- Clinical science
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 presents with groin pain, which may radiate to the knee or ipsilateral buttock, and limited range of motion at the hip. Diagnosis is based on x-ray, followed by MRI. No curative treatments have been identified. Initial nonsurgical treatment focuses on preventing collapse of the femoral head, although surgical intervention may be required if the disease progresses. However, there is no consensus regarding the best treatment options.
For avascular necrosis of the femoral head in children, see .
- Peak incidence: 20–40 years
Epidemiological data refers to the US, unless otherwise specified.
Several traumatic and atraumatic factors are known contribute to the etiology of osteonecrosis, all of which contribute to changes in blood supply.
- Glucocorticoid use (35–40% of cases)
- Alcohol (20–40% of cases)
- Traumatic factors
- Slowly progressive groin pain, which may radiate to the knee or ipsilateral buttock
- Limited active and passive range of motion at the hip
- Bilateral in 50% of cases
X-ray (best initial test)
- Cystic and sclerotic changes in the femoral head
- Subchondral collapse
- Flattening of the femoral head
- MRI (best confirmatory test) : used to the visualize necrotic-viable bone interface
- Evidence the bone is pre/post-collapse
- Size of the necrotic component
- Amount of femoral head depression
- Acetabular involvement
- Stage 0 (initial stage) → normal imaging studies; histological evidence of change
- Stage I (reversible early stage) → positive MRI, normal x-ray
- Stage II (irreversible early stage) → X-ray and MRI positive, preserved contour
- Stage III (transitional stage) → X-ray: subchondral fracture
- Stage IV (late stage) → calcification, resorption cysts and formation of new cartilage in the x-ray image
Early diagnosis via MRI or scintigraphy is possible!
- No known curative treatment
- Reduce risk factors (smoking cessation, alcohol abstinence, reduce corticosteroid use if possible)
- Conservative treatment: indicated in early stages of disease to the reduce risk of femoral head collapse
- Surgery: indicated in later stages of disease when bone structure is compromised
- Femoral head collapse
We list the most important complications. The selection is not exhaustive.