Osteonecrosis of the femoral head is a consequence of insufficient vascular supply to the femoral head. Most cases are either idiopathic or associated with alcohol, corticosteroid therapy, or trauma. The condition manifests with groin pain, which may radiate to the knee or ipsilateral buttock, and a limited range of motion at the hip. Diagnosis is based on x-ray, followed by MRI. No curative treatments have been identified and there is no consensus on the best treatment options. Initial nonsurgical treatment focuses on preventing collapse of the femoral head, but surgical treatment is commonly required. Core decompression may improve the prognosis in early stages. If the disease progresses, arthroplasty may be necessary.
For avascular necrosis of the femoral head in children, see “ .”
- Peak incidence: 20–40 years 
Epidemiological data refers to the US, unless otherwise specified.
Atraumatic factors 
- Glucocorticoid use (35–40% of cases)
- Alcohol use disorder (20–40% of cases)
- Hemoglobinopathies (e.g., sickle cell disease)
- Myeloproliferative disorders
- Autoimmune diseases (e.g., SLE, antiphospholipid syndrome)
- Hyperuricemia, hyperlipoproteinemia, diabetes mellitus
- Traumatic factors
Reduced blood supply and bone marrow infarction
- The femoral head is at particular risk of developing avascular necrosis because there is an area of reduced vascularization (watershed zone) between the cranial and caudal parts.
- The foveolar artery is the main artery implicated in avascular necrosis of the femoral head
- X-ray: best initial test ;
- MRI: confirmatory test
- CT: superior to MRI for detecting insufficiency fractures; also used for preoperative planning 
There are several staging systems for osteonecrosis of the femoral head; in general, the following four important findings are used to assess severity:
Nonoperative management can provide relief in early stages of the disease, but operative treatment is usually necessary for most patients.
- Nonoperative management: for symptomatic relief in early disease stages and patients who are not surgical candidates 
- Surgical treatment: may improve prognosis if performed in early stages 
- Femoral head collapse
- Secondary coxarthrosis
We list the most important complications. The selection is not exhaustive.