The sagittal plane angle and tunnel-related complications in double-bundle anterior cruciate ligament reconstruction using the transportal technique: An in vivo imaging study

Purpose To evaluate the relationbetween the tunnel angle in the 3 orthogonal planes, especially the sagittal plane,which can be influenced by knee flexion during drilling, and the incidence of complications fromthe transportal technique using in vivo imagingdata.Methods: Fifty-one patientswhounderwent anatomic double-bundleanterior cruciate ligament reconstruction by the transportal techniquewere evaluated retrospectively.A3-dimensional surfacemodelwasmadeusing anaxial computed tomography scan obtained after anterior cruciate ligament reconstruction. The tunnel length, posterior cortical damage, proximity between the outer orifice of the tunnel and lateral collateral ligament (LCL) origin, and medial femoral condyle cartilage damage were evaluated on a 3-dimensional computed tomography scan and 3-T magnetic resonance imaging. Correlations between those parameters and the tunnel angle in the coronal, axial, and sagittal planes were analyzed. Results: A tunnel length of less than 30mmdeveloped in 4 cases (8%) in the anteromedial tunnel and in 1 case (2%) in the posterolateral (PL) tunnel.Posterior cortical damage developed in12 cases (23%).Adistance fromthe outer orificeof the tunnel to the LCL origin of less than 3mmoccurred in 18 cases (35.2%) in the PL tunnel.Medial femoral condyle cartilage damagewas detected in 3 cases (6%). A positive correlation was observed between the sagittal angle and anteromedial tunnel length (P =.002, r=0.547).Thesagittal angle inthe groupwithposterior corticaldamagewas lower thanthat inthe groupwithnoposterior cortical damage (P=.002).A negative correlation was observed between the distance fromthe outer orifice of the PL tunnel to the LCL origin and the sagittal angle (P =.002, r =-0.55). Conclusions: Drilling at a higher angle in the sagittal plane decreased the incidence of posterior cortical damage and a short anteromedial tunnel. However, drilling at a higher angle shortened the distance to the LCL origin for the PL tunnel. Level of Evidence: Level IV, therapeutic case series.