What is Pagets Disease of Bone
Pagets disease is a condition that makes the bones grow faster than normal. Healthy bones rebuild themselves by breaking down old bone and replacing it with new bone tissue (bone turnover) on a regular basis.
5 Interesting Facts of Pagets Disease of Bone
1. Paget’s disease of bone (PDB) is a chronic condition characterized by focal areas of abnormal osteoclasts that cause excessive bone resorption, followed by abnormal bone formation resulting in disorganized, weak bone.
2. PDB commonly presents as an incidental discovery of elevated alkaline phosphatase (ALP), or bone abnormality on a nonrelated imaging study.
3. Plain radiographs are used to diagnose PDB and nuclear medicine bone scans are used to evaluate the extent of disease.
4. The treatment of choice of Pagets Disease of Bone is intravenous (IV) zoledronate, and treatment is indicated in PDB patients with symptomatic bone pain, hypercalcemia, and those at high risk of developing complications from PDB or undergoing surgery at or near a pagetic site.
5. Osteoarthritis (OA) is common in PDB, in part due to pagetic involvement adjacent to joints and alterations in gait, force transmission, and stress on joints.
Pagets disease of bone is a disorder of increased bone turnover that is believed to have a viral etiology, and it is most common in older patients.
Spinal involvement is characterized by an enlarged vertebra with thickened sclerotic cortices resulting in a “picture frame” appearance along with trabecular thickening
This process normally slows down with age. However, the process speeds up and becomes abnormal when you have Paget’s disease. This may cause bones to:
- Be larger and weaker than normal.
- Have abnormal shapes (deformities).
- Break more easily than healthy bones.
Paget’s disease may affect just a few bones, or it may affect bones all over the body. Bones in the arms, legs, spine, pelvis, and skull are often affected.
Pagets Disease of Bone is a chronic disease characterized by abnormal bone remodeling in one or more bones. Pagetic osteoclasts (bone cells responsible for bone resorption) are abnormally large and overactive causing focal areas of excessive bone resorption.
Compensatory increases in bone formation (by osteoblasts) at pagetic sites result in disorganized, structurally weaker bone that is often increased in size. Sir James Paget first described this condition in 1876 and referred to it as osteitis deformans ; however, there is evidence that the condition existed in Western Europe during the Roman period.
Pagets Disease of Bone can lead to bone pain, skeletal deformities, pseudofractures, and OA, though many people with PDB are asymptomatic at diagnosis.
Paget disease is an uncommon cause of back pain that is frequently diagnosed on plain radiographs obtained for other purposes or when the patient notices swelling of a long bone. Paget disease is also known as osteitis deformans , and its cause is unknown. The incidence of Paget disease is approximately 2%, with the disease occurring much less commonly in India, Japan, the Middle East, and Scandinavia. A familial form of Paget disease is related to mutation of the SQSTM1 gene. Whether infection with paramyxoviruses such as measles is a factor in the pathogenesis of Paget disease is a subject of ongoing scientific debate.
In the early phase of the disease, resorption of bone occurs, and the affected areas become vascular. The resorption phase is followed by the formation of new pagetic bone that is laid down in a dense, haphazard fashion. This process of bone resorption and formation can be quite active, with the bone turnover rate increased 20 times above normal. This process results in a characteristic pattern on plain radiographs that includes areas of bone resorption termed osteoporosis circumscripta . Areas of new bone formation show an irregularly widened cortex, with a dense, striated pattern and focal variations in density that reflect the chaotic nature in which the pagetic bone is laid down.
Although many patients with Paget disease are asymptomatic, and their disease is a fortuitous finding when radiographs are obtained for other reasons, back pain also may occur. It is thought that the cause of the back pain associated with Paget disease is multifactorial. The pain may be caused by the bone resorption process itself or distortion of the facet joints as new pagetic bone is formed. Both of these processes may alter the functional stability of the spine and exacerbate preexisting facet arthropathy.
Patients with Paget disease may experience thickening and widening of the long bones or enlargement of the skull resulting from new bone formation. Rarely, exuberant bone growth at the base of the skull may cause compression of the brainstem, with disastrous results. Hearing loss secondary to compression of the eighth cranial nerve by new bone formation or by direct involvement of the ossicles themselves may occur.
Occasionally, excessive bone formation in the dorsal spine may result in spinal cord compression, which, if untreated, may result in paraplegia. Pathological fractures resulting from excessive resorption of the vertebra may occur, with resultant acute back pain. Hip pain secondary to calcific periarthritis also may be present. An increased incidence of renal calculi and gout may occur, especially in men with Paget disease. In less than 1% of patients, a pagetic bone lesion may transform into a malignant osteosarcoma.
What are the causes?
The cause of Pagets Disease of Bone is not known.
What increases the risk?
Pagets Disease of Bone is more likely to develop in:
- People who have a family history of the Pagets Disease of Bone.
- People who are 50 or older.
- People of European descent.
What are the symptoms of Pagets Disease of Bone?
Symptoms of Pagets Disease of Bone include:
- Bone pain.
- Neck pain.
- Joint pain or stiffness.
- Tingling or numbness.
- Legs that bend outward from the hips to the ankles (bowed legs).
- Bones that break easily.
- A feeling of warmth in areas of skin that are over the affected bone.
- Loss of height.
- Changes in the shape of the skull or other bones.
- Hearing loss, if the skull bones are affected.
Some people have no symptoms.
Although the disease is often asymptomatic, pain is the most common clinical symptom that ultimately leads the clinician to the diagnosis of Paget disease. Seemingly minor trauma may cause pathological vertebral compression fractures. Pain on movement of the affected bones is a common finding on physical examination, as is excess bone growth on palpation of the skull and other affected bones.
Neurological findings based on neural compression secondary to either excessive bone growth or pathological fracture may be present. Pain on range of motion of the peripheral joints, especially the hip, owing to calcific periarthritis is a common physical finding in patients with Paget disease. Hearing loss may be noted on physical examination. In rare patients with Paget disease, high-output cardiac failure resulting from increased blood flow to new bone may be present.
How is Pagets Disease of Bone diagnosed?
Pagets Disease of Bone may be diagnosed based on:
- A physical exam.
- Your medical history.
- Blood and urine tests.
- Imaging tests, such as X-rays and bone scans.
- Removal and testing of a bone sample (bone biopsy). This is rarely needed.
As mentioned previously, Paget disease is often fortuitously diagnosed when the patient is undergoing radiographic testing for an unrelated problem, such as intravenous pyelography for renal calculi. The classic radiographic appearance of areas of bone resorption with surrounding areas of dense, chaotic bone points strongly to the diagnosis of Paget disease.
In patients with Paget disease, radionucleotide bone scanning and positron emission tomography (PET) can be used to assess the extent of the disease because many bone lesions are clinically silent. Magnetic resonance imaging (MRI) is indicated in any patient thought to have Paget disease who exhibits signs of spinal cord compression.
Serum creatinine testing and automated blood chemistries, including serum calcium determinations, are indicated in all patients with Paget disease. Alkaline phosphatase levels are elevated, especially during the resorption phase of the disease. Given the increased incidence of hearing loss in patients with Paget disease, audiometric testing is indicated.
Numerous other diseases of the bone, including osteoporosis, multiple myeloma, osteopetrosis, and primary and metastatic bone tumors, can mimic the clinical presentation of Paget disease. Acromegaly also shares many common clinical signs and symptoms.
Metastatic disease from prostate and breast cancer can produce pathological fractures of the spine and ribs and calvarial metastases that may be mistaken for Paget disease.
How is Pagets Disease of Bone treated?
Treatment for this condition depends on your symptoms and which areas of your body are affected.
If you have no symptoms, you may not need treatment. However, you may need treatment if the condition is causing symptoms, affecting your skull, or putting you at risk for broken bones (fractures).
The goals of treatment are to relieve bone pain and to prevent the condition from getting worse. Treatment may include:
- Medicines for pain, such as NSAIDs.
- Medicines that slow down abnormal bone turnover (bisphosphonates or calcitonin).
- Calcium and vitamin D supplements.
- Devices to help you move around (assistive devices or mobility aids), such as a cane, walker, or brace.
- Surgery to treat problems that are caused by the disease. Surgery is rarely used.
Most patients with asymptomatic Paget disease require only reassurance. Initial treatment of the pain associated with Paget disease should include aspirin, nonsteroidal antiinflammatory drugs (NSAIDs), or cyclooxygenase-2 (COX-2) inhibitors. Opioid analgesics may be needed to control the more severe pain of pathological fractures. Orthotic devices such as the Cash brace and rib belts may help stabilize the spine and ribs and should be considered if pathological fractures occur. Local application of heat and cold may be beneficial. The repetitive movements that incite the syndrome should be avoided. For patients who do not respond to these treatment modalities, the injection of the affected areas with a local anesthetic and steroid using either intercostal or epidural nerve blocks is a reasonable next step. Spinal administration of opioids may be beneficial in selected cases.
In patients who fail to respond to these treatments, calcitonin and etidronate have been used with some degree of success. Cytotoxic drugs, including dactinomycin, may rarely be required if excessive bone destruction occurs. High-dose pulsed steroids have been shown to provide symptomatic relief in patients with Paget disease.
Follow these instructions at home:
- Take over-the-counter and prescription medicines only as told by your health care provider.
- Take calcium and vitamin D supplements as told by your health care provider.
- If you are taking a bisphosphonate by mouth:
- Take the medicine with a large glass of water.
- Take it in the morning.
- Do not eat or drink anything for 30 minutes after taking the medicine.
- Stay upright for 30 minutes after taking the medicine. Avoid lying down during this time.
Preventing falls and fractures
- Pagets Disease of Bone may put you at greater risk for falls and fractures. To help prevent falls:
- Use mobility aids as needed, such as a cane or walker.
- Wear closed-toe shoes that fit well and support your feet. Wear shoes that have rubber soles or low heels.
- Remove clutter and tripping hazards from all walkways.
- Use good lighting in all rooms. Use a night-light to help you see during the night.
- Install and use handrails on stairways and in the bathroom.
- Have your eyes checked regularly. If you wear glasses, wear them at all times.
- Ask your health care provider what activities are safe for you. You may need to avoid activities that put you at risk for falls or injuries, such as contact sports.
- Wear braces as told by your health care provider.
- You may need to have regular blood tests to monitor your treatment.
- Keep all follow-up visits as told by your health care provider. This is important.
Contact a health care provider if you:
- Have bone pain or joint pain that gets worse.
- Have hearing loss.
- Have swelling in your legs or ankles.
- Have abdominal pain.
- Lose your appetite.
- Are not able to have a bowel movement (constipated).
Get help right away if you:
- Think that you might have a broken bone.
- Have fatigue or weakness.
- Have chest pain.
- Have shortness of breath.
- Have numbness or an inability to move.
Complications and Pitfalls
The primary complications associated with Paget disease are related to the resorptive and formation phases of the disease. Excessive resorption of bone may result in vertebral compression fractures, rib fractures, and occasionally fractures of the long bones. Excessive bone formation may result in compression of neural structures, which may result in hearing loss, brainstem compression, myelopathy, and paraplegia. An increased incidence of renal calculi and gout is seen, especially in men with Paget disease. Rarely, the formation of new bone is so great that high-output cardiac failure secondary to increased blood flow may result. As mentioned earlier, pagetic lesions undergo malignant transformation in approximately 1% of patients with Paget disease.
Careful evaluation of patients with Paget disease is mandatory to help avoid the potential complications of the disease. The clinician must look carefully for subtle signs of brainstem or spinal cord compression. Epidural and intercostal injection of local anesthetics and steroids can provide excellent palliation of the pain associated with Paget disease that fails to respond to pharmacological treatment.
- Pagets Disease of Bone is a condition that makes the bones grow faster than normal. This causes bones to be larger and weaker than normal, have abnormal shapes (deformities), and break more easily than healthy bones.
- Pagets Disease of Bone is more likely to develop in people who have a family history of the disease, are 50 or older, are male, or are of European descent.
- The goals of treatment are to relieve bone pain and to prevent the condition from getting worse. Treatment may include pain medicine, medicines that slow down abnormal bone turnover (bisphosphonates or calcitonin), and in rare cases, surgery.
- You may need to have regular blood tests to monitor your treatment. Keep all follow-up visits as told by your health care provider. This is important.