Paget's Disease Of Bone

Overview

Paget's (PAJ-its) disease of bone interferes with your body's normal recycling process, in which new bone tissue gradually replaces old bone tissue. Over time, bones can become fragile and misshapen. The pelvis, skull, spine and legs are most commonly affected.

The risk of Paget's disease of bone increases with age and if family members have the disorder. However, for reasons unknown to doctors, the disease has become less common over the past several years and is less severe when it does develop. Complications can include broken bones, hearing loss and pinched nerves in your spine.

Bisphosphonates — the medications used to strengthen bones weakened by osteoporosis — are the mainstay of treatment. Surgery may be necessary if complications occur.

Symptoms

Many people with Paget's disease do not have any symptoms at all. The disease is often first discovered when X-rays are taken for another reason or when routine blood work indicates an elevated blood serum alkaline phosphatase level.

Pain

In patients who do have symptoms, bone pain is the most common complaint. This pain can be related to active Paget's disease or to its complications, which include:

• Fractures due to brittle bone.
• Deformity of bone, including bowing of the affected bone.
• Advanced arthritis in joints near the affected bone.
• Compression on neighboring nerves from enlarged bones, leading to a loss of sensation or movement.

Other Symptoms

Symptoms can also arise from the effect of the disease on calcium levels in the blood stream. When Paget's disease is active in several bones, overactive osteoclasts may release enough calcium from the bone as they break it down to cause an elevated calcium level in the blood. This rare complication can lead to a number of symptoms, including:

• Fatigue
• Weakness
• Loss of appetite
• Abdominal pain
• Constipation

Very rarely, Paget’s disease can progress to a type of bone cancer called Paget’s sarcoma. When this occurs, symptoms may include severe and unrelenting pain in the area affected by Paget’s disease.  Paget's sarcoma occurs in only about 1 percent of patients with Paget's disease. These patients are usually over the age of 70. This type of malignant bone tumor is very aggressive and has a poor prognosis. None of the medical treatments for Paget's disease are known to lower the risk for the development of Paget's sarcoma.

Causes

Researchers are yet to definitively establish the cause of Paget’s disease.

Paget’s disease appears to run in families. According to the American College of Rheumatology, more than one family member has the disorder in 30 percent of cases.

Another suggestion is that the disorder possibly occurs due to infection by the measles virus during childhood. Recent studiesTrusted Source put forward that measles might alter the mechanism of bone formation, leading to Paget’s disease.

However, researchers have not yet uncovered a clear connection between the virus and Paget’s disease.

Evidence suggests that the number of people with Paget’s disease has been decreasing Trusted Source over the last 25 years. Some scientists have linked the increase in vaccination in many countries and the resulting drop in the number of people with measles to falling rates of Paget’s disease.

Around 1 million people in the United States have Paget’s disease.

Paget’s disease tends to occur in older adults as well as people from Northern Europe. The disorder occurs in three men to every two women with Paget’s disease.

Diagnosis

Paget's disease of bone can be diagnosed with a blood test and an X-ray or scan.

Blood test

A simple blood test can be carried out to check the level of a substance called alkaline phosphatase (ALP) in your blood.

People with Paget's disease of bone often have raised levels of ALP, although some people with the condition have a normal ALP level and a high level can also be caused by some other conditions.

An X-ray or scan is therefore also needed to confirm the diagnosis.

X-ray and bone scan

An X-ray can show whether your bones have become enlarged as a result of Paget's disease of bone.

Sometimes a bone scan called scintigraphy may also be carried out to check how much of your body is affected by the condition.

For this scan, a small amount of a radioactive substance is injected into your blood. This collects in areas where there's a lot of bone renewal taking place.

A gamma camera is then used to detect the radiation and highlight affected parts of the body.

Further tests

Further tests are usually only needed if you have signs of more severe Paget's disease of bone or your doctor thinks there's a chance you could have bone cancer (although this is very rare).

In these cases, you may be advised to have a:

bone biopsy – a sample of bone is removed under anaesthetic so it can be looked at in detail

CT scan – a series of X-rays of the affected bone are taken to create a detailed 3-dimensional image

MRI scan – a strong magnetic field and radio waves are used to create an image of the affected bone

Treatment

There's currently no cure for Paget's disease of bone, but treatment can help relieve the symptoms.

If you do not have any symptoms, your doctor may suggest keeping an eye on your condition and delaying treatment until any problems occur.

Bisphosphonates

Bisphosphonates are medicines that help regulate bone growth. They work by affecting the cells that absorb old bone (osteoclasts).

There are several bisphosphonates available, including:

• risedronate – a tablet taken once a day for 2 months
• zoledronate – a one-off injection
• pamidronate – either 6 weekly injections or 3 injections every 2 weeks

These can help regulate bone growth and reduce pain for several years at a time. Treatment can be repeated when the effect starts to wear off.

The most common side effect of risedronate is an upset stomach. The main side effects of zoledronate and pamidronate are flu-like symptoms that last a day or 2.

If you're unable to have bisphosphonates, you may need daily injections of another medicine that prevents bone loss called calcitonin.

Painkillers

Over-the-counter painkillers such as paracetamol and ibuprofen can help relieve pain caused by Paget's disease of bone.

Make sure you read the packet or leaflet before taking painkillers, to check whether they're suitable for you and to find out how much to take.

If these do not help reduce your pain, your GP can prescribe more powerful painkillers.

Supportive therapies

Some people with Paget's disease benefit from supportive therapies such as physiotherapy or occupational therapy.

These therapies involve exercises and techniques that can help reduce pain, improve movement and make everyday tasks easier.

Devices that reduce the weight placed on the affected bones may also help, such as:

• a walking stick or frame
• orthotics – insoles made of plastic that fit inside your shoe to help support your feet
• braces that support the spine in the correct position

Some therapists also use treatments such as transcutaneous electrical nerve stimulation (TENS) – a method of pain relief involving the use of a mild electrical current. The scientific evidence for TENS is not strong, but some people find it helpful

Surgery

Surgery is usually only needed if further problems develop, such as fractures, deformities or severe osteoarthritis.

Operations that may be done include procedures to:

• realign the bones after a fracture so that they heal correctly
• remove and replace a damaged joint with an artificial one, such as a hip replacement or knee replacement
• cut and straighten deformed bones
• move bone away from a squashed (compressed) nerve

These operations are usually done under general anaesthetic, so you'll be asleep and will no t experience any pain while they're carried out.

Diet and nutrition

Calcium and vitamin D help keep your bones healthy. If you have Paget's disease of bone, it's important to ensure you get enough of these.

You get calcium from your diet. It's found in foods such as:

• dairy foods – such as milk and cheese
• green leafy vegetables – such as broccoli and cabbage
• soya beans, soya drinks with added calcium and tofu
• You get most of your vitamin D from sunlight, although it's also found in some foods such as oily fish.
• Sometimes your GP may suggest taking extra calcium and/or vitamin D supplements to ensure you're getting enough.

Complications

Broken bones

Bones affected by Paget's disease of bone tend to be more fragile than normal bone and are more likely to break (fracture) – even after a relatively minor injury.

Signs of a fracture include:

• sudden, severe pain
• swelling or tenderness around the injured area
• bleeding, if the bone has damaged the tissue and skin 

It's not clear whether bisphosphonate medication helps prevent or treat fractures. If you break a bone, you may need surgery to align the broken bones so that they heal correctly.

Bone deformities

It's common for Paget's disease of bone to affect the appearance of affected bones.

For example, the condition can cause:

• enlarged or misshapen bones
• the legs to curve outwards (bow legs)
• the spine to curve to the sides (scoliosis)
• the upper back to become very hunched over (kyphosis)

As with fractures, it's not clear whether bisphosphonates can help prevent deformities. If they do occur, surgery may be carried out to correct them.

Hearing loss

If Paget's disease of bone affects the skull, there's a significant risk that it could lead to permanent hearing loss and possibly total deafness.

This can occur as a result of damage to the bones or nerves that connect the ears to the brain.

It's not known whether treating Paget's disease of bone helps reduce the risk of losing your hearing, but treatment is usually recommended if the condition is affecting your skull.

Too much calcium in the blood

In rare cases, the increased cycle of bone renewal in Paget's disease of bone can result in calcium building up in the blood. This is known as hypercalcaemia.

It usually only occurs in people who have been confined to bed after an operation or a fracture.

Symptoms of hypercalcaemia can include:

• extreme tiredness
• depression
• drowsiness
• constipation
• new or worsening bone pain

Hypercalcaemia can be treated using medicines to lower blood calcium levels and slow down bone regeneration.

Heart failure

The new bone that forms in people with Paget's disease of bone often contains more blood vessels than normal bone, which can mean the heart has to work harder to pump blood around the body.

Very occasionally, the heart may not be able to pump enough blood around the body. This is known as heart failure.

• Symptoms of heart failure can include:
• shortness of breath
• extreme tiredness and weakness
• swelling in the legs, ankles and feet (oedema)

Heart failure can be treated with medicine and in some cases heart surgery. Read more about how heart failure is treated.

Bone cancer

Bone cancer is a rare complication of Paget's disease of bone. It's estimated to affect between 1 in 100 and 1 in 1,000 people with the condition.

Symptoms of bone cancer are similar to those of Paget's disease of bone. They can include:

• bone pain
• swelling around the affected bone
• a lump in the affected bone

Osteosarcoma is a very serious type of cancer that can spread to other parts of the body quickly. But if it's caught early enough, it may be possible to cure it by removing the affected bone.