Tibial attachment area of the anterior cruciate ligament in the extended knee position. Anatomy and cryosections in vitro complemented by magnetic resonance arthrography in vivo

Knowledge of the anatomy of the anterior cruciate ligament (ACL), including its course and orientation in relation to the roof of the intercondylar fossa, is a prerequisite for successful intra-articular ACL reconstruction. To attain precision placement of the tibial attachment site and to avoid graft/roof conflict in the extended knee position, we assessed the anteroposterior tibial insertion of the ACL in the midsagittal plane of the extended knee. We measured the anterior-posterior (AP) limits and the center of the tibial attachment area of the ACL from the anterior tibial margin. The inclination angle of the intercondylar fossa roof was measured with respect to the shaft axis of the femur. The tibial attachment area of the ACL was determined in ten cadaveric knees. Using the cryoplaning technique, we determined the tibial attachment of the ACL in five knees. Using contrast magnetic resonance arthrography (MRA), we measured the tibial insertion of the ACL in 35 patients (23 male and 12 female) with intact ACLs. The total AP midsagittal diameter of the tibia averaged 51.0 +/- 5.8 mm in the cadaveric knees, 49 mm on cryosections, and 53.7 mm in men and 49.0 mm in women with MRA. The average anterior limit of the ACL, measured from the anterior tibial margin, was 14 +/- 4.2 mm in the cadaveric knees, 12.1 mm at cryosectional anatomy, and 15.2 mm in men and 13.4 mm in women with MRA.