What are the potential complications of Paget's disease?

Complications of Paget's Disease of Bone

Paget's disease of bone leads to multiple serious complications that significantly impact morbidity and quality of life, including bone deformity, pathological fractures, neurological compression syndromes, secondary osteoarthritis, hearing loss, high-output heart failure, and rarely osteosarcoma. 1, 2

Musculoskeletal Complications

Bone Deformity and Structural Changes

• Bowing deformities of long bones develop due to the disorganized mosaic of woven and lamellar bone that becomes enlarged and structurally weakened 3
• The abnormal bone architecture results from increased osteoclast-mediated bone resorption followed by compensatory but disorganized bone formation 3
• These deformities are often irreversible once established, emphasizing the importance of early treatment 4

Pathological Fractures

• Fractures occur through weakened pagetic bone that has lost its normal structural integrity 2, 5
• The highly vascular, disorganized bone is particularly vulnerable to fracture even with minimal trauma 3
• Excessive bleeding during orthopedic surgery is a recognized complication due to the hypervascular nature of pagetic bone 6

Secondary Osteoarthritis

• Arthritis develops in joints adjacent to pagetic bone due to altered biomechanics and bone deformity 2, 5
• This complication contributes significantly to pain and disability, and notably does not respond well to antiresorptive therapy 5

Neurological Complications

Nerve Compression Syndromes

• Spinal stenosis can occur when pagetic vertebrae compress the spinal cord 6
• Nerve entrapment syndromes develop as enlarged pagetic bone compresses peripheral nerves 6, 5
• These neurological complications may cause pain that does not respond to bisphosphonate therapy, requiring alternative management strategies 5

Hearing Loss and Deafness

• Deafness occurs when Paget's disease affects the skull, particularly the temporal bone 6, 2
• This is one of the complications that current treatments have not been shown to prevent 5

Cardiovascular Complications

High-Output Heart Failure

• Heart failure can develop due to the increased vascularity of pagetic bone creating arteriovenous shunting and increased cardiac demand 6, 2
• The vascular steal syndrome associated with highly vascular pagetic bone contributes to this complication 6

Metabolic Complications

Hypercalcemia

• Hypercalcemia may occur, particularly during periods of immobilization when bone resorption exceeds formation 6
• This complication requires monitoring and appropriate management of calcium and vitamin D levels 4

Malignant Transformation

Osteosarcoma

• Sarcomatous degeneration is a rare but devastating complication of Paget's disease 6, 2
• Malignant degeneration represents one of the most serious potential outcomes, though it occurs infrequently 3

Dental and Oral Complications

• Dental problems can arise when Paget's disease affects the maxilla or mandible 6

Impact on Quality of Life

• The constellation of these complications results in musculoskeletal pain, significant disability, and impaired quality of life 2
• Many complications, once established, are irreversible, which is why treatment before complications develop is increasingly recommended for patients with active disease at high-risk sites 4, 3

Critical Clinical Caveat

Current bisphosphonate therapy, while effective at suppressing bone turnover and improving bone pain, has not been definitively proven to prevent major complications such as deafness, fracture, or bone deformity 5. However, restoration of normal bony architecture through aggressive treatment offers theoretical prospects for reducing complications related to deformity and increased bone fragility 2. This uncertainty underscores why treatment decisions for asymptomatic patients remain controversial, though many experts recommend treating active disease at sites where progression would significantly impair quality of life 4, 3.