This study tested whether MR imaging could reliably identify ACL tears confirmed at arthroscopy. It compared MR performance against two standard clinical exams: the Lachman and anterior drawer tests. Seventy-nine knee MR studies were reviewed, with arthroscopy as the reference standard.
When you suspect an ACL tear but the exam is equivocal, MR imaging gives you direct visualization the physical exam cannot. This early study established the three MR criteria still used today: contour irregularity, intrasubstance T2 signal, and discontinuity. Learn to read the sagittal T2 sequence first, where joint fluid outlines the ligament in an "arthrographic" pattern.
MR's edge over the Lachman and drawer tests matters most in the acute knee, where pain and hamstring spasm defeat the physical exam. Note that this cohort was mostly nonacute, which is why the clinical tests performed better here than in other series.
The practical lesson: a torn ACL travels with meniscal and collateral injury the majority of the time, so MR earns its keep by mapping the whole injury pattern, not just confirming the ACL.
This study tested whether MR imaging could reliably identify ACL tears confirmed at arthroscopy. It compared MR performance against two standard clinical exams: the Lachman and anterior drawer tests. Seventy-nine knee MR studies were reviewed, with arthroscopy as the reference standard.
When you suspect an ACL tear but the exam is equivocal, MR imaging gives you direct visualization the physical exam cannot. This early study established the three MR criteria still used today: contour irregularity, intrasubstance T2 signal, and discontinuity. Learn to read the sagittal T2 sequence first, where joint fluid outlines the ligament in an "arthrographic" pattern.
MR's edge over the Lachman and drawer tests matters most in the acute knee, where pain and hamstring spasm defeat the physical exam. Note that this cohort was mostly nonacute, which is why the clinical tests performed better here than in other series.
The practical lesson: a torn ACL travels with meniscal and collateral injury the majority of the time, so MR earns its keep by mapping the whole injury pattern, not just confirming the ACL.