Influence of Graft Bending Angle on Femoral Tunnel Widening After Double-Bundle ACL Reconstruction: Comparison of Transportal and Outside-In Techniques

Abstract

Background: Previous studies have suggested that increased mechanical stress due to acute graft bending angle (GBA) is associated with tunnel widening and graft failure after anterior cruciate ligament (ACL) reconstruction. Few studies have compared the GBA between the outside-in (OI) and the transportal (TP) techniques. Purpose: To evaluate the influence of GBA on clinical outcomes and tunnel widening after ACL reconstruction with OI versus TP technique. Study Design: Cohort study; Level of evidence, 3. Methods: Included in the study were 56 patients who underwent double-bundle ACL reconstruction (n = 28 in the OI group and n = 28 in the TP group). Clinical outcomes (Lysholm, International Knee Documentation Committee, Tegner score, and knee laxity) 1 year postoperatively were evaluated. Computed tomography scans at 5 days and 1 year postoperatively were used for imaging measurements, and the femoral tunnel was divided into the proximal third, middle, and aperture sections. The GBA and cross-sectional area (CSA) were measured using image analysis software and were compared between groups. A correlation analysis was performed to determine if the GBA affected clinical outcomes or tunnel widening. Results: No significant difference was observed in clinical outcomes between the groups. The GBA of both the anteromedial (AM) and posterolateral bundles were more acute in the OI group compared with the TP group ( P < .05). The CSA at the AM tunnel aperture increased significantly in the OI group (84.2% ± 64.3%) compared with the TP group (51.4% ± 36.7%) ( P = .04). However, there were no differences in the other sections. In the Pearson correlation test, GBA was not correlated with tunnel widening or clinical outcomes. Conclusion: Regardless of technique, the GBA did not have a significant influence on tunnel widening or clinical outcomes. Considering a wider AM tunnel aperture, a more proximal and posterior AM tunnel position might be appropriate with the OI technique.

Eccentrically widened bone tunnels after all-inside anterior cruciate ligament reconstruction: a computed tomography and three-dimensional model-based analysis

“…Although a greater GBA was correlated with some of worse patient-reported outcomes in our study, these correlations were too weak to verify that the GBA affects clinical outcomes. In a previous study, Lee et al [ 23 ] also demonstrated that the GBA did not significantly affect the enlargement of bone tunnels and clinical outcomes, regardless of the surgical techniques. However, several other studies found that an acute GBA contributed to the occurrence of tunnel widening, but did not negatively affect the clinical outcomes [ 26 , 47 ].…”

Modification of Outside-In Technique In Preparing Femoral Tunnel During Anterior Cruciate Ligament Reconstruction—“PL-Portal Outside-In Technique”

“…There are differences among the 3 ACLR femoral tunnel preparation techniques (TT, AMP, OI) in terms of the length and obliquity of the femoral tunnel, 2 , 7 , 8 , 9 , 10 the rate of complication, and possibly the clinical outcomes after ACLR 2 , 9 , 11 ( Table 2 ). In spite of these, the choice of femoral tunnel preparation technique is usually a preference of the surgeon.…”

“…Besides, the OI technique allows posterior placement of the graft with avoidance of posterior wall blowout. 4 , 10 …”

Graft impingement increases anterior cruciate ligament graft signal more than acute graft bending angle: magnetic resonance imaging‐based study in outside‐in anterior cruciate ligament reconstruction

“…The graft bending angle plane, in which the centers of the extra‐ and intra‐articular apertures of the femoral tunnel and the center of the intra‐articular aperture of the tibial tunnel are shown together, was selected to measure the bending angle, as described in previous studies (Fig. 2B) [16, 21].…”