Purpose: To compare drilling the femoral tunnel with an offset aimer and BullsEye guide (ConMed Linvatec, Largo, FL) to perform an anatomic single-bundle reconstruction of the anterior cruciate ligament (ACL) through the anteromedial portal.
Methods: Seven matched pairs of cadaveric knees were studied. The intent was to drill the femoral tunnel anatomically in all cases. In group A the femoral tunnel was drilled arthroscopically with an offset aimer. In group B the femoral tunnel was drilled arthroscopically with the BullsEye guide. Two tunnels were drilled through the same entry point in each knee. One was done at 110° of knee flexion and the other at 130°. They were scanned by computed tomography and reconstructed 3-dimensionally. Volume-rendering software was used to document relations of the drilled tunnel to the bony anatomy and tunnel length.
Results: In group B the femoral tunnel was placed at the center of the femoral insertion site. The center of the tunnel was 9.4 mm from the high cartilage margin and 8.6 mm from the low cartilage margin. In group A the tunnels were placed deeper (5.4 mm and 12.6 mm, respectively) (P = .018). There were no differences in tunnel length for either knee flexion degree. Three of the tunnels drilled at 110° in group A compromised the posterior tunnel wall and measured less than 25 mm in length.
Conclusions: Accurate placement in the center of the femoral footprint of the ACL is better accomplished with the BullsEye guide rather than 5-mm offset aimers. Five-millimeter offset aimers might cause posterior tunnel blowout and present the risk of obtaining short tunnels when performing oblique femoral tunnel placement through the anteromedial portal at 110° of knee flexion.
Clinical relevance: The BullsEye guide might be better than standard offset aimers in the performance of anatomic single-bundle ACL reconstruction.
Copyright © 2011 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.