Arthroscopic Visualization of Femoral Cortical Button Deployment During Anterior Cruciate Ligament Reconstruction

Abstract

Background:

Up to 25% of femoral cortical suspensory fixation devices are reported to be deployed inappropriately during anterior cruciate ligament (ACL) reconstruction. Most techniques for visualizing suspensory button deployment reported in the literature are for adjustable loop buttons and outside-in femoral tunnel technique. Intraoperative radiographs are inconvenient and involve exposure to radiation. No “gold standard” technique for visualization of femoral cortical button deployment has been described yet.

Indications:

This technique can be employed for all patients requiring ACL reconstruction surgery.

Technique Description:

The femoral tunnel is prepared from the anteromedial portal. With the knee in flexion, a beath pin loaded with a suture loop is passed via the anteromedial portal through the femoral tunnel; the eyelet of the pin with the suture loop is retained in the femoral tunnel. The knee is extended without fear of bending the beath pin. The arthroscope is shifted into the lateral gutter. An outside-in lateral parapatellar portal is made at the level of the center of the patella, 1 cm lateral to its lateral edge. The joint capsule and soft tissues in the lateral gutter are resected using a shaver. The beath pin is identified without fear of lacerating the suture loop. The exit point of the pin depends on the knee flexion at the time of femoral tunnel preparation, and more flexion results in more anterior pin exit and vice versa. The rest of the surgery is performed as planned. The definitive sutures of the desired femoral cortical suspensory device are passed from the tibial tunnel into the femoral tunnel. The arthroscope is then positioned in the lateral gutter and the cortical button is deployed appropriately under vision, onto the lateral femoral cortex. If required, the cortical button can be manipulated to seat it appropriately, using an instrument from the lateral parapatellar portal. The remainder of the surgery is performed as per the surgeon’s preference.

Results:

We routinely perform this step during ACL reconstruction. It adds 2 to 4 minutes to the surgical time. We have not encountered any complications of this procedure.

Discussion/Conclusion:

This maneuver is effective in facilitating appropriate deployment of femoral cortical suspensory devices under vision.

Graphical Abstract

This is a visual representation of the abstract.

Video Transcript

These are our disclosures.

Femoral cortical suspensory fixation devices for anterior cruciate ligament (ACL) reconstruction are popular, because they are easy to use and are biomechanically and clinically validated.

The most common method for confirmation of deployment of femoral cortical button is by calculating the length of the femoral tunnel and marking the graft appropriately. The button is then delivered by pulling on the flipping suture. This is perceived mechanically but is not visualized.

Technical problems with this method have been reported to result in inappropriate deployment of femoral cortical buttons in 15% to 25% of the cases.^6,11 This could either result from soft tissue interposition between the button and the femoral cortex, or premature flipping of the button inside the femoral tunnel.

Techniques described to prevent inappropriate deployment of the femoral cortical button include the use of tactile feel, viewing through the femoral tunnel, the use of special portals, and intraoperative radiographs.^1,2,4,5,7-10

These techniques described in the literature are predominantly for adjustable loop buttons and outside-in femoral sockets. The accessory portals used in these techniques are either technically challenging or can lead to laceration of the sutures.

The femoral tunnel is created through the anteromedial portal with the knee in flexion greater than 110°. A 4.5-mm tunnel is made by drilling over the beath pin and the length of the tunnel is measured. Depending on the graft size and the length of the fixed loop button being used, an appropriately sized femoral socket is created. The integrity of the lateral femoral cortex is ascertained by viewing through the femoral socket. A beath pin loaded with a suture loop is passed from the anteromedial portal into the femoral tunnel, but not pulled out completely. The eyelet of the beath pin and the suture loop are retained in the femoral socket. The knee can be safely extended now without fear of bending the pin. The arthroscope is then shifted into the lateral gutter. At the level of the midpoint of the patella and 1 cm lateral to it, a lateral parapatellar portal is made. A shaver is passed through this portal. The capsule and soft tissues are resected to identify the beath pin without the fear of lacerating the suture loop. The exit point of the beath pin depends on the degree of knee flexion at the time of femoral tunnel preparation. An anterior exit point is seen in high degrees of knee flexion, and a posterior exit point is seen when the knee flexion is less. Once the beath pin is completely exposed and the soft tissues around it are cleared, a radiofrequency device is used to resect the remaining soft tissue and achieve hemostasis. The passing suture loop is now retrieved outside. The sutures attached to the femoral button are shuttled using this suture loop. The traction suture is used to deliver the button outside the lateral femoral cortex. The button is flipped under vision. Application of traction to the distal tibial side sutures ensures that the button is seated on the femoral cortex without soft tissue interposition.

Lateral parapatellar portal is made 1 cm lateral to the lateral edge of patella and in line with the equator of the patella. This portal is used for instrumentation while viewing from the anterolateral portal.

An antegrade femoral socket was created from the anteromedial portal, and the adjustable loop button was passed into the femoral tunnel. The arthroscope was shifted to the lateral gutter, where the femoral button was seen to be engulfed in the soft tissues. The button was manipulated using the sutures attached to it and the distal graft sutures. It was gently delivered out of the soft tissues and flipped over the lateral femoral cortex under vision.

In this video, the button can be seen entrapped in the lateral soft tissues as it could not be manipulated by applying traction on the sutures. An artery clip was inserted from the lateral parapatellar portal, and the button was teased out of the soft tissues.

There was no iatrogenic damage to the sutures attached to the button. Traction on the distal graft sutures seated the button flush on the lateral femoral cortex.

The capsule and soft tissues in the lateral gutter were resected to identify the beath pin. A radiofrequency device was used to identify the pre-existing button.

After the redundant intra-articular part of the graft was excised, an artery clip was introduced through the lateral parapatellar portal to gently remove the button with its loop. A view from the lateral parapatellar portal shows the relationship between the 2 tunnels.

Important precautions: The exit point on the lateral femoral cortex is determined by the knee flexion at the time of femoral tunnel preparation. Care must be taken to ensure that the eyelet of the beath pin and the suture loop are parked in the femoral socket in order to extend the knee without the fear of bending the pin. Bleeding from the terminal branches of lateral genicular vessels can be controlled using a radiofrequency device.

Advantages of this technique: There is no major structure at risk during creation of the lateral parapatellar portal. There is no fear of lacerating the sutures when the shaver and radiofrequency devices are used. Buttons entangled in soft tissues can be retrieved and repositioned on the lateral femoral cortex under vision. Inadvertent deployment of the button in the femoral tunnel can be avoided; no exposure to radiation is required.

These are our references.

Thank you.