A comparison of the effect of central anatomical single-bundle anterior cruciate ligament reconstruction and double-bundle anterior cruciate ligament reconstruction on pivot-shift kinematics.

BACKGROUND: Biomechanical differences between anatomical double-bundle and central single-bundle anterior cruciate ligament reconstruction using the same graft tissue have not been defined.

PURPOSE: The purpose of this study was to compare these reconstructions in their ability to restore native knee kinematics during a reproducible Lachman and pivot-shift examination.

STUDY DESIGN: Controlled laboratory study.

METHODS: Using a computer-assisted navigation system, 10 paired knees were subjected to biomechanical testing with a standardized Lachman and mechanized pivot-shift examination. The navigation system recorded the 3D motion path of a tracked point at the center of the tibia, center of the medial tibial plateau, and center of the lateral tibial plateau with each maneuver. The testing protocol consisted of evaluation in the intact state, after complete anterior cruciate ligament transection, after medial and lateral meniscectomy, and after anterior cruciate ligament reconstruction with (1) a single-bundle center-center or (2) anatomical double-bundle technique. Repeated-measures analysis of variance with a post hoc Tukey test was used to compare the measured translations with each test condition.

RESULTS: A significant difference in anterior translation was seen with Lachman examination between the anterior cruciate ligament- and medial and lateral meniscus-deficient condition compared with both the double-bundle and single-bundle center-center anterior cruciate ligament reconstruction (P < .001); no significant difference was observed between reconstructions. The double-bundle construct was significantly better in limiting anterior translation of the lateral compartment compared with the single-bundle reconstruction during a pivot-shift maneuver (2.0 +/- 5.7 mm vs 7.8 +/- 1.8 mm, P < .001) and was not significantly different than the intact anterior cruciate ligament condition (2.7 mm +/- 4.7 mm, P > .05).

DISCUSSION: Although double-bundle and single-bundle, center-center anterior cruciate ligament reconstructions appear equally effective in controlling anterior translation during a Lachman examination, analysis of pivot-shift kinematics reveals significant differences between these surgical reconstructions. An altered rotational axis resulted in significantly greater translation of the lateral compartment in the single-bundle compared with double-bundle reconstruction.

CLINICAL RELEVANCE: A double-bundle anterior cruciate ligament reconstruction may be a favorable construct for restoration of knee kinematics in the at-risk knee with associated meniscal injuries and/or significant pivot shift on preoperative examination.