Anterior cruciate ligament tear: indirect signs at MR imaging.
OBJECTIVE
To establish the sensitivity and specificity of indirect signs at magnetic resonance (MR) imaging of anterior cruciate ligament (ACL) tear.


METHODS
MR images of the knees of 89 consecutive patients (54 with torn and 35 with normal ACLs) were reviewed.


RESULTS
The indirect signs were as follows (first percentage is sensitivity; the second, specificity): angle between lateral tibial plateau and ACL less than 45 degrees (90%, 97%); angle between Blumenstaat line and ACL more than 15 degrees (89%, 100%); bone contusions in lateral compartment (54%, 100%); position of posterior cruciate ligament (PCL) line (52%, 91%); PCL angle less than 107 degrees (52%, 94%); PCL bowing ratio more than 0.39 (34%, 100%); posterior displacement of lateral meniscus more than 3.5 mm (44%, 94%); anterior displacement of tibia more than 7 mm (41%, 91%); and lateral femoral sulcus deeper than 1.5 mm (19%, 100%).


CONCLUSIONS
Because the specificity is high, the presence of indirect signs corroborates the diagnosis of ACL tear. Because the sensitivity is low, the absence of these signs does not exclude the diagnosis of ACL tear.
Department of Radiological Sciences, University of California Los Angeles Center for the Health Sciences.
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Gentili
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Seeger
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Yao
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Do
D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries; D001182:Arthroscopy; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D012189:Retrospective Studies; D012680:Sensitivity and Specificity