The Stress of Extra Weight on the Knee

Knee cartilage loss greater in people with higher trunk and overall body fat percentage

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Extra pounds from fat can stress the body in a number of ways. For older adults, excess weight can rub the knees the wrong way.

Higher levels of body fat were tied to greater knee cartilage losses in older adults, a recently published study found.

Such cartilage loss can lead to osteoarthritis and joint pain.

Having more muscle mass, on the other hand, was linked with less cartilage loss.

These results suggest that finding ways to reduce body fat and increase muscle could reduce knee cartilage loss, according to the researchers.

"Maintain a healthy weight."

A study led by Changhai Ding, MD, principal research fellow from the Menzies Research Institute at the University of Tasmania in Australia, looked at the links between body composition and knee cartilage loss over a three-year period in older adults.

The study included 395 randomly selected adults who were 62 years of age on average. Half of the adults were female.

The researchers measured the cartilage volume in each participant's right knee at the start of the study and three years later using magnetic resonance imaging (MRI).

The researchers noted the surface area of each participant's tibias, which is the bone in the lower part of the leg underneath the cartilage in the knee.

The severity of patients' osteoarthritis was also measured, as well as their height, weight and body mass index (BMI), a measure of height and weight. The researchers also recorded participants' fat and muscle mass.

Participants who lost more knee cartilage had a greater BMI, total body fat and trunk fat than those who lost less cartilage, the researchers found.

Participants with more muscle mass also had more knee cartilage.

Over the three year period, tibial cartilage volume decreased by 2.3 percent on average each year. Cartilage loss ranged between 2 and 2.7 percent.

Changes in cartilage volume were not tied to differences in age or gender.

"Body fat adversely affects tibial cartilage loss over time, whereas [muscle] mass is protective," the researchers wrote in their report. "Strategies aimed at reducing body fat but increasing [muscle] mass may reduce knee cartilage loss in older people."

The authors noted that they could not get follow-up measurements from all the participants because an MRI scanner was missing at that time. They also did not look at whether changes in body composition were linked to changes in cartilage volume.

Some of the participants also had other diseases, though the authors said that their results largely went unchanged.

The study was published in the June issue of the International Journal of Obesity. The authors did not declare any conflicts of interest.

The National Health and Medical Research Council of Australia; Australian Research Council Future Fellowship; Tasmanian Community Fund; Arthritis Foundation of Australia; University of Tasmania Grant-Institutional Research Scheme and Rising Star Programme supported the study.

Reviewed by: 
Review Date: 
July 1, 2013
Last Updated:
July 25, 2013