Deep Lateral Femoral Notch Sign

The deep lateral femoral notch sign suggests an impacted osteochondral fracture of the lateral femoral condyle, and may be seen with an anterior cruciate ligament tear. On the lateral radiograph of the knee, there is an abnormally deep depression of the lateral femoral notch (condylopatellar sulcus).

Here we see a radiograph (top image) with a deep lateral femoral notch (gray arrow) and an effusion (pink arrow). The bottom image is a fluid-sensitive MR sequence showing an osteochondral defect along the lateral femoral condyle (gray arrow) and abnormal signal in the posterolateral tibial plateau ("kissing contusions"). This pediatric patient did not have an anterior cruciate ligament tear.

A lateral femoral notch deeper than 1.5-2.0 mm in depth (depending on the study) is thought to be a highly suggestive, but inconsistent, indirect sign of an anterior cruciate ligament injury.

References

Pao DG. The lateral femoral notch sign. Radiology. 2001 Jun;219(3):800-1.