Exercise and Osteoarthritis of the knee

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Regular physical activity may strenghten knee cartilage

Category: Bones/Orthopaedics News

Article 30 Oct 2005

 

 

 

 

 

Osteoarthritis (OA) is the leading cause of disability among adults.

As the population ages, increased intervention efforts are vital to

controlling the individual and public health toll of this chronic,

crippling joint disease. Along with early diagnosis, moderate

exercise is one of the most effective ways to reduce pain and improve

function in patients with OA of the knee and hip. Yet, more than 60

percent of U.S. adults with arthritis fail to meet the minimum

recommendations for physical activity.

 

Based on the " wear and tear " nature of OA, the commonly held belief

is that exercise will not strengthen joint cartilage and may even

aggravate cartilage loss. Until recently, investigators were unable

to put that belief to the test. Radiographs, the standard measure of

OA's progression, made it impossible to assess cartilage before

severe cartilage damage had occurred. Advances in magnetic resonance

imaging (MRI) now make it possible to study cartilage changes earlier

in the course of OA. Two researchers in Sweden, Leif Dahlberg, M.D.,

Ph.D., and Ewa M. Roos, P.T., Ph.D., used a novel MRI technique to

determine the impact of moderate exercise on the knee cartilage of

subjects at high risk for developing OA--middle-aged men and women

with a history of surgery for a degenerative meniscus tear. In the

November 2005 issue of Arthritis & Rheumatism

(interscience.wiley.com/journal/arthritis), they share evidence to

support the therapeutic value of exercise for OA patients, for

improving not only joint symptoms and function, but also the quality

of knee cartilage.

 

Working with the Department of Orthopedics at Malmö and Lund

University Hospitals and the medical faculty of Lund University, Drs.

Dahlberg and Roos recruited 29 men and 16 women, between the ages of

35 and 50, who had undergone meniscus repair within the past 3 to 5

years. Subjects were randomly assigned to either an exercise group or

a control group. The exercise group was enrolled in a supervised

program of aerobic and weight-bearing moves, for 1 hour, 3 times

weekly for 4 months. At the study's onset and follow-up, subjects

from both groups underwent MRI scans to evaluate knee cartilage. The

technique used focused specifically on the cartilage's

glycosaminoglycan (GAG) content, a key component of cartilage

strength and elasticity. Subjects also answered a series of questions

about their knee pain and stiffness, as well as their general

activity level. Of the original 45 subjects, 30--16 in the exercise

group and 14 in the control group--completed the trial and all post-

trial assessments.

 

In the exercise group, many subjects reported gains in physical

activity and functional performance tests compared with subjects in

the control group. Improvements in tests of aerobic capacity and

stamina affirmed the self-reported changes. What's more, MRI measures

of the GAG content showed a strong correlation with the increased

physical training of the subjects who had regularly participated in

moderate, supervised exercise.

 

" This study shows compositional changes in adult joint cartilage as a

result of increased exercise, which confirms the observations made in

prior animal studies but has not been previously shown in humans, "

notes Dr. Dahlberg. " The changes imply that human cartilage responds

to physiologic loading in a way similar to that exhibited by muscle

and bone, and that previously established positive symptomatic

effects of exercise in patients with OA may occur in parallel or even

be caused by improved cartilage properties. "

 

As Drs. Dahlberg and Roos acknowledge, the study does have

limitations--its small sample size and narrow focus on

meniscectomized knee joints--and makes no claims for predicting the

long-term effects of exercise on cartilage. The conclusion, however,

remains worthy of serious consideration: " Exercise may have important

implications for disease prevention in patients at risk of developing

knee OA. "

 

Article: " Positive Effects of Moderate Exercise on Glycosaminoglycan

Content in Knee Cartilage: A Four-Month, Randomized, Controlled Trial

in Patients at Risk of Osteoarthritis, " Ewa M. Roos and Leif

Dahlberg, Arthritis & Rheumatism, November 2005; 52:11; pp. 3507-

3514.

 

John Wiley & Sons, Inc.

interscience.wiley.com