Alternative Anterior Cruciate Ligament Fixation Techniques: Retroscrew

Melissa D. Koenig MD

James P. Bradley MD

Since the first anterior cruciate ligament (ACL) reconstruction was performed, surgeons have continued to strive for ways to make the construct as anatomic as possible. This concept has led to developments in graft type, tunnel location, and graft fixation. The concept of aperture fixation, that is fixation at the intraarticular ends of the femoral and tibial tunnels, was popularized in the 1990s. Although early results were promising, this technique was technically demanding. The development of the Retroscrew (Arthrex, Inc, Naples, Fla), an interference screw placed retrograde in a standard tibial tunnel, has made this procedure more feasible.

Benefits of aperture fixation include increased graft pullout strength, decreased graft “windshield wiper” motion, decreased tunnel widening, and a more stable construct throughout knee range of motion. The Retroscrew can be used to fix any graft including autogenous bone-patellar-tendon bone and hamstring grafts as well as all allograft options. The Retroscrew construct has been described for fixation of both single tunnel reconstructions and single femoral socket and double bundle constructs.

Surgical Technique

The graft and tunnels are prepared using standard techniques. Both tunnels are notched with the Retro Tunnel Notcher (Arthrex, Inc, Naples, Fla). Before the graft is passed, a FiberStick (Arthrex, Inc, Naples, Fla) is passed into the tibial tunnel. The suture end is grasped and withdrawn through the anteromedial portal. The suture is kept anterior as the graft is passed into the joint and seated into the femoral tunnel.

To fix the graft using a femoral Retroscrew (Fig. 40-1A,B,C,D,E), the cannulated screwdriver is placed over the stiff end of the FiberStick. The driver is advanced through the tibial tunnel anterior to the graft. Outside of the knee, the free end of the suture is passed through the head of the screw and out of the other end. A Mulberry knot is tied to secure the screw on the suture. The screw is secured into the plastic cannula and inserted into the joint through the anteromedial portal. An obturator is used to push the screw into the joint.

The suture exiting the screwdriver handle is pulled to guide the screw onto the tip of the driver. Any visible soft tissue must be removed to allow the screw to seat fully. The suture is removed with a grasper from the anteromedial portal and the screw is advanced to the opening of the femoral tunnel. The graft is tensioned and the screw is advanced into the tunnel. The screwdriver is disengaged from the screw and kept in the tibial tunnel.

To place the tibial Retroscrew (Fig. 40-2A,B,C,D,E), another FiberStick is advanced through the screwdriver. The suture is retrieved through the anteromedial portal as described above. The screw is secured to the suture with a Mulberry knot tied behind the head of the screw. The screw is passed into the joint as previously described. Pulling on the suture guides the screw tip onto the screwdriver. Once the screw is fully seated, the suture is secured around the grommets on the handle of the screwdriver. The graft is tensioned and the screw is inserted in a counterclockwise fashion until the head is flush with the tibial tunnel. The suture is grasped at the knot through the anteromedial portal and removed. Secondary tibial fixation can be performed, if desired, according to the surgeon’s preference.

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