Single-Bundle Anterior Cruciate Ligament Reconstruction: A Biomechanical Cadaveric Study of a Rectangular Quadriceps and Bone-Patellar Tendon-Bone Graft Configuration Versus a Round Hamstring Graft

Purpose: The purposes of this study were to investigate anterior tibial translation under loading conditions after single-bundle (SB) anterior cruciate ligament (ACL) reconstruction using a rectangular tunnel placement strategy with quadriceps and bone-patellar tendon-bone (BPTB) graft and to compare these data with a SB hamstring reconstruction with a round tunnel design. Methods: In 9 human cadaveric knees, the knee kinematics were examined with robotic/universal force-moment sensor testing. Within the same specimen, the knee kinematics under simulated pivot-shift and KT-1000 arthrometer (MEDmetric, San Diego, CA) testing were determined at 0 degrees, 15 degrees, 30 degrees, 60 degrees, and 90 degrees of flexion under different conditions: intact knee, ACL-deficient knee, and SB ACL-reconstructed knee. For the SB ACL-reconstructed knee, 3 different SB reconstruction techniques were used: a rectangular tunnel strategy (9 x 5 mm) with quadriceps graft, a rectangular tunnel strategy with BPTB graft, and a round tunnel strategy (7 mm) with hamstring graft. Results: In a simulated Lachman test, a statistically significant difference was found at 0 degrees and 15 degrees of knee flexion between the rectangular reconstruction with quadriceps graft (5.1 +/- 1.2 mm and 8.3 +/- 2 mm, respectively) or BPTB graft (5.3 +/- 1.5 mm and 8 +/- 1.9 mm, respectively) and the reconstruction using hamstring graft (7.2 +/- 1.4 mm and 12 +/- 1.8 mm, respectively) (P = .032 and P = .033, respectively, at 0 degrees; P = .023 and P = .02, respectively, at 15 degrees). On the simulated pivot-shift test at 0 degrees and 15 degrees, rectangular ACL reconstruction with quadriceps graft (3.9 +/- 2.1 mm and 6.5 +/- 1.7 mm, respectively) or BPTB graft (4.2 +/- 1.8 mm and 6.7 +/- 1.7 mm, respectively) showed a significantly lower anterior tibial translation when compared with round tunnel reconstruction (5.5 +/- 2.1 mm and 7.9 +/- 1.9 mm, respectively) (P = .03 and P = .041, respectively, at 0 degrees; P = .042 and P = .046, respectively, at 15 degrees). Conclusions: Under simulated Lachman testing and pivot-shift testing, a reconstruction technique using a rectangular tunnel results in significantly lower anterior tibial translation at 0 degrees and 15 degrees of flexion in comparison to knees reconstructed with a hamstring SB graft using a round tunnel strategy.