[Bore canal site in surgical reconstruction of the anterior cruciate ligament. Position--placement errors--anatomic measurement]

The goal of surgical reconstruction of the anterior cruciate ligament (ACL) is restoration of its function as closely as possible to a physiological roll-and-glide mechanism. Clinical success means knee joint stability, physiological joint biomechanics, and full range of motion. Anatomical placement of the graft insertion points and anatomical direction of the drilled tunnels are necessary to obtain isometric (anatometric) conditions. Despite technical advances in (arthroscopic) surgery, it is not yet possible to obtain absolute "isometricity" for ACL grafts. However a "physiological" or "relative" isometricity seems to be sufficient for successful clinical results. In 1986 Werner Müller proposed the term "anatometrics" in ACL reconstruction to describe this graft behavior and function. The knee joint is a complex motion system including many active and passive stabilizing elements (ligaments, tendons, muscles) as well as a proprioceptive function of the central column ligaments. Reconstruction of this "system" required the surgeon to have good surgical skills and a well-based knowledge of knee anatomy and function. Wrong placement of insertion points and bone tunnels carry the risk for ensuing graft insufficiency and resultant joint instability. The knee "prefers" a destroyed graft over an overconstrained biomechanical situation! Intraoperative factors for failure may be technical mistakes and intraoperative measuring devices for isometry, which might not guarantee true relations in a ligamentous deficient knee. Therefore, visualization of insertion points (and drilling) under direct arthroscopic view is still preferred over generalized rules and distances as proposed by many commercially available rulers and tapers. Recently, navigation and computer-assisted placement techniques have been developed. The clinical standards of those techniques are still under investigation. At our institution, an arthroscopic approach (visualization, palpation) for ACL reconstruction with a bone-patellar-tendon-bone graft technique is used.