This 22 year old football player with knee pain. Felt a pop running to his car. What happened?
Noted here is a “notch” in the femoral condyle. What does it mean???
The “deep lateral femoral notch” sign refers to an osteochondral impaction injury of the lateral femoral condyle that is associated with disruption of the anterior cruciate ligament (ACL). At the time of injury, the tibia translates anteriorly relative to the femur resulting in an impaction injury of the lateral femoral condyle against the posterior tibial plateau. Identification of the “deep” sulcus on the lateral radiograph of the knee is a clear indicator of significant trauma and has a high association with ACL disruption.
Sagittal MRI of the knee demonstrates the deep lateral notch (red arrows) on the lateral femoral condyle. There is evidence of bone marrow edema (blue arrows) on both the femoral condyle and posterior tibia. These are the area that both bones impacted on each other. You could define this as a kissing contusion.
This is where the ACL should be.
Lateral Sulcus Sign/Deep Sulcus Sign/Deep Lateral Sulcus Sign:
A depth greater than 2.0 mm had a specificity of 100%, sensitivity of 3.2%, accuracy of 60%, and a positive predictive value of 100% for complete ACL tear.
Plain film radiography can still be a helpful tool in evaluating for suspected soft tissue injuries (such as ACL tears) if you know what you’re looking for. Of course MRI is a much better modality, but x-ray can help guide you with your clinical evaluation.