Avascular necrosis of hip

Case contribution: Dr Radhiana Hassan


  • A 43 years old lady
  • With underlying connective tissue disease
  • On prolong steroid treatment
Abdominal radiograph

Radiographic findings:

  • There is flattening of left femoral head (white arrow)
  • The flattening involving less than one third of the head region
  • Associated with mixed lytic and sclerotic changes
  • There is presence of crescent sign
  • The joint space is not narrowed
  • Medullary nephrocalcinosis also noted at both renal region (yellow arrows), more on the right side
MRI of pelvis in coronal plane, T1 and T2-weighted images.

MRI findings:

  • There is abnormal flattening of left femoral head, about 2-3 mm depression
  • Abnormal signal intensity which is hypointense on both T1 and T2-weighted images
  • Area of abnormal signal involving less than 30% of femoral head region
  • No joint effusion, no joint space narrowing
  • No obvious acetabular involvement is seen.

Diagnosis: Avascular necrosis of left hip.


  • Avascular necrosis also known as osteonecrosis
  • It can be traumatic or non-traumatic, bilateral in 40-80% of non traumatic cases
  • Risk factors: chronic corticosteroid therapy, alcoholism, smoking, SLE, hyperlipidaemias, HIV, hemoglobinopathies, chronic renal failure, DM and pregnancy-related.
  • A few classification and staging based on clinical, x-rays, mri and bone scan
    Stage Ficat and Arlet classification Steinberg staging
    Stage 0 Plain radiograph normal, MRI normal, clinical symptoms nil normal or non-diagnostic radiograph, MRI or bone scan
    Stage 1 Plain radiograph normal or minor osteopenia, MRI oedema, Bone scan increased uptake, clinical symptoms: pain at groin Normal radiograph, abnormal bone scan and/or MRI;

    A-mild head involvement <15%, B-moderate: 15-30% and C severe >30%.

    Stage II Plain radiograph mixed osteopenia and/or sclerosis and/or subchondral cyst without any subchondral lucency, MRI geographic defect, bone scan increased uptake, clinical symptoms pain and stiffness Cystic and sclerotic radiographic change

    A-mild head involvement <15%, B-moderate: 15-30% and C severe >30%.

    Stage III Plain radiograph crescent sign and eventual cortical collapsed, MRI same as plain radiograph, clinical symptoms pain and stiffness +/- radiation to knee and limp Subchondral lucency or crescent sign;  A-mild <15% head involvement, B-moderate, 15-30% and C-severe >30%
    Stage IV Plain radiograph end stage with evidence of secondary degenerative change, MRI same as plain radiograph, Clinical sypmtoms oain and limp Flattening of femoral head, with depression graded into A mild (<2mm), B-moderate (2-4 mm) and C-severe (>4 mm)
    Stage V Joint space narrowing with or without acetabular involvement (A, B, C-depends on femoral head involvement as in Stage IV)
    Stage VI Advanced degenerative changes
Mitchell classification T1WI T2WI Signal analogous
Stage A Hyperintense intermediate To that of fat
Stage B Hyperintense Hyperintense To that of subacute blood
Stage C Hypointense Hyperintense To that of fluid or odema
Stage D Hypointense Hypointense To that of fibrosis
Author: radhianahassan