Avascular Necrosis Flashcards
Why does avascular necrosis occur?
Interruption of
- Arterial inflow
- E.g. fracture - Venous outflow
- E.g. infiltrative disorders that block sinusoids (Gaucher’s disease)
List the causes of AVN
- Fracture or dislocation
- Sickle cell disease - infarcted areas of bone become infected with salmonella
- Decompression sickness (Caisson disease)
- Gaucher’s
- Drug-induced (corticosteroids)
- Idiopathic
How is AVN classified?
By Ficat, according to:
- Symptoms
- Clinical findings
- Radiological findings
How does AVN appear on X-rays?
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
How does AVN appear on bone scans?
Area of increased uptake due to vascular reaction in adjacent bone
What are the 2 main symptoms of AVN?
- Pain
- Stiffness
Overall limited range of movement
What is osteochondritis. Name the two subgroups?
Aka idiopathic AVN - a group of conditions in which areas of patchy AVN cause pain and limitation of movement, usually in adolescents
- Traction apophysitis
- Osteochondritis dessicans
In what age group is osteochondritis most commonly seen?
Adolescents
What is Freiberg’s disease?
AVN of the 2nd metatarsal head
What is Kohler’s disease?
AVN of the navicular
What is Kienboch’s disease?
AVN of the lunate
What is Panner’s disease?
AVN of the capitulum of the humerus
What is an apophysis?
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
What is traction apophysitis?
Inflammation of an apophysis where a tendon attaches due to repetitive pulling forces
What is the commonest traction apophysitis?
Osgood-Schlatter disease - pull of the quadriceps on the tibial tuberosity
What is Osgood-Schlatter disease and how does it present?
A traction apophysitis due to pull of the quadriceps on the tibial tuberosity
Commonly presents as knee pain in growing adolescents.
What is Sever’s disease?
A traction apophysitis of the calcaneum due to pull from the Achilles tendon
How is Osgood Schlatter disease treated?
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
Is surgery indicated in the treatment of Osgood-Sclatter disease?
Only in chronic cases where there is a bony ossicle in the patellar requiring surgical excision
What is osteochondritis dessicans?
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
What is the commonest site for osteochondritis dessicans?
Knee
What symptoms are associated with osteochondritis dessicans?
- Pain
- Swelling
- Limitation of movement
What are the radiological features of osteochondritis dessicans in the knee?
X-rays may show:
- A loose body
- A crater on the articular surface of the medial femoral condyle from which the fragment has fallen
How is osteochondritis dessicans treated?
Depends on size and symptoms Severe cases require surgery: - Drilling - Osteochondral autografting - Autologous chondrocyte implantation
What is the main long-term complication of osteochondritis dessicans?
Osteoarthritis
