Seating of TightRope RT Button Under Direct Arthroscopic Visualization in Anterior Cruciate Ligament Reconstruction to Prevent Potential Complications

Abstract

The ACL TightRope RT (Arthrex, Naples, FL) is a recently introduced fixation device. The adjustable graft loop allows the surgeon some freedom in terms of the length of the femoral socket, eliminates the need for bothersome intraoperative calculations for selecting loop length, ensures that the socket is completely filled with graft, and provides the possibility of tensioning the graft even after graft fixation. However, the device can be associated with the same complications that have been described with EndoButton (Smith & Nephew Endoscopy, Andover, MA) fixation. For example, in our experience, sometimes the button of the TightRope RT may not flip, may become jammed inside the femoral canal, or may flip in the substance of the vastus lateralis. To prevent this, we have introduced 2 additional steps in our procedure: (1) direct visualization of the TightRope RT button in the femoral socket with the arthroscope during its passage and (2) a controlled push directly on the button with the help of a guide pin. Thus proper seating of the button is ensured by direct visualization and the crucial push helps in flipping and seating of the button.

The ACL TightRope RT (Arthrex, Naples, FL) is a newer fixation device that makes ligament fixation fast, easy, and secure.¹ The TightRope button is attached to graft through a loop that can be tightened even after insertion into the canal. The adjustable loop allows the surgeon some freedom in terms of the length of the femoral socket, eliminates the need for bothersome intraoperative calculations for selecting loop length, ensures that the socket is completely filled with graft, and provides the possibility of tensioning the graft even after graft fixation.¹ Good initial results have been reported in the literature with these devices, using the all-inside technique.¹ Because the basic structure of the TightRope button is the same as that of the EndoButton (Smith & Nephew Endoscopy, Andover, MA), theoretically, it can be associated with the same complications that have been described with EndoButton fixation.^2-5 The button may become jammed in the femoral guide pin hole in the region of the cortical bone bridge. In our experience with the TightRope RT, the button became jammed in the femoral guide pin hole in 1 of our patients. Unlike the EndoButton, there is no side suture in the TightRope RT button for flipping. This increases the possibility that the button may not flip even after passing through the lateral femoral cortex. When the graft is pulled back in the reverse direction to check whether the button has flipped, the end of the button may temporarily become stuck at the lateral opening of the guide pin hole, giving the false impression that it has flipped and engaged on the lateral femoral cortex. This would subsequently result in postoperative graft loosening and failure of reconstruction. Another complication is that the button can be pulled out through the skin laterally while one is pulling it from the outside or it may flip within the substance of the vastus lateralis.⁴ The risk of this happening is greater with the TightRope RT than with the EndoButton because the loop of the TightRope RT is longer than that of the EndoButton. We have experienced this twice in our practice. In such a situation, the repositioning of the button back on the femoral cortex may result in soft-tissue interposition between the button and the cortex. This can potentially result in late graft loosening after ischemic necrosis of the interposed tissues.

Learning from our experience, we have introduced two additional steps in our procedure to ensure proper seating of the button on the femoral cortex.

• 1We visualize the TightRope RT button in the femoral socket and guide pin hole with the arthroscope during its passage.
• 2We try to push the button past the guide pin hole.

Technique

The sockets are made and graft is prepared and looped with the Tight Rope RT as described in the literature.¹ We prepare the femoral socket inside out from the anteromedial portal. The guide pin is introduced through the anteromedial portal, inserted at the femoral footprint of the anterior cruciate ligament, and brought out through the lateral cortex. The femoral socket is then created with a drill of the size determined from the diameter of the graft, leaving about 7 to 10 mm of cortical bone bridge laterally.

A mark is made on the loop equal to the femoral intraosseous distance, measuring from the distal tip of the button with the button held parallel to the loop (i.e., the pre-flipped position). This indicates the flip distance, that is, the point at which the button has completely passed through the femoral guide pin hole and is ready for flipping. Another mark is made on the graft, with measurement from its femoral end, equal to the length of the femoral socket. During graft passage, the reaching of this mark at the internal opening of the femoral socket marks the endpoint for graft tensioning.

We drill a through-and-through tibial tunnel for fixation with a Bio-Interference screw (Arthrex, Naples, FL) on the tibial side. A braided No. 5 suture is passed from the anteromedial portal through the femoral socket and pin hole and brought out of the skin laterally. Its medial end is passed through the tibial tunnel and brought out medially using a suture grasper. By use of this suture, the TightRope RT passing sutures are passed through the tibial tunnel and then through the femoral socket and brought out laterally. The passing sutures are then pulled from the lateral side, with the TightRope RT button being pulled into the femoral socket under direct arthroscopic vision (Fig 1, Video 1).

Figure 1.

Arthroscopic view of lateral wall of femoral intercondylar notch of right knee, showing femoral socket end-on. The patient is lying supine with the knee and hip flexed, and the arthroscope has been inserted through the anterolateral portal. The guide pin hole is seen in the center of the socket. The depth of the socket is 25 mm, and the length of the pin hole through the cortical bone bridge is 10 mm. The TightRope RT button is seen entering the pin hole. The loop of the TightRope RT is lying in the femoral socket. Because the loop is long, the graft has not yet entered into the joint.

As the button reaches the guide pin hole, resistance is felt. At this crucial juncture, no further pulling force is applied. Under arthroscopic vision, a 2.4-mm guide pin (Arthrex) is negotiated against the free end of the button until its tip engages in the small depression located on the side of the button. The button is then pushed gently or tapped slowly through the pinhole with the help of this guide pin (Fig 2, Video 1). When there is a feel of loss of resistance or giving way, the button slips away from the guide pin tip. The guide pin is then withdrawn, the graft is pulled from the tibial end, and the button becomes seated at the femoral cortex. The remaining process of surgery is completed without any modification.

Figure 2.

A guide pin is introduced through the anteromedial portal parallel to the socket and pin hole. Its tip is engaged in the depression located on the side of the free end of the button (the side facing the arthroscope in the socket). A controlled push is then applied on the button with the help of this pin, as viewed from the anterolateral portal for a right knee joint.

Discussion

Graft fixation with the TightRope RT is a recent technique, and complications with this technique have not yet been reported. However, in our patients, we have experienced some of the complications with the TightRope RT that have earlier been described in the literature for the EndoButton, such as jamming in the femoral tunnel and soft-tissue interposition. Both of these complications can lead to late graft loosening. By introducing the 2 small modifications described in this report during the insertion of the TightRope RT with graft in our practice, we have ensured proper seating of the button on the femoral cortex.

We have found no difficulty in visualizing the whole socket and the guide pin hole with the arthroscope, as well as the passage of the button and the graft through the socket. This is possible because the loop in the TightRope RT is longer than that in the EndoButton. When the button reaches the outer cortex of the femur, the graft has still not reached the opening of the femoral socket, and the socket is occupied only by the loop. We have found that the direct and controlled push on the button until the feeling of giving way occurred was an easier, safer, and sure way to seat the button on the femoral cortex compared with the pull.

The guide pin engages adequately in the depression present on the end of the button. The button also passes snugly through the guide pin hole. As a result, there is no risk of toggling or change of direction of the button while pushing, provided that the pushing guide pin is held parallel to the guide pin hole. The only precaution that needs to be kept in mind is to prevent widening of the femoral guide pin hole or breaking of the cortical bone bridge by the guide pin by an uncontrolled push. Unlike the EndoButton, the button of the TightRope RT does not have the provision of flipping and toggling. The push of the button with the guide pin past the guide pin hole helps in not only delivering the button out of the pin hole but also flipping it on the cortex.

Supplementary data

Video 1

Direct arthroscopic visualization of TightRope RT button in femoral socket. The right knee is being operated on. The patient is lying supine with the hip flexed at about 50° and knee flexed at about 100°. The viewing portal is the anterolateral portal. The depth of the femoral socket is 25 mm, and the pin hole through the cortical bone bridge is 10 mm long. The femoral socket is visualized end-on, and the TightRope RT button is passed through it. A guide pin is then introduced through the anteromedial portal. Its tip is engaged in the depression located on the side of the free end of the button, and a controlled push is then applied on the button with its help, until the button has passed completely through the femoral cortical bone bridge, as visualized arthroscopically.