Biomechanical comparison of anatomic double-bundle, anatomic single-bundle, and nonanatomic single-bundle anterior cruciate ligament reconstructions.
BACKGROUND
Although both anatomic double-bundle and single-bundle anterior cruciate ligament reconstruction procedures are in use, it remains controversial whether the anatomic double-bundle procedure is biomechanically superior.


OBJECTIVE
The anatomic double-bundle procedure would be better than both laterally placed anatomic and nonanatomic transtibial single-bundle procedures at restoring to normal the tibial anterior translation, internal rotation, and pivot-shift instability. It was also hypothesized that tibial internal rotation would be closer to normal after laterally placed anatomic single-bundle reconstruction than after the nonanatomic reconstruction.


METHODS
Controlled laboratory study.


METHODS
Eight cadaveric knees were mounted in a 6 degrees of freedom rig and tested using the following loading conditions: 90-N anterior and posterior tibial forces, 5-N·m internal and external tibial rotation 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, (4) nonanatomic single-bundle reconstruction, and (5) laterally placed single-bundle reconstruction.


RESULTS
Rotational laxity with internal tibial torque and anterior laxity in the simulated pivot shift were significantly less in the double-bundle reconstruction and laterally placed single-bundle reconstruction compared with the nonanatomic single-bundle reconstruction. There were no significant differences between the 3 procedures when anterior and posterior tibial translation forces and external rotation torques were applied. In addition, there were no significant differences between the double-bundle reconstruction and laterally placed single-bundle reconstruction.


CONCLUSIONS
The postoperative rotational and pivot-shift laxity after anatomic double-bundle anterior cruciate ligament reconstruction was significantly better than that after nonanatomic single-bundle reconstruction. However, there were no significant differences between the double-bundle reconstruction and laterally placed single-bundle reconstruction.


CONCLUSIONS
This work suggests that a single-bundle reconstruction may be better able to control both knee laxity and pivot-shift instability if the femoral tunnel is moved to a more lateral position and that then the double-bundle reconstruction may not offer significant further advantages.
Department of Mechanical Engineering, Imperial College London, London, United Kingdom.
Eiji
E
Kondo
Azhar M
AM
Merican
Kazunori
K
Yasuda
Andrew A
AA
Amis
D000368:Aged; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001696:Biomechanical Phenomena; D002102:Cadaver; D006801:Humans; D007593:Joint Instability / Q000601:surgery; D007719:Knee Joint / Q000601:surgery; D008875:Middle Aged; D020127:Recovery of Function / Q000502:physiology; D013314:Stress, Mechanical; D013709:Tendon Transfer / Q000379:methods*; D019415:Torque