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The Relationship Between ACL Femoral Tunnel Position and Postoperative MRI Signal Intensity

Background: The purpose of this study was to find the ideal femoral tunnel position in single-bundle anterior cruciate ligament (ACL) reconstruction using three-dimensional computed tomography (3D-CT) by comparing clinical scores, stability of the knee joint, and graft signal intensity on follow-up magnetic resonance imaging (MRI). We hypothesized that positioning the femoral tunnel near the anteromedial bundle or center would lead to better results in terms of clinical outcomes and graft signal intensity on follow-up MRI than would positioning the tunnel near the posterolateral bundle. Methods: Two hundred patients underwent arthroscopic single-bundle ACL reconstruction with a soft-tissue graft; all patients had the same surgeon, surgical technique (anteromedial transportal technique), and rehabilitation protocol. Each patient underwent 3D-CT within 1 week after the operation and MRI at 1 year after the operation. Outcomes were evaluated in terms of clinical scores and the stability of the knee joint. We classified patients into three groups based on the femoral tunnel position: the anteromedial position group, the posterolateral position group, and the center position group. We evaluated graft signal intensity on follow-up MRI. Results: This study included 77 patients: 25 patients in the anteromedial position group, 15 patients in the posterolateral position group, and 33 patients in the center position group. Four patients had an eccentric tunnel position and were excluded. The 3 groups did not differ significantly (p > 0.05) in preoperative demographic characteristics. There were no significant differences (p > 0.05) between groups in clinical outcomes. However, patients in the anteromedial position group and in the center position group had better graft signal intensity on follow-up MRI than those in the posterolateral position group. Conclusions: Positioning the femoral tunnel near the anteromedial bundle and center led to better graft signal intensity on follow-up MRI in anatomic single-bundle ACL reconstruction than did positioning the femoral tunnel near the posterolateral bundle. There were no differences in clinical scores or stability of the knee joint among the three groups. Level of Evidence: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.