What is Paget's disease of the bone?

From the Guidelines

Paget's disease of bone is a chronic disorder that causes abnormal bone remodeling, resulting in enlarged, weakened bones that may be painful and prone to fractures. It occurs when the normal bone recycling process becomes unbalanced, with excessive breakdown and formation of new bone that is structurally irregular. The disease typically affects older adults, particularly those over 50, and commonly involves the pelvis, skull, spine, and legs. Symptoms can include bone pain, joint pain, headaches, hearing loss if skull bones are affected, and bone deformities. Many people with Paget's disease have no symptoms and are diagnosed incidentally. Treatment typically includes bisphosphonate medications such as zoledronic acid (5mg IV once yearly), risedronate (30mg daily for 2 months), or alendronate (40mg daily for 6 months), which slow bone turnover and can provide pain relief 1. Adequate calcium (1000-1500mg daily) and vitamin D (800-1000 IU daily) intake is also recommended. Pain medications may be used for symptom management. The exact cause remains unknown, though genetic factors and viral infections may play a role. Regular monitoring with bone scans and alkaline phosphatase blood tests helps track disease progression and treatment effectiveness. Some key points to consider in the diagnosis of Paget's disease include a family history, pelvic or skull localization, raised alkaline phosphatase, deformities, and a characteristically mixed osteolytic and osteosclerotic aspect on imaging, with an age of onset usually over 50 years 1. It is also important to differentiate Paget's disease from other conditions such as osteosarcoma, which can be associated with Paget's disease as a risk factor 1.

Some of the key characteristics of Paget's disease include:

• Abnormal bone remodeling
• Enlarged, weakened bones
• Pain and fractures
• Commonly affects the pelvis, skull, spine, and legs
• Typically affects older adults over 50
• May have no symptoms and be diagnosed incidentally
• Treatment includes bisphosphonate medications and adequate calcium and vitamin D intake
• Regular monitoring with bone scans and alkaline phosphatase blood tests is necessary to track disease progression and treatment effectiveness.

In terms of diagnosis, it is essential to consider Paget's disease in the differential diagnosis of chronic bone disorders, particularly in older adults with bone pain, deformities, or elevated alkaline phosphatase levels 1. A thorough medical history, physical examination, and imaging studies such as X-rays, CT scans, or bone scans can help confirm the diagnosis. Additionally, laboratory tests such as alkaline phosphatase and calcium levels can aid in diagnosis and monitoring of the disease.

Overall, Paget's disease of bone is a chronic disorder that requires prompt diagnosis and treatment to prevent complications and improve quality of life. With proper management, including bisphosphonate medications, adequate calcium and vitamin D intake, and regular monitoring, patients with Paget's disease can experience significant improvement in symptoms and reduction in the risk of fractures and other complications 1.

From the Research

Definition and Characteristics of Paget's Disease

• Paget's disease of bone (PDB) is a focal bone disorder caused by a marked dysregulation of osteoblasts and osteoclasts, leading to abnormal and disorganized deposition of collagen fibers 2.
• The disease is characterized by increased bone remodeling and abnormal bone architecture, resulting in a disorganized mosaic of woven and lamellar bone 3.
• PDB can lead to enlarged and deformed bones, bone pain, deformities, fractures, osteoarthritis, and rarely, neoplastic degeneration 2.

Clinical Manifestations and Diagnosis

• Common clinical manifestations of PDB include bone pain, bowing of long bones, enlarged skull, and hearing loss 4.
• The diagnosis is confirmed by characteristic radiographic findings and by nuclear scintigraphy of the bone, with elevated serum alkaline phosphatase levels correlating with disease activity 4.
• The disease may be monostotic or polyostotic, with the pelvis, femur, spine, tibia, skull, and humerus being the most commonly involved sites 3.

Treatment and Management

• Bisphosphonates, such as zoledronic acid, pamidronate, alendronate, and risedronate, are the mainstay of treatment for PDB 4.
• The primary goal of treatment is to restore normal bone turnover, relieve bone pain or other symptoms, and prevent complications 2.
• Treatment indications and goals of therapy have changed with the availability of safer and more effective therapies, with some experts recommending treatment of asymptomatic patients with active disease at sites where complications are likely to develop 3.

Epidemiology and Prevalence

• PDB is a chronic disorder that commonly affects older adults, with significant geographical variations in prevalence 5.
• The incidence of PDB has been found to be low but increasing, particularly among women, in some populations 5.
• Despite the established efficacy of bisphosphonates in managing PDB, their use has been found to be low in some studies, highlighting the need for greater clinical awareness and more proactive management strategies 5.