Rheumatology 2003; 42: 693-694
© 2003 British Society for Rheumatology
Letters to the Editor |
Reply
Kuopio Regional Institute of Occupational Health, PL BOX 93, FIN-70701 Kuopio, Finland
I read with interest the results of the study by Galois et al. [1]. Physical loading of a joint from work or from free-time physical activity is a risk factor for osteoarthritis (OA) if the exposure level is high or if the joint is injured. There is already a lot of evidence that moderate physical exercise does not increase the risk of developing OA if the joint is not injured [2–4]. During recent years it has been speculated that physical loading or exercise can prevent OA. Recently two good reviews have been published [5, 6]. In the review by Helminen et al. [6] it is suggested that regular load-bearing directs the development and fate of the collagen fibril network of articular cartilage in the synovial joint, especially in young persons. These effects probably contribute to the establishment and strengthening of the network and prevent OA in middle and old age.
In this field of research, there are many methodological problems with regard to epidemiology, and animal studies are probably also needed. The diagnosis of OA is not easy. Symptoms and radiographic changes should be considered. Microscopic findings after prolonged joint loading are not known to be due to degeneration or adaptation [6]. Because OA develops gradually over a long period, assessment should be made of physical exercise throughout the patient's life. Future studies should also focus on measuring levels of exposure to activity. According to the review by Helminen et al. [6], age probably also influences the effect of joint loading in the prevention of OA. In the study of Galois et al. [1], a favourable effect of physical exercise in the prevention of secondary OA was observed. However, finding the optimal level of joint loading in the prevention of secondary OA after injury may be even more complicated than preventing primary OA. I agree with the excellent old aphorism by Sokoloff [7]: ‘Cartilage can survive in a large range of solicitation, but below and beyond it will suffer’. A lot of work remains to be done before the optimal range of joint loading is found.
Notes
Correspondence to: P. Manninen. E-mail: pirjo.manninen{at}ttl.fi 
References
- Galois L, Etienne S, Grossin L et al. Moderate impact exercise is associated with decreased severity of experimental osteoarthritis in rats. Rheumatology 2003;42:000–000.
- Lane NE. Physical activity at leisure and risk of osteoarthritis. Ann Rheum Dis 1996;55:682–4.
[Abstract/Free Full Text] - Buckwalter JA, Lane NE. Athletics and osteoarthritis. Am J Sports Med 1997;25:873–81.
[Abstract/Free Full Text] - Lequesne MG, Dang N, Lane NE. Sport practice and osteoarthritis of the limbs. Osteoarthritis Cartilage 1997;5:75–86.[CrossRef][Web of Science][Medline]
- Arokoski JAP, Jurvelin JS, Väätäinen U, Helminen HJ. Normal and pathological adaptations of articular cartilage to joint loading. Scand J Med Sci Sports 2000;10:186–98.[CrossRef][Medline]
- Helminen HJ, Hyttinen MM, Lammi MJ et al. Regular joint loading in youth assists in the establishment and strengthening of the collagen network of articular cartilage and contributes to the prevention of osteoarthrosis later in life: a hypothesis. J Bone Miner Metab 2000;18:245–57.[Medline]
- Sokoloff L. The biology of degenerative joint disease. Chigaco: Chicago University Press, 1969.
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