Paget’s Disease of Bone

Author: DAVID P JOHNSON MB ChB FRCS FRCS. MD
Consultant Orthopaedic Surgeon

Summary
This booklet has been produced for anyone suffering from Paget’s disease of bone. We want to explain as much as we can about this condition, how it is diagnosed and how it can be treated. Sir James Paget was born in Great Yarmouth, Norfolk, and was a surgeon at St Bartholomew’s Hospital, London, in the late 19th century. He wrote an early and very clear description of the disease which now bears his name. Paget’s disease of the nipple was another of his discoveries, but there is no other connection between these two conditions.

What is Paget’s disease of bone?
In order to understand this it helps to know a little about normal bone. Bone is not a dead, inactive substance but a living, active tissue made up of three main components:

mineral (mainly calcium)
matrix (tough collagen fibres and other substances, which give bone its resilience)
cells: osteoblasts (bone-forming cells) and osteoclasts (bone-eroding cells).

Bone changes constantly. ‘Old’ bone is continually removed and replaced by new bone. This turnover or renewal of bone is carefully balanced. If it weren’t, you could suffer from bone ‘fatigue’ (rather like metal fatigue in old machines). If that happened your bones would be more likely to break.

Paget’s disease affects bone growth. The abnormality occurs in the bone cells. The regular, ordered process of bone loss and formation is disrupted. The bone cells increase in number, become larger and also become more active. Bone turnover increases by up to forty times, and the new bone is abnormal in shape and structure. It is also weaker than usual. The increased activity of the bone cells also increases the blood flow through the bone.

How common is Paget’s disease?
Paget’s disease is not rare. It is most common in the UK and in countries where large numbers of British people have emigrated in the past. It is most likely to affect older people. In the UK about 5% of people over the age of 50 have Paget’s disease in some part of the skeleton, although it is often unnoticed and may not cause any symptoms. For some reason, Paget’s disease is even more common in Lancashire where up to 8% of people over 50 have the disease. Younger or non-white people are less likely to have Paget’s, though it can occur in any race.

What causes Paget’s disease?
At present, the cause of Paget’s disease of bone is unknown. Because of the racial and geographical pattern mentioned above, some doctors have concluded that the disease may be inherited. It is certainly true that in some families several people are affected, but this is quite rare. However, it has been suggested that Paget’s may be caused by a ‘slow virus’ infection of bone cells. It is called ‘slow’ because the virus may settle in the bone cells early in life and only cause the disease many years later.

Link: http://www.arc.org.uk/arthinfo/patpubs/6031/6031.asp
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