A Cadaver Study of the Structures and Positions of the Anterior Cruciate Ligament in Humans

BACKGROUND The anterior cruciate ligament (ACL) is one of the major knee structures. It consists of anteromedial bundle (AMB) and posterolateral bundle (PLB). Rupture of the ACL is one of the most prevalent traumas among athletes. There are two ways to reconstruct the rupture; Single-bundle and double-bundle (DB) reconstruction. Precise study on bundles anatomy, the exact number of attachments and knee flexion angle with an appropriate place of bundles and also choosing the best angle for the grafts are so important in successful reconstructing of the bundles. In this research, the general attempt was to assess anatomy and the act of the ACL is and bundles in Iranian population. METHODS We obtained twelve fresh-frozen cadaver knees (two females, ten males). The average age of them was 30 years; they were mostly between 27 and 34 years old. Initially, skin, muscles, and patellar and articular capsule were removed. Then, bundle attachments, knee movements in flexion angle, extension and stiffness of both bundles were evaluated. Thereafter, on 0, 30, 60, 90, 120, and 180° angle knee flexion the bundles degree stiffness evaluated in different directions. During the process, to measure bundles size, digital camera for photography, oblique for measuring the angles, and micrometer were utilized. From all next of kin written consent testimonial form was obtained. RESULTS In all knees, two bundles were identified as distinct. AMB attachment location in the anterior region observed as semi-lunate and in one case, it was rounded. In all cases, two bundles of full knee extension were paralleled, and the AMB was anterior to the PLB; with increasing flexion angle, femoral attachment location of AMB was in back direction and femoral attachment location of PLB moved toward the front direction. Two bundles were in the most amount of cross state, which the angle was 90°. From the stiffness point of view in all 6 samples, the PLB had the most tension in extension state, and the AMB had the most tension in 120° flexion. CONCLUSION In the current study, we realized that the ACL is a DB ligament in Iranian population. The AMB in full extension has the least stiffness and in 90° flexion has the most; the PLB also in full knee extension and in 160° flexion has the most and least stiffness, respectively.