Knee iSAWE 13

Question

A 19 year old man treated for acute lymphoblastic leukaemia in childhood has bilateral knee pain.

Knee iSAWE 13, coronal STIR MRI of both knees
Coronal STIR MRI of both knees. Image by Christaras A, Wikimedia Commons, CC BY 2.5.
  1. Describe the MRI.
  2. Compare this condition with spontaneous osteonecrosis of the knee (SONK).
  3. Outline management.

Answer

MRI

  • Multiple serpiginous geographic lesions in the distal femora and proximal tibiae
  • Bilateral, metaphyseal and epiphyseal
  • Secondary osteonecrosis after leukaemia treatment with high dose corticosteroids

Secondary osteonecrosis versus SONK

FeatureSecondary osteonecrosisSONK (subchondral insufficiency fracture)
AgeUnder 45Over 60, women
Risk factorsSteroids, alcohol, sickle cell, GaucherOsteoporosis, meniscal root tear
SitesMultiple, bilateral, femur and tibiaSingle, weight bearing medial femoral condyle
OnsetInsidiousSudden pain
Other jointsHip, shoulder involvement commonIsolated

Management

  • MRI of both hips, as the hip is often involved
  • Protected weight bearing and analgesia for small lesions
  • Core decompression for pre collapse lesions
  • Osteochondral allograft for focal collapse in young patients
  • Arthroplasty for collapse with arthritis, using stems to bypass weak metaphyseal bone

Related pages

Author Contributions

Orthofracs team

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.