Influence of femoral tunnel exit on the 3D graft bending angle in anterior cruciate ligament reconstruction

Abstract

Purpose To quantify the influence of the femoral tunnel exit (FTE) on the graft bending angle (GBA) and GBA-excursion throughout a full range of motion (ROM) in single-bundle anterior cruciate ligament (ACL) reconstruction. Methods Three-dimensional (3D) surface models of five healthy knees were generated from a weight-bearing CT obtained throughout a full ROM (0, 30, 60, 90, 120°) and femoral and tibial ACL insertions were computed. The FTE was simulated for 16 predefined positions, referenced to the Blumensaat's line, for each patient throughout a full ROM (0, 30, 60, 90, 120°) resulting in a total of 400 simulations. 3D GBA was calculated between the 3D directional vector of the ACL and the femoral tunnel, while the intra-articular ACL insertions remained unchanged. For each simulation the 3D GBA, GBA-excursion, tunnel length and posterior tunnel blow-out were analysed. Results Overall, mean GBA decreased with increasing knee flexion for each FTE (p < 0.001). A more distal location of the FTE along the Blumensaat's line resulted in an increase of GBA and GBA-excursion of 8.5 ± 0.6° and 17.6 ± 1.1° /cm respectively (p < 0.001), while a more anterior location resulted in a change of GBA and GBA-excursion of -2.3 ± 0.6° /cm (+ 0.6 ± 0.4°/ cm from 0–60° flexion) and 9.8 ± 1.1 /cm respectively (p < 0.001). Mean tunnel length was 38.5 ± 5.2 mm (range 29.6–50.5). Posterior tunnel blow-out did not occur for any FTE. Conclusion Aiming for a more proximal and posterior FTE, with respect to Blumensaat’s line, reliably reduces GBA and GBA-excursion, while preserving adequate tunnel length. This might aid to reduce excessive graft stress at the femoral tunnel aperture, decrease femoral tunnel widening and promote graft-healing. Level of Evidence IV

Osteoconductive Scaffold Placed at the Femoral Tunnel Aperture in Hamstring Tendon ACL Reconstruction: A Randomized Controlled Trial

“…1,18,22 This apparent discrepancy may be a result of different primary etiologic factors at play. Whereas the tendon graft is bent at the femoral aperture by approximately 70 , 15,21,33 in the tibia the graft exits the tunnel almost straight, irrespective of the knee flexion angle. Consequently, graft tension yields higher graft-bone contact pressure in the femoral tunnel, which may induce cell necrosis and subsequent bone resorption.…”

A novel approach for joint line restoration in revision total ankle arthroplasty based on the three‐dimensional registration of the contralateral tibia and fibula

“…The ankle JL was defined as the average plane of five surface registration points on the tibial plafond in a standardized fashion (two at the anterior ridge, two at the posterior ridge and one at the center) (Fig. 2 ) as described by Hodel et al [ 10 ] The approximation of the JL based from the contralateral side was measured in mm in direction of the anatomical tibia axis (z-axis) (positive values indicating an elevation of the JL, negative values indicating a distalisation). In addition, the mean absolute error of the approximated JL compared to the original JL was calculated for each segment and is subsequently referred to as JL error.…”

Tibial internal rotation in combined anterior cruciate ligament and high-grade anterolateral ligament injury and its influence on ACL length

“…The intra-articular tibial and femoral ACL insertion points were defined based on weighted means of anatomic insertion sites as described by Parkar et al [ 24 ] who reported the tibial insertions according to Stäubli et al [ 25 ] and the femoral insertions according to Bernard et al [ 26 ], as described in a previous study [ 27 ].…”