Equal kinematics between central anatomic single-bundle and double-bundle anterior cruciate ligament reconstructions.

Purpose: The purpose of this study was to compare the kinematics of a central anatomic single-bundle anterior cruciate ligament (ACL) reconstruction with a double-bundle ACL reconstruction by use of hamstring grafts and anatomic tunnel placement.

Methods: Anterior tibial translation and rotation were measured with a computer navigation system in 8 pairs of fresh-frozen cadaveric knees by use of a 133-N anterior force, an internal and external torque of 10 Nm, and an anterior force (133 N) combined with an internal rotation torque (10 Nm). Tests were performed at 30 degrees and 60 degrees of flexion with the ACL intact, the ACL transected, and after reconstruction of one side of a pair with either a single or a double-bundle construct.

Results: At 30 degrees of flexion, cutting the ACL increased anterior translation under an anterior force (P < .0001), an internal rotation torque (P = .02), and a combined anterior force plus internal rotation torque (P = .01). At 60 degrees of flexion, transecting the ACL led to increased anterior translation only when an anterior force was used (P < .0001). Both single- and double-bundle reconstructions restored normal kinematics at 30 degrees and 60 degrees of knee flexion.

Conclusions: Central anatomic single-bundle ACL reconstruction with tunnels centered within the tibial and femoral insertions and double-bundle ACL reconstruction can restore normal anterior translation to the knee under anterior and rotational loads applied at 30 degrees and 60 degrees of flexion.

Clinical Relevance: The primary kinematic effect of an ACL injury is an increase in anterior tibial translation, but there is no significant change in maximum internal or external rotation. Single- and double-bundle ACL reconstructions are equally effective in restoring normal anterior translation to the knee under both anterior and rotational loads.