Characteristics

• Sir James Paget described the disease in 1877 as a chronic inflammatory remodelling disease of bones. He labelled the condition osteitis deformans.

• Characterised by bony thickening and enlargement secondary to increased bone turnover.

• The bone is weak and brittle due to abnormal bone structure.

• Unknown aetiology (possible link with paramxyovirus) occurring in approximately 3% of the population over 40.

• Environmental and family clustering is seen – 7% males in Lancashire (north-west UK).

Clinical features

• Pain is the commonest symptom, but most patients asymptomatic.

• Monostotic or polyostotic.

• Sarcomatous change within the abnormal bone is the most sinister complication – said to be 1%.

• Other complications include pathological fractures, bony impingement on nerves and secondary arthritis.

• Deafness may occur secondary to nerve impingement or involvement of the ossicles.

• Frequently affected bones include the pelvis, lumbar and thoracic vertebrae, proximal femur, calvarium and tibia.

• High-output heart failure is a rare complication.

Radiological features

• Thickened coarse trabeculae with cortical enlargement.

• Cyst-like areas during the lytic phase.

• Skull – both tables are involved with diplopic widening. Well-defined lytic areas more common anteriorly. The bony texture resembles ‘cotton wool’.

• Pelvis – ilio-pectineal line thickening. Trabecular coarsening.

• Long bones – curved femur and tibia.

• Spine – ‘ivory vertebrae’ (sclerotic in appearance) or ‘picture frame’ appearance seen secondary to peripheral trabecular thickening and a relatively radiolucent central portion of the vertebral body.

• Bone scan – marked increased uptake in affected bones. May be normal in ‘burned out’ disease.

Management

• Often directed towards symptomatic relief.

• Drugs such as bisphosphonates (and calcitonin) suppress bone turnover.

• Surgical treatment of complications such as pathological fractures and secondary arthritis. Nerve entrapment may respond to decompression.

• Sarcomatous change generally has a very poor prognosis.