A spate of recent studies have focused on knee osteoarthritis, a degenerative joint condition that affects an estimated 10 to 15 percent of adults over age 60 in the U.S. All the studies described here except the last one analyzed data from the nationwide NIH-sponsored Osteoarthritis Initiative, which has followed people who have knee osteoarthritis or are at high risk for developing it.
- Noisy knees may be a sign that you will develop knee arthritis pain within the year, according to a study in Arthritis Care & Research of nearly 3,500 people. Those who reported the most crepitus—grinding, grating, cracking, or popping sounds in or around the knee joint—were more likely to develop symptomatic knee osteoarthritis (meaning there is both radiographic evidence of cartilage loss and frequent pain) over the next one to four years. This was especially the case for people who had osteoarthritis at the start (based on X-rays) but not frequent pain. The association between crepitus and osteoarthritis was stronger in men and older people.
- A Mediterranean-style diet may help reduce symptoms of knee osteoarthritis. In a study in the American Journal of Clinical Nutrition, researchers analyzed the eating patterns of 4,470 Americans and found that those who came closest to a Mediterranean diet had better quality of life and decreased knee pain, disability, and depression, compared to those whose diets were least Mediterranean, even after adjustments were made for factors such as age, weight, other medical conditions, and smoking. The traditional Mediterranean diet is characterized by a high intake of olive oil, fruits, nuts, vegetables, and whole grains; moderate intake of fish and poultry; low intake of dairy products, red or processed meats, and sweets; and moderate intake of wine (usually red).
- And so might getting more fiber, suggested a study in the Annals of the Rheumatic Diseases, which assessed the diets of thousands of people using food frequency questionnaires. Those with the highest total fiber intake (21 grams a day, on average, from grains, legumes, nuts, fruits, and vegetables) had a 30 percent lower risk of developing symptomatic knee osteoarthritis over four years, compared to those with the lowest intake (9 grams a day), along with less worsening of pain. This was true after the researchers controlled for knee injuries, medications, alcohol use, exercise, and other potential confounding factors and regardless of obesity status. The study also included data from participants in the Framingham Offspring Study, which showed even greater reductions in risk (61 percent) among those with the highest fiber intake (26 grams a day). Though the observational data did not prove cause and effect, fiber may benefit osteoarthritis by reducing inflammation and promoting weight control. The amount of fiber in the highest-intake groups was within the range of (or slightly below) what is commonly recommended for general health.
- Weight loss may slow cartilage loss in the knee, a study in Radiology of 640 overweight or obese people found. Carrying extra pounds increases the load on cartilage and joints, while body fat produces substances that have pro-inflammatory effects in joints. Study participants who lost 5 to 10 percent of body weight over four years slowed progression of degenerative changes in their knee cartilage, as shown on MRI, compared to those who remained at a stable weight. Losing more than 10 percent of weight was even better.
- Steroid injections into arthritic knees may not help pain more than a placebo and may actually increase cartilage loss, according to a randomized clinical trial of 140 people, published in the Journal of the American Medical Association. Participants, who had knee osteoarthritis with synovitis (inflammation), received intra-articular injections of either triamcinolone (a corticosteroid) or saline every three months for two years. As shown on MRI, the steroid group lost twice as much cartilage as the saline (control) group; what’s more, there was no difference between the groups in severity of knee pain or in function (at least at the time of assessment). It has been thought that corticosteroids might reduce cartilage loss by reducing inflammation, but some lab and clinical research has demonstrated that they have catabolic (breakdown) effects. “Although the cartilage loss was not associated with worsening of symptom outcomes, rates of cartilage loss have been associated with higher rates of arthroplasty [a surgical procedure], raising the possibility of potential for long-term adverse consequences on the health of the joint,” the authors wrote. A previous smaller study did not find cartilage loss associated with steroid injections, but it used X-rays, which are not as sensitive as MRI to changes in cartilage.
Bottom line: While certain genetic factors may increase the risk for knee osteoarthritis, there is increasing evidence that the condition has some of the same metabolic characteristics as cardiovascular disease, which suggests that following heart-healthy lifestyle measures will help prevent or at least slow its progression. Those include eating a healthy high-fiber diet, keeping your blood sugar under control, losing weight if you’re overweight, and getting regular physical activity. These exercises that target the quadriceps, hamstrings, and gluteal muscles may especially help keep knees healthy.
Also see Osteoarthritis: Causes and Treatments.