Knee iSAWE 9

Question

A 45 year old man is struck on the outside of the knee by a car bumper. His knee is tense and swollen.

Knee iSAWE 9, imaging of the knee
Imaging of the knee. Image by LottieLattes, Wikimedia Commons, CC BY-SA 4.0.
  1. How are these fractures classified?
  2. What investigations and early management are needed?
  3. What are the principles of fixation?

Answer

Schatzker classification

TypeDescription
ILateral split
IILateral split depression
IIIPure lateral depression
IVMedial plateau
VBicondylar
VIMetaphyseal diaphyseal dissociation

Investigation and early care

  • CT for fragment mapping
  • MRI for meniscal and ligament injury
  • Monitor for compartment syndrome, especially in types IV to VI
  • Check pulses, as type IV can be a fracture dislocation
  • Spanning external fixator for high energy injuries until the soft tissues settle

Fixation principles

  • Elevate depressed articular fragments and support them with graft or substitute
  • Restore alignment with buttress plating
  • Lateral approach with submeniscal arthrotomy and posteromedial approach for medial fragments
  • Repair the lateral meniscus
  • Early motion with delayed weight bearing

Related pages

Author Contributions

Orthofracs team

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