Introduction

Anterior cruciate ligament (ACL) reconstruction has traditionally been performed using two arthroscopic portals: the anterolateral (AL) and the anteromedial (AM) portal. In the two-portal technique, the AL portal is used as the arthroscopic viewing portal and the ACL femoral tunnel is drilled through the AM portal. A disadvantage of the two-portal technique is that the lateral wall of the intercondylar notch is viewed through the AL portal, resulting in a tangential view of the ACL femoral attachment site, which can compromise the surgeon’s ability to accurately place the ACL femoral tunnel. Drilling the ACL femoral tunnel through the AM portal can also result in a shorter femoral tunnel length, limiting the amount of ACL graft that can be inserted into the ACL femoral tunnel when a cortical suspensory femoral fixation device is used. The use of three portals ensures that adequate length femoral tunnel and optimal visualization of the ACL femoral and tibial attachment sites are achieved.

Three-Portal Technique for Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction

In the three-portal technique, the AL and AM portals are used as viewing portals and the ACL femoral tunnel is drilled through an accessory anteromedial (AAM) portal. The three-portal technique allows the surgeon to interchange the working and viewing portals according to the specific task that is being performed. In the three-portal technique, the lateral wall of the intercondylar notch can be viewed orthogonally through the AM portal while the AAM portal is used as a working portal for instrumentation. This approach allows the surgeon to look and work in the same direction, making it easier to achieve more accurate femoral tunnel placement ( Fig. 35.1 ). Viewing the lateral wall of the intercondylar notch through the AM portal also eliminates the need to perform a notchplasty for visualization purposes. Drilling the ACL femoral tunnel through the AAM portal increases the obliquity of the ACL femoral tunnel relative to lateral wall of the intercondylar notch, resulting in a longer femoral tunnel length and a more elliptical shape to the ACL femoral tunnel aperture. An elliptically shaped ACL femoral tunnel aperture has the advantage of covering more of the native ACL femoral attachment site, compared with a circular femoral tunnel. Another advantage of the three-portal technique is that the lateral wall of the intercondylar notch can be viewed through the AM portal and an ACL ruler (Smith & Nephew Advanced Surgical Devices, Andover, Massachusetts) can be inserted through the AL portal and positioned along the lateral wall of the intercondylar notch while an angled microfracture awl is inserted into the notch through the AAM portal. This approach allows positions along the lateral wall of intercondylar notch to be accurately measured and marked. Finally, when drilling the ACL femoral tunnel with the knee in hyperflexion, a motorized shaver blade can be inserted into the notch through the AL portal. Areas of the fat pad limiting visualization can be resected, and bony debris created during drilling of the femoral tunnel can be suctioned out of the knee joint. These steps help improve visualization in the intercondylar notch when drilling the ACL femoral tunnel.

Anteromedial portal view of the anterior cruciate ligament (ACL) femoral attachment site in hyperflexion. The ACL femoral tunnel is drilled with a single-fluted drill bit introduced through the accessory anteromedial portal. Using two medial portals allows the surgeon to look and work in the same direction, making it possible to see exactly where in the ACL femoral attachment site the ACL femoral tunnel will be created.

Indications and Contraindications

The three-portal technique is versatile and can be used for any primary, revision, single-, or double-bundle ACL reconstruction and with any type of ACL graft and most ACL femoral fixation devices. The only contraindication to drilling the ACL femoral tunnel through the AAM portal using a rigid guide pin and drill bit is the inability to flex the knee to at least 120 degrees. This limitation may be encountered in some obese patients, in which case consideration should be given to drilling the ACL femoral tunnel using an outside-in technique or using a flexible guide pin and flexible reamers.

Patient Positioning

It is important to have the ability to achieve full, unrestricted knee flexion during the procedure. Keeping the operating room table flat and using a padded thigh post allows full unrestricted knee flexion and prevents the hip from abducting and the leg from externally rotating during the procedure. Using two L -shaped foot supports allows the knee to be maintained at the two most commonly used flexion angles during the procedure, 70–90 degrees and greater than 120 degrees, eliminating the need for an assistant to manually hold the leg. Although it is possible to tape sandbags or rolled blankets to the operating table to maintain the knee at these flexion angles, using foot supports that can be moved along the side rail of the operating room table allows the knee flexion angle to be adjusted during the procedure. Another advantage of using two foot supports is that the relative height of the two foot supports can be adjusted such that the knee can be maintained at a known flexion angle during final tensioning and fixation of the ACL graft ( Fig. 35.2 ).

Patient positioning.

A, The distal foot support is secured to the side rail of the operating room table near the end of the table. The patient’s torso is moved down the table until the knee is maintained at 90 degrees of knee flexion. B, The proximal foot support is adjusted to maintain the knee in hyperflexion during drilling of the anterior cruciate ligament (ACL) femoral tunnel. C, The height of the proximal and distal foot supports can be adjusted to maintain the desired degree of flexion during ACL graft tensioning and fixation.

Arthroscopic Portals

Proper placement of the arthroscopic portals is critical to the success of the procedure. With the knee at 90 degrees of flexion, the borders of the patella, patellar tendon, tibial tubercle, and the medial and lateral joint lines are marked on the skin with a sterile surgical marking pen. The vertical AL portal is marked at the level of the inferior pole of the patella, as close as possible to the lateral border of the patellar tendon. The vertical AM portal is positioned medial to the medial border of the patellar tendon, slightly higher than the inferior pole of the patella. It is important to place the AM portal high above the medial joint line; otherwise instrument crowding will occur when the AM portal is used as a viewing portal and the AAM portal is used as a working portal. The preliminary location for the AM portal is marked on the skin. However, the final portal position is made under direct arthroscopic visualization. With the knee at 90 degrees of flexion, an 18-gauge spinal needle is passed into the knee joint medial to the medial border of the patellar tendon and directed toward the roof of the intercondylar notch. The height of the spinal needle is adjusted to ensure that the shaft of the spinal needle comes to lie parallel to the roof of the intercondylar notch. This step results in the external position of the spinal needle being located proximal to the inferior pole of the patella. Placing the AM portal at this location ensures adequate spatial separation between the viewing AM and working AAM portals. Due to the curvature of the inferior pole of the patella, moving the AM portal more medially makes it possible to achieve a higher AM portal position, creating greater separation between the AM and AAM portals.

The preliminary location for the AAM portal is marked just proximal to the medial joint line. Similar to the AM portal, the final position for the AAM portal is created under arthroscopic visualization ( Fig. 35.3 ). Proper placement of the AAM portal is one of the most critical aspects of the technique. The location of the AAM portal is the major factor determining the length of the ACL femoral tunnel. When properly placed, drilling the ACL femoral tunnel through the AAM portal results in a longer ACL femoral tunnel compared with drilling through the AM portal. A more medial placement of the AAM portal will result in a more perpendicular orientation of the drill bit with respect to the lateral wall of the notch, producing a more circular-shaped tunnel aperture and a shorter femoral tunnel. A more circular ACL femoral tunnel aperture covers a smaller area of the ACL femoral attachment site compared with an elliptically shaped ACL femoral tunnel aperture. A short femoral tunnel limits the length of hamstring tendon graft that can be inserted into the ACL femoral socket when using fixed looped suspensory cortical femoral fixation devices. However, placing the AAM too far medially can also result in iatrogenic injury to the articular cartilage of the medial femoral condyle as the endoscopic drill bit is passed into the knee joint while drilling the ACL femoral tunnel. Moving the AAM portal more laterally orients the drill bit more obliquely with respect to the lateral wall of the notch, producing a more elliptically shaped femoral tunnel aperture and a longer femoral tunnel. An elliptically shaped femoral tunnel aperture restores a greater percentage of the native ACL femoral attachment site and is the preferred shape for hamstring tendon and other soft tissue grafts. However, placing the AAM portal too laterally can result in the ACL femoral tunnel violating the posterior cortex of the lateral femoral condyle.

Surface landmarks and arthroscopic portals: anterolateral portal (AL), anteromedial (AM) portal, accessory anteromedial (AAM) portal.

The AAM portal is created under direct vision using an 18-gauge spinal needle. The location of the AAM portal is adjusted based on the ACL graft type and femoral fixation method. For example, if a bone–patellar tendon–bone ACL graft is used with interference screw fixation of the femoral bone block, a 25–30-mm femoral tunnel length will allow the bone block to be fully seated in the ACL femoral socket. In this situation, the AAM portal can be positioned more medially. For hamstring tendon grafts fixed with a femoral cortical suspensory fixation device, a femoral tunnel length in the 35–45-mm length range is preferred. In this situation, the AAM portal is moved more lateral to achieve a longer femoral tunnel length. The AAM portal should be placed as low as possible above the medial joint line while avoiding the anterior horn of the medial meniscus. A transverse skin incision is preferred for this portal as this will allow adjustments in the medial-lateral position of the femoral guide pin to be made. The skin and fat are incised by passing a #11 knife blade along the upper aspect of the spinal needle under direct vision. This step protects the anterior horn of the medial meniscus from iatrogenic injury. Future instrument passage through the AAM portal can be eased by dilating the portal in line with the skin incision, using the tips of Metzenbaum scissors or a curved clamp.

Anatomic Anterior Cruciate Ligament Femoral Tunnel Placement

Although there is an ongoing debate about the optimal position for the ACL femoral tunnel, it is widely accepted that when performing an anatomic ACL reconstruction, the ACL femoral tunnel should be placed within the native ACL femoral attachment site. Anatomic ACL femoral tunnel placement is best achieved by first identifying the center of the native ACL femoral attachment site. Using the center of the native ACL femoral attachment site as a defined anatomic reference point, the surgeon may choose to alter the location of the ACL femoral tunnel within the ACL femoral attachment site based on different philosophies. A central position within the native ACL femoral attachment site is favored by many surgeons, based on biomechanical studies demonstrating that a single-bundle ACL graft positioned at the center of the native ACL femoral and tibial attachment sites best controls anterior tibial translation and tibial rotation during a simulated pivot shift test, and more closely restores knee kinematics to that of the normal knee compared with other anatomic ACL graft placements. Moving the center of the ACL femoral tunnel toward the region of the center of the AM bundle attachment site will result in an ACL graft that has smaller graft-length changes (isometric) and experiences lower and relatively constant in situ ACL graft forces. Lower in situ ACL graft forces may theoretically reduce the risk of ACL graft re-rupture compared with a centrally placed ACL graft, which experiences higher in situ ACL graft forces. However, moving the center of the ACL femoral tunnel toward the center of the AM bundle attachment site results in a more vertical orientation of the ACL graft that is not as well aligned as a centrally placed graft to control the pivot-shift phenomena. Moving the center of the ACL femoral tunnel toward the center of the posterolateral bundle attachment site will result in an ACL graft that experiences larger graft-length changes and higher in situ ACL graft forces as the knee is extended. Although this femoral tunnel position results in a more horizontal ACL graft orientation that is better aligned to control the pivot shift, higher in situ ACL graft forces and greater ACL ligament strain could theoretically increase the risk of ACL graft re-rupture.