gap sign: fluid signal and/or a gap between the medial aspect of the lateral femoral condyle and the lateral aspect of the mid-ACL, can be seen on either axial or coronal MRI images.Imaging signs of isolated posterolateral bundle tear are as follows: If the angle is still normal and there is a hyperintense signal, a partial rupture is more likely than a complete rupture.ĪCL tear may only involve one bundle. The signal of the ACL can be more hyperintense on T2.
empty notch sign: a fluid signal at the site of femoral attachment at the intercondylar notch, denotes avulsion at the femoral attachment.ĪCL tears typically occur in the middle portion of the ligament (midsubstance tears) and appear as discontinuity of the ligament or abnormal contour.ACL angle (angle between the intercondylar line and ACL) >15° with the apex of the angle located anteriorly, indicating a less steep ACL line - this indicates a ruptured and collapsed ligament.ACL fibers are subjectively less steep than a line tangent to the intercondylar roof ( Blumensaat's line).abnormal anterior cruciate ligament orientation relative to intercondylar ( Blumensaat's) line.increased signal on T2 or fat-saturated PD.Secondary signs are those which are closely related to anterior cruciate ligament injuries. Primary signs are those that pertain to the ligament itself. Imaging of anterior cruciate ligament tears should be divided into primary and secondary signs. CT helps characterize the avulsion bone fragment when it is present. deep lateral sulcus sign - depression of lateral femoral condyle representing impaction fractureĬonsidered to have high specificity and sensitivity in detecting anterior cruciate ligament disruption 6.In younger patients, avulsion of the tibial attachment may be seen. posteromedial corner injury of the knee.soccer, basketball, tennis, netball, and snow skiing). The anterior cruciate ligament is the most commonly disrupted ligament of the knee, especially in athletes who participate in sports that involve rapid starting, stopping, and pivoting (e.g. The combination of the Lachman, pivot shift and anterior drawer tests are used to clinically confirm diagnosis 9. apprehension with an attempt at non-linear movements.knee felt to "gives way" especially during pivoting movement.initial inability to weight bear, which improves in a short period.popping sensation at the time of injury, followed by swelling.The following signs and symptoms are common: Patients typically present with symptoms of knee instability, usually after acute trauma.