In 1877 Sir James Paget, british surgeon and physiologist first described chronic inflammation of bone, using the term osteitis deformans. Paget’s disease is a disorder of bone remodeling, with increased osteoclast-mediated bone resorption followed by increased bone formation. This process leads to a disorganized, mosaic pattern of woven and lamellar bone often associated with increased vascularity, marrow fibrosis, and mechanical weakness.
- Paget’s disease of bone is an osteoclastic disease of unknown etiology resulting in abnormal bone remodeling and deformity.
- Paget’s disease can be mono- or polyostotic with a predilection for pelvis, spine, femur, skull, tibia, and humerus resulting in pain, deformity, nerve compression, fracture, and rarely sarcomas.
- Intravenous bisphosphonate therapy is the most effective therapy.
Paget’s disease affects all races. This disease is rare in the Far East, India, Africa, and the Middle East and more common in whites of northern European ancestry. Men have a slightly higher risk
Asymptomatic patients are usually identified by an elevated alkaline phosphatase obtained on routine chemistry panels or by typical radiographic abnormalities noted on examination for some other complaint.
10% to 30% of patients are symptomatic. Bone pain is the most common symptom (80%), followed by joint pain (50%) resulting from secondary osteoarthritis usually involving the knee, hip, or spine. Bone deformities, such as tibial bowing and skull thickening, may occur in advanced cases. Neurologic complications can be caused by enlarging bone compressing neural tissue. Spontaneous fractures, most commonly in the femur, tibia, humerus, and forearm, may also occur.
Characteristic radiographic and scintigraphic findings:
Paget’s can be evaluated both by plain radiography and technetium bone scanning (99mTc-bisphosphonate); however, there is some discordance. Approximately 12% of the lesions seen on a bone scan will not be seen on a radiograph, and 6% of radiographic abnormalities are absent on bone scanning.
Plain radiographs reveal osteolytic, osteoblastic, or mixed lesions. Cortical thickening is usually present, along with adjacent trabecular thickening. The edge of lytic fronts extending from the subchondral region in long bones gives a “blade of grass”“osteoporosis circumscripta.” This is followed by excessive new bone formation leading to cortical thickening and the “cotton wool” appearance. When atraumatic fractures of long bones occur they typically are transverse (“chalk stick”) and not spiral, reflecting the weakened bony microarchitecture of Pagetic woven bone.