Pathological fractures profoma

Question 1

Define fracture

Answer 1

loss of continuity of the cortex of a bone.

Question 2

Define pathological fracture

Answer 2

a fracture through bone weakened by a pre-existing pathological process.

Question 3

Epidemiology of pathological fractures

Answer 3

Occurs in 8% to 30% of patients w/ bone metastases

80% occur in breast (50%), prostate, kidney, lung, or thyroid cancer.

Proximal long bones are more commonly involved than distal bones.
- 50% of pathologic fractures occur in femur
- 15% occur in humerus

Femoral neck & head - most common location for pathological fracture due to tendency for metastases to involve proximal bones & because of the stress of weight placed on this part of the femur.

Question 4

Aetiology (causes) of pathological fractures

Answer 4

• Bone tumours- benign or malignant.
• Paget’s disease of bone
• Lymphoma or multiple myeloma (MM can cause lytic lesions & osteoporosis).
• Osteoporosis
• Osteomalacia or rickets
• Hyperparathyroidism
• Hyperthyroidism
• Rheumatoid Arthritis
• Osteomyelitis
• Osteogenesis imperfecta

NOTE: Too much thyroxine speeds up the rate of bone resorbtion, leading to osteoporosis.

Question 5

Pathophysiology of pathological fractures

Answer 5

Fractures occur in patients w/ decreased bone strength & those who experience an injury.
- Factors that determine bone strength= age, bone mass, bone quality.

Tumour= uncontrollable cell division
- if it remains stationery= benign
- if it invades other tissues & metastasizes= malignant

Primary malignancies arise from bone cells, secondary malignancies develop elsewhere e.g. breast, prostate, thyroid and kidneys.

Bone are made from:
- Osteoblasts → build new bone
- Osteoclasts → breakdown bone (resorption)
- Mesenchymal stem cells + neuroectodermal cells which can differentiate into other cell types

Proto-oncogenes stimulate normal cell growth
- These can mutate & become oncogenes which overstimulate cell growth.

Tumour suppressor genes promote apoptosis
- mutated tumour suppressor genes = cause growth of tumours.

E.g. of bone tumours:
- osteochondroma
- giant cell tumour
- osteoblastoma
- osteoid sarcoma

Question 6

Presentation of pathological fractures

Answer 6

Deformity- angulation or shortness. e.g. Neck of femur fractures are shortened, externally rotated & abducted.

Affected limb will be swollen & bruised

Significant tenderness to palpation.

Mild or severe pain near affected joint

Numbness & tingling

Skin - open or closed fractured.

Question 7

Investigation for pathological fractures

Answer 7

1. Neurovascular examination
2. Blood tests:
   - Serum calcium
   - PTH
   - ALP
   - Vitamin D
   - Myeloma screen
   - Thyroxine screen
   - Phosphate
   - FBC
3. Evaluation of possible primary sites - breast, prostate, lung, thyroid, kidney.
4. X-ray - taken in 2 planes (anteroposterior (AP) & lateral), 90° degrees to each other, of injured bones. Surrounding bones should also be examined- above & below
5. N-telopeptide & C-telopeptide-
   markers of bone collagen breakdown measured in urine & serum
   - confirm increased destruction caused by bone metastasis & measure the overall extent of bone involvement.
6. Biopsy- confirm diagnosis in suspected primary malignant tumour - for patients over 40 w/ lesions of unknown cause. - However, can cause seeding of cancer cells.

Question 8

Initial management of pathological fractures

Answer 8

• Analgesia
• Control any external bleeding by direct pressure.
• For open fractures, cover wounds w/ sterile dressings & give IV antibiotics
• Immobilise the fractured bone - plaster, splint, brace, sling.
• Arrange imaging & further investigations.

Question 9

Definitive management for pathological fractures

Answer 9

1. Reduction of any deformities (displacement, angulation, rotation)
   - Closed reduction- performed by manipulating the fracture into position - can be done under sedation or a general anaesthetic.
   - Open reduction - involves surgical procedure to open fracture site & reduce the bones accurately - usually accompanied by operative stabilisation.
   - Intra-articular fractures are treated w/ open reduction so that joint can be accurately reduced, minimizing the risk of secondary osteoarthritis.
2. Stabilisation (maintain reduction until healing occurs).
   - Allows for early mobilisation.
   - Achieved by external splinte.g. plaster cast, without an operation.
   - Intra-operative fixation can be w/ percutaneous pinning w/ wires, plates & screws, intra-medullary nail for long-bone fractures or external frame fixation

NOTE- View notes for diagrams!

3.Rehabilitation (rehabilitate the limb & patient).
- Range-of-movement exercises.
- Physiotherapist
- Following hip fracture, elderly patients require input from physiotherapy, occupational therapy & social workers to become self-caring & safe prior to discharge

4. Prevention of further fractures
   - Bisphosphonates - stops bone resorbtion.
   - Adcal
   - Denosumab - RANK-ligand inhibitor - stops osteoclast differentiation.

NOTE: Bisphosphonates can cause osteonecrosis of jaw

Question 10

Prognosis for pathological fractures

Answer 10

Prognosis extremely poor

Pathological fractures are frequently a marker of end-stage cancer & the end of functional independence.

Surgery successfully reduces local pain & allows early mobilisation - low complication rate too.