Intraoperative comparisons of knee kinematics of double-bundle versus single-bundle anterior cruciate ligament reconstruction

Purpose Based on biomechanical anatomical studies, double-bundle reconstruction of the anterior cruciate ligament (ACL) was introduced to achieve better stability in the knee, particularly in respect of rotatory loads. An in vivo, computer-assisted, double-bundle (DB) ACL reconstruction is superior to a single-bundle (SB) ACL reconstruction at reducing rotatory, and AP laxities of the tibia at 20 degrees of knee flexion and also during the pivot shift test. Methods The data of 63 patients who had ACL reconstruction were prospectively collected. Thirty-two patients had single-bundle reconstruction (SB group), and 31 received double-bundle reconstruction (DB group). The per-operative navigation system (Praxim ACL surgetics System) helped to search for a minimal anisometry profile of the grafts, which was favorable (graft loosened with flexion) in the anatomic area of ACL insertion and preventing any conflict between the graft and the femoral notch. The system also evaluated anteroposterior (AP) rotational stabilities and pivot shift. The value of the pivot shift was calculated from the values of the maximum rotation and AP translation obtained when performing the manoeuver before and after ACL reconstruction, comparing SB and DB reconstruction. Results The post-operative AP displacement of the lateral compartment during the Lachman test was statistically reduced in DB group in comparison with SB group (5.1 ± 4.4 mm vs. 7.1 ± 3.2 mm, P = 0.04), whereas the AP displacements of the medial compartment were also reduced (3.4 ± 3.7 mm vs. 4.5 ± 2.6 mm, P = 0.15) but with no statistical significance. Internal and external rotations at 20 of knee flexion were lower in the DB group than in SB group with statistical significance (respectively, 13.2 ± 4.9 vs. 17.5 ± 4.0, P\0.001 and 9.1 ± 3.6 vs. 11.5 ± 3.5, P = 0.01). During the pivot shift test, the post-operative AP maximal translation was statistically different in both groups: 4.5 ± 2.1 mm in DB group and 6.3 ± 2.7 mm in SB group (P = 0.01)), whereas the maximal rotation was not statistically different: 3.8 ± 2.5 in DB group and 3.4 ± 1.2 in SB group (n.s.). Therefore, Colombet’s index was similar in DB group and SB group (respectively, 0.21 ± 0.16 and 0.17 ± 0.06, (n.s.)). Conclusions This study shows a significant intraoperative advantage in anterior and rotational stability for fourtunnel DB ACL reconstruction compared with SB ACL reconstruction. Level of evidence II.