Biomechanical Comparison of Anterior Cruciate Ligament Reconstruction Using a Single-Bundle Round or Ribbon-like Hamstring Tendon Graft

Background: Persistent instability of the knee is reported in up to 30% of patients after anterior cruciate ligament (ACL) reconstruction. Based on anatomic findings showing that ACL is a flat ribbon-like structure that twists during knee flexion, a new surgical ACL reconstruction technique using a ribbon-like graft has been developed. However the effect of this surgical technique on knee kinematics has not yet been evaluated. Purpose: To compare the anteroposterior and rotational stability of the knee after ACL reconstruction using single-bundle (SB) round and ribbon-like grafts in anterolateral-intact/deficient knees. Study Design: Controlled laboratory study. Methods: Twelve human fresh-frozen cadaveric knees were tested with a 6 degrees of freedom robotic system. Internal rotation and anterior translation of the knee were recorded from 0 degrees to 90 degrees of flexion. A full kinematic assessment was performed in each of the following conditions: (1) intact knee, (2) after sectioning of the ACL, (3) after ACL reconstruction using a SB hamstring tendon graft in a round configuration and a ribbon-like configuration, and (4) after sectioning of the anterolateral structures. One-way analysis of variance and post hoc Tukey tests were used for statistical analyses. Results: When compared with the intact knee, the ACL-deficient knee demonstrated a mean +/- SD increase in anterior translation and internal rotation of 6.3 +/- 2.5 mm (P < .01) and 5.8 degrees +/- 2.3 degrees (P < .01), respectively. After ACL reconstruction using a SB ribbon-like graft, the mean difference in anterior translation and internal rotation as compared with the intact knee was -0.1 +/- 1.5 mm (P = .842) and 0.0 degrees +/- 1.1 degrees (P = .999). These differences from the intact knee were also not significant after ACL reconstruction using a round graft (-0.1 +/- 1.3 mm, P = .999; -0.5 degrees +/- 1.5 degrees, P = .401). In the ACL-reconstructed knee using either a ribbon-like or round graft, sectioning of the anterolateral structures did not induce a significant increase of anterior translation and internal rotation of the knee. Conclusion: ACL reconstruction using a SB ribbon-like or round graft restored the kinematics of the intact knee at time zero. Secondary sectioning of the anterolateral structures in the ACL-reconstructed knee using both types of graft did not significantly affect the anterior translation and internal rotation of the knee.

Automated summary

This study compared the anteroposterior and rotational stability of the knee after ACL reconstruction using single-bundle round and ribbon-like grafts. It was found that both types of graft restored the stability of the knee, and the sectioning of the anterolateral structures did not significantly affect knee stability.