Avascular necrosis (osteonecrosis)
Avascular necrosis (osteonecrosis) is ischemic bone death, most commonly of the femoral head, driven chiefly by glucocorticoid use and alcohol overuse; management pivots entirely on whether subchondral collapse has occurred, since joint-preserving surgery works only before collapse and total joint arthroplasty is required after it.
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What this article covers
- Overview
Avascular necrosis (osteonecrosis) is ischemic death of bone and marrow from interrupted blood supply, most commonly affecting the femoral head, a vascular watershed area; it also occurs at the…
- Epidemiology
Occurs more frequently in men than women, at an approximate ratio of 8:1 for nontraumatic disease.
- Risk factors
Glucocorticoid use, dose- and duration-dependent: long-term, higher-dose therapy (prednisone above 20 mg/day) carries the greatest risk; this and alcohol are the two most common and modifiable risk factors.
- Pathophysiology
A vascular insult interrupts blood flow to the affected bone segment, directly (femoral neck fracture severing the medial femoral circumflex artery, capsular tamponade after hip dislocation) or…
- Clinical features
Insidious groin or hip pain that worsens with weight-bearing, walking, climbing stairs, and prolonged standing, typically without a preceding traumatic event in nontraumatic disease.
- Differential diagnosis
Septic (infectious) arthritis of the hip: fever, warmth, erythema, acute pain interfering with weight bearing; discriminated by joint aspiration with elevated synovial white blood cell count and…
- Diagnosis
The diagnosis is established by imaging, not a single laboratory test, and staged with the Ficat and Arlet classification (stages 0 through IV) once osteonecrosis is confirmed: stage 0: an…
- Management
First, for every stage, modify reversible risk factors: if glucocorticoids are the precipitant, taper to the lowest dose that controls the underlying condition; counsel alcohol cessation.
- Complications
Subchondral collapse of the articular surface: irreversible once it occurs, converting a joint-preservable problem into one that requires joint replacement.
- Prognosis
Lesion size and stage at diagnosis are the main prognostic drivers: small lesions can improve or resolve without invasive treatment, but larger lesions usually progress to bony collapse and structural sequelae if untreated.
- Prevention
No routine imaging screening for osteonecrosis is recommended in asymptomatic at-risk patients; instead, correct or minimize modifiable risk factors when possible.
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