Validation of a New Technique to Determine Midbundle Femoral Tunnel Position in Anterior Cruciate Ligament Reconstruction Using 3-Dimensional Computed Tomography Analysis Jonathan H. Bird, F.R.C.S.(Tr&Orth), Michael R. Carmont, F.R.C.S.(Tr&Orth), Manpreet Dhillon, F.R.C.R., Nick Smith, M.R.C.S., Charlie Brown, M.D., Peter Thompson, F.R.C.S.(Tr&Orth), and Tim Spalding, F.R.C.S.(Tr&Orth) 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. T he ultimate goal of anterior cruciate ligament (ACL) reconstruction is the restoration of normal knee kinematics in patients with functionally unstable ACL-deficient knees. It has been hypothesized that abnormal knee kinematics is one of the primary causes of the development of osteoarthritis after ACL recon- struction. 1,2 It is hoped that a more anatomic ACL reconstruction will reduce the long-term incidence of osteoarthritis. The femoral tunnel has a major effect on the length-tension pattern of the reconstruction, and nonanatomic femoral tunnel placement is one of the most common causes of a failed ACL reconstruc- tion. 3 Surgical techniques for placement of the femo- ral tunnel previously have been based on the concept of ACL graft isometry 4 or the use of offset femoral guides that reference the over-the-top position of the lateral femoral condyle. In the 1990s the transtibial technique was developed as a quick reproducible method; the femoral tunnel is drilled through the tibial tunnel by use of an offset femoral drill guide, and both tunnels are therefore effectively linked. Independent drilling methods can produce tunnels with superior function compared with tunnels produced by conven- From the Departments of Trauma and Orthopaedic Surgery (J.H.B., M.R.C., N.S., P.T., T.S.) and Radiology (M.D.), University Hospitals Coventry and Warwickshire NHS Trust, Coventry, Eng- land; and Abu Dhabi Knee and Sports Medicine Centre (C.B.), Abu Dhabi, United Arab Emirates. The authors report no conflict of interest. Received August 9, 2010; accepted March 10, 2011. Address correspondence to Tim Spalding, Department of Trauma and Orthopaedics, University Hospitals Coventry and Warwickshire NHS Trust, 5th Floor, Clifford Bridge Road, Cov- entry CV2 2DX, England. E-mail: info@timspalding.com © 2011 by the Arthroscopy Association of North America 0749-8063/10477/$36.00 doi:10.1016/j.arthro.2011.03.077 1259 Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 27, No 9 (September), 2011: pp 1259-1267