Paget's disease of bone

Question 1

definition of paget’s disease of bone

Answer 1

characterised by excessive bone remodelling at 1 (monostotic) or more (polystotic) sites = bone that is structurally disorganised

Question 2

cause of paget’s disease of bone

Answer 2

unknown

genetic and viral - suggested by familial and pathologic studies

excessive bone resorption by abnormally large osteoclasts, followed by increased bone formation by osteoblasts in a disorganised fashion

results in abnormal (mosaic) pattern of lamellar bone

marrow spaces filled by an excess of fibrous tissue with marked increase in bv

bone enlargement, deformity and weakness

Question 3

epidemiology of paget’s disease of bone

Answer 3

older age

3% of all >50yrs

10% of all >80yrs

common in temperate climates and anglo-saxons

Question 4

symptoms of paget’s disease

Answer 4

asymptomatic

insidious onset pain, aggravated by weight bearing and movement (may be caused by pagetic process, associated degenerative joint disease and stress fractures)

headaches

deafness

increasing skull size

bony deformity and enlargement - pelvis, lumbar spine, femur nad tibia (bowed sabre tibia)

Question 5

signs of paget’s disease of bone

Answer 5

bitemporal skull enlargement with frontal bossing

spinal kyphosis

anterolateral bowing of femur, tibia or forearm

skin over involved bone may be warm - from increased vascularity

sensineural deafness - compression of the vestibulocochlear nerve

Question 6

classes of investigations for paget’s disease of bone

Answer 6

blood

XR

bone scan - 99mTC MDP

resorption markers

Question 7

blood results indicating paget’s disease of bone

Answer 7

high AlkPhos

Ca and phos normal - except if immobilised

Question 8

bone XR for paget’s disease

Answer 8

enlarged deformed bones

mixed lytic, sclerotic appearance

eg osteoporosis circumscripta of the skull

lack of distinction between cortex and medulla

cotton wool appearance

affinity for axial skeleton, long bones and skull

Question 9

bone scan for pagets disease

Answer 9

assess extent of skeletal involvement

not specific for dx

pagetic bone lesions seen as focal areas of markedly increased uptake - hot spots

Question 10

resorption markers for paget’s disease

Answer 10

urinary hydroxyproline

Question 11

complications of paget’s disease`

Answer 11

pathological fractures

osteoarthritis

increase Ca

nerve compression due to bone overgrowth - deafness, root compression

high output CCF if >40% skeleton involved

osteosarcoma - suspect if sudden onset or worsening

Question 12

mx of pagets disease of bone

Answer 12

bisphosphonate