Anatomical study of the human anterior cruciate ligament stump’s tibial insertion footprint

The aim of this study is to define the topographical relationship of the anatomical bundles of the human anterior cruciate ligament’s (ACL) stump over the tibial insertion site. Between January and April 2007, a total of 36 resected tibial plateaus were retrieved from patients who underwent total knee replacements. These samples had intact cruciate ligaments with no major osteophyte around the ACL tibial insertion footprint. The anatomical bundles of the ACL were identified and mapped, based on the topographical relationship over the tibial insertion footprint. Measurements of the dimensions of the ACL tibial footprint and tibial plateau were performed. The mean width and midsagittal depth of the tibia plateau was 78.7 ± 6.5 and 46.4 ± 5.0 mm, respectively. The mean width and midsagittal depth of the ACL tibial footprint was 10.3 ± 1.9 and 19.5 ± 2.6 mm, respectively. Out of the 36 freshly dissected ACL stumps, it was not possible to distinguish separate bundles in 14 (38.9%) cases. The average distance between the centers of the two bundles was 9.3 ± 1.8 mm. The mean AP alignment of the tibial footprint was 89.6° ± 26.4°, with a very wide range of 23°–158°. Of the 22 specimens with separate anatomical bundles, the alignment of the tibial footprint was AM–PL in six (27.3%), sagittal (85°–95°) in five (22.7), AL–PM in nine (40.9%), and lateral–medial (L–M) in two (9.1%) cases. This study provides new information about the topographical anatomy of the ACL tibial insertion footprint. Based on gross anatomy, separate anatomical bundles of the ACL can be distinguished in 61.1% [22] of the specimens. The topographical alignment of the separate bundles is varied on a very wide range.