Descriptive anatomy of the anterior cruciate ligament femoral insertion.

Objective: To evaluate the morphology of the anterior cruciate ligament (ACL) femoral insertion in order to describe its anatomical features and insertion site location, with the aim of verifying if the ACL femoral insertion has individual characteristics and to provide information for appropriate femoral tunnel placement on anatomic ACL reconstruction.

Methods: Sixteen knees obtained from amputations were studied. The ACL femoral bundles and insertion shape were observed macroscopically, and the ligaments insertion length and thickness were measured with a digital caliper. The distances between the limits of the ligament to the articular cartilage, and the measurement of the area of insertion were checked using ImageJ software.

Results: The ACL femoral insertion site was eccentric, closer to the deep condyle cartilage. In ten knees (62.5%), the ACL femoral insertion was oval; the mean length of the insertion was 16.4 mm, varying from 11.3 to 19.3 mm, the mean thickness varied from 7.85 to 11.23 mm, and the mean area of the insertion was 99.7 mm2 , varying from 80.9 a 117.2 mm2 . The mean distances between the limits of the ligament to the superficial, deep, and inferior articular cartilage were 9.77 ± 1.21, 2.60 ± 1.20, and 1.86 ± 1.15 mm, respectively.

Conclusion: There was a 30% to 40% difference between the minimum and maximum results of measurements of ACL femoral insertion length, thickness, and area demonstrating an important individual variation. The insertion site was eccentric, closer to the deep cartilage of the lateral femoral condyle.