Osteonecrosis/ Avascular necrosis (AVN)

Definition: 

• Death of bone due to impairment of its blood supply. 

Most commonly affected sites:

• femoral head, 
• humeral head 
• navicular and scaphoid. 

Etiological type:

1. Traumatic: usually unilateral
2. Non traumatic:usually bilateral 

Causes/ Predisposing factors: 

• direct trauma that interrupts the blood supply; eg. osteonecrosis of the femoral head following fractures of the femoral neck.
• thrombophilia, antiphospholipid syndrome, Gaucher’s disease,
• haemoglobinopathies, eg. sickle cell disease (SCD),
• high-dose glucocorticoid treatment,
• alcohol excess, 
• SLE, HIV 
• radiotherapy, 

Presentation: 

• pain localized to the affected site, exacerbated by weight-bearing. 

Investigation:

Management:

• no specific treatment. 
•  pain control 
• encouraging mobilization. 
• Joint replacement may be required