Learning objectives
To illustrate the imaging criteria leading to diagnosis in common and uncommon lesions of the Anterior Cruciate Ligament (ACL).
Background
The normal ACL appears on MRI as a dark band which originates from the posterior medial surface of the lateral femoral condyle where it attaches in a semicircle. Its broader and stronger tibial insertion is large and fanlike, and is located in the anterior intercondylar area, slightly lateral and anterior to the anterior tibial spine. The ACL is in average 4 cm long and 1 cm thick. It is intra-articular but extrasynovial, being covered, together with the PCL, by a fold of synovial membrane.The ligament...
Imaging findings OR Procedure details
DIRECT SIGNS OF ACL TEAR1. LIGAMENT DISCONTINUITY OR NON VISUALIZATIONThis sign is defined as failure to directly visualize the ACL in each plane (sagittal, axial and coronal). When the ACL is seen, it is evaluated for thinning (decrease of fascicles) or discontinuity, focal or diffuse. Discontinuity is defined as a focal gap in the ligament, or depiction of more than one ligament fragment. Disruption of fibers appears in MRI as a discrete band of high s.i. within the ligament on T2 W images. Discontinuity of...
Conclusion
MRI has proved to be very accurate in the evaluation of the ACL (95%). The three direct, primary signs of ACL are very reliable, and numerous secondary signs can be used to corroborate the diagnosis. In a few cases the appearance of the ACL on MRI may be equivocal. Although chronic and acute ACL tears usually have distinct findings at MRI, a chronic tear will occasionally be difficult to distinguish from an intact ligament. MRI is significantly less sensitive for partial ACL rupture, half or...
References
1. Stoller DW ed., Magnetic Resonance Imaging in Orthopaedics & Sports Medicine. 2nd ed. Lippincot Raven Philadelphia 1997; pp 311-3412. Stabler A, Glaser, Reiser M, Musculoskeletal MR: Knee review article. Eur Radiol 2000; 10:230-2413. Vahey TN, Mayer SF, Shelbourne KD, Klootwyk TE. MR imaging of anterior cruciate ligament injuries. MRI Clinics North Am 1994; 2:(3) 365-3804. Recht MP, Parker RD, Irizarry JM. Second time around: Evaluating the postoperative anterior cruciate ligament. MRI Clinics North Am 2000; 8:(2) 285-2975. Remer EM, Fitzgerald SW, Friedman H et...
Personal Information
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