Graft Bending Angle at the Intra-articular Femoral Tunnel Aperture after Single-Bundle Posterior Cruciate Ligament Reconstruction

Background: To date, no in vivo 3-dimensional computed tomography (3D-CT) studies have compared graft bending angles at the femoral tunnel aperture and femoral tunnel length in patients who underwent posterior cruciate ligament (PCL) reconstruction with outside-in (OI) and inside-out (IO) techniques. Purpose/Hypothesis: This study used in vivo 3D-CT analysis to compare graft bending angles at the femoral tunnel aperture and femoral tunnel lengths after OI and IO femoral drilling techniques in single-bundle PCL reconstruction. It was hypothesized that the graft bending angle at the femoral tunnel aperture would be less acute with the OI compared with the IO technique, with no difference in femoral tunnel lengths. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Immediate postoperative in vivo 3D-CT and curved planar reformation were used to assess the graft bending angles and femoral tunnel lengths in the sagittal, axial, and coronal planes in 67 patients who underwent single-bundle PCL reconstruction with the OI (n = 37) and IO (n = 30) techniques. Results: The mean graft bending angles on the sagittal and axial planes were 8.2° more acute (23.5° vs 15.3°, P =.011) and 5.3° more acute (49.0° vs 43.7°, P =.013), respectively, with the IO compared with the OI technique, but the difference in the coronal plane was not statistically significant (25.3° vs 24.8°, P =.623). Femoral tunnel length was similar in the 2 groups. Conclusion: The graft bending angles in single-bundle PCL reconstruction were more acute in the sagittal and axial planes with the IO compared with the OI technique, but there was no difference in the coronal plane. In addition, femoral tunnel lengths did not differ significantly in patients who underwent OI and IO single-bundle PCL reconstructions. Although further biomechanical studies are needed to evaluate the effect on graft failure of a <10° difference in graft bending angle, the small magnitude of this difference would likely have little adverse effect on graft survival.