Bone pathology

Question 1

Identify these two types of bone?

Answer 1

Left: woven bone

Right: lamellar bone

Question 2

Define a fracture?

Answer 2

A disruption in the integrity of a living bone

Question 3

How can fractures be classified?

Answer 3

Complete vs incomplete

Dsiplaced

Comminuted

Open vs closed (compound vs simple)

Munted

Stress

Pathological

Question 4

Describe the difference between a complete and incomplete fracture?

Answer 4

Complete: break all of cortex

Incomplete: just break one side of cortex

Question 5

Describe a comminuted fracture?

Answer 5

Multiple bone fragments

Question 6

Define a stress fracture?

How are they detected?

Answer 6

Repeated low force injury to a normal bone

Use bone scan to see where tissue is active

Question 7

Define a pathological fracture?

Answer 7

A fracture that occurs in abnormal bone (e.g. osteoporosis, metastases)

Question 8

What are the stages of fracture healing?

Answer 8

1) Haematoma formation
2) Soft callus formation
3) Hard callus formation
4) Remodelling

Question 9

Describe the haematoma stage of fracture healing?

How long does this stage last?

Answer 9

Fibrin mesh creates framework

Platelets and leukocytes release inflammatory cytokines >

• granulation tissue
• bone cells activated

Variable necrosis

Lasts hours-days

Question 10

Describe the soft callus stage of fracture healing?

How long does this stage last?

Answer 10

Fibrocartilage formation > holds ends together

Periosteum repairs itself over the outside

Lasts days to weeks

Question 11

Describe the hard callus stage of fracture healing?

How long does this stage last?

Answer 11

Cartilage removal > osteoid formation > woven bone (endochondral ossification)

Lasts weeks to months

Question 12

Describe the remodelling stage of fracture healing?

How long does this stage last?

Answer 12

Woven bone transformed into lamellar bone

Result is completely reconstituted bone

Lasts months to years

Question 13

Describe the components of fracture healing present in this image?

Answer 13

Haematoma (left, dark purple)

Granulation tissue (next to haematoma)

Question 14

Describe the difference in fracture healing when the two ends of the fracture are closely apposed?

Answer 14

May not need soft callus at all

Faster healing

Similar to intramembranous ossification

Question 15

Describe the clinical management of a fracture?

Answer 15

Union of broken ends by:

• minimising the gap
• minimising the strain or movement (fixation)

Minimise any factors that slow healing (poor blood supply, infection, smoking)

Question 16

List the factors that slow fracture healing?

Answer 16

Age > 40 yo

Comorbidities, especially diabetes

NSAIDS or corticosteroids

Smoking

Poor nutrition

Open fracture

Poor blood supply

Multiple traumatic injuries

Local infection

Question 17

Describe some of the complications of fracture healing?

Answer 17

Non-union: fracture will not heal, despite persistent primary management

Delayed union: fracture does not heal as fast as expected

Mal-union: healing of a bone in an unacceptable position

Infection > osteomyelitis

Osteonecrosis: ischaemic bone when blood supply damaged

Question 18

What is Paget’s disease?

Answer 18

Large, overactive osteoclasts

Osteoblasts produce more bone

Results in thick soft cortex and coarse trabeculae

Question 19

What are the three stages of Paget’s disease?

Answer 19

Osteolytic: many osteoclasts

Mixed: bone breakdown and building

Osteosclerotic: heavy bone, abnormal structure, osteoclasts wear out

Question 20

Describe the presentig symptoms of bony mets?

Answer 20

Pathological fracture

Hypercalcaemia

Bone marrow failure

Bone pain

Question 21

Describe how malignant cells influence bone?

Answer 21

Malignant cells produce RANKL or PTHrP

Do not influence bone directly

Question 22

Which primary tumours commonly give rise to bony mets?

Answer 22

Breast

Bronchus

Byroid

Bidney

Bostate

(rarely, bowel)