The Relationship Between Graft Tensioning and the Anterior-posterior Laxity in the Anterior Cruciate Ligament Reconstructed Goat Knee

The tension applied to the anterior cruciate ligament (ACL) graft at time of fixation is thought to influence graft healing, knee kinematics, and joint contact forces; however, the optimal tensioning procedure remains unclear. An animal model provides a means by which the effect of graft tensioning on healing can be studied. Prior to using the model, the relationship between graft tensioning and knee kinematics at time of surgery should be established. Our objective was to explore the relationship between graft tensioning and anterior-posterior (A-P) laxity of the reconstructed goat knee. Eight cadaver knees were tested. The A-P laxity values of the intact knee were measured with the knee at 30 degrees, 60 degrees. and 90 degrees flexion. The ACL was then severed and the laxity measurements were repeated. The ACL was reconstructed using a bone-patellar tendon-bone autograft. The laxity measurements were repeated for nine different tensioning conditions; three tension magnitudes (30, 60, and 90 N), each applied with the knee at three angles (30 degrees, 60 degrees and 90 degrees). Both graft tension and the knee angle at which it was applied produced significant changes on A-P laxity values. An increase in tension reduced laxity values. A tension level of 60 N applied with the knee flexed to 30 degrees was the best combination for restoring normal A-P laxity values at all knee angles tested.