Musculoskeletal & Rheumatology
Avascular Necrosis (Osteonecrosis)
~1 min read1 sections
Contents (1)
Avascular necrosis is bone death from interrupted blood supply, most often affecting the femoral head, where the blood supply is precarious and largely retrograde through the medial femoral circumflex artery.
- Causes — the classic list: corticosteroids and alcohol (the two commonest atraumatic causes), trauma (femoral neck fracture, hip dislocation), sickle cell disease, systemic lupus erythematosus, caisson disease (decompression), Gaucher disease, radiation, and pregnancy.
- Sites at risk share a watershed supply: femoral head, scaphoid proximal pole, talus, humeral head, and the lunate (Kienböck).
- Presentation: insidious groin pain worse with weight-bearing, progressing to rest pain, with limited internal rotation on examination.
- Imaging: plain radiographs are normal early, later showing sclerosis and the crescent sign of subchondral collapse. MRI is the test of choice and detects disease before radiographic change.
- Management depends on stage: protected weight-bearing and bisphosphonates have limited benefit; core decompression may help before collapse; once the head has collapsed, arthroplasty is definitive.
- In children, the equivalent idiopathic entity at the femoral head is Legg–Calvé–Perthes disease.
(Seed article — remaining sections to be written and reviewed.)