MPI has proved to be very reliable in evaluating the menisci and cruciate ligaments. On MRI, several diagnostic criteria of ruptured ACL were reported. Boeree and Ackyroyd reported that when the ACL is ruptured the PCL may appear to be curled up
or
sigmoid. But the these morphologic changes may be shown in the normal ACL, so the quantitative analysis of these morphologic changes in considered as a way to increase the diagnostic sensitivity, We have used 1.0 tesla MRI scanner(SIMENS W.
Germany)
with a surface coil. We compared two groups of patients: a ruptured ACL group(16 patients) in which had indicated and arthroscopy confirmed ruptured of the ACL and control group(46 patients), in which had shown the ACL to be entirely normal, At
first,
we made a line(basal line) between the femoral attachment and tibial attachment of the PCL and decided the point(apex) which was located for distant from the line. And we made a line(A line) between the femoral attachment and apex of the PCL,
another
line(B line) between the tibial attachment and apex of the PCL. We divided the basal line into the four areas. We measured the each angle between basal line and A line(angle a), between basal line and B line(angle b). And we measured the entire
length
of basal line, each height of the PCL previously divided point of the basal line(H1, H2, H3) and the apex of the PCL on the basal line. We compared the control group and ruptured ACL group by t-test from the measured factor angle, a angle b, H1,
H2, H3,
H4, and length of basal line.
We studied factors which were able to decide whether the ACL was ruptured or not in MRI finding by logistic regression.
1. H1, the distance from the basal line to the PCL at 1/4 point on the basal line, were 5.7±1.6mm in ruptured ACL group, 4.7±1.3mm in control group, so there was statistically significant increase in ruptured ACL group.
2. The angle a were 56.0±14.4°in ruptured ACL group, 39.7±10.1°in control group, so there was statistically significant increase in ruptured ACL group.
3. From the measured factors angle a was able to decide whether the ACL was ruptured or not in MRI and the slope of angle a in logistic regression was 0.1.
In conclusion, when the apex of the PCL is located at proximal 1/4 of the PCL and greater curve, above signs will be considered to be a sign of ruptured ACL in MRI.
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