Relationship between thickness of the anteromedial bundle and thickness of the posterolateral bundle in the normal ACL

Purpose Since the development of the anatomic double-bundle anterior cruciate ligament (ACL) reconstruction, many studies have focused on excursion and/or tension of each graft. However, no studies to date have adequately investigated thickness of the graft in anatomic double-bundle ACL reconstruction. To obtain basic knowledge from which an ideal graft thickness can be inferred, thicknesses of the anteromedial bundle (AMB) and posterolateral bundle (PLB) was measured in the normal ACL. Methods The right knees of 50 cadavers donated for anatomy instruction were studied. Each ACL was separated into the AMB and PLB, and circumferences at the mid-substance and cross-sectional area at the femoral and tibial footprints were measured in each. Results Cross-sectional areas of the AMB and PLB were 36 ± 10 and 32.1 ± 10.2 mm 2 at the femoral footprint, and 60.9 ± 21.8 and 52.2 ± 17.3 mm 2 at the tibial footprint, respectively. Circumferences at the mid-substance were 14.3 ± 3.3 mm for the ALB and 10.8 ± 3.1 mm for the PLB. A positive correlation was seen between AMB and PLB at each of the three sites. Conclusion The AMB is thicker than the PLB, showing a constant correlation in the normal ACL. This suggests that the anteromedial graft must be thicker than the posterolateral graft at least in actual operations.