Abstract
The outcome of single-bundle anterior cruciate ligament (ACL) reconstruction depends
largely on the anatomic placement of bone tunnel. The lateral intercondylar ridge
(LIR) and bifurcate ridge (BR) are useful bony landmarks for femoral tunnel placement.
The purpose of our study was to compare the bony landmarks of ACL footprint on femur
by three-dimensional computed tomography (3D CT) scan and arthroscopy in chronic ACL-deficient
knees. Fifty patients above 18 years of age who were diagnosed of having ACL tear
were selected for the study. All the cases were more than 6 months old since the injury.
Preoperative 3D CT scan of the affected knee was obtained for each of them. They underwent
single-bundle anatomic ACL reconstruction. Measurements were done on the preoperative
3D CT and arthroscopy to quantify the position of the LIR and BR. The proximodistal
distance of lateral femoral condyle was 21.41+/−2.5 mm on CT scan and 22.02+/−2.02 mm
on arthroscopy. On preoperative 3D CT scan, the midpoint of the LIR was found to be
located at a mean distance of 11.17±2.11 mm from the proximal margin of the lateral
femoral condyle. On arthroscopy, it was at 10.18+/−1.52 mm from the proximal margin
the lateral femoral condyle. The “bifurcate ridge”(BR) was not visible in any of the
cases during arthroscopy or CT scan. We concluded that LIR is an easily identifiable
bony landmark on arthroscopy in all cases. It can also be identified on CT scans.
BR is not identified both on arthroscopy and CT scans in chronic ACL tears. The arthroscopic
measurements of bony landmarks are quite close to those of CT scan. Midpoint of LIR
is at 52.185% of the proximodistal distance on CT scan evaluation and it is at 46.21%
on arthroscopic evaluation.
Keywords
anatomic single-bundle reconstruction - anterior cruciate ligament - lateral intercondylar
ridge - femoral tunnel
