Paget disease of bone

contributed by Dr Frank Gaillard on May 2, 2008

System: Musculoskeletal

Paget’s disease of the bone is a chronic bone disorder characterised by excessive abnormal bone remodelling.

Epidemiology

It is relatively common and can affect upto 4% of individuals over 40 and up to 11% over the age of 80 ¹ . There may a slight male predilection.

Pathology

The aetiology is not entirely known, however viral infection in association with genetic susceptibility has been postulated.

There are three stages classically described (but is part of continuous spectrum)

lytic (incipient active) : predominated by osteoclastic activity
mixed (active) : osteoblastic as well as osteoclastic activity
sclerotic / blastic (late inactive)

These stages correspond to scintigraphic stages : hot; intermediate; and cold.

Polyostotic disease is more common than the monostotic type ¹. The most frequent sites of involvement are :

spine
pelvis (often asymmetric)
skull
proximal long bones

Markers

serum alkaline phopatase (ALP) elevated
urine hydroxyproline increased

Radiographic features

Plain film

The early phase features osteolytic (lucent) region which is later followed by coarsened trabeculae and bony enlargement. Sclerotic changes occur much later in the disease process. In the skull the thickening involves both the inner and outer table.

Bone scintigraphy

Extremely sensitive but not specific. Demonstrates marked increased uptake in all phases of disease ¹ .

Other Paget's disease related signs include

Complications

osseous weakening resulting in deformity and fractures
arthritis
neural compression
- deafness is the most common complication
- cranial nerve paresis may occur
- basilar invagination may occur in advanced cases with hydrocephalus or brainstem compression
secondary development of tumours (e.g. osteosarcoma : ≈ 1 % of cases), which is often highly resistant to treatment
high output congestive cardiac failure
hyperparathyroidism (approximately 10 %)