Validation of a new technique to determine midbundle femoral tunnel position in anterior cruciate ligament reconstruction using 3-dimensional computed tomography analysis.

PURPOSE The purpose of this study was to investigate and report on a new intraoperative measuring technique to place the anterior cruciate ligament (ACL) femoral tunnel in the center of the native ACL femoral insertion site. METHODS We investigated a novel measuring technique based on identifying the proximal border of the articular cartilage and using a specific ruler parallel to the femoral axis to locate the origin of the ACL. The accuracy of this technique was validated by measuring tunnel position on postoperative 3-dimensional computed tomography scans. Bony tunnels created by the ruler technique were compared with tunnels drilled by a traditional technique referenced from the back wall of the notch. RESULTS Fifty ACL reconstructions were performed by the novel measuring technique, with placement of the femoral tunnel at the center of the femoral insertion. The mean position for the center of the femoral tunnel measured by the ruler technique was 0.9 mm from the theoretic optimal center position but was a very distinct 5 mm from the mean position in the traditional tunnels. CONCLUSIONS The ruler technique produced femoral tunnels comparable to published radiographic criteria used for tunnel placement and is reproducible and accurate. We recommend placement of the femoral tunnel at the midpoint of the lateral femoral condyle when using the anatomic single-bundle technique. LEVEL OF EVIDENCE Level IV, case series.