Loss of knee cartilage linked to overweight

According to a new report being overweight or obese can cause rapid deterioration of cartilage in the knee, leading to osteoarthritis - one more reason for people to maintain a healthy body weight.

Obesity, among other factors, is strongly associated with an increased risk of rapid cartilage loss, according to the study published in the journal Radiology.

Osteoarthritis is the most common form of arthritis, affecting 27 million people, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). In osteoarthritis, the cartilage breaks down and wears away completely in severe cases, leaving the joint without a cushion. The bones rub together, causing further damage, significant pain, and loss of mobility.

Osteoarthritis usually progresses slowly, but some patients experience a more rapid progression. This is the first study to connect obesity with fast progression of the disease and cartilage loss.

"We have isolated demographic risk factors and based on MRI for progressive cartilage loss," says Dr. Frank W. Roemer, lead author of the study and adjunct associate professor at Boston University and co-director Quantitative Image Center in the Department of Radiology, Faculty of Medicine, University of Boston. "Increased baseline body mass index (BMI) was the only predictor based on the non-MRI identified," he added.

Studied cartilage loss

The researchers recruited 336 patients from a major osteoarthritis study. All were overweight and at risk of osteoarthritis, but had minimal or no loss of cartilage in their knees.

During the 30 months follow-up, 20.2 percent of patients showed a slow loss of knee cartilage and 5.8 percent had rapid cartilage loss, the study found.

The main risk factors for cartilage loss were pre-existing cartilage damage, being overweight or obese, tears or other injury to the cartilage in the knee joint (meniscus), and severe lesions seen on an MRI.Other factors include inflammation of the membrane lining the joints and abnormal accumulation of fluid in the joint, according to the report.

Dr. Roemer's team found that being overweight was associated with rapid cartilage loss. In fact, for every one-unit increase in BMI, the odds of rapid cartilage loss increased by 11 percent.

Excess weight a key factor

Researchers say that the association between obesityand rapid cartilage loss remained even after taking into account age, sex and ethnicity.

"[Osteoarthritis] is a disease without treatment at present other than symptomatic - mostly pain therapy and total joint replacement surgery," says Dr. Roemer.

"We know that weight loss is probably the most important in reducing disease progression factor," Dr. Roemer continues. "Further studies will have to show if other measures, such as vitamins or specific treatment of bone marrow lesions, will help reduce the progression," he says.

"Osteoarthritis is the most common musculoskeletal disorder with major health and socio-economic impact our aging society," adds Dr. Roemer.

Weight control is important

Dr. Sean Scully, professor of orthopedics at the University of the Miller School of Medicine, Miami, Florida, agrees that the risk of developing osteoarthritis is another reason to control weight.

"Do not be heavy," says Dr. Scully. "This study shows a direct correlation - people who are heavy are the ones that are getting worse," he says.

Keeping your weight down - through diet and exercise or weight loss surgery - could prevent the need for knee replacement surgery, he adds.

Always consult your doctor for more information.