Femoral footprint variation of the posterolateral bundle of the anterior cruciate ligament and double-bundle reconstruction

• What is known about this subject: Complete restoration of the ACL footprint is essential for ACL reconstruction.
• What this study adds to existing knowledge: The insertions and centers of the PLB cannot be exactly anatomically determined with one size.

BackgroundThe study is aimed to observe the range of variation of the ACL PLB femoral footprint and investigate countermeasures for accurate femoral bone tunnel placement during double-bundle ACL reconstruction.MethodsThe femoral insertions of the anteromedial bundle (AMB) and PLB of the ACL were dissected in 30 male cadaveric knees. The ACL footprint on the lateral intercondylar wall (LIW) was observed, and the shape of the LIW, the resident ridge, the angle between the ACL long axis and femoral axis (AA), and the vertical distance from the center of the PLB to the lowest cartilage border of the LIW (PD) were measured.ResultsThe area most populated by the ACL fibers was directly under the resident ridge. AA = 18.7° ± 15.25° with variation from – 18° to 56°, and PD = 7.02 ± 1.47 mm with variation from 3.75 to 11.08 mm. Both discrete values were very large in both groups of data. There were two kinds of LIW: trapezoidal (8 knees) and triangular (21 knees). Both AA and PD values exhibited significant differences between the two types of LIWs (P = 0.00).ConclusionAA and PD vary among individuals. The insertions and centers of the PLB cannot be exactly anatomically determined with one size. For double-bundle ACL reconstruction, an individualized intraoperative footprint observation for fresh cases with footprint remnants, or resident ridge and anteromedial bundle-interval identification for old ACL tears, can be reasonable methods for posterolateral tunnel orientation.Clinical relevanceClinical relevance is observe the range of variation of the PLB femoral footprint for clinical double-bundle ACL reconstruction.