• male > females

• average age at presentation is 35 to 50

• bilateral hips involved 80% of the time

• Risk factors

  • direct causes

    • irradiation

    • trauma ( neck fractures)

    • hematologic diseases (leukemia, lymphoma)

    • dysbaric disorders (decompression sickness, "the bends") - Caisson disease

    • marrow-replacing diseases (e.g. Gaucher's disease)

    • sickle cell disease 

  • indirect causes

    • alcoholism

    • hypercoagulable states

    • steroids (either endogenous or exogenous)

    • systemic lupus erythematosus (SLE)

    • transplant patient

    • virus (CMV, hepatitis, HIV, rubella, rubeola, varicella)

    • protease inhibitors (type of HIV medication)

    • idiopathic

• Symptoms

  • insidious onset of pain

  • pain with stairs, inclines, and impact

  • pain common in anterior hip

• Physical exam

  • mostly normal initially

  • advanced stages similar to hip OA (limited motion, particularly internal rotation)

• Imaging

  • Xrays ( bilateral): AP + L + frog leg

  • MRI:

    • double density appearance

      • T1: dark (low intensity band)

      • T2: focal brightness (marrow edema)

    • order when radiographs negative and osteonecrosis still suspected

    • presence of bone marrow edema on MRI is predicitve of worsening pain and future progression of disease

Nonoperative Treatment

• bisphosphonates

  • indicated for precollapse AVN (Ficat stages 0-II)

  • prevents collapse ??

Surgical treatment

• core decompression with or without bone grafting

  • indications

    •  for early AVN, before subchondral collapse occurs

    • reversible etiology

• Total hip arthroplasty