Determinants of Femoral Tunnel Length in Anterior Cruciate Ligament Reconstruction: CT Analysis of the Influence of Tunnel Orientation on the Length

Abstract

PurposeThe purpose of the study was to identify the femoral tunnel orientation that consistently results in a tunnel length of more than 35 mm in anterior cruciate ligament reconstruction.Materials and MethodsComputed tomography (CT) scans were obtained from 30 patients who did not have any pathology in the distal femur. Virtual tunnels were marked on 3D (3-dimensional) reconstructed CT images after determining the orientation defined by sagittal inclination and axial angle. The length of a femoral tunnel in 64 different combinations of orientations (between 30° and 65° in 5° increments in two planes) was measured on 3D reconstructed images in both knees in 30 patients. Reliability of measurement was assessed with correlation coefficient for intra-observer and inter-observer measurements. A one-way analysis of variance (ANOVA) was used for statistical analysis.ResultsThe mean femoral tunnel length varied significantly with each 10° change in orientation in both planes (p<0.05, ANOVA). A femoral tunnel of more than 35 mm in length could be obtained only with a sagittal inclination of more than 50° and axial angle of 30°-45°. When the axial angle was kept constant, the tunnel length increased with the increase in sagittal inclination. Higher sagittal inclinations consistently resulted in longer tunnels (r>0.9) and reduced the incidence of posterior cortical breakage.ConclusionsA tunnel orientation with an axial angle between 30°-45° and a sagittal inclination of more than 50° can result in a tunnel length of more than 35 mm.

Influence of change of tunnel axis angle on tunnel length during double-bundle ACL reconstruction via the transportal technique

“…The lack of graft incorporation is a common cause of surgical failure [ 14 ]. Greis et al reported that the length of a tendon placed within a bone tunnel influences tendon pullout strength, and advocated maximizing the tendon length inside the bone tunnels [ 22 ]. Previous cadaveric and clinical studies reported that the mean femoral tunnel length drilled through AM portals ranges from 15.7 − 34.2 mm [ 23 , 24 ].…”

“…We thought it was necessary to investigate tunnel configurations made using curved guides with a three-dimensional approach because it allows a certain degree of control over intra-articular tunnel orientation. Few previous studies have investigated the ideal tunnel axis angle for longer tunnel lengths [ 22 , 28 ]. These studies were limited because they were experimental studies using a bone saw or cadaver, and the results are difficult to reproduce in a practical surgical situation.…”

Functional outcome of an early anterior cruciate ligament reconstruction in comparison to delayed: Are we waiting in vain?

“…The transportal guide wire was placed 30-45 in the sagittal plane and horizontal to the floor via the accessory anteromedial portal. 15 Then a 4.5 mm cannulated drill was used to drill a tunnel and the length was measured. Then the femoral tunnel was made larger as needed according to the width of the graft with flower head tipped drills.…”

Dimensional assessment of continuous loop cortical suspension devices and clinical implications for intraoperative button flipping and intratunnel graft length

“…The above concerns are magnified for anatomic ACL reconstructions, which utilize an anteromedial arthroscopic portal for femoral tunnel reaming and subsequently create shorter femoral tunnels, relative to the transtibial technique . Recent studies have demonstrated an ability to create femoral tunnels greater than 30 mm in length; however, Golish et al reported the median length to be 25 mm for anteromedial reamed tunnels which is consistent with the technique and experience of the senior surgeon. Therefore, the current study results are schematically represented in 25 mm femoral tunnels for ACL reconstruction (Fig.…”