A Biomechanical Comparison of Single-, Double-, and Triple-Bundle Anterior Cruciate Ligament Reconstructions Using a Hamstring Tendon Graft

Purpose: The first objective of our cadaveric study was to perform a biomechanical comparison of single-bundle (SB), double-bundle (DB), and triple-bundle (TB) anterior cruciate ligament (ACL) reconstructions using a hamstring tendon graft to determine the laxity match pre-tension (LMP) value, which is the tension within the graft required to re-create the same anterior laxity as the ACL-intact knee. The second objective was to determine the anterior laxity and force distribution during the application of both an anterior force and a simulated pivot-shift test. Methods: Eleven fresh-frozen cadaveric knees were tested using a robotic/universal force-moment sensor system in the intact state, TB-reconstructed knee, DB-reconstructed knee, and SB-reconstructed knee. The LMP in each reconstruction was recorded. Each reconstructed knee was tested with an external load of 100-N anterior drawer and combined rotatory loads of 10-Nm valgus moment and 5-Nm internal rotation. The anterior tibial translation and tensile forces of each graft bundle were measured. Results: The LMP values for the TB reconstruction were 1.7 N for the anteromedial-medial graft, 1.7 N for the anteromedial-lateral graft, and 3.4 N for the posterolateral graft (PLG). The LMP value was 5.6 N for the anteromedial graft and PLG in the DB reconstruction. The LMP value was 26.3 N for the whole graft in the SB reconstruction. No statistically significant difference in stability was found between TB and DB reconstructions during the anterior load and the combined rotatory load test. For force distribution, the PLG tension in the TB reconstruction was statistically lower than that in the DB reconstruction. Conclusions: Anatomic TB ACL reconstruction with the lowest initial tension on the graft stabilized the knee equally to DB or SB reconstruction, which required greater initial tension.