Presentation
Sports trauma 1 month ago.
Patient Data
The anterior cruciate ligament shows swelling, abnormally increased signal intensity on T2 with total fiber discontinuity, abnormal contour and change in the expected course on sagittal images with a positive empty notch sign on coronal images; the findings in favor of complete ACL tear.
The posterior horn of medial meniscus shows a small central T2 hyperintensity not extending to meniscal periphery favoring grade I meniscal degeneration
The posterior horn of lateral meniscus shows a vertical T2 linear hyperintensity in the outer third of the menisci disrupting the superior articular surfaces favoring a vertical tear.
Mild joint effusion
Case Discussion
The diagnosis of anterior cruciate ligament (ACL) tears is made by detection of primary and secondary signs.
The primary sign includes discontinuity and an abnormal signal of ACL fibers and the secondary signs includes:
- empty notch sign
- bone marrow contusion in the lateral femoral condyle and the posterolateral tibial plateau
- anterior subluxation of an upper tibia in relation to lower femur > 7 mm (anterior translocation of the tibia)
- avulsion fracture of the tibial insertion
- bony fragment from the lateral tibial condyle (Segond fracture)
- uncovered posterior horn of the lateral meniscus
- reduced PCL angle due to buckling of PCL
- positive PCL line sign