6 Age-related bone loss and osteoporosis

Osteoporosis is a disease characterised by low bone strength leading to fragility and increased fracture risk. Bone strength is represented by two components: bone mineral density (BMD) and bone quality. Bone mass in old age is dependent both on the peak bone mass achieved and its subsequent rate of loss. Deterioration of bone mass and bone quality leave no identifiable skeletal lesions (and, indeed, cause no symptoms in the living), so, unlike other diseases discussed in this book, the study of osteoporosis in the past is not lesion-based. Instead, bone mass or quality is measured directly. Guidance on assessment of BMD and bone quality using radiographic and microscopic techniques is provided using information on the basic biological mechanisms that underlie bone mass and quality attained discussed in Chapter 3. Advice is given on the evaluation of fractures. A series of bullet points are used to summarise the core concepts covered.