography/Getty Images
  • Researchers are reporting that having stronger quadricep muscles may help lower a person’s risk of having knee replacement surgery.
  • They explain that stronger muscles in the thigh can help stabilize the knee joint and reduce pressure on it.
  • Experts say running, cycling, weightlifting, and yoga are among the ways to strengthen leg muscles.

Weightlifters have a mantra about “leg days.” Don’t skip them.

The authors of a new study would likely agree. They say having stronger quadriceps – those big muscles around the front of the thighs – relative to the hamstrings may lower the risk of total knee replacement.

The research was recently presented at the annual meeting of the Radiological Society of North America (RSNA).

The scientists say their findings, which haven’t been published yet in a peer-reviewed journal, could help with strength-training programs for people with advanced arthritis in the knee.

The authors said in a statement that advanced knee osteoarthritis is a major cause of pain and disability worldwide. In the United States, an estimated 14 million adults have symptomatic knee osteoarthritis and more than half of those diagnosed will likely undergo total knee replacement surgery.

Although stronger muscle groups are generally believed to be associated with a lower rate of total knee replacement, their relative importance is not well established, the study authors said.

They added that of particular interest is the relationship between the extensors and the hamstrings, which are the two most important muscle groups in the knee.

The extensors are the muscles on the front of the thigh, also known as the quadriceps. They’re one of the body’s strongest muscle groups and have an essential influence on gait, biomechanics, and other activities.

The muscles around the back of the thigh are the hamstrings, which are responsible for extension of the hip and flexion of the knee, making them 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,” said Dr. Upasana Upadhyay Bharadwaj, a post-doctoral scholar in radiation at the University of California, San Francisco and the study’s lead author, in the statement. “An imbalance, in addition to other factors, leads to a change in the biomechanics resulting in the progression of osteoarthritis.”

The researchers said their findings have implications for the interpretation of imaging exams and clinical management.

They said the results suggest training programs to strengthen the quadriceps in relation to the hamstrings may be beneficial.

“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.

Although the study focused on people with arthritis, the results could help inform strength training for a wider segment of the population.

“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.

Dr. Timothy Gibson, an orthopedic surgeon and medical director of the MemorialCare Joint Replacement Center at Orange Coast Medical Center in California who was not involved in the study, told Medical News Today it’s already understood strong quadriceps muscles can delay knee replacement surgery or help symptoms of an arthritic knee.

“The idea that the ratio of the extensor muscles to the hamstring muscle is important may be new,” Gibson said. “It is an interesting study. However, in clinical practice, it may not change current treatment recommendations. I have recommended for years to my patients with knee arthritis to work hard on quadricep strength since they act as shock absorbers to control forces across the knee with each step, especially with stair climbing.”

Gibson added that the quadriceps starts as a muscle in the thigh bone and crosses over the front part of the knee and connects shin bone (tibia) via the patella and patellar tendon.

“It is a strong extensor of the knee,” Gibson said. “More importantly it controls eccentric muscle contraction with weight-bearing or ascending/descending stairs. With a strong quadriceps, the force across the knee is distributed more evenly and in a more controlled manner which helped reduce pain with each step.”

Gibson said, other than weight loss, quadricep strength is the most important nonoperative treatment in people with knee arthritis.

“It makes them more mobile and less likely to fall,” he said. “It can really help with pain and prolong the period of time in which surgery can be delayed.

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