What is Paget's disease of bone?
Paget’s disease of bone is named after Sir James Paget, who first identified the condition in the 19th century. It affects the way your bone develops and renews itself, causing it to become weaker than normal.
Bone is a living, active tissue that's constantly being renewed and repaired. Old and damaged bone is removed by cells called osteoclasts, while new, healthy bone is produced by cells called osteoblasts. This process is carried out in an orderly and balanced way to make sure that your bones stay strong and healthy.
In Paget’s disease, the process of renewal and repair is disrupted:
- Bone cells increase in number and become larger and more active.
- The renewal and repair of bone is uncontrolled and the rate of bone turnover increases by up to 40 times.
- The new bone is abnormal in shape and structure and is weaker than usual.
- The weakened bones become bent or deformed and can cause damage to your joints.
The increased activity of the bone cells also increases the blood flow through your bone. The bones most commonly affected are:
- thigh bones
- shin bones
Who gets Paget's disease of bone?
Paget’s disease is most common in the UK, but it also occurs in people from western and southern Europe, Australia and New Zealand.
Paget’s is rare in people under 40 but becomes increasingly more common with age. In the UK, it has been estimated that about 2–3 people in 100 over the age of 50 have Paget’s disease in some part of their skeleton, but it may not cause any symptoms and often goes unnoticed. Paget’s is most common in white people, although it can occur in any race.
If you have Paget’s disease you may not have any symptoms at all. It’s not unusual for Paget’s to be diagnosed by chance when you have an x-ray or blood test for a completely different reason.
If you do have symptoms, pain is the most common problem, and it’s usually felt in the bone itself or in the joints near the affected bones. There are many possible causes of bone pain in people with Paget’s disease, including:
- increased blood flow – this often causes the affected parts of your body to feel slightly warmer to the touch, especially if the bone is close to your skin, for example your shin
- the nerve fibres surrounding your bone becoming stretched as a result of bone enlargement or bending
- osteoarthritis (a common complication of Paget’s disease), which often causes pain in the joints near the affected bones
- enlarged bone pressing on nerves, causing pain in your back, neck and legs.
We don’t yet know exactly what causes Paget’s disease but the following factors may play a part:
Genetic factors – About 10–15 in every 100 people with Paget’s disease have relatives who also have the condition. In these cases the condition can be passed on from one generation to the next. But often there’s no family history of the condition.
Lifestyle factors – There's some evidence that poor diet or a bone injury early in life may act as triggers for the later development of Paget’s in people who also have genetic risk factors.
Another theory is that Paget's disease may be linked to a viral infection early in life, but some experts dispute this.
Your doctor may be able to diagnose Paget’s from your symptoms and a physical examination if your bone is deformed in a way that’s typical of the condition, but often you’ll need x-rays and blood tests to confirm it. Some blood tests will point to Paget’s disease even if you don’t have any obvious symptoms.
A blood test may show you have a raised level of an enzyme called alkaline phosphatase. There are many reasons why you might have this blood test, and many conditions besides Paget’s disease can cause the level of alkaline phosphatase to rise, so you’ll need further tests before a definite diagnosis of Paget’s disease can be made.
Sometimes the doctor will ask for an isotope bone scan, which is the most effective way of pinpointing where your affected bone is, how much bone is affected and how active it is. A tiny, well-tolerated dose of radioactive isotope, which can be detected by the bone scan, is injected into your vein and your whole skeleton is scanned several hours later. The amount of radioactivity injected is far too small to cause any harm to the body. The isotope is concentrated in the areas of bone affected by Paget’s disease so that they show up clearly when the body is scanned with a special camera. After the scan, the radioactive material quickly passes out of your body in your urine.
Once the diagnosis has been made, you may be referred to a specialist clinic for assessment and treatment.
Learn more about the treatments for Paget's disease of bone.
Paget’s disease is often treated with a group of drugs called bisphosphonates. These drugs are often used in the treatment of osteoporosis but at a different dose and for a different length of time. They work by damping down the overactive renewal and repair process, which in Paget’s disease is much faster than normal. These drugs act mainly on the osteoclasts (the cells that break down old bone) to slow down the rapid bone turnover. Drugs in this group include:
|Pamidronate||Series of weekly or fortnightly injections (6 in total) or as a single infusion|
|Risedronate||Tablets given daily for 2 months|
|Tulidronate||Tablets given daily for 3 months|
|Etidronate||Tablets given daily for 3–6 months|
If you're taking bisphosphonate tablets, you should take them around the same time each day. You shouldn’t take them within two hours either side of taking a calcium supplement because calcium can reduce the amount of the drug your body absorbs.
Bisphosphonates are often effective at easing bone pain caused by Paget’s disease, but it may take 3–6 months for your symptoms to improve. You may need further courses if your symptoms come back, but their effect often lasts for at least a year and sometimes for much longer.
These treatments are well tolerated and unlikely to cause serious side-effects. The most common side-effects are:
- flu-like symptoms lasting 1–2 days – with pamidronate and zoledronate
- a mild stomach upset – with risedronate, tiludronate and etidronate.
If you can’t tolerate bisphosphonates, you may be treated with a drug called calcitonin, which can be given as a daily injection.
You’ll probably also need painkillers such as paracetamol and/or non-steroidal anti-inflammatory drugs (NSAIDs), which are especially effective at reducing pain caused by osteoarthritis and nerve compression.
A therapy assessment, generally by a physiotherapist, can be very helpful. They can, for example, identify whether one of your legs has become shorter because your thigh and shin bones have become curved. In this case, a built-up insole in your shoes can reduce any feelings of lopsidedness.
Physiotherapists can also give you muscle-strengthening exercises that may be useful, while an occupational therapist can offer you advice on walking aids and other aspects of daily living.
You probably won’t need surgery, but sometimes if a bone breaks you’ll need an operation to fix it, depending on the type of break and how bad it is. If you later develop osteoarthritis as a result of having Paget's disease, then joint replacement surgery may sometimes be necessary.
Back surgery is occasionally needed if a bone in your back is enlarged and causing pressure on the nerves in the spine.
Diet and nutrition
If you have Paget's disease it’s important to eat a good diet with enough calcium and vitamin D.
The best sources of calcium are:
- dairy products such as milk, cheese, yogurt – low-fat ones are best
- milks made from soya, rice or oats with added calcium
- fish that are eaten with the bones (such as sardines).
We recommend that you have a daily calcium intake of 1,000 milligrams (mg), possibly with added vitamin D if you’re over 60. Skimmed and semi-skimmed milk contain more calcium than full-fat milk. If you don’t eat many dairy products or calcium-enriched foods, then you may need a calcium supplement. You should talk to your doctor or a dietitian about this.
Your body needs Vitamin D to absorb and process calcium, and there’s some evidence that arthritis progresses more quickly in people who don’t have enough vitamin D.
Vitamin D is sometimes called the sunshine vitamin because it’s produced by the body when your skin is exposed to sunlight. A slight lack of vitamin D is quite common in winter. You can also get Vitamin D from your diet (especially from oily fish) or from supplements such as fish liver oil. However, it’s important not to take too much fish liver oil.
If you’re over 60, dark-skinned or don’t expose your skin to the sun very often and are worried about a lack of vitamin D, you should talk to your doctor about whether a vitamin D supplement would be right for you.
Read more about diet and arthritis.
There’s no scientific evidence that suggests any form of complementary medicine helps to ease the symptoms of Paget’s disease. Generally speaking, though, complementary and alternative therapies are relatively well tolerated if you want to try them, but you should always discuss their use with your doctor before starting treatment. There are some risks associated with specific therapies.
In many cases, the risks associated with complementary and alternative therapies are more to do with the therapist than the therapy. This is why it’s important to go to a legally registered therapist, or one who has a set ethical code and is fully insured.
If you decide to try therapies or supplements, you should be critical of what they’re doing for you, and base your decision to continue on whether you notice any improvement.
Read more about complementary and alternative medicine for arthritis.
Paget’s disease can lead to a number of other symptoms or complications that are potentially more serious:
Bone expansion – Affected bone expands and may become deformed due to the unusual cell activity. Long bones can curve so that one of your legs may end up shorter than the other.
Fractures – Although bone affected by Paget’s disease expands, it’s weaker than usual and is more likely to break than normal, healthy bone. Occasionally it may take longer for your bone to heal.
Nerve compression – When your bones expand they can sometimes squeeze nearby nerves. This most commonly happens in your spine, which can lead to weakness and tingling in your legs.
Deafness – If bones in your head have been affected it can result in a loss of hearing or deafness. This seems to be caused by thickening of the bones around your ear.
Osteoarthritis – If the condition reaches the end of your bone it can lead to osteoarthritis in your joint, causing pain and stiffness when it’s moved.
Tumours – Very rarely, a cancerous tumour can develop in a bone affected by Paget’s disease. It's estimated that this happens in less than 1 in 500 cases. The first signs of this are increased pain and swelling at the site of the tumour.