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The Pathogenesis of Osteoporosis

  • Chapter
Osteoporosis

Abstract

Contrary to the popular image of the skeleton as an inert structure supporting the rest of the body, bone is a dynamic tissue which also serves as a mineral reservoir and undergoes constant remodelling throughout life. If it were not for this remodelling, then the skeleton would be incapable of increasing in size during growth, adapting to the physical stresses placed on it, or of repairing structural damage due to fatigue failure or trauma. Bone mass changes throughout life in three major phases: growth, consolidation and involution. Up to 90% of the peak bone mass is deposited during the growth phase, which lasts until the closure of the epiphyses. There is then a phase of consolidation lasting for 10–15 years, when the bone mass increases further until the peak bone mass is achieved in the mid-30s. Involutional bone loss starts shortly after this, between the ages of 35 and 40. Both cortical and trabecular bone are lost with advancing age in women and men, though the rate of bone loss differs in cortical and trabecular bone and at different anatomical sites. The initial rate of cortical bone loss is 0.3–0.5% annually in both men and women, though this increases to 2–3% in women after the menopause, before returning to the slower rate of loss 8–10 years later. The rate of trabecular bone loss ranges from 0.6 to 2.4% per year in women and is about 1.2% per year in men1. In total, women lose 35–50% of trabecular and 25–30% of cortical bone mass with age, whilst men lose 15–45% of trabecular and 5–15% of cortical bone2–5.

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  1. Department of Medicine (Geriatrics), University of Newcastle upon Tyne, Newcastle General Hospital, NE4 6BE, Newcastle upon Tyne, UK

    R. M. Francis MB, ChB, MRCP (Honorary Consultant Physician Senior Lecturer in Medicine (Geriatrics) (Honorary Consultant Physician Senior Lecturer in Medicine (Geriatrics)

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Francis, R.M. (1990). The Pathogenesis of Osteoporosis. In: Francis, R.M., Dick, W.C. (eds) Osteoporosis. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-9580-8_3

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