Pathological fracture (MSK)

Question 1

Define pathological fracture.

Answer 1

A spontaneous fracture following mild physical exertion or minor trauma due to abnormal weakness of the bone that is caused by an underlying condition

Occurs in abnormal bone due to insignificant injury

Question 2

What are the two types of causes of pathological fracture?

Answer 2

• disorders affecting bone metabolism:
  
  • osteoporosis/osteopenia
  • Paget disease
  • osteopetrosis - rare diseases that causes bone to grow abnormally and become overly dense and brittle
  • osteomalacia
  • osteogenesis imperfecta
• masses:
  
  • malignant bone tumours e.g. osteosarcoma (sunburst pattern on XR), chondrosarcoma, Ewing’s tumour (onion skin appearance on XR)
  • bone metastases
  • benign bone tumours
  • multiple myeloma

Question 3

What are some examples of disorders affecting bone metabolism causing pathological fracture? (5)

Answer 3

• osteoporosis/osteopenia
• Paget’s disease
• osteopetrosis (causes bone to grow abnormally and become overly dense and brittle)
• osteomalacia
• osteogenesis imperfecta

Question 4

What are some examples of masses that can cause pathological fracture? (4)

Answer 4

• malignant bone tumours e.g.
  
  • osteosarcoma (sunburst on XR)
  • chondrosarcoma
  • Ewing’s tumour (onion skin on XR)
• bone metastases
• benign bone tumours
• multiple myeloma

Question 5

What are the common locations of pathological fractures? (3)

Answer 5

• spine
• hip
• wrist

Question 6

What finding could raise suspicion of Paget’s disease?

Answer 6

Isolated ALP elevation

Question 7

How would you treat Paget’s disease?

Answer 7

Bisphosphonates (Alendronate)

Question 8

What is the initial investigation for suspected malignant bone tumours, and how do we confirm diagnosis?

Answer 8

• plain radiograph
• biopsy done to confirm radiological diagnosis

Question 9

What will be raised in bone metastases? (2)

Answer 9

• calcium
• ALP

Question 10

What can bony metastases from other organs be? (2)

Answer 10

Blastic or lytic:

• blastic = prostate
• blastic/lytic = breast
• lytic = kidney, thyroid, lung

Question 11

What are some x-ray findings of pathological fracture? (2)

Answer 11

• sclerotic lesions
• osteolytic lesions

Question 12

What is osteoporosis/osteopenia (pathological fracture)?

Answer 12

• reduced bone mineral density –> increases likelihood of fracture
• osteoclast activity > osteoblast activity
• female: ability to regulate osteoblast activity decreases after menopause
• senile patients at higher risk
• secondary causes of OP: hypogonadism, glucocorticoid excess, alcoholism

Question 13

What DEXA scan scores indicate osteoporosis and osteopenia?

Answer 13

• T-score -1 to -2.5 –> osteopenia
• T-score <-2.5 –> osteoporosis

Question 14

How do we manage osteoporosis/osteopenia? (3)

Answer 14

• calcium and vitamin D supplements
• stimulate bone formation
• alendronate (bisphosphonate) - inhibits osteoclast activity

Question 15

Describe vitamin D deficiency (as a cause of pathological fracture).

Answer 15

• inadequate sun exposure, malabsorption, liver disease, renal disease, receptor deficits
• children = RICKETS –> varus deformities due to inapt bone formation before physis closure
• adults = OSTEOMALACIA –> bone pain
• DEXA scan: demineralisation of bone

Question 16

What is osteogenesis imperfecta (as a cause of pathological fracture)?

Answer 16

• autosomal dominant or recessive
  
  • inherited condition - mutation in COL1A1 gene –> increased steric hindrance between different chains, disrupts disulfide bridges –> decreased type 1 collagen
• brittle bones, blue sclera, hearing difficulties, heart pathology

Question 17

What is Paget’s disease (as a cause of pathological fracture)?

Answer 17

• excessive bone breakdown and disorganised remodelling
• deformities, pain, fractures, arthritis –> malignant disease
• treat with bisphosphonates

Question 18

What are the stages of Paget’s disease? (4)

Answer 18

1. osteoclastic activity
2. mixed osteoclastic-osteoblastic activity
3. osteoblastic activity
4. malignant degeneration