Bone infarct

 

Bone infarct kneeShoulder AVNHip AVN

 

Etiology

 

Same as AVN

 

AS IT GRIPS 3Cs

 

Alcohol

- > 4000 ml / week

 

Steroids

- > 20mg / day

- often bilateral

 

Idiopathic

- incidence of hypercoagulability

- alcohol probably related to most idiopathic

 

Trauma 

- displaced subcapital

- dislocation

 

Gout, Gaucher's

Rheumatoid, radiation

Infection, increased lipids, inflamm (arteritis)

Pancreatitis, pregnancy

SLE, Sickle cell, smoking

CRF, chemotherapy, Caisson

 

DDx

 

Chondroblastoma / Chondrosarcoma

Enchondroma

Bone island

 

Bone Scan

 

No increased uptake

 

MRI

 

- key feature central signal same as cancellous bone (intermediate) on both T1 and T2

- rim enhances on both T1 and T2 with contrast

- can be centrally enhancing in acute setting on T2

 

Shoulder AVN xrayShoulder AVN MRI

 

Prognosis

 

Pleomorphic sarcoma may arise from long standing bone infarcts