Bone and ageing

Abstract

Bone involution has become an important clinical problem and it of primary importance for the differentiation etween bone loss with age and pathologic bone loss. In order to eliminate this problem it is necessary to define bone loss (osteoporosis). The classical definition of osteoporosis by Albright and Reifenstein (1948), 'Too little bone, but what bone there is, is normal', has been widely accepted. This fundamental definition has never been seriously challenged and a clear distinction made between osteoporosis and osteomalacia. Albright's definition does not define 'too little bone'. If this means too little by the standards for adults in the prime of life, many persons who have no symptoms have osteoporosis simply because physiological changes of ageing have affected their bone. In order to determine the decline in skeletal mass some standard of normal is necessary. The following subjects are discussed: skeletal mass and ageing; fracture epidemiology and ageing; relation of bone mass or bone density to bone strength; bone composition and ageing: biochemical parameters of skeletal metabolism, and ageing; bone remodelling and ageing; bone remodelling in pathologic conditions versus bone remodelling in ageing; pathophysiology of bone loss; and treatment of bone loss.