Paget disease of bone


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Paget disease of bone


Pediatric musculoskeletal conditions

Radial head subluxation (Nursemaid elbow)

Developmental dysplasia of the hip

Legg-Calve-Perthes disease

Slipped capital femoral epiphysis

Transient synovitis

Osgood-Schlatter disease (traction apophysitis)

Musculoskeletal injuries and trauma

Rotator cuff tear

Dislocated shoulder

Radial head subluxation (Nursemaid elbow)

Winged scapula

Thoracic outlet syndrome

Carpal tunnel syndrome

Ulnar claw

Erb-Duchenne palsy

Klumpke paralysis

Iliotibial band syndrome

Unhappy triad

Anterior cruciate ligament injury

Patellar tendon rupture

Meniscus tear

Patellofemoral pain syndrome

Sprained ankle

Achilles tendon rupture



Degenerative disc disease

Spinal disc herniation


Compartment syndrome


Bone disorders

Osteogenesis imperfecta


Pectus excavatum


Genu valgum

Genu varum

Pigeon toe

Flat feet

Club foot

Cleidocranial dysplasia



Bone tumors




Osteomalacia and rickets


Paget disease of bone


Lordosis, kyphosis, and scoliosis

Joint disorders



Spinal stenosis

Rheumatoid arthritis

Juvenile idiopathic arthritis


Calcium pyrophosphate deposition disease (pseudogout)

Psoriatic arthritis

Ankylosing spondylitis

Reactive arthritis


Septic arthritis


Baker cyst

Muscular disorders

Muscular dystrophy



Inclusion body myopathy

Polymyalgia rheumatica



Neuromuscular junction disorders

Myasthenia gravis

Lambert-Eaton myasthenic syndrome

Other autoimmune disorders

Sjogren syndrome

Systemic lupus erythematosus

Mixed connective tissue disease

Antiphospholipid syndrome

Raynaud phenomenon


Limited systemic sclerosis (CREST syndrome)

Musculoskeletal system pathology review

Back pain: Pathology review

Rheumatoid arthritis and osteoarthritis: Pathology review

Seronegative and septic arthritis: Pathology review

Gout and pseudogout: Pathology review

Systemic lupus erythematosus (SLE): Pathology review

Scleroderma: Pathology review

Sjogren syndrome: Pathology review

Bone disorders: Pathology review

Bone tumors: Pathology review

Myalgias and myositis: Pathology review

Neuromuscular junction disorders: Pathology review

Muscular dystrophies and mitochondrial myopathies: Pathology review

Pediatric musculoskeletal disorders: Pathology review


Paget disease of bone


0 / 22 complete

USMLE® Step 1 questions

0 / 2 complete

High Yield Notes

16 pages


Paget disease of bone

of complete


USMLE® Step 1 style questions USMLE

of complete

A 65-year-old man comes to the office because of deep and aching hip pain. The pain is constant throughout the day and worsens with weight-bearing activity. The patient also reports that his shoe size has increased over the past year, and he has progressively lost hearing from both ears. Medical history includes admission for a renal calculus one-month ago. Laboratory investigations demonstrate an isolated increase in serum alkaline phosphatase. A pelvic x-ray is obtained, and the results are as follows:

Reproduced from: Wikimedia Commons

The patient’s current condition places him at risk of developing which of the following pathologies?  

External References

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Alkaline phosphatase (ALP) p. 399, 473

Paget disease of bone p. 473

Arthritis p. 476

Paget disease of bone p. 718


in Paget disease of bone p. 473

Head size

Paget disease of bone p. 473

Hearing loss p. 552

Paget disease of bone p. 473

Heart failure p. 318

Paget disease of bone p. 473

Osteitis deformans p. 473

Osteoblasts p. 473

Paget disease of bone p. 473

Osteoclasts p. 473

Paget disease of bone p. 473

Paget disease of bone p. 473

bisphosphonates p. 499

lab values in p. 474

osteosarcomas and p. 474

presentation p. 718

woven bone in p. 456

Parathyroid hormone (PTH) p. 336

Paget disease of bone p. 473

Phosphorus in Paget disease of bone p. 473

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Content Reviewers

Rishi Desai, MD, MPH


Evode Iradufasha, MD

Evan Debevec-McKenney

Pauline Rowsome, BSc (Hons)

Paget disease of bone is a disorder in which there’s a lot of bone remodeling that happens in some regions of the bone.

Typically there’s excessive bone resorption followed by excessive bone growth, and it leads to skeletal deformities and potential fractures.

Normally, bones undergo a continuous process of bone remodeling.

Old brittle bone tissue gets reabsorbed by multinucleated bone cells called osteoclasts, which have 5 to 20 nuclei per cell.

The resorbed bone tissue gets replaced by a new one made by another type of bone cell called an osteoblast.

At the cellular level, the process begins when osteoblasts release receptor activator of nuclear factor κβ ligand, or RANKL for short, which is a substance that binds to RANK receptors on the surface of osteoclast.

When RANKL binds to the RANK receptor, it activates the osteoclasts, and they start secreting lysosomal enzymes like collagenase as well as hydrochloric acid.

Together they digest the collagen protein and dissolve the minerals that make up the bone matrix.

Once there’s been sufficient bone demineralization, the osteoblasts secrete another substance called Osteoprotegerin, or OPG for short, which binds RANKL and prevents it from activating the RANK receptors. This causes the osteoclasts to stop demineralizing the bones.

Once that happens, the osteoblasts start secreting a substance called osteoid seam, which is mainly made up of collagen and acts like a scaffold upon which calcium and phosphate can get deposited. And that’s how new bone begins to get formed again.

The exact cause of Paget disease of bone is unclear, but it can get triggered by infections like the measles virus, and is linked to genetic mutations like the SQSTM1 mutation, which encodes a protein involved in regulating osteoclasts.


Paget's disease of bone, also known as osteitis deformans, is a chronic bone disorder that causes the bone to become thick, weak, and deformed. It commonly affects the pelvis, femur, and lower lumbar spine though it can affect any bone in the body.

Paget disease is associated with an increased risk of fractures, arthritis, and bone tumors. Symptoms may include pain in the affected bone or due to arthritis or nerve impingement. Treatment involves medications to slow the progression of the disease, such as bisphosphonates, pain relievers, and surgery to correct deformities or stabilize fractures.


  1. "Robbins Basic Pathology" Elsevier Canada (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 7/E (ENHANCED EBOOK)" McGraw Hill Professional (2014)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Paget's Disease of Bone" New England Journal of Medicine (2013)
  6. "Epidemiology and pathology of Paget’s disease of bone – a review" Wiener Medizinische Wochenschrift (2016)
  7. "Pathogenesis of Paget Disease of Bone" Calcified Tissue International (2012)

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