Femoral Graft Bending Angle and Femoral Tunnel Geometry of Transportal and Outside-In Techniques in Anterior Cruciate Ligament Reconstruction: An In Vivo 3-Dimensional Computed Tomography Analysis

Relationship between femoral tunnel location and graft bending angle in outside-in and transportal technique for ACL double bundle reconstruction in 3D-CT study

“…Previously, Kim et al [12] analyzed the femoral tunnel position after ACL-DBR using transportal and outside-in techniques and reported that there was significant difference in the PLB femoral tunnel position between two drilling methods. Park et al [18] compared femoral tunnel position between transportal and outside-in techniques after ACL single bundle reconstruction, and indicated that the outside-in technique showed a significantly shallower femoral tunnel position than did in the transportal technique.…”

“…Park et al [18] compared femoral tunnel position between transportal and outside-in techniques after ACL single bundle reconstruction, and indicated that the outside-in technique showed a significantly shallower femoral tunnel position than did in the transportal technique. They [12,18] created femoral tunnels through the central midpatellar portal using FlipCutter (Arthrex) in outside-in technique, whereas femoral guide (Smith and Nephew) was inserted through a conventional anterolateral portal in outside-in technique in our study. Kim et al [12] suggested that the guide tip of the FlipCutter impacting the medial wall of the lateral femoral condyle during outside-in femoral drilling causes a mismatch between the aimed centre and the drilling centre.…”

“…At an alpha level of 0.05 and a power of 0.8, 17 patients for each group would be required to detect a mean difference of 8 degrees for the femoral graft bending angle as calculated using power and sample size calculations version 3.0 based on previous reports [12,23].…”

“…Some previous studies have analyzed the femoral graft bending angle between femoral tunnel axis and graft at the femoral tunnel aperture in ACL reconstruction [12,16,18,23,26,27]. However, the relationship between femoral tunnel location and femoral graft bending angle has been little investigated.…”

Effects of femoral bone tunnel characteristics on graft-bending angle in double-bundle anterior cruciate ligament reconstruction: a comparison of the outside-in and transportal techniques

“…A large GBA indicates that the graft is acutely bent and stretched at the femoral bone tunnel aperture. To date, several advantages to the OI technique have been put forward, such as a low incidence of posterior wall blowout of the lateral femoral condyle, a lack of cartilage damage at the medial femoral condyle during drilling, and easy handling of cases with a narrow notch [11]. However, whether acute GBA in the OI technique actually impairs graft-healing and, if so, what the safe range is, remain unclear.…”