Ageing and osteoarthritis: application of gerontological concepts;

Osteoarthritis (OA) is a multifac{orial chronic disease with high incidence and prevalence in the elderly. Age is a major 'risk factor' in the occurrence ol OA. ln the populat¡on, few individuals suffer from 'early onset OA'. The maiority of individuals have 'late onset OA', whereas a minority of elderly lacks OA. Such a profile is comparable to three parts of the human surv¡val curve: lnitial Mortality Rate, Mortality Rate Doubling Time, and 'successful ageing'. Determinants ol OA in the population are lifestyle, environmental factors, genetic predisposition, and physiological ageing. Physiological age-changes relevant for OA can result from: 1) Programmed events: such as menopause (changes in sex hormones, changes in bone mineral density), and apoptosis of chondrocyles; 2) Pleiotropic events: such as the age-related decline in IGF-1 level, fluctuations in glucocorticoid concentrations, .and late-acting mutations in candidate genes for OA (such as collagen type ll, lX and Xl genes); 3) Accumulation of somatic defects: the age-related accumulation of damage to macromolecules, is illustrated by fragmentation of proteoglycan aggregates and accumulat¡on of collagen crosslinks by nonenzymatic glycation. Application of these gerontological concepts will give more insight into the complicated interaction of physiological ageing, genet¡c, life style, and environmental factors involved in the occurrence of the muhifactorial disease OA. ln addition to studying these aspects in the general population, 'early onset' OA cases and elderly individuals without OA, may contribute to a better understanding of risk factors lor OA. A gerontological approach of OA will leam which risk factors are ¡nherent to life, thus impossible lo avoid, and which factors can be modified to delay the onset of OA.