Anterior Cruciate Ligament Femoral Tunnel Placement: An Analysis of the Intended Versus Achieved Position for 221 International High-Volume ACL Surgeons

Abstract

Background: Femoral tunnels that are not anatomically placed within the native anterior cruciate ligament (ACL) footprint during ACL reconstruction are associated with residual instability, graft rupture, and poor clinical outcomes. Although surgeons may intend to place their femoral tunnels within the native ACL attachment, this is not always achieved. This study assesses the variation between intended and achieved femoral tunnel positions in a large cohort of experienced ACL surgeons. Hypothesis: The accuracy with which experienced ACL surgeons achieve their intended femoral tunnel position is dependent on viewing portal, localization strategy, and drilling technique. Study Design: Controlled laboratory study. Methods: A total of 221 surgeons indicated their intended femoral tunnel location on a true lateral radiograph of a cadaveric knee specimen and a scaled photograph. Each surgeon then arthroscopically demonstrated the femoral tunnel on the specimen. The position was captured using fluoroscopy. The Euclidean distance (the straight-line distance between 2 points) between the intended and achieved tunnel positions, referenced to a grid applied to the lateral femoral condyle, was compared. Data were analyzed according to surgeons’ viewing portal (anteromedial [AM] or anterolateral [AL]), tunnel localization strategy (offset aimer, estimation from landmarks, ACL ruler, or C-arm fluoroscopy), and stated drilling technique (transtibial, AM portal, or outside-in). Results: Surgeons who viewed the lateral intercondylar notch wall through the AM portal were closer (mean distance, 9.5) to their intended position than those who viewed through the AL portal (mean distance, 15.1; P < .0001). By localization strategy, the mean distance between achieved and intended tunnel positions was greater for surgeons who used an offset aimer (14.5) and estimated the femoral tunnel position (12.9) than for those using a malleable ACL ruler (8.1; P < .0001) and fluoroscopy (4.3; P < .0001). Surgeons’ preferred drilling technique (AM portal, transtibial, or outside-in) had no effect on distance between intended and achieved positions. However, the mean achieved position was higher in the intercondylar notch for those using transtibial drilling ( P < .042). Conclusion: Surgeons using the AM portal to view the femoral attachment site were closer to their intended tunnel position than those who viewed it with the arthroscope in the AL portal. Surgeons who used fluoroscopy to localize femoral tunnel position were the closest to their intended position. Those who used estimation or an offset aimer had the farthest distance between achieved and intended tunnel positions. Clinical Relevance: Although accurate tunnel placement can be achieved using any method, given the disparity between intended and achieved tunnel positions, it may be advisable, even for high-volume surgeons, to verify the placement of their tunnels using either fluoroscopy or a malleable ACL ruler to ensure that they achieve their intended position. Fluoroscopy may be particularly useful for cases where the native femoral stump is no longer visible and for revisions. Viewing through the AM portal is recommended to aid accuracy of tunnel placement.

Clinical and Radiological Outcomes of Anteromedial Portal Versus Transtibial Technique in ACL Reconstruction: A Systematic Review

“…Some radiographic studies have revealed that drilling the femoral tunnel through the AM arthroscopy portal rather than using a TT drilling technique resulted in a graft position more posterior and closer to a position that has been suggested as favorable on a lateral radiograph of the knee. 2,26,59,61,66,70,79,84 In the frontal plane, the bone tunnel is inclined more toward the lateral cortex of the lateral femoral condyle when drilled through the AM portal, eventually resulting in superior rotatory stabilization of the knee joint compared with TT drilling. 12 In general, it is difficult to accurately identify the tunnel location on 2dimensional images (radiograph, CT, or MRI) and impossible to accurately measure tunnel diameter (the tunnels appear as ellipses on the axial images).…”

“…30 An AM tunnel is more precise and closer to the anatomic femoral ACL insertion than a TT tunnel, allowing for a more horizontal placement. 59,73 It was recently proposed that vertical and anterior graft placement is required for the TT technique owing to drilling through the tibial tunnel, increasing biomechanical demand during rehabilitation. 58 A vertical graft orientation leads to worse clinical outcomes (pivot shift, KT-1000 arthrometer measurements, and Lysholm score) compared with a more oblique graft placement.…”

Clinical Outcome of Remnant‐Preserving and I.D.E.A.L. Femoral Tunnel Technique for Anterior Cruciate Ligament Reconstruction

“…philosophy lies in that it enables an anterior medial or transtibial drilling technique while providing the ability to consistently place the tunnel within the green zone and allows a small amount of latitude in order to support the individuality of the patient's anatomy and notch. However, the achieved tunnel position for transtibial drillers was found to be higher in the intercondylar notch than that for other drilling techniques (outside‐in and AM portal) 26 . In this study, the use of an AM‐portal ACLR technique could initially mark the tunnel position with an electrocautery device and then verify this position by switching to the AM portal.…”

Biomechanical Analysis of Ideal Knee Flexion Angle for ACL Graft Tensioning Utilizing Multiple Femoral and Tibial Tunnel Locations

“…7,8,17 Studies have demonstrated the difficulty in reproducibility of intraoperative placement of the tibial and femoral tunnels. 18 Therefore, it is important to understand the effect of tunnel placement on graft tension to limit graft excursion. Varady et al completed a computational model to simulate double-bundle reconstruction with various PL tunnel locations and simulated graft fixation at both 0 and 30 degrees.…”