Femoral tunnel positioning using an anteromedial technique for ACL reconstruction: A radiographic study with a cadaveric model

BACKGROUND: We studied the anatomic positioning of the femoral tunnel during simulated anterior cruciate ligament reconstruction using an anteromedial portal approach in cadaveric models. METHODS: In thirty cadaveric human knee specimens, simulation of an arthroscopic anterior cruciate ligament reconstruction was performed and the femoral tunnel was drilled using an anteromedial portal. A Kirschner wire was passed into the tunnel and radiographs were obtained. These radiographs were then evaluated in the coronal and sagittal planes. Angles between the axis of the femoral tunnel and the joint line in the coronal plane (alpha, alpha) or the femoral long axis in the sagittal plane (beta, beta) were calculated for each specimen. The external aperture of the femoral tunnel was defined as the point of exit of the Kirschner wire from the lateral femoral cortex. This was evaluated relative to a prescribed rectangle and coordinate axis, with the radiographic quadrant method of Bernard, to assess the accuracy of femoral tunnel placement. RESULTS: The mean alpha in the coronal plane was 48.53 degrees, the mean beta in the sagittal plane was 32.23 degrees. All of the femoral tunnel external apertures were located outside of the rectangle CONCLUSION: We evaluated the positioning of the femoral tunnel and the external aperture of the femoral tunnel with the anteromedial portal technique. This study provides a reference standard to assess accurately femoral tunnel positioning on postoperative radiographs.