Biomechanical Comparisons of Knee Stability After Anterior Cruciate Ligament Reconstruction Between 2 Clinically Available Transtibial Procedures

Abstract

Background: Several trials have compared the clinical results between anatomic double-bundle and single-bundle anterior cruciate ligament reconstruction procedures. However, it remains controversial whether the anatomic double-bundle procedure is superior to the single-bundle procedure. Hypothesis: The anatomic double-bundle procedure will be better than the single-bundle procedure at resisting anterior laxity, internal rotation laxity, and pivot-shift instability. Study Design: Controlled laboratory study. Methods: Eight cadaveric knees were tested in a 6 degrees of freedom rig using the following loading conditions: 90-N anterior tibialforce, 5-N·m internal and external tibial torques, and a simulated pivot-shift test. Tibiofemoral kinematics during the flexion-extension cycle were recorded with an optical tracking system for (1) intact, (2) anterior cruciate ligament–deficient knee, (3) anatomic double-bundle reconstruction, and (4) single-bundle reconstruction placed at 11 o’clock in the intercondylar notch. Results: There were significant reductions of anterior laxity of 3.5 mm at 20° of flexion, internal rotational laxity of 2.5° at 20° of flexion, and anterior translations (2 mm) and internal rotations (5°) in the simulated pivot-shift test in the double-bundle reconstruction com-pared with the single-bundle reconstruction. There were no significant differences between the 2 procedures for external rotation laxity. Conclusion: The postoperative anterior translation and internal rotation stability after anatomic double-bundle anterior cruciate ligament reconstruction were significantly better than after single-bundle reconstruction, in both static tests and the pivot shift. Clinical Relevance: Unlike previous laboratory studies, this work used clinical arthroscopic methods for anterior cruciate ligament reconstruction, and found that the anatomic reconstruction was superior to a single graft placed at 11 o’clock.