Musculoskeletal complaints are one of the most common reasons for office visits. According to the 2010 National Health Interview Survey, 29% of U.S. individuals over the age of 18 years have chronic joint symptoms defined as having pain, aching or stiffness in and around a joint in the past 30 days.
No day on the “front lines” is complete without being asked to triage knee pain in a patient who is simultaneously battling excessive body weight. I’ve heard it said that every extra pound over ideal body weight puts an extra four pounds of stress across the knee. Is it any wonder that we perform over 600,000 knee replacements in the U.S. annually? To be fair, obesity is not the only culprit accounting for knee osteoarthritis requiring surgical intervention, but it’s the elephant in the room on this issue.
How many times have we half-heartedly told our patients to lose weight in order to decrease knee symptoms, while feeling certain that they won’t adhere to this advice since their exercise ability is compromised? Some physicians also may question the evidence behind this clinical wisdom.
The fact is that weight loss is indeed a first-line treatment for knee osteoarthritis (OA). Evidence shows that OA symptoms tend to worsen in obese patients, and that weight loss prevents the development of OA. A direct relationship exists between weight loss and the degree of symptomatic improvement among obese patients with OA. But what about patients whose X-rays show significant degeneration? Is it too late for their OA to improve by losing weight?
A recent study from the Parker Institute at Copenhagen University Hospital provides evidence that the degree of baseline structural damage does not predict changes in pain and function with weight loss among obese patients with OA. In this study, knee OA patients with an age greater than 50 years and a body mass index of at least 30 received 16 weeks of a weight loss intervention. Baseline MRI and radiographs were obtained on the most symptomatic knee. More than 10% of patients achieved significant weight loss and almost two-thirds achieved significant symptomatic improvement (Osteoarthritis Cartilage 2012;20:495-502).
The results indicate that for obese patients with OA, weight loss will reduce pain and improve function regardless of the degree of structural damage. This information should help clinicians feel more confident in making their usual recommendations. For patients who suggest that they cannot lose weight because they cannot exercise, it is helpful to remind them that significant weight loss can occur with modifications to total calorie intake and types of calories consumed in the absence of significant increases in activity.
Jon O. Ebbert, M.D, is a professor of medicine and a primary care clinician at the Mayo Clinic in Rochester, Minn. He declares having no conflict of interest. The opinions expressed are solely those of the author. Contact him at ebbert.jon@mayo.edu.