A review study from Houston Methodist orthopedic surgery researchers debunks the commonly held belief that runners have worse knees than non-runners.

The review, a meta-analysis of 17 studies involving the medical records of more than 14,000 patients (approximately 7,000 runners and 7,000 non-runners) found no evidence that regularly participating in running as a form of exercise increases one's risk of developing knee osteoarthritis (OA) or making knee osteoarthritis worse.

"Patients come into the clinic all the time asking if it's okay to run, or saying someone told them they shouldn't run," said Dr. Patrick McCulloch, the John S. Dunn Chair in Orthopedic Surgery at Houston Methodist and the study's primary investigator. "We wanted to know, looking at all the available literature, is running actually hard on your knees or does it just get a bad rap?"

What they found was encouraging for those with a passion for pounding the pavement.

The review, published recently in the Orthopedic Journal of Sports Medicine, showed a significantly higher prevalence of knee pain in the non-runner group (P < .0001) than the runner group. It also showed a significantly higher risk of knee OA progressing to total knee replacement among non-runners than among runners (4.6% vs 2.6%; P = .014).

While one study found a significantly higher prevalence of osteophytes in the tibiofemoral and patellofemoral joints within the runner group, multiple other studies found no significant differences in the prevalence of radiographic knee OA or cartilage thickness on MRI between runners and non-runners (P > .05).

The mean age among runners was 56.2 years and 61.6 years among non-runners. The mean BMI was 26.7 kg/m² in the runner group and 28 kg/m² in the non-runner group. The mean follow-up time was 55.8 months in the runner group and 99.7 months in the non-runner group. The overall percentage of men was 58.5%.

"I think this study clearly shows that if you like running, and your body tolerates it well, you should not be afraid to do it because of what it might do to your knees," said Dr. Matthew Kraeutler, an orthopedic surgery fellow at Houston Methodist and co-author of the study. "It's incredibly beneficial to your cardiovascular health and the most efficient way to burn calories, which is why runners tend to be leaner and more fit."

Unlike running, being overweight is a well-validated risk factor for the development of knee OA or worsening the condition's progression. Being only 10 pounds overweight increases the force on the knee by 30-60 pounds with each step, and being overweight increases the risk of knee OA by four to five times.

"There's a cost-benefit to every activity, and we're not saying people who experience knee pain while running or have preexisting knee osteoarthritis shouldn't consider less high-impact options," Dr. McCulloch said. "Our study looked at self-classified runners vs. non-runners. It may be that they self-selected based on how well they tolerate running — perhaps runners tend to have better baseline joint health than non-runners, which may help explain these results."