Avascular necrosis

Question 1

What?

Answer 1

Failure of blood supply to femoral head

Question 2

Causes?

Answer 2

Can be primary, idiopathic or secondary to alcohol abuse, steroids, hyperlipidaemia or throombophilia

Question 3

AVN associated with trauma?

Answer 3

Due to injury of femoral head blood supply (medial femoral circumflex)

Question 4

Who?

Answer 4

Males > females

30- 50

Question 5

Bilateral or unilateral?

Answer 5

Bilateral in 80% cases

Question 6

Risk factors?

Answer 6

Irradiation 
Trauma 
Hematologic diseases
Dysbaric disorders
Alcoholism 
Steroid use 
Although most cases are idiopathic

Question 7

Presentation?

Answer 7

Insidious onset of groin pain
Exacerbated by stairs or impact
Examination is usually normal unless disease advanced to collapse/ OA
Severe hip pain

Question 8

Investigations?

Answer 8

MRI (most sensitive)

X-ray

Question 9

What does imaging show?

Answer 9

Early cases - only on MRI
Later - patchy sclerosis with lytic zone formed by granulation tissue
Bone marrow oedema (MRI)

Question 10

Classic sign?

Answer 10

Hanging rope sign

Question 11

What do Xrays show?

Answer 11

After a few weeks - well demarcated area of inc bone density at upper pole of femoral head

Question 12

What can happen to femoral head?

Answer 12

Can collapse with irregularity of articular surface and subsequent secondary OA

Question 13

What can be done if AVN is detected early (pre- collapse)?

Answer 13

Drill holes can be made up femoral neck and into abnormal area in head to relieve pressure, promote healing and prevent collapse

Question 14

Management?

Answer 14

Bisphosphonates
Core decompression +/- bone grafting
Curettage and bone grafting
Vascularized fibular bone graft 
THR