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Document Title: Petersen-AJSM-Feb07.shtml
Article Title: Biomechanical Evaluation of Two Techniques for Double-Bundle Anterior Cruciate Ligament Reconstruction
One Tibial Tunnel Versus Two Tibial Tunnels
Authors: Wolf Petersen, MD, Henning Tretow, MS, Andre Weimann, MD, Mirco Herbort, MS, Freddie H. Fu, MD, Michael Raschke, MD and Thore Zantop, MD
Publication: American Journal of Sports Medicine, Baltimore, Maryland
Date: February 2007
Volume 35, pages 228-234
Keywords: Anatomically correct double-bundle ACL reconstruction, dual-bundle, knee motion, biomechanics, kinematics, kinetics.
(Reference-denoting numbers appear in the same font and point size as the document text. As with all Knee Library documents, this article is provided in full-text form, complete with all figures and tables.)
Comments: This study makes it clear that a dual-bundle (using a single femoral tunnel and two tibial tunnels) ACL graft is biomechanically superior to the traditional single-bundle ACL graft. Such a construct nicely duplicates the knee motion, particularly at and near full extension. Two other intriguing studies in this same vein are Chouliaras-AJSM-Feb07.shtml and Zantop-AJSM-Feb07.shtml. A double-bundle ACL reconstruction should be considered to be a modified installation procedure (i.e. two tibial tunnels instead of one) of the standard single-bundle graft, but the fundamental aspects and considerations pertinent to graft-source choice (e.g. patellar-tendon autograft versus hamstring/DLSTG autograft versus allograft) remain essentially the same. But because of the inherently increased complexity of double-bundle ACL grafting, the demands on the surgeon's skill are commensurately increased. In the future, widespread use of double-bundle ACL grafting should become more feasible as advanced technological tools enter the operating room. Given that the major cause of ACL-graft failure continues to be improper tunnel location (i.e. surgeon error), an ideal solution might entail having an automated electronic instrument that could scan a knee, then compute and indicate where the bone tunnels must be drilled. But for the meantime, traditional single-bundle grafting may be a safer choice simply because it brings less likelihood of surgeon error.
ABSTRACT
Background: This research was undertaken to determine whether there is a need for a second tibial tunnel in anatomic anterior cruciate ligament reconstruction.
Hypothesis: Anatomic two-bundle reconstruction with two tibial tunnels restores knee anterior tibial translation in response to 134 N and to 5-N·m internal tibial torque combined with 10-N·m valgus torque more closely to normal than does double-bundle reconstruction with one tibial tunnel.
Study Design: Controlled laboratory study.
Methods: Ten cadaveric knees were subjected to a 134-N anterior tibial load at 0°, 30°, 60°, and 90° and to 5-N·m internal tibial torque and 10-N·m valgus torque at 15° and 30°. Resulting knee kinematics and in situ force in the anterior cruciate ligament or replacement graft were determined by using a robotic/universal force-moment sensor testing system for (1) intact, (2) anterior cruciate ligament–deficient, (3) double-bundle/one tibial tunnel, and (4) double-bundle/two tibial tunnels.
Results: Anterior tibial translation for the reconstruction with two tibial tunnels was significantly closer to that of the intact knee than was the reconstruction with one tibial tunnel at 0° and 30° of flexion (0° = 3.82 vs 6.0 mm, P < .05; 30° = 7.99 vs 11 mm, P < .05). The in situ force normalized to the intact anterior cruciate ligament for the reconstruction with two tibial tunnels was significantly higher than the in situ force of the reconstruction with one tibial tunnel (30° = 89 vs 82 N, P < .05). With a combined rotatory load, the anterior tibial translation of specimens with a tibial two-tunnel technique was significantly lower than that of specimens with one tunnel (0° = 5.7 vs 8.4 mm, P < .05; 30° = 7.5 vs 9.5 mm, P < .05).
Conclusions: Anatomic reconstruction with two tibial tunnels may produce a better biomechanical outcome, especially close to extension.
Clinical Relevance: At the time of initial fixation, there appears to be a small biomechanical advantage to the second tibial tunnel in the setting of two-bundle anterior cruciate ligament reconstruction.
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