Knee iSAWE 19

Question

A 38 year old motorcyclist has a painful swollen knee after a crash. Plain radiographs were reported as showing only an effusion.

Knee iSAWE 19, coronal and axial CT of the knee
Coronal and axial CT of the knee. Image by Samba Koné, Abdoulaye Bana, Stanislas André Touré, Seydou Koné, Ange-Sylvain Allou, Adelaide Natacha Kouassi, Akue Gerard Koffi, Innocent M'bra Kouamé, Wikimedia Commons, CC BY-SA 2.0.
  1. Describe the CT and name the fracture.
  2. Why is it easily missed and how is it classified?
  3. How would you fix it?

Answer

CT

  • Coronal plane fracture of the posterior femoral condyle
  • Hoffa fracture (AO 33 B3)
  • Lateral condyle more common

Missed diagnosis

  • Fracture plane is coronal, so the AP radiograph often looks normal
  • A true lateral may show a double contour
  • CT for all distal femoral fractures, as Hoffa fragments occur in up to 38% of intercondylar fractures

Letenneur classification

TypeDescription
IWhole posterior condyle, line parallel to the posterior femoral cortex
IIBasal fragment, subtypes a to c by size
IIIOblique fracture

Fixation

  • Unstable and displaced, so non-operative care fails
  • Anatomical reduction through a lateral parapatellar or posterolateral approach
  • Anterior to posterior lag screws perpendicular to the fracture, countersunk
  • Posterior to anterior screws are stronger
  • Buttress plate for basal or comminuted fragments
  • Early motion

Related pages

Author Contributions

Orthofracs team

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