Normally ACL may show a striated signal distally caused by interspersed fat and synovium between the 2 bundle and proximal ligament appears. Any discontinuity or signal change in the ligament is indicative of ACL tear. There are some indirect signs of ACL tear like focal areas of increased signal in the lateral tibial plateau and femoral condyle, pivot shift injury (combination of signal changes in lateral femoral condyle and posteror lateral tibial plateau, abnormal slope of ACL, avulsion of the anterior tibial spine, segond fractur (capsular avulsion fracture of the lateral tibial plateau and kissing contusions involving the anterior tibia and femur resulting from hyperextension injury. This case shows ACL avulsion tear on MRI image.
Dr.Sumer K Sethi, MD