OSTEOPOROSIS

(Abnormal rarefaction of bone)

Definition:

This is a condition of atrophy of bones characterised by reduction of the amount of bone mass in relation to normal volume of bone.

It is the commonest metabolic disease of bone and is found most frequently in elderly women when it is known as post menopausal osteoporosis. It may occur in elderly men (senile osteoporosis) and rarely in younger people (idiopathic osteoporosis).

Causes:

(1) Endocrinal—Hypogonadism, Cushing’s Syndrome, Acromegaly, Thyrotoxicosis. (2) Nutritional— Scurvy, Calcium or protein deficiency, etc. (3) Idiopathic— Juvenility, pregnancy or senility. (4) Inherited. (5) Immobilisation of a limb. (6) Loss of gravity, when in space. (7) Miscellaneous—Rheumatoid arthritis, chronic alcoholism, diabetes, chronic hepatic insufficiency, osteogenesis imperfecta prolonged use of heparin etc.

Pathology:

The histological appearances are in keeping with Albright’s original conception of a primary osteoblastic hypoplasia. The bone is deficient in quantity but theft is no abnormality of its quality or architecture, in contrast to osteomalacia where there are abnormally large a mounts of osteoid tissues.

Signs and Symptoms

(1) The patient is usaully an elderly woman who is otherwise healthy. (2) In early stage—asymptomatic. (3) Osteoporotic bones are brittle and so get fractured easily. (4) Later, there is shortening of the trunk due to a series of fractures of different vertebral bodies. (5) Severe pain then sets in, which diminishes within 4 to 8 weeks. (6) Constant pain in the back is a late symptom due to forward curvature. (7) Besides the vertebrae, the pelvis, the ribs and the long bones are also affected. (8) Later, there is formation of a characteristic transverse skin crease across the upper abdomen which may be keratinised.

Investigations:

(1) The radiological changes are more marked in the bones of the axial skeleton than in the limbs; they consist of loss of bone density, reduction in the number and size of trabeculae and thinning of the cortex. (2) Calcium, phosphorus and alkaline phosphatase levels in the blood are normal in contrast to osteomalacia.

Treatment:

No treatment has yet been proved to be clearly effective. However, the patient should know that the natural history of the disease is marked by spontaneous improvement and that suitable exercise is beneficial. Cyclical oestrogen therapy may be given for otherwise healthy post- menopausal women. The use of testosterone in males for senile osteoporosis is extremely dubious. On general principles, at least an adequate intake of Vit. D and calcium should be ensured. Cow’s milk is the best source of the latter.