Being more physically active and fit in childhood is linked to greater knee cartilage and tibial bone area in adulthood according to new research findings by researchers at the University of Tasmania's Menzies Research Institute Tasmania.

Being more physically active and fit in childhood is linked to greater knee cartilage and tibial bone area in adulthood according to new research findings by researchers at the University of Tasmania's Menzies Research Institute Tasmania.

Nearly one in five Australians has arthritis; indeed more Australians have arthritis than any other national health priority condition. In 2007, there was an estimated 3.85 million people (18.5 per cent of the Australia population) with arthritis. *

By 2050, it is projected there will be seven million Australians with arthritis. Osteoarthritis is predicted to remain the most prevalent arthritic condition, affecting 3.1 million Australians in 2050. *

Arthritis costs the Australian economy around $23.9 billion a year. *

The knee is the leading site of osteoarthritis. Knee osteoarthritis is caused by cartilage breakdown in the knee joint. Osteoarthritis is still considered an irreversible disease. Factors that increase the risk of knee osteoarthritis include obesity, age, prior injury to the knee, extreme stress to the joints, and family history.

Chief investigator Associate Professor Changhai Ding, says that while physical activity in childhood is often recommended as a means to improve adult health, little evidence exists to illustrate the correlation between childhood physical performance measures and joint structure in adulthood later on.

"The aim of the study was to determine if physical activity in childhood was associated with more knee cartilage and tibial bone area (the bone that forms the lower part of the knee joint) 25 years later," A/Prof Ding said.

Subjects were selected from the Childhood Determinants of Adult Health Study (CDAH) which was a 20-year follow-up of the Australian Schools Health and Fitness Survey (ASHFS) conducted in 1985.

In the 2008-2010 follow-up study, the 298 subjects, now aged between 31 - 41 years, underwent a magnetic resonance imaging (MRI) scan. The participant's knee cartilage and tibial bone area were measured using the MRI results. Their corresponding childhood performance measures (7-15 years) were collected from the ASHFS of 1985. Adjustments were made for age, gender, body mass index and past joint injuries that may affect the cartilage or bone area.

The results showed that childhood physical performance measures, including physical work capacity, leg and hand muscle strength, sit-ups, and long and short runs had a significant association with greater tibial bone area. In addition, higher childhood physical work capacity measures were associated with greater tibial cartilage volume.

"A number of childhood physical performance measures were found to be significantly associated with increased knee bone area and cartilage volume in adulthood," A/Prof Ding said.

Rheumatologist and senior investigator, Professor Graeme Jones says the findings suggest that physical activity in childhood can independently influence adult knee joint health possible through adaptive mechanisms of the knee joint during growth.

"We don't yet know how physical activity may build bone and cartilage years later, but I would contend that as the bone area gets larger to cope with the extra demands put on it by higher levels of physical activity, this leads to more cartilage, as cartilage covers the surface of bone," he said.

"This study adds to the growing body of research into osteoarthritis.

"This study provides further support of the benefits of physical activity in childhood and another reason why parents should strongly encourage their children to be physically active," Prof Jones said.

The study was funded by the National Health & Medical Research Council of Australia and is part of the PhD work of Dr Benny Antony.

*Access Economics' Painful Realities Report 2007

Information Released by:

Fiona Horwood, Communications Manager

Phone: 6226 7751 Mobile: 0409 357 384

Email: Fiona.Horwood@menzies.utas.edu.au

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