Paget's Disease of Bone
An Information Booklet
About this booklet
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. Unfortunately, we cannot hope to answer all your questions because everyone is different, and this booklet is not intended to replace an individual consultation with a doctor. Near the end of the booklet you will find addresses of organizations that can offer further help, including information on how to contact the Arthritis Research Campaign (arc).
Who was Paget?
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).
The structure of normal bone is shown in Figure 1. Bone changes constantly. 'Old' bone is continually removed by the action of the osteoclast cells. It is replaced by new bone – made by the osteoblast cells. 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. The bones which are most commonly affected are shown in Figure 2.
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 people in 100 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 per cent 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 we have just mentioned, 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.
What are the symptoms?
Sometimes there are no symptoms at all. It is quite common for the disease to be discovered by accident on an x-ray which has been taken for a quite different purpose. Similarly it may be detected after a blood test taken for another reason.
Pain is the most common symptom and is usually felt in the bone itself. Paget's disease can sometimes be associated with osteoarthritis in the joints nearby and this can be painful. The increased blood flow through the bone, which is a feature of Paget's disease, also stimulates nerve fibres in the bone which send out pain signals. Because of the increased blood flow, the parts of the body affected by Paget's disease may feel unusually warm to the touch, especially if the bone is close to the skin, for example, in the shin.
What are the complications of Paget's disease?
Bone expansion
Bone which is affected by Paget's disease expands and may cause deformity due to the disorganized cell activity. Any bone in the skeleton can be affected but the most common are the pelvic bones, the spine, the thigh and shin bones, and the skull. Long bones can curve, so that some people may end up with one leg effectively shorter than the other.
Fractures
Although bone affected by this condition usually expands, it is weaker than usual and is more likely to break than normal healthy bone. Fortunately, however, the bone heals just as well as normal bone.
Nerve compression
When Pagetic bone expands it can sometimes squeeze nearby nerves. This can happen in the skull, where it can cause deafness, or in the spine, which can lead to weakness and tingling in the legs.
Arthritis
If the disease reaches to the end of the bone, it can lead to arthritis in the joint. This is the same as osteoarthritis, and can cause pain and stiffness on moving the joint (see arc booklet 'Osteoarthritis').
Gout
People with Paget's disease have an increased risk of developing gout. Gout causes pain and swelling in a joint, often the big toe joint. If this happens the usual treatments for gout are effective (see arc booklet 'Gout').
Heart failure
When the Paget's disease is very extensive the increased blood flow through the bone can put a strain on the heart. Fortunately, with the newer, more effective treatments for Paget's this complication is rarely seen nowadays.
Tumours
In a very small number of people with longstanding Paget's disease tumours may develop in the bone, which can sometimes be cancerous. The first signs of this are increased pain and swelling at the site of the tumour. Fortunately this is a very rare complication.
How is Paget's disease diagnosed?
Your doctor will have listened to your symptoms and examined you. If the bone is deformed in a way that is typical of the disease, it is an easy diagnosis. Often, however, x-rays and blood tests will be necessary to confirm it.
Sometimes the doctor will recommend an isotope bone scan. This is the most effective way of pinpointing where the Pagetic bone is and how active it is. A tiny dose of radioactive isotope (a radioactive substance which can be detected by the bone scan) is injected into a vein and then the whole skeleton is scanned several hours later. The radioactive material quickly passes out of the body in the urine. An isotope scan is important as it will show how many bones are affected by the disease.
Once the diagnosis has been made, most patients will be referred to a specialist clinic for assessment and treatment.
How is it treated?
Paracetamol and/or non-steroidal anti-inflammatory drugs (NSAIDs) may help to reduce the pain in some people although they are not always very effective (see arc leaflet 'Non-Steroidal Anti-Inflammatory-Drugs'). Simple measures are sometimes useful. If, for example, one leg has effectively been shortened because the thigh and shin bones have grown curved, a built-up insole in the shoe can reduce the feeling of 'lop-sidedness'.
Treatment of the causes of Paget's disease will usually be with a group of drugs called bisphosphonates, which are very effective. They act primarily on the osteoclasts (the bone-eroding cells) to slow down the rapid bone turnover. The choice falls between pamidronate, a drug which is injected into a vein, and two oral drugs, risedronate and tiludronate. Pamidronate is given either as a series of weekly or fortnightly injections (6 in total) or, in some centres, as a single injection which may be repeated after 6 months if necessary. The advantage of the injection is that the drug is all absorbed into the body. Risedronate is a 2-month course of tablets and tiludronate is a 3-month course. Some people may prefer tablets to injections and the choice is available. Further courses may be given if necessary. See the series of arc drug information sheets for more information.
The pain in the bone is often relieved within 3–6 months and sometimes more quickly than this. Most people have few side effects from the drugs, although pamidronate occasionally causes flu-like symptoms lasting 1–2 days, and risedronate and tiludronate can sometimes cause indigestion.
Will surgery be necessary?
Surgery is not normally necessary, but sometimes if the bone breaks an operation will be needed to fix it. This depends on the type and severity of the break, as with any fracture. If osteoarthritis results from the disease then a new joint may be necessary – treatment with bisphosphonates prior to the operation helps to reduce the blood loss that can occur with this operation. For more information on joint replacement surgery see arc booklets 'A New Hip Joint' and 'A New Knee Joint'.
Finally...
We do not yet have a cure for Paget's disease. However, there are treatments which can suppress the disease, and delay or even prevent the complications, and research continues which we hope will lead to even more effective treatments.
Useful addresses
The Arthritis Research Campaign (arc)
PO Box 177
Chesterfield
Derbyshire S41 7TQ
Phone: 0870 850 5000
www.arc.org.uk
As well as funding research, we produce a range of free information booklets and leaflets. Please contact the address above for a list of titles or, on this website, see Publications for People with Arthritis.
Arthritis Care
18 Stephenson Way
London NW1 2HD
Phone: 020 7380 6500
Helpline (freephone): 0808 800 4050
www.arthritiscare.org.uk
Offers self-help support, a helpline service, and a range of leaflets on arthritis.
The National Association for the Relief of Paget's Disease
323 Manchester Road
Walkden
Worsley
Manchester M28 3HH
Phone: 0161 799 4646
www.paget.org.uk
Provides support and information to people with Paget's disease.
Information on drugs
Separate arc leaflets are available on many of the drugs used for arthritis and related conditions. We would recommend that you read the relevant leaflets for more detailed information about your medication.
