The Function of the Human Anterior Cruciate Ligament and Analysis of Single- and Double-Bundle Graft Reconstructions

CONTEXT: There exists controversy on the ability of a single or double anterior cruciate ligament graft technique to restore anterior cruciate ligament function. This article examines the published experimental and clinical data supporting these surgical procedures in the ability to restore knee stability. EVIDENCE ACQUISITION: An analysis of anterior cruciate ligament function and single- and double-graft reconstructions defined by selected biomechanical, robotic, kinematic, anatomical, and clinical studies. RESULTS: The anterior cruciate ligament resists the combined motions of anterior tibial translation and internal tibial rotation, which defines the concept of rotational stability. This function prevents anterior tibial subluxation of the lateral and medial tibiofemoral compartments that accounts for the pivot-shift phenomena. The placement of single anterior cruciate ligament grafts high and proximal at the femoral attachment and posterior at the tibial attachment results in a vertical graft orientation. This graft placement results in a limited ability to provide rotational stability and is inferior when compared to a double-bundle graft procedure. Studies show that a more oblique single-graft orientation, in the sagittal and coronal plane, achieved from a central anatomic femoral and tibial location provides rotational stability similar to a double-bundle anterior cruciate ligament graft. CONCLUSION: There exists insufficient experimental and clinical data to recommend the more complex double-bundle anterior cruciate ligament graft technique over a well-placed central anatomic single graft in terms of restoring knee rotational stability. Meticulous surgical technique for anterior cruciate ligament graft placement is necessary to avoid failure.