Does the position of interference screw in tibial tunnel effect anatomic orientation in single bundle anterior cruciate ligament reconstruction?

BACKGROUND/OBJECTIVE: The purpose of the study was to evaluate the change in orientation of the reconstructed ACL with the change in position of the interference screw in the tibial tunnel. METHOD: It was a retrospective review of Magnetic Resonance Imaging (MRI) in which 51 normal and 61 MRI of patients who had undergone ACL reconstruction at our institute were evaluated. Postoperative ACL reconstruction group MRI studies were obtained and evaluated by two sports medicine fellows independently to assess the position of interference screw, distance of the graft from the anterior cortex of tibia and inclination of the graft. The data was collected and compared with MRI data of normal ACL patients. RESULTS: There were total 61 patients with ACL reconstruction. 32 patients had anterior screw placement and 29 patients had posterior screw placement in the tibial tunnel. The distance of the graft from the anterior cortex was 39.18% in ACL intact group, 50.35% in anterior screw group and 41.64% in posterior screw group. The inclination angle was 44.49⁰ in intact group, 49.69° and 42.20° in anterior and posterior screw group respectively. The difference between intact group and anterior screw group was statistically significant. CONCLUSION: Posterior position of interference screw in tibial tunnel increases graft obliquity than anterior position and decreases its distance from the anterior tibial cortex. This increased graft obliquity and distance from the anterior tibial cortex is similar to the native ACL.