Lateral femoral notch sign (knee)

The (deep) lateral femoral notch sign describes a depression on the lateral femoral condyle at the terminal sulcus, a junction between the weight bearing tibial articular surface and the patellar articular surface of the femoral condyle.

Pathology

The likely mechanism is a hyperextension or impaction injury with a collision of the femoral condyle and the posterior tibial plateau. 

Radiographic appearance

Lateral femoral notch sign is usually first appreciated on the lateral radiograph and is suggestive of an osteochondral fracture 1-2. The depth of the lateral femoral notch sign has been shown to correlate with anterior cruciate ligament (ACL) tear 2

Plain radiograph

On a lateral projection, a line is drawn from the normal articular surface of the lateral femoral condyle. The depth of the abnormal depression/notch can then be measured. A study compared the depth of the lateral femoral notch in patients with proven ACL tear and healthy individuals. A notch depth of 1.5 mm is shown as a useful additional sign of a torn ACL 2.

Share article

Article Information

rID: 21374
Section: Signs
Synonyms or Alternate Spellings:
  • Deep lateral femoral notch sign
  • Deep sulcus sign - ACL
  • Lateral femoral notch sign - ACL

Support Radiopaedia and see fewer ads

Cases and Figures

  • Drag
    Case 1
    Drag here to reorder.
  • Drag
    Case 2
    Drag here to reorder.
  • Drag
    Case 3
    Drag here to reorder.
  • Drag
    Case 4
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.