A CT based evaluation of femoral and tibial tunnel widening after double bundle ACL reconstruction

Abstract

IntroductionAmong the postoperative phenomenon of ACL reconstruction, tunnel enlargement has been reported consistently, regardless of the technique used. It could be clinically relevant in post operative follow up and revision surgery. This study evaluated the magnitude of tibial and femoral bone tunnels enlargement after arthroscopic double-bundle anterior cruciate ligament (ACL) reconstruction by the Computed Tomography Scan. MethodsForty patients undergoing arthroscopic double-bundle ACL reconstruction using multistranded hamstring graft, were included in the study. CT scan was performed on second postoperative day and at follow-up of 6 month. Tunnels were evaluated by digitally measuring the widths, perpendicular to the long axis of the anteromedial (AM) and posterolateral (PL) tunnels, on an oblique coronal, saggital and axial plane at 3 levels: aperture, midway, and suspension point. Bony bridge thickness at aperture and minimum distance between two tunnels to anticipate communication was also computed. ResultsFemoral tunnel measurement showed statistically significant enlargement at aperture and midway. At the aperture, enlargement of AM and PL tunnel was 21.95% and 26.16% whereas at midway, enlargement was 20.05% and 24.5%. At the suspension point, enlargement was 3.97% and 7.1%. On tibial side, order of significant enlargement was midway of AM = 21.16% and PL = 31.78% followed by aperture of AM = 18.9% and PL = 28.84% and finally suspension point of AM = 17.84% and PL = 25.21%. Average bony bridge thickness at femoral and tibial aperture was 0.291 ± 0.059 and 0.231 ± 0.105 cm respectively with 10% of the patients showed merging of tunnels at aperture. ConclusionCT scan is an effective way to determine the tunnel position and enlargement after ACL reconstruction. There is a significant widening of femoral and tibial tunnels at 6 months follow-up of arthroscopic double bundle anterior cruciate ligament reconstruction. Tunnel widening could be a serious problem after double-bundle ACL reconstruction.