Metabolic Bone Diseases

Question 1

This deck covers

Answer 1

Paget’s Disease

Rickets/Osteomalacia

Osteogenesis Imperfecta

Question 2

What is Paget’s Disease?

Answer 2

A localised disease of increased but uncontrolled bone turnover

Resorption increases and leads to increased formation

Typically affects old men

Question 3

What effect does Paget’s disease have on bone?

Answer 3

It becomes extremely disorganised:

• Bigger
• Less Compact
• More vascular
• More susceptible to deformity & fracture

Question 4

What bones are most commonly affected in Pagets disease?

Answer 4

Skull

Spine & pelvis

Long bones of lower extremities

Question 5

Describe the typical presentation of Paget’s disease

Answer 5

Majority asymptomatic with incidental finding of raised ALP

If symptomatic:

• bone pain - deep, boring
• deformity - bowing of tibia or bossing of skull

Question 6

What are some complications of Paget’s disease?

Note - as its usually asymptomatic, these may be the presentations/first symptoms

Answer 6

Fractures

Deafness

Osteosarcoma

Skull thickening

Question 7

How do we test for Paget’s disease?

What findings are in keeping with it?

Answer 7

Blood tests:

Raised ALP with normal Ca²⁺ and Phosphate

LFTs

Can x-ray for lytic lesions and thickened bone cortices

Question 8

how do we treat Paget’s?

Answer 8

IV bisphosphonates

(Zoledronic acid)

Only indicated when symptomatic, affecting the skull or in area requiring surgical intervention

Question 9

What are rickets and osteomalacia?

Answer 9

Diseases of insufficient bone mineralisation due to a deficiency of Vit D or Ca

Question 10

What’s the primary difference between rickets and osteomalacia?

Answer 10

Rickets = in growing kids

Osteomalacia = in adults*

(*following closure of growth plates)

Question 11

How do Rickets and osteomalacia each affect the structural integrity of the bones?

Answer 11

Rickets - problems are more to do with growth of bones:

• softening
• impaired growth
• malformations

Osteomalacia - affects bones once fully formed:

• weakening - thus more associated with fractures
• softening

Question 12

What are the typical features of rickets?

Answer 12

Skeletal deformities:

• Bow legged (younger) - varus
• Knocked knees (older kids) - valgus
• (more in another slide)

Growth retardation & failure to thrive

Hypotonia (low Vit D)

Question 13

What skeletal deformities may be seen in Ricket’s?

Answer 13

Bow legs (varus)

Knocked knees (valgus)​

Wide joints (wrists, elbows, ankles)

Kyphoscoliosis

Rickety rosary (deformed ribs)

Frontal bossing of skull

Question 14

What are the features of osteomalacia?

Answer 14

In adults with:

• Bone pain/tenderness
• Proximal myopathy (waddling gait)
• Increased falls & fractures

Question 15

How do we test for Rickets & Osteomalacia?

What results would be in keeping?

Answer 15

Bloods:

• 25-OH Vit D - low
• Calcium - low
• Phosphate - low
• ALP - high
• PTH - high

Xray?

Bone biopsy?

Question 16

How do we treat Rickets & osteomalacia?

Answer 16

Look for any thing that could cause a deficiency e.g. Liver damage, anti-convulsant drugs, renal failure or malabsoption disorders

Assuming it’s a primary deficiency then treat with Ca & Vit D supplements

Question 17

What is Osteogenesis Imperfecta?

Answer 17

A genetic disorder of absent/defective type 1 collagen that is characterized by incredibly fragile bones - leading to fractures due to mild trauma or activities of daily living

Question 18

When does OI onset?

Answer 18

Can be from pre-natally fatal all the way up to 40yr olds diagnosed with “Early onset OP”

Question 19

How does OI present?

Answer 19

Main thing is easy fractures but also:

• Growth deficiency
• Dentigenesis imperfecta
• Hearing loss
• Blue sclera (Vitreous humour is blue, the sclera become see through)
• Scoliosis or barrel chest
• Ligamentous laxity
• Easy bruising

Question 20

What is ligamentous laxity?

How is this scored?

Answer 20

An effect of OI, essentially its joint hypermobiltiy

Scored using the beighton score

Question 21

How do we manage osteogenesis imperfecta?

Answer 21

Surgical management of fractures

IV bisphosphonates to prevent fractures

Education & Social adaptations to prevent fractures

Potentially genetic counselling