Avascular Necrosis

Question 1

Why does avascular necrosis occur?

Answer 1

Interruption of

1. Arterial inflow
   - E.g. fracture
2. Venous outflow
   - E.g. infiltrative disorders that block sinusoids (Gaucher’s disease)

Question 2

List the causes of AVN

Answer 2

1. Fracture or dislocation
2. Sickle cell disease - infarcted areas of bone become infected with salmonella
3. Decompression sickness (Caisson disease)
4. Gaucher’s
5. Drug-induced (corticosteroids)
6. Idiopathic

Question 3

How is AVN classified?

Answer 3

By Ficat, according to:

1. Symptoms
2. Clinical findings
3. Radiological findings

Question 4

How does AVN appear on X-rays?

Answer 4

Initially no changes.
After a few weeks:
- Increased area of density in adjacent tissue (reactive bone formation)
Later on:
- Distorted outline as necrotic bone crumbles

Question 5

How does AVN appear on bone scans?

Answer 5

Area of increased uptake due to vascular reaction in adjacent bone

Question 6

What are the 2 main symptoms of AVN?

Answer 6

1. Pain
2. Stiffness
   Overall limited range of movement

Question 7

What is osteochondritis. Name the two subgroups?

Answer 7

Aka idiopathic AVN - a group of conditions in which areas of patchy AVN cause pain and limitation of movement, usually in adolescents

1. Traction apophysitis
2. Osteochondritis dessicans

Question 8

In what age group is osteochondritis most commonly seen?

Answer 8

Adolescents

Question 9

What is Freiberg’s disease?

Answer 9

AVN of the 2nd metatarsal head

Question 10

What is Kohler’s disease?

Answer 10

AVN of the navicular

Question 11

What is Kienboch’s disease?

Answer 11

AVN of the lunate

Question 12

What is Panner’s disease?

Answer 12

AVN of the capitulum of the humerus

Question 13

What is an apophysis?

Answer 13

A type of growth plate that occurs at the end of a bone, when there is no other bones on the other side, e.g. the calcaneal apophysis

Question 14

What is traction apophysitis?

Answer 14

Inflammation of an apophysis where a tendon attaches due to repetitive pulling forces

Question 15

What is the commonest traction apophysitis?

Answer 15

Osgood-Schlatter disease - pull of the quadriceps on the tibial tuberosity

Question 16

What is Osgood-Schlatter disease and how does it present?

Answer 16

A traction apophysitis due to pull of the quadriceps on the tibial tuberosity

Commonly presents as knee pain in growing adolescents.

Question 17

What is Sever’s disease?

Answer 17

A traction apophysitis of the calcaneum due to pull from the Achilles tendon

Question 18

How is Osgood Schlatter disease treated?

Answer 18

Typically self-limiting - may take months to years to resolve entirely.

• Conservative measures
• Stop sports
• Surgical excision in chronic cases where there is a bony ossicle in the patellar

Question 19

Is surgery indicated in the treatment of Osgood-Sclatter disease?

Answer 19

Only in chronic cases where there is a bony ossicle in the patellar requiring surgical excision

Question 20

What is osteochondritis dessicans?

Answer 20

A condition where a fragment of bone and its overlying articular cartilage may dissect off and into the joint space due to repeated minor stresses

Question 21

What is the commonest site for osteochondritis dessicans?

Answer 21

Knee

Question 22

What symptoms are associated with osteochondritis dessicans?

Answer 22

1. Pain
2. Swelling
3. Limitation of movement

Question 23

What are the radiological features of osteochondritis dessicans in the knee?

Answer 23

X-rays may show:

• A loose body
• A crater on the articular surface of the medial femoral condyle from which the fragment has fallen

Question 24

How is osteochondritis dessicans treated?

Answer 24

Depends on size and symptoms
Severe cases require surgery:
- Drilling
- Osteochondral autografting
- Autologous chondrocyte implantation

Question 25

What is the main long-term complication of osteochondritis dessicans?

Answer 25

Osteoarthritis