Anterior cruciate ligament femoral footprint anatomy: systematic review of the 21st century literature.

PURPOSE: The purpose of our study was to systematically review current arthroscopic and related literature and to characterize the anatomic centrum of the anterior cruciate ligament (ACL) femoral footprint.

METHODS: On June 2, 2011, 2 independent reviewers performed a Medline search using the terms "anterior cruciate ligament" or "ACL," "femur" or "femoral," and "anatomy" or "origin" or "footprint." We included anatomic, cadaveric, and radiographic studies of adult, human, ACL femoral anatomy. Studies not published in the English language, studies published before January 1, 2000, and review articles were excluded. References of included articles were also searched according to our inclusion/exclusion criteria. Included studies were subjectively and quantitatively synthesized to define the anatomic centrum of the ACL femoral footprint.

RESULTS: The Medline search produced 533 articles. After application of inclusion and exclusion criteria and reference search, 20 articles were included and systematically reviewed. With regard to arthroscopically measurable landmarks, the anatomic centrum of the ACL femoral footprint is, on average, (1) in the sagittal plane, 43% of the distance from the proximal articular margin (arthroscopically visualized osteochondral junction) to the distal articular margin on the lateral wall of the intercondylar notch, and (2) in the axial plane, socket radius plus 2.5 mm anterior to the posterior articular margin, with a 2.5-mm rim of bone between the posterior ACL fibers and the posterior articular cartilage margin.

CONCLUSIONS: Our results show that the anatomic centrum of the ACL femoral footprint is 43% of the proximal-to-distal length of lateral, femoral intercondylar notch wall and femoral socket radius plus 2.5 mm anterior to the posterior articular margin.

CLINICAL RELEVANCE: This systematic review of basic science studies may have clinical relevance for surgeons who believe that anatomic ACL reconstruction can result in improved outcomes.