Patient information: Paget disease of bone (osteitis deformans)

PAGET DISEASE OVERVIEW

Paget disease of bone is a disorder that affects the size and shape of some bones. This can sometimes lead to pain in the joints or abnormally shaped bones. The condition is slightly more common in men and tends to occur in middle age or older people. Certain areas of bone tend to be affected by Paget disease more than others, including the pelvis, spine, skull, arms, and legs.

There is a type of breast cancer that is referred to as Paget disease of the breast; this is not related to Paget disease of bone and will not be discussed here.

NORMAL BONE GROWTH

To understand Paget disease it is important to know how bones grow. Bones are active, living tissues. The bones you have today are not really the same bones you will have next year; the bones are constantly recreating themselves.

The bones contain cells called osteoclasts that constantly work to break down small portions of bones. Other cells called osteoblasts are also at work, making new bone to replace bone that has been broken down. In Paget disease, the process of bone turnover is faster than normal. This results in the formation of abnormal bone.

PAGET DISEASE CAUSES

The cause of Paget disease is unknown. A person's genes may predispose them to developing Paget disease, while viruses and other environmental exposures may trigger its development.

PAGET DISEASE SYMPTOMS

Most people with Paget disease have no signs or symptoms of bone disease. When there are symptoms, such as pain or deformity, it can be related to Paget disease itself or to complications that occur because of abnormal bone growth. In some people, only one bone is affected while in others there are several affected bones.

Pain — Pain may develop directly from a bone affected by the Paget disease, or more often, from complications related to the presence of abnormal bone. Examples of complications include arthritis (when bones near a joint are affected) and numbness or weakness (due to pressure from a bone on a nerve).

Deformities — Abnormal bone growth may cause visible deformities, particularly in the arms, legs, skull, and clavicle (collar bone). If the leg is affected, there can be bowing of the leg, which can cause a limp or back or joint pain. If the skull is involved, the head may slowly enlarge (picture 1).

Fractures — The abnormal bone of Paget disease is more likely to fracture when exposed to weight-bearing stresses.

Bone tumors — Although rare, the risk of developing tumors (both cancerous and noncancerous) of the bone is increased in people with Paget disease (picture 2). This complication occurs in less than one percent of people with Paget, most commonly in those with several affected bones.

Calcium and phosphate — The breakdown and build up of bone is essential in regulating the levels of calcium and phosphorus in the blood. In most people with Paget disease, these levels remain normal.

However, certain conditions can cause the balance to be disrupted, such as inactivity (eg, after a fracture), or the presence of a second disorder such as hyperparathyroidism (overactive parathyroid glands). (See "Patient information: Primary hyperparathyroidism".)

PAGET DISEASE DIAGNOSIS

Most people are diagnosed with Paget disease using a combination of a blood test and x-rays.

Blood test — A blood test for alkaline phosphatase is usually elevated in people with Paget disease. Alkaline phosphatase is an enzyme that is normally produced in several organs, including the bones, where it is made by osteoblasts.

Bone scan — A bone scan may be done to confirm the diagnosis of Paget disease and/or identify other bones that are involved. A bone scan is a test that can detect new areas of bone growth using medication that is injected into a vein; the scan may examine bones of the entire body or a single area.

X-rays — Paget disease may be diagnosed with x-rays. Changes in the bones seen on x-ray may include thickening of the outside of the bone (the cortex), and enlargement or deformity of the bone itself (picture 1). X-rays are usually done after a bone scan to evaluate potentially affected bones.

PAGET DISEASE TREATMENT

Many patients with Paget disease do not have symptoms and do not need treatment. However, treatment may be recommended to decrease the risk of future complications, even if the person has no current symptoms. This may include people who have involvement of the skull, spine, or lower limbs.

Medications — Patients who have pain, bone deformities, or other symptoms related to Paget are usually treated with medications that stop the abnormal bone turnover. The treatment of choice is an aminobisphosphonate.

Bisphosphonates — Aminobisphosphonates inhibit the breakdown and removal of bone by inhibiting the osteoclast. The aminobisphosphonates include alendronate (Fosamax®), risedronate (Actonel®), pamidronate (Aredia®), and zoledronic acid (Zometa® or Aclasta®). The older bisphosphonates, etidronate and tiludronate, are not aminobisphosphonates and are not usually recommended for people with Paget disease of bone.

Bisphosphonates are usually given for a limited period of time, followed by a period of monitoring (see 'Medication monitoring' below. These drugs also offer the possibility of a long-lasting remission. However, if problems recur, treatment may be repeated. While taking a bisphosphonate, it is important to consume at least 1000 mg of calcium and 400 IU of vitamin D every day. Calcium and vitamin D can be taken as a supplement (table 1); many foods and drinks contain calcium (table 2)

• Zoledronic acid is given as an injection into a vein over 15-20 minutes.
• Alendronate (Fosamax®) and risedronate (Actonel®) are taken as a pill for 6 months or 2 months, respectively. These need to be taken first thing in the morning on an empty stomach with a full 8 ounce glass of plain water (not sparkling). Liquids other than plain water, such as mineral water, coffee, or juice may interfere with absorption of the medication from the stomach and intestine. After taking alendronate or risedronate, the person must remain upright (sitting or standing, not lying down) and must wait 30 minutes before eating or drinking anything.
• Pamidronate is an older, less potent aminobisphosphonate that is also effective in many patients with Paget disease. It is given into a vein over two to four hours.

Side effects of bisphosphonates — Most people who take bisphosphonates do not have any serious side effects related to the medication. Transient fever or flu-like symptoms are the most common side-effects.

There has been concern about use of aminobisphosphonates in people who require invasive dental work. A problem known as avascular necrosis or osteonecrosis of the jaw has rarely developed in people who used these drugs. This is seen more commonly in people with cancer who are given a monthly dose of the aminobisphosphonate. The risk of this problem is much less in people who take bisphosphonates for Paget disease. However, it is reasonable to have dental work done prior to treatment for Paget's disease of bone.

Calcitonin — Synthetic calcitonin is a hormone that is given as an injection three times a week. The dose may be increased up to five times weekly as tolerated. Calcitonin may be recommended for people who are unable to tolerate the new aminobisphosphonates because of kidney disease or intolerable side effects. Calcitonin is a safe drug that can ease pain and is partially effective in reducing new bone growth.

Medication monitoring — During and after treatment, blood tests are performed every few months to check the level of alkaline phosphatase; a falling level is a good indicator that treatment is working. A urine test for other markers of bone turnover may also be recommended.

When it appears that the medication is effectively reducing new bone growth, less frequent tests are needed. If the alkaline phosphatase level increases or symptoms worsen, this may be a sign of resistance to treatment and may indicate the need for a change in therapy.

Other treatments — People with Paget disease may have pain that is related to Paget as well as pain that is unrelated to the condition. As the skeleton ages, a number of conditions can cause pain in the bones and/or joints, including the following:

• Arthritis of the hip, spine, or knee
• A pinched nerve (eg, sciatica)
• Compression fractures of the spine related to osteoporosis

Pain medications (eg, acetaminophen [Tylenol®] or ibuprofen [Motrin® or Advil®]) are recommended as needed for treatment of pain that does not improve with the treatment of Paget disease (table 3). Consultation with a healthcare provider is recommended to determine which medications and/or other treatments may be most helpful. In some cases, a cane or physical therapy may be recommended.

Surgery — The joints adjacent to affected bones may become stiff and painful due to arthritis. Some patients with severe arthritis pain benefit from surgery to replace the joint. (See "Patient information: Total knee replacement (arthroplasty)" and "Patient information: Total hip replacement (arthroplasty)".)

Most people who plan to have surgery are treated for Paget disease of bone for at least two to three months before surgery. This can help to decrease blood flow to the bone, which will help decrease bleeding during and after surgery.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Primary hyperparathyroidism
Patient information: Total knee replacement (arthroplasty)
Patient information: Total hip replacement (arthroplasty)

Professional Level Information:
Clinical manifestations and diagnosis of Paget disease of bone
Diagnosis and classification of osteoarthritis
Etiology of hypercalcemia
Treatment of Paget disease of bone

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• American Academy of Orthopaedic Surgeons

      (http://orthoinfo.aaos.org/)

• American College of Rheumatology

      (www.rheumatology.org)

• Arthritis Foundation

      (www.arthritis.org/conditions/DiseaseCenter/Pagets_disease.asp)

• Paget Foundation for Paget's Disease of Bone and Related Disorders

      (www.paget.org)

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