importance of ancillary findings on MR imaging of the chronically torn anterior cruciate ligament

ABSTRACT

Magnetic Resonant Imaging [MRI] is the examination of choice in diagnosing anterior cruciate ligament [ACL] tear. Direct signs of ACL tear on sagittal images, include focal or diffuse increased signal intensity within the ligament, focal discontinuity, acute angulation and wavy contour of the ligament. The ACL appears abnormal on sagittal images in some cases in spite of the absence of ligamentous tear, which may be due to oesinophilic or mucoid degeneration within the ligament, partial volume effect with the lateral femoral condyle or periligamentous fat, or due to suboptimal selection of the sagittal planes. For these reasons many authors recommend to look for indirect signs of ACL tear on sagittal MRI. These signs are due to instability associated with ligament deficiency. To study the value of indirect signs in cases of ACL tear, we retrospectively reviewed the MR images in patients with ACL tear which were confirmed surgically, and compared them with those of patients with normal ACL on MRI and surgery