Paget's disease of the bone is the second most common bone disorder in elderly patients. (Osteoporosis is the most common.) Paget's disease, also known as osteitis deformans, is a disorder that affects the normal remodeling process of bone. In normal bone, the bone constantly remodels. In the remodeling process, old bone is removed and new bone is formed. In patients with Paget's disease, this process is altered. These patients have an excessive amount of bone resorption (removal) followed by an even more excessive amount of new bone formation. Unfortunately, this increased rate of bone remodeling leads to new bone that is not as strong as normal bone. This abnormal bone is weaker, has more blood vessels, and is larger in size than normal bone. While most cases do not cause symptoms, some patients may develop bone pain, fractures, deformities, and sometimes malignant transformation into sarcoma (a bone cancer), although this is rare.
Men are affected by Paget's disease slightly more often than women. Paget's disease is more common in people of Northern European ancestry, most commonly in those from Great Britain. It is rare in Asia and Africa. It is more common with increasing age, typically diagnosed in people in their 50s. In the United States, a small percent of the general population is estimated to have Paget's disease.
The exact cause of Paget's disease remains uncertain. Several theories have been suggested, including a viral cause (such as paramyxovirus including measles, respiratory syncytial virus, or human parainfluenza virus).
There is also thought to be a genetic link for Paget's disease with a possible autosomal dominant inheritance.
Being over 55 years of age is a risk factor for Paget’s disease. Certain genes have been identified that increase the risk of Paget’s disease. Paget’s disease is common in England, Scotland, Central Europe, and Greece, as well as in countries and cities settled by European immigrants, such as those in Australia, Canada, and the United States.
Most people with Paget's disease do not have symptoms. It is often discovered as an incidental finding on routine X-ray films or blood tests.
When symptoms do occur, the most common ones include pain, commonly joint pain, hip pain, neck pain, and low back pain. Other less common symptoms include fractures, bowing deformities of the bones (such as bowlegs), hearing loss, headaches, and muscle weakness. Pagetic bone contains numerous blood vessels, so a traumatic fracture through pagetic bone may result in significant blood loss. A patient can rarely develop congestive heart failure because of the increased blood flow. Increased calcium levels from the bone remodeling process can cause kidney stones.
Fractures and bowing deformities can occur because the increased rate of remodeling caused by Paget's disease makes the bone weaker, predisposing patients to fractures or deformity. Hearing loss can result from involvement of the small bones of the inner ear. Headaches result from involvement of the skull and facial bones. Muscle weakness can occur if the spine is involved, leading to stenosis or a narrowing of the spinal canal and pinching of the spinal cord and nerve roots.
People should seek medical care if they have increasing bone pain or deformities potentially related to Paget's disease. Also, people with weakness or a change in bowel or bladder function should seek immediate care to assess for involvement of the spine, leading to compression of the spinal cord and nerve roots.
People with Paget's disease should ask the doctor if they would benefit from medication. Additionally, people with Paget's disease should be periodically seen by their physician throughout their lives due to the low risk of malignant transformation to sarcoma.
Physicians diagnosing and treating Paget's disease include primary-care providers (including internists and family practitioners), rheumatologists, geriatricians, endocrinologists, and orthopedists. Radiologists and nuclear-medicine doctors can help to diagnose Paget’s disease. Spine surgeons may treat Paget’s disease when spinal surgery is needed (rarely).
Laboratory studies include both blood and urine studies. Bone-specific alkaline phosphatase is a specific laboratory study that provides information on the rate of bone turnover, which is increased in people with Paget's disease. Other laboratory studies include assessment of calcium, phosphate, and parathyroid hormone levels. In many cases, these levels remain normal. Urine tests include procollagen type I N-terminal propeptide (PINP), serum C-telopeptide (CTx), urinary N-telopeptide (NTx), and urinary hydroxyproline, which measure bone degradation products secreted in the urine. These studies may be useful in both diagnosis and long-term monitoring of the disease process and response to medical treatment.
Imaging studies are often limited to plain radiographs (X-ray films). Early in the disease process, osteolysis, or softening and destruction of bone mass, is seen on X-ray films. Later in the course of the disease, there is increased bone mass, or sclerosis. Radiographs are also necessary if fracture is suspected. Radiographs should also be used to evaluate for possible malignant transformation.
Bone scans are useful in assessing the extent of disease throughout the entire body.
CT scan and magnetic resonance imaging (MRI) can be useful in the evaluation of patients with neurologic dysfunction or muscle weakness to assess for involvement of the spine and compression of the spinal cord or nerve roots. Rarely, a bone biopsy is required, especially if malignancy is suspected.
Most people with Paget's disease do not have symptoms. Treatment in such patients would be based on the location of the pagetic bone or if the alkaline phosphatase level is elevated two to four times the normal limits. People with symptoms are treated in various ways.
Medical treatment is geared toward pain relief and reducing the amount of bone turnover with medications.
The following oral medications may be prescribed by your doctor to control bone or joint pain related to Paget's disease:
Intravenous zoledronic acid is a potent bisphosphonate and is generally very effective in treating symptoms of Paget’s disease. A single dose is given, with possible redosing if symptoms recur. Oral bisphosphonates such as alendronate and risendronate may be used for people who do not want to take an intravenous medication. For people who do not tolerate oral or intravenous bisphosphonates, intranasal calcitonin is a reasonable alternative to inhibit bone loss.
The following are specific instructions for taking oral bisphosphonates and are important to assure proper absorption by the body. Beverages other than plain water (including mineral water), food, and some medications are likely to reduce the absorption of bisphosphonates. Take first thing upon awakening in the morning before other medications and food. Do not take within 30 minutes of consuming food. Take antacids, calcium, vitamin, and mineral supplements, at least two hours after bisphosphonates. Additionally, sit upright or stand for 30 minutes to avoid erosion to your esophagus.
Serum alkaline phosphatase levels are monitored to determine duration of treatment as well as to monitor disease activity and need for retreatment.
Indications for surgery for Paget's disease include bony deformity, pathologic fractures, and neurologic dysfunction due to spinal stenosis, degenerative joint disease, or malignant transformation to sarcoma.
While many cases of deformity and fractures can be treated non-operatively, some people benefit from surgery to realign the bone and allow for healing in a more natural position.
Patients with neurologic dysfunction due to involvement of the spine may benefit from spinal decompression. This involves removing portions of the bone surrounding the spinal cord and nerve roots to alleviate compression of these structures.
Cases of severe degenerative joint disease, most commonly the hip and knee, may be treated with joint replacement surgery to relieve pain and improve function and mobility.
In the rare cases of malignant transformation to sarcoma, removal of the affected bones may be required.
People with involvement of the joints often benefit from a physical therapy and muscle strengthening program.
Due to the small risk of malignant transformation (formation of bone tumors) associated with Paget's disease, those affected should see their physicians periodically throughout their lives.
No measures are currently known to prevent Paget's disease.
For most people, medical treatment of Paget's disease can effectively control symptoms, and patients can remain pain free. A small portion of patients can develop more severe symptoms as stated above, including deafness, congestive heart failure, fractures, arthritis, and development of bone tumors (sarcomas). These complications are rare. Most patients remain symptom free and pain free with treatment of the Paget's disease.
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Joint pain can be caused by injury or disease affecting any of the ligaments, bursae, or tendons surrounding the joint. Injury or disease can also affect the ligaments, cartilage, and bones within the joint, leading to a painful joint. Pain is also a feature of joint inflammation (arthritis) and infection and can be a feature of rare tumors of the joint.
