Paget's Disease

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Original Editors - Kevin Schoenfeld from Bellarmine University's Pathophysiology of Complex Patient Problems project.

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Definition/Description

Also known as Osteitis Deformans, Paget's disease of the bone is a metabolic bone disease caused by increased bone resorption followed by excessive unrestricted bone formation, due to activated osteoclasts. The normal bone marrow is replaced by increased and unorganized collagen and fibrous tissue, which lacks the structural stability of normal bone. This increased bone mass formation leads to complications such as fractures, arthritis, deformities, pain, and to a patient's weakened condition. 

Prevalence

• After Osteoporosis, Paget's disease is the most common skeletal disorder. Paget's disease affects approximately 2% to 5% of the population older than 40, and seen in 10% of the population over the age of 70 years old.
• Paget's disease affects men more than woman by a 3:2 ratio. 
• Evidence has shown that genetic factors of 40% of the individuals with Paget's disease have first-degree relatives with Paget's disease.
• Recently, the prevalence of Paget's disease has decreased by 50% of the prevalence in 1983.

Goodman C, Fuller K. Pathology: Implications for the Physical Therapist. St. Louis, Missouri: Saunders Elsevier;2009. 

Goodman C, Snyder T. Differential Diagnosis for Physical Therapists: Screening for Referral. St. Louis, Missouri: Saunders Elsevier, 2007.

Characteristics/Clinical Presentation

A patient with Paget's disease will present many times asymptomatic. However, the clinical presentation of a symptomatic patient varies greatly, due to the different levels of severity of this condition.

• Bones most commonly affected by Paget's disease include: Pelvis, Lumbar spine, Sacrum, Femur, Tibia, Skull, Shoulders, Thoracic spine, Cervical spine, and the ribs.
• The most common symptom experienced with symptomatic Paget's disease is an aching pain worse at night that decreases with physical activity.
• Muscular pain may present as referred pain from bony structures involved or as a complication due to the mechanical changes from the joint and bone defects.

Associated Co-morbidities

• Paget's disease has an insidious onset and the disease progresses slowly. When Paget's disease is present in many bones the overactive osteoclasts have the ability to release enough calcium in the blood stream to cause hypercalcemia, which can cause symptoms such as fatigue, weakness, loss of appetite, abdominal pain, and constipation.
• Neurological complications due to nereve entrapment syndromes or nerve root compression as they exit the foramina which is narrowed by the increased bone mass of Paget's disease.
• Hearing loss due to increased temporal bone mass and 8th spinal nerve compression.
• Bone deformities such as increased skull size and bowing of limbs.
• People with Paget's disease are also more susceptible to fractures because Pagetic bone is weaker than normal bone.
• Cardiovascular problems may arise when 1/3 to 1/2 of the skeleton is involved, heart failure is possible due to an increased cardiac output (this is the most common cause of death in people with advanced Paget's disease).

Goodman C, Fuller K. Pathology: Implications for the Physical Therapist. St. Louis, Missouri: Saunders Elsevier;2009. 

Josse R, Hanley D, Kendler D, Marie LG, Adachi J, Brown J. "Diagnosis and Treatment of Paget's Disease of the Bone". Clin Invest Med August 2007: E210-E223.

Medications

• Although only 5% of people with Paget's disease experience pain, the type of pain is very important to determine.
• Pain that is caused by an elevated SAP (Serum Alkaline Phosphatase) and resulting in an increased bone turnover, responds well to osteoclasts inhibitors such as bisphosphonates (ex. Zoledronic acid, Risedronate, Alendronate, Pamidronate, Etidronate Disodium).
• The gold standard for drug therapy for Paget's disease is bisphosphonates is aimed at decreasing abnormal bone resorption. The goal is to cause full remission of Paget's disease and establishing normal levels of SAP.
• Pain caused by nereve compression (caused by bone deformity or arthritis) should be treated with standard pain relievers such as NSAIDS and analgesics.

Goodman C, Fuller K. Pathology: Implications for the Physical Therapist. St. Louis, Missouri: Saunders Elsevier;2009. 

Josse R, Hanley D, Kendler D, Marie LG, Adachi J, Brown J. "Diagnosis and Treatment of Paget's Disease of the Bone". Clin Invest Med August 2007: E210-E223.

Diagnostic Tests/Lab Tests/Lab Values

• Radiographic Imaging (primary): Plain X-Ray should be performed in at least one skeletal area (usuallly in a painful area) to help confirm the diagnosis of Paget's disease. X-rays can also diagnose secondary conditions such as a fracture or arthritis.
• Isotopic Bone Scan (Scintigraphy) are more sensitive radiographic images which highlights affected areas of Paget's disease, but the Scintigraphy is only positive if the condition is active.
• Scintigraphy is recommended for patients with symptomatic and asymptomatic Paget's disease to determine the severity and involvement of the skeletal structures.
• Scintigraphy can also be used to monitor a patient's therapeutic response to therapy based on the results of a second diagnostic test.
• A Bone Biopsy may also be performed (especially if the X-ray and CT scan are negative) to make a differential diagnosis which would rule out hyperparathyroidism, bone metastasis, multiple myeloma, and fibrous dysplasia.
• Biochemical Tests: Serum Alkaline Phosphatase (SAP) is an enzyme that is produced by bone cells and are excessively produced in bone containing Paget's disease.
• In 85% of patients with Paget's disease, SAP levels are elevated. A solid relationship exists between the severity of the disease measured by the scintigraphy, and the increased levels of SAP in untreated Paget's disease.
• Many other biochemical tests are available which assess bone matrix resorption such Urinary and Serum Deoxypyridinoline, N-telopeptide, and Alpha and Beta C telopeptides, but none of these tests are as readily available as the SAP diagnostic lab test.

Causes

• The exact cause of Paget's disease is unknown, though it is thought to be a slow, viral bone infection due to risk factors that include a gene-environment interaction.
• The prevalence and causes of Paget's disease has been associated with genetic and geographical factors.
• Paget's disease is mostly seen in an autosomal dominant distribution, and there have been three identifiable chromosomal regions associated with Paget's disease.
• Geographically, populations in European, British, and Australian origin, and a migratory influence also play an important role especially in countries which migrated from Britain (United States, Australia, New Zealand, Canada).

Goodman C, Fuller K. Pathology: Implications for the Physical Therapist. St. Louis, Missouri: Saunders Elsevier;2009.

Systemic Involvement

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Medical Management (current best evidence)

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Physical Therapy Management (current best evidence)

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Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

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Case Reports

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Recent Related Research (from Pubmed)

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References1.   

1.  Goodman C, Fuller K. Pathology: Implications for the Physical Therapist. St. Louis, Missouri: Saunders Elsevier;2009.

2.  Goodman C, Snyder T. Differential Diagnosis for Physical Therapists: Screening for Referral. St. Louis, Missouri: Saunders Elsevier, 2007.

3.  Josse R, Hanley D, Kendler D, Marie LG, Adachi J, Brown J. "Diagnosis and Treatment of Paget's Disease of the Bone". Clin Invest Med August 2007: E210-E223.