The manifestations of scurvy include abnormal calcification at the epiphyses, and capillary fragility which leads to subperiosteal haemorrhage.

Treatment. Ascorbic acid (vitamin C).

Osteogenesis imperfecta, or fragilitas ossium, is often sporadic, but can be inherited through either autosomal recessive or autosomal dominant genes (Fig. 19.2). Although the brittleness of bone is the most obvious feature, it is essentially a disorder of type 1 collagen synthesis.

The brittleness of the bones is only part of the syndrome (Fig. 19.3). The teeth may also be affected and are often discoloured and abnormally thick – dentogenesis imperfecta. The ground substance in the sclerae of the eye may be abnormal, so that the retinal pigmentation is seen through the sclerae, producing a characteristic bluish discoloration. This is characteristic of the condition but not present in every patient. Mutations in the COL1A1, COL1A2, CRTAP and LEPRE1 genes appear to be the cause.

Bones affected by osteogenesis imperfecta are more plastic than normal and bowing is a recurring problem needing correction by multiple osteotomy and internal fixation.

There are three grades of severity:

Lack of oestrogen causes a reduction in the amount of collagen in the bones of postmenopausal women, which become thin and ‘porotic’. Affected bone, particularly cancellous bone, is weaker than normal and susceptible to fractures (Fig. 19.4). Fractures of the femoral neck and crush fractures of the vertebrae are common after trivial injuries in elderly women with senile osteoporosis.

Clinical and radiological features. The patients experience pain in the bones, especially the back. A kyphosis gradually develops. Radiologically, the bones look ‘thinner’ than normal and pathological fractures may be present.

Treatment. The treatment of osteoporosis is generally unsuccessful because the condition takes so long to appear that, by the time it is recognized, it is too late to treat it. If recognized early, hormonal treatment can be instituted, which can, at best, reverse the osteoporosis and restore normal bone texture.

The first line of treatment has been hormone replacement therapy (HRT) with special emphasis on oestrogen. The second line is low dose bisphosphonates (etidronate) given intermittently.

The ideal treatment has yet to be found but there has been a drive to make people and clinicians aware of the problems. Screening programmes have been started and these will hopefully allow earlier detection; this, together with the newer treatments, may help reduce the morbidity suffered by patients.

Disuse osteoporosis is seen in bones that are not stressed normally. Patients confined to bed are particularly affected, as are paralysed limbs and fractures that are treated as non-weight-bearing. Astronauts undergo gross disuse osteoporosis.

Rickets is due to deficiency of calcium and phosphate in childhood (Fig. 19.5). Although much less common than in former times, rickets still occurs widely in developing countries. There are four causes: