[Intraoperative and postoperative insertion control of anterior cruciate ligament-plasty. A radiologic measuring...

The best proximal insertion for an ACL graft is an anatomic insertion. The anatomic landmarks of this insertion area are well known, but it is sometimes difficult to find these anatomic landmarks during the operation. Thus, it is desirable to have an objective method to control the insertion. This study was undertaken because no description is available how you can localize the projection of the anatomic ALC insertion exactly in an X-ray picture. We dissected ten human cadaveric knees with intact ACLs. The most ventral, dorsal, distal and proximal borders of the insertion area were marked with 4 K-wires. The K-wires were shortened exactly on the bone border of the intercondylar space. Then the knees were X-rayed in a strictly lateral position. Thus, the shortened ends of the K-wires determined the projection of the ACL insertion in the X-ray picture. The center of this marked area was called point K. Then we determined 4 distances in the X-ray picture: distance t: the sagittal diameter of the lateral condyle, measured along the Blumensaat line distance h: the maximal height of the notch distance a: the distance between K and the dorsal border of the condyle, measured along t distance b: the distance between t and K, measured on a perpendicular line on t Distance a is a partial distance of t and distance b is a partial distance of h. Because of varying projection factors and varying knee sizes, absolute values of these distances are not helpful. This is the reason why we expressed a and b as a proportion of t and h. Distance a was measured 24.8% of distance t. Distance b was measured 28.5% of distance h. The maximal deviation of a and b was 2.2% and 2.5%. Therefore, you can say: In a strictly lateral X-ray picture the distance of K (midpoint of proximal ACL insertion) from the dorsal border of the condyle is 24.8% of the whole diameter of the condyle, and the distance of K from the roof of the notch is 28.5% of the notch-height. This method does not depend on the size of the knee and the distance between the X-ray unit and the knee. The only condition is that the X-ray of the knee must be strictly lateral. This method is easy to handle and is reproducible. It can be used intraoperatively if the surgeon is not sure about the right insertion or if the anatomic landmarks cannot be seen exactly. It can be used postoperatively for documentation of the right position of the substitute. It can be used to find out the possible reason for rupture of a transplant (insertion too ventral) before the revision operation.