The Anteromedial Portal for Anterior Cruciate Ligament Reconstruction

Chapter 19 The Anteromedial Portal for Anterior Cruciate Ligament Reconstruction



Manfred Bernard, Stavros Ristanis, Vassilis Chouliaras, Hans Paessler, Anastasios Georgoulis



Introduction


The correct placement of the femoral tunnel is very essential for the success of the anterior cruciate ligament (ACL) reconstruction. The transtibial drilling of the femoral tunnel has been very much popularized because of its simplicity and good visualization. However, there is evidence that drilling the femoral tunnel through the tibial tunnel can result in a nonanatomical placement of the graft in the femur.1


In the past, drilling the femoral tunnel more laterally at the medial surface of the lateral femoral condyle (LFC) (2 or 10 o’clock) has been proposed for better functional results, especially to avoid not only the anterior drawer but also the pathological rotation of the tibia.2–4 Recently it was shown the tension curve of grafts in the 9-o’clock position is similar to the characteristic pattern of the normal ACL’s tension curve.5 To reach this position (centered at 2 or 10 o’clock with the lowest point near 9 or 3 o’clock), the anteromedial portal is essential.


Thus, the anteromedial portal has become more and more attractive lately, and a large number of orthopaedic surgeons prefer this portal.6–12



Advantages


The advantages of this technique are as follows:


1 Easy manipulation of the instruments to drill the tunnel in any position at the medial side of the LFC without considering the placement of the tibial tunnel.

2 The femoral and tibial tunnels are drilled separately. Thus, one can choose the desired placement of the femoral tunnel without considering the placement of the tibial tunnel.

3 There is no risk of enlarging the tibial tunnel posteriorly, which can lead to poor fitting and stabilization of the graft in the tunnel.

4 By using bone–patellar tendon–bone (BPTB) graft, there is not any divergence when placing the interference screw.

5 In two-bundle ACL reconstruction, it is easier to choose the two entry points.

6 The drilling can be performed with the knee flexed to 120 degrees. In this position the 10-o’lock and also the 9-o’clock position can easily be reached without the risk of a blow-out fracture of the dorsal corticalis of the femoral condyle.

7 The correct rotation of the graft insertion toward the long femur axis (important to restore the anteromedial and posterolateral bundle using BPTB graft) is easily found because it is parallel to the tibia plateau in the 120-degree flexion position.


Technique


The technique is as follows:


1 Place the anterolateral portal for the arthroscope 2 to 3 cm higher than the tibial plateau between the lateral distal border of the patella and the LFC. Place the anteromedial portal 1 cm higher than the tibial plateau and very close to the medial border of the patellar tendon.

2 Resect the ligamentum mucosum and, if needed, pieces of infrapatellar fat for better visualization. In 90 degrees of flexion, débride the posterior surface of the medial side of the LFC from soft tissues. The posterior margin of the notch must be clearly identified to ensure an over-the-top position. This identification is very important to place the femoral tunnel as far posteriorly as desired. Introduce a femoral guide (6 mm offset for an 8-mm hamstring graft or 7 mm offset for a 10-mm BPTB graft) through the medial portal.

3 Slowly flex the knee to 120 degrees, and check for good visualization. Sometimes, higher fluid pressure is demanded, or parts of the fat pad have to be removed to have good visualization of the femoral footprint of the ACL. The center of the femoral tunnel is the center of the ACL footprint at 10 o’clock in the left knee and 2 o’clock in the right knee. Drill a 2.5-mm guidewire through the LFC with the knee in 120 degrees of flexion; the drill exits from the skin at the lateral side of the femur. In this position (120 degrees of flexion), the drill should be aligned parallel to the tibial plateau. Thus, a dorsal blow-out fracture is surely avoided.

4 If you are certain that the guidewire is in the correct position, overdrill the guidewire with a reamer in the chosen depth (8-mm diameter and 35-mm depth for a hamstring graft stabilized by Endobutton or 10-mm diameter and 25-mm depth for a BPTB graft).

5 If you are not sure about the correct position, the placement of the guidewire should be controlled fluoroscopically (recommended for all arthroscopic procedures) as follows:

Related posts:

Anatomical Anterior Cruciate Ligament Reconstruction with Double-Bundle, Double-Stranded Hamstring Autografts: A Four-Tunnel Technique Proprioception and Anterior Cruciate Ligament Reconstruction Anterior Cruciate Ligament Reconstruction Utilizing the Rigidfix for Femoral-Sided Fixation Revision Anterior Cruciate Ligament Reconstruction Using Autologous Hamstring Tendons High-Stiffness, Slippage-Resistant Cortical Fixation Has Many Advantages over Intratunnel Fixation Endobutton Anterior Cruciate Ligament Reconstruction Femoral Fixation

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Mar 9, 2016 | Posted by in Reconstructive surgery | Comments Off on The Anteromedial Portal for Anterior Cruciate Ligament Reconstruction

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