Anatomic placement of the femoral tunnel by a modified transtibial technique using a large-offset femoral tunnel guide: A cadaveric study

• Feasibility of modified transtibial technique for anatomical femoral tunnel placement in ACL reconstruction was tested.
• Authors' modified transtibial technique comprising lateral rotation of a large-offset guide was assessed on cadaveric knees.
• More anatomic placement of femoral tunnel is feasible by the authors' modified transtibial technique in ACL reconstruction.

BackgroundThe purpose of this study was to assess whether the use of a 10 mm-offset femoral tunnel guide with lateral rotation allows more anatomic placement of femoral tunnel compared to the conventional seven millimeters-offset guide in transtibial anterior cruciate ligament (ACL) reconstruction.MethodsSixteen knees from eight cadavers were employed. Four guide pins were inserted using a seven millimeters- or 10mm-offset transtibial femoral tunnel guide with or without lateral rotation technique in each knee. The pin positions were assessed by the quadrant method. Femoral tunnels were then reamed along the guide pins inserted through the laterally rotated guides: seven millimeters-offset for right knees and 10 mm- offset for left knees. The percentages of the coverage of native ACL femoral footprints were analyzed.ResultsLateral rotation of the seven millimeters- & 10mm-offset guides placed the pins more posteriorly (lower) by 15.7% and 24.5%, respectively (p < 0.001). Laterally rotated 10 mm-offset guides placed the guide pins more distally by 6.2% and more posteriorly by 6.6% than laterally rotated seven millimeters-offset guides. Laterally rotated seven millimeters- & 10 mm-offset guides resulted in average coverage of 52.3% and 61.8% of the native ACL femoral footprints, respectively (p < 0.001). The lengths of the tunnels were acceptable.ConclusionCompared to the conventional seven millimeters-offset guide, the use of a 10mm-offset femoral tunnel guide with lateral rotation allows more anatomic placement of femoral tunnel in transtibial ACL reconstruction.Clinical relevanceAnatomic single bundle ACL reconstruction by transtibial technique seems feasible by using the technique described in this study.