Paget's disease of bone Flashcards
Define Paget’s disease of bone.
Increased but uncontrolled bone turnover
A chronic bone disorder that is characterised by focal areas of increased bone remodelling, resulting in overgrowth of poorly organised bone.
How common is Paget’s?
Second most common chronic bone-remodelling disorder after osteoporosis
Paget’s disease is common (UK prevalence 5%) but symptomatic in only 1 in 20 patients
What are the degrees of bone involvement in Paget’s disease?
Monostotic (25%) - one bone (femur most common)
Polyostotic (75%) - more than one bone (femur, pelvis, skull or tibia)
What is the aetiology of Paget’s disease?
UNKNOWN
Genetics - ?autosomal dominant pattern
Infection - ?paramyxoviruses e.g. measles, RSV, canine distemper virus
Environmental -?high arsenic, contact with cattle, dogs, other pets.
What is the pathophysiology of Paget’s?
Localised areas of hyperactivity of bone - osteoclasts responsible; abnormally large with excess nuceli cause increased bone resorption –> large pits and cavities.
To compensate osteoblast activity is increased but newly formed bone is not organised and remains irregular and woven in nature → fracture risk
Paget’s disease evolves through three distinct phases:
- Short-osteoclastic phase
- A mixed phase of both osteoclastic and osteoblastic activity
- Chronic sclerotic phase, when bone formation outweighs bone resorption.
What are the risk factors for Paget’s?
- FH
- Age >50yrs
- Male sex
- Infection - paramyxoviruses such as the measles virus, respiratory syncitial virus, and canine distemper virus
- Environmental factors - ?arsenic, cattle, dogs, pets
What are the signs and symptoms of Paget’s disease?
Asymptomatic OR
- old male with bone pain and raised ALP
- long-bone/back pain
- bony deformities - frontal bossing, proganthism, bone bowing, loosening of teeth and disturbance in chewing
Other:
- locally warm
- hearing loss - in cranial nerve VII involvement
- facial pain - CNV
- deterioration of visual acuity
What investigations would you do for Paget’s disease?
Plain X ray -
- Early - mostly lytic lesions, common in skull
- Advancing - V shaped lytic lesions in long bones, occasional fractures; mostly incomplete
- Later- sclerotic picture predominated over osteolytic
Bone scan (e.g. scintigram, technetium) - areas of dense uptake in pagetoid bone
Serum ALP - elevated in 85-100%; bone specific ALP is more specific
Serum calcium - normal (rare hypercalcaemia; usually indicates PHPT)
Bone biopsy - osteoclasts with multile nuclei, wide canaliculi with dosorganised matrix in bone, mosaic pattern of poorly organised lamellar bone
Other:
Other markers of bone turnover:
- procollagen type I N-terminal propeptide (PINP)
- serum C-telopeptide (CTx)
- urinary N-telopeptide (NTx)
- urinary hydroxyproline
How is Paget’s managed?
If asymptomatic → monitoring alone.
If symptomatic :
1st line: Bisphosphonate (e.g. oral risedronate or zoledronic acid) - slows down excessive osteoclastic activity
+ Monitoring - at 6months then every 6-12 months
+ Physiotherapy
+/- Orthoses e.g. walking aids, sticks, crutches and walkers
+/- Hearing aids
+/- Analgesia
Clacitonin (less commonly used now) - may heal lytic lesions
Surgery - for complications like fractures or osteoarthritis; laminectomy for spinal stenosis
What are the risk factors for Paget’s?
- Increasing age
- Male sex
- Northern latitude
- FH
What are some indications for treatment in Paget’s?
Indications for treatment:
- bone pain
- skull or long bone deformity
- fracture
- periarticular Paget’s
What is used for monitoring treatment in Paget’s disease?
- Bone specific ALP
- P1NP
- CTX
Measure every 6-12 months of treatment
What are the complications of Paget’s?
- Arthritis
- Hearing loss/tinnitus
- Spinal stenosis
- Osteosarcoma
- High output cardiac failure
- Pathological fractures
- Oesophagitis - from bisphosphonates
- Hydrocephalus
- Kidney stones
What is the prognosis with Paget’s?
Varies, usually good.
Better if treatment started before any complications develop.
