Osteonecrosis of the femoral head

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 a 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 “Legg-Calvé-Perthes disease.”

• Peak incidence: 20–40 years ^[1]

Epidemiological data refers to the US, unless otherwise specified.

Though often idiopathic, several traumatic and atraumatic factors may contribute to the development of osteonecrosis.

• Atraumatic factors ^[1][2]
  • Glucocorticoid use (35–40% of cases)
  • Alcohol use disorder (20–40% of cases)
  • Legg-Calvé-Perthes
  • Smoking
  • Hemoglobinopathies (e.g., sickle cell disease)
  • Radiation
  • Myeloproliferative disorders
  • Autoimmune diseases (e.g., SLE, antiphospholipid syndrome)
  • Hyperuricemia, hyperlipoproteinemia, diabetes mellitus
  • Pancreatitis
  • Infection
  • Gaucher disease
  • Decompression sickness
• Traumatic factors
  • Femoral neck fractures, particularly with dislocation ^[1]
  • Femoral head fracture
  • Slipped capital femoral epiphysis (SCFE)

ASEPTIC: Alcohol, Sickle cell disease/SLE, Exogenous steroid, Pancreatitis, Trauma, Infection, Caisson disease (decompression sickness)

• 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 cranial part receives blood from a branch of the obturator artery.
    • The caudal part receives blood from medial and lateral femoral circumflex arteries.
  • The foveolar artery is the main artery implicated in avascular necrosis of the femoral head
    • Most commonly originates from the obturator artery and less commonly from the medial circumflex femoral artery ^[3]
    • Passes through the ligament of the femur head
    • Supplies the head of the femur

• Slowly progressive groin pain, which may radiate to the knee or ipsilateral buttock ^[1]
• Limited active and passive range of motion at the hip
• Bilateral in up to 70% of cases ^[1]

Consider osteonecrosis in patients presenting with groin pain and a history of corticosteroid use or alcohol abuse.

Diagnosis of osteonecrosis of the femoral head ^[1]

• 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 visualize necrotic-viable bone interface

Staging of osteonecrosis of the femoral head

• Several staging systems have been described. In general, these four important findings are routinely used to formulate a treatment plan:
  • Evidence the bone is pre/postcollapse
  • Size of the necrotic component
  • Amount of femoral head depression
  • Acetabular involvement
• ARCO staging ^[4]
  • Stage 0 (initial stage): normal imaging studies but histological evidence of change
  • Stage I (reversible early stage): positive MRI but normal x-ray
  • Stage II (irreversible early stage): x-ray and MRI are positive but contours are preserved
  • Stage III (transitional stage): x-ray shows subchondral fracture
  • Stage IV (late stage): x-ray shows flattening of the femoral head
  • Stage V: x-ray shows flattening of the femoral head and osteoarthrotic changes (e.g., decreased joint space and acetabular changes)
  • Stage VI: x-ray shows complete joint destruction

• General
  • No known curative treatment
  • Reduce risk factors (e.g., 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 but often ineffective ^[1][2]
  • Decreased weight bearing
  • Statins and bisphosphonates
• Surgery ^[1][2][5][6]
  • Indicated if conservative treatment fails and/or when bone structure is compromised
  • Frequently performed in early stages (early surgery improves prognosis)
    • Prophylactic
      • Core decompression: decompressing femoral head to restore normal vascular flow
      • Bone graft to fill necrotic areas
      • Osteotomy to redistribute weight load
    • Reconstructive
      • Hemi-resurfacing arthroplasty
      • Hip replacement for advanced disease

• Femoral head collapse
• Secondary coxarthrosis

We list the most important complications. The selection is not exhaustive.