Synonym: osteitis deformans
Sir James Paget described Paget's disease of bone in 1877. There is increased bone turnover in focal areas of the skeleton and one or many bones can be affected:
- There is a lytic phase to the disease process with an increase in bone resorption and abnormal osteoclast activity. This leads to a rapid increase in bone formation by osteoblasts. In the sclerotic phase, the focus is on bone formation.
- The structure of this new bone is disorganised and it is mechanically weaker, more bulky, less compact, more vascular, and liable to pathological fracture and deformity.
- Burnt-out Paget's disease is the term for when the abnormal activity and hypercellularity die down.
- Paget's disease of bone has a predilection for the axial skeleton, particularly the lumbosacral spine and pelvis, as well as the skull, femur and tibia.
- The thoracic spine, sacrum and humerus may also be affected. The hands and feet are rarely affected.
For the rest of this article 'Paget's disease' means 'Paget's disease of bone'.
- Paget's disease has been estimated to occur in 1-3% of people over age 55 years, and in as many as 8% of people over the age of 80 years in certain countries.
- The highest prevalence is in England, the USA, Australia and New Zealand, mainly among patients older than 55 years. It is rare in Asia, Scandinavia and most of Latin America.
- There is a male preponderance of about 3:2.
- Both genetic and environmental factors are thought to play a role.
- Autosomal dominant inheritance has also been described in some families.
- Mutations have been identified in four genes that cause Paget's disease, of which sequestosome 1 (SQSTM1) mutation is the most important. Patients carrying this mutation seem to be severely affected by Paget's disease and there is a high degree of penetrance.
- The mechanisms underlying the focal nature of the disease are unclear. Mechanical stress may play a role.
- Paramyxovirus infection (including measles and respiratory syncytial virus) has been suggested as a possible trigger but this has been disputed.
- It is commonly asymptomatic and is discovered by the incidental finding of an elevated serum alkaline phosphatase or characteristic abnormality on X-ray.
- When symptoms occur, the most common complaints are bone pain and/or deformity.
- Pain may be present at rest, at night and on movement but does not tend to be focused around a joint.
- Other presentations include pathological fractures or one of the other complications listed below.
- Skin temperature may be increased over areas of active disease.
- It is monostotic (affecting one bone) in a third of cases and polyostotic (affecting two or more bones) in the remaining two thirds.
Complications from Paget's disease depend on the site affected and the activity of the disease.
- Bone pain.
- Bone deformity (including sabre tibia (bowing of the tibia), kyphosis, frontal bossing of the skull, an enlarged maxilla, an increase in head size).
- Pathological fractures (may produce heavy bleeding from the very vascular bone).
- Osteoarthritis (due to Paget's disease around a joint).
- Deafness and tinnitus may be due to compression of cranial nerve VIII, effects on ear ossicles (eg, stapes fixation) and cochlear dysfunction.
- Hypercalcaemia (with immobilisation, usually due to dehydration).
- High-output cardiac failure (due to increased blood flow through affected bone).
- Paraplegia (can occur in disease affecting the spine).
- Bone-specific alkaline phosphatase levels are raised.
- Serum calcium, phosphorus, and parathyroid hormone levels are usually normal but immobilisation may lead to hypercalcaemia.
- X-rays may show a number of signs:
- Both osteolysis (seen as radiolucency) and excessive bone formation occur.
- There are specific X-ray features of Paget's disease that include:
- A classical V-shaped pattern between healthy and diseased long bones, known as 'the blade of grass' lesion.
- The 'cotton wool' pattern in the skull that is also characteristic (multifocal sclerotic patches).
- Osteosarcomas also have a distinct radiological appearance.
- Radionuclide bone scans can show the extent of the disease.
- Bone biopsy may be needed if malignant change is suspected.
- The objectives of treatment are control of pain and to reduce or prevent disease progression and complications.
- There is debate as to when to start medical treatment. Some start treatment if alkaline phosphatase levels are raised; others only start treatment if there are symptoms.
- Specific treatment is required for complications.
- Because of the risk of osteosarcoma, patients should be monitored indefinitely. Presentation of osteosarcoma is classically with increased bone pain that is poorly responsive to medical treatment, local swelling, and possibly a pathological fracture. X-ray and bone biopsy can help to confirm the diagnosis (see 'Investigations', above).
- Orthotic devices, sticks and walkers may be useful for disease of the legs if it causes problems with walking.
- Patients taking bisphosphonates should maintain an adequate intake of calcium and vitamin D.
- Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol may be effective for pain.
- Anti-resorptive therapy is usually with bisphosphonates. For those intolerant of bisphosphonates, subcutaneous calcitonin can be used for a limited period due to its associated risk of malignancy with long-term use.
- Oral or intravenous bisphosphonates are the mainstay of treatment.
- They are thought to reduce bone turnover, improve bone pain, promote healing of osteolytic lesions and restore normal bone histology.
- Zoledronate is a popular option as it can achieve high rates of biochemical remission and sustain long duration of suppression by a single intravenous dose.
- Any calcium and vitamin D deficiency needs to be corrected before starting a bisphosphonate to avoid hypocalcaemia.
- Bisphosphonate may cause osteonecrosis of the jaw. The risk of osteonecrosis of the jaw is substantially greater for patients receiving intravenous bisphosphonates in the treatment of cancer than for patients receiving oral bisphosphonates for osteoporosis or Paget's disease.
- Serial monitoring of alkaline phosphatase is used to monitor the effects of treatment and disease activity.
- Bone deformity, osteoarthritis, pathological fractures and nerve compression may necessitate surgery.
- Bisphosphonates should be used pre-operatively to try to reduce disease activity in order to prevent severe bleeding during surgery.
- After surgery, bone healing may be prolonged, and lengthy rehabilitation may be necessary.
- Amputation may be necessary for osteosarcoma of long bones.
- Decompressive laminectomies may be necessary if medical therapy fails to help those with neurological problems from spinal cord compression.
- This depends on the extent and degree of disease activity.
- Remission may be possible with successful treatment.
- Those who develop osteosarcoma have a very poor prognosis.
- James Paget was born in Great Yarmouth in Norfolk in 1814.
- At 16 he became apprentice to a local surgeon and apothecary and four years later he entered St. Bartholomew's Hospital, London, to which he was associated throughout his life and where he studied or worked from 1834 to 1871.
- He is regarded as one of the great founders of modern pathology.
- In 1854 he became surgeon extraordinary to Queen Victoria and, a few years later, surgeon ordinary to the Prince of Wales.
- He became professor of anatomy and surgery at the Royal College of Surgeons of England (1847-1852) and was elected fellow of the Royal Society in 1851, becoming its vice president in 1873-1874 and president in 1875.
- He was honorary vice chancellor of the University of London and was named doctor of honour of law at the universities of Oxford, Cambridge and Edinburgh.
Further reading and references
Ralston SH, Langston AL, Reid IR; Pathogenesis and management of Paget's disease of bone. Lancet. 2008 Jul 12372(9633):155-63.
Seton M; Paget disease of bone: diagnosis and drug therapy. Cleve Clin J Med. 2013 Jul80(7):452-62. doi: 10.3949/ccjm.80a.12142.
Paget Disease of Bone 5, Juvenile-onset, PDB5; Online Mendelian Inheritance in Man (OMIM)
Griz L, Fontan D, Mesquita P, et al; Diagnosis and management of Paget's disease of bone. Arq Bras Endocrinol Metabol. 2014 Aug58(6):587-99.
Ferraz-de-Souza B, Correa PH; Diagnosis and treatment of Paget's disease of bone: a mini-review. Arq Bras Endocrinol Metabol. 2013 Nov57(8):577-82.
Paget Disease of Bone; PDB, Online Mendelian Inheritance in Man (OMIM)
Bertoldi I, Cantarini L, Filippou G, et al; Paget's disease. Reumatismo. 2014 Jul 2866(2):171-83. doi: 10.4081/reumatismo.2014.789.
Ralston SH; Clinical practice. Paget's disease of bone. N Engl J Med. 2013 Feb 14368(7):644-50. doi: 10.1056/NEJMcp1204713.
Singer FR, Bone HG 3rd, Hosking DJ, et al; Paget's disease of bone: an endocrine society clinical practice guideline. J Clin Endocrinol Metab. 2014 Dec99(12):4408-22. doi: 10.1210/jc.2014-2910.
Wat WZ; Current perspectives on bisphosphonate treatment in Paget's disease of bone. Ther Clin Risk Manag. 2014 Nov 2010:977-83. doi: 10.2147/TCRM.S58367. eCollection 2014.
British National Formulary (BNF); NICE Evidence Services (UK access only)
Karaoglan A, Akdemir O, Erdogan H, et al; A rare emergency condition in neurosurgery: foot drop due to Paget's disease. Turk Neurosurg. 2009 Apr19(2):208-10.