What is the proper position of the femoral tunnel in Anterior Cruciate Ligament (ACL) reconstruction?

From the Guidelines

The proper position of the femoral tunnel in Anterior Cruciate Ligament (ACL) reconstruction should be in the anatomic footprint of the native ACL on the lateral wall of the intercondylar notch. However, the provided evidence 1 does not specifically address the proper position of the femoral tunnel in ACL reconstruction. Based on general medical knowledge and the principles of ACL reconstruction, the tunnel should be placed low on the lateral wall (posteriorly) and slightly superior, avoiding the "high noon" position which can lead to graft impingement and failure. Ideally, the center of the tunnel should be positioned to preserve the native ACL's obliquity and biomechanics, providing superior rotational stability and more natural knee kinematics. Some key considerations for femoral tunnel placement include:

• Placing the tunnel at approximately the 10 o'clock position for a right knee or 2 o'clock position for a left knee
• Positioning the tunnel 7-8 mm anterior to the posterior cortex of the lateral femoral condyle
• Preserving about 2 mm of posterior wall to prevent blow-out
• Using the anteromedial portal technique with the knee hyperflexed to 110-120 degrees to access this position properly It is essential to note that non-anatomic placement can result in persistent rotational instability and potentially earlier graft failure despite achieving anterior-posterior stability, emphasizing the importance of precise tunnel placement in ACL reconstruction 1.

From the Research

Femoral Tunnel Placement in ACL Reconstruction

The proper position of the femoral tunnel in Anterior Cruciate Ligament (ACL) reconstruction is crucial for a successful outcome. Several studies have investigated the optimal placement of the femoral tunnel, including the use of landmarks and computer-assisted planning systems.

• The posterior horn of the lateral meniscus has been identified as a reliable landmark for femoral tunnel placement, with a study finding that it is always located directly below the desired femoral ACL tunnel position when the knee is brought to deep flexion (> 120°) 2.
• Computer-assisted planning and placement systems have also been shown to improve the accuracy of femoral tunnel positioning, with one study finding an accuracy of 2.7 mm for the anteromedial bundle and 3.2 mm for the posterolateral bundle 3.
• The apex of the deep cartilage has been proposed as a landmark to help guide femoral tunnel placement, with a study finding that it is an easily identifiable landmark during arthroscopy and can be used to reference the position of the ACL femoral footprint 4.
• Guidelines for femoral tunnel placement based on height and depth on the lateral wall of the notch have been developed, with a study finding that the center of the ACL can be located on the lateral notch at a height of 8.7 ± 0.6 mm from the lowest point and anterior 11.5 ± 1.3 mm from the deepest point 5.
• The use of the anteromedial portal for drilling the femoral tunnel has been shown to result in a more accurate placement of the tunnel, with a study finding that it allows for stabilization of both anterior tibial translation and rotational instability when using a single bundle reconstruction technique 6.

Key Findings

• The posterior horn of the lateral meniscus is a reliable landmark for femoral tunnel placement 2.
• Computer-assisted planning and placement systems can improve the accuracy of femoral tunnel positioning 3.
• The apex of the deep cartilage can be used as a landmark to guide femoral tunnel placement 4.
• Guidelines for femoral tunnel placement based on height and depth on the lateral wall of the notch have been developed 5.
• The anteromedial portal is a more accurate method for drilling the femoral tunnel compared to the transtibial approach 6.