Like bones which, broke in sunder, and well set, knit the more strongly … but old bones are brittle. John Webster (1580–1625)
Osteoporosis, which literally means porous bone, is reduced bone mass per unit volume (see FIG. 89.1), thus predisposing the person with it to an increased risk of fracture. It also refers to the increased bone fragility that accompanies ageing and many illnesses. Following the menopause, women begin to lose calcium from their bone at a much faster rate than men, presumably as a direct response to low levels of oestrogen. Within 5–10 years of the menopause, women can be seen to suffer from osteoporosis and by the age of 65 the rate of fractures in women has increased to 3–5 times that of men.1 However, a third of all hip fractures in the community occur in men.
Osteoporosis is reduced bone mass per unit volume
In recent decades osteoporosis was largely prevented by correction of oestrogen deficiency through the use of hormone replacement therapy but the balance has changed since the association of HRT with breast cancer was reported.
Key facts and checkpoints
Osteoporosis is silent, common, measurable, treatable and potentially lethal (analagous to hypertension).2
Osteoporosis is commonest in postmenopausal women.
Up to 50% of women will develop fractures in their lifetime and 30% of all women reaching 90 years of age will suffer a hip fracture.1,3
Osteoporosis leads to reduced bone strength and susceptibility to fracture, even with minor trauma.
Osteoporosis usually causes pain when complicated by fracture.
First presentation is usually a fracture (Colles, femoral neck and vertebra) or height shrinkage.
Vertebral collapse is the hallmark of osteoporosis.
The disorder is of low bone mass.
For osteoporosis in a vertebra including a pathological fracture, multiple myeloma needs exclusion.
The first step in prevention is regular exercise, an adequate dietary intake of calcium (1500 mg per day) and maintenance of adequate serum vitamin D levels.
Type 1: Postmenopausal (vertebral or distal forearm fractures between the ages of 51 and 75). Due to increased osteoclast activity. It is six times more common in women than men.
Type 2: Involutional or senile osteoporosis (fracture of proximal femur and other bones). It affects patients over 60 years and is twice as common in women as in men.
Idiopathic osteoporosis: Occurs in children and young adults of both sexes with normal gonadal function.
Secondary to various endocrine disorders, malabsorption and malignancies. Various causes and risk factors are presented in Table 89.1.
Osteoporosis: risk factors and/or causes3