Surgical Setup

The patient is placed supine on the operating table. A pneumatic tourniquet is placed around the proximal thigh to allow the safe percutaneous passage of Beath needles distally. A lateral post, resting against the tourniquet, controls external rotation of the hip. The foot rests against a distal support that maintains the knee at 90 degrees of flexion. This setup allows the knee to be moved freely throughout its complete range of flexion and is essential for drilling the femoral tunnels through the AM portal.

Graft Harvesting

The gracilis and semitendinosus tendons are harvested using a tendon stripper as per a routine single-bundle hamstring reconstruction. The maximal length of tendon is harvested and the residual muscle removed. The gracilis graft (future PL bundle) is passed through a 15-mm continuous loop Endobutton-CL (Smith & Nephew, Mansfield, MA). A 20- to 30-mm Endobutton-CL is used for the semitendinosus graft (future AM bundle) due to the longer femoral AM tunnel. Each graft is then placed on a tensioning board and whipstitched with an absorbable #1 suture over 40 mm of its length. The two bundles are then calibrated. Grafts and the corresponding tunnel diameters are sized in 0.5-mm increments. The diameters of the double-stranded grafts are on average 6 mm for the PL bundle and 7 mm for the AM bundle (Fig. 23-1). If the diameter of the PL bundle graft measures less than 5 mm, we recommend attempting to triple the graft to increase its diameter. This is usually possible because the required length of the PL graft is shorter than the AM. If, however, the length is insufficient, then we recommend converting to a single-bundle technique.

Fig. 23-1 Distribution of graft diameters for 140 reconstructions. AM, Anteromedial; PL, posterolateral.

Arthroscopic Reconstruction

The position of the arthroscopy portals is critical to allow the correct positioning of the bone tunnels. We recommend that the AM and anterolateral portals are made just adjacent to the corresponding borders of the patella tendon. Both should be placed as high as possible, just beneath the inferior border of the patella. The high anterolateral portal allows the tibial attachment of the ACL to be well visualized in the flexed knee. We do not find it necessary to use an accessory medial portal as proposed by Yagi et al.²² Following the arthroscopic evaluation and treatment of meniscal and articular lesions, the intercondylar notch is prepared. Scar tissue and ligament remnants are cleared from the 9 to 12 o’clock positions (the 12 to 3 o’clock positions in left knees), allowing the limits of the femoral ACL footprint to be well visualized.

Preparation of the Femoral Tunnels

Both femoral tunnels are drilled via the AM portal. In order to do this successfully, two critical steps must be observed. First (as described earlier), it is important that the AM tunnel is placed as midline as possible (i.e., just adjacent to the patella tendon) so that the drill does not damage the articular surface of the medial femoral condyle. Second, when placing the guidewires and during cannulated drilling, the knee should be flexed beyond 120 degrees. This is particularly important for the correct positioning of the AM femoral tunnel guidewire into the correct anatomical position “high” and “deep” (using notch navigation terminology) in the intercondylar notch.

The choice to drill the femoral tunnels via the AM portal and not via a transtibial approach is based on anatomical considerations. Several authors have shown that it is difficult to place a femoral tunnel in the anatomical attachment of the ACL via the transtibial approach.^28–30 The advantages of using the AM portal have been outlined by Cha et al³⁰ and Aglietti et al,²¹ who found that not only can the femoral tunnel be placed more anatomically, but that the femoral and tibial tunnels can be made independent of each other and that tunnel placement is also independent of graft type.

Although it is possible to drill the femoral AM tunnel via the tibial tunnel,²⁴ it is not possible to reach the anatomical attachment of the PL bundle on the femur via this approach. In order to achieve anatomical placement of both tunnels on the femur, the alternative would be to use an “outside-in” approach.^21,23 This necessitates the use of a second incision, made laterally, in order to position the drill guide. This approach is more invasive (incising both the lateral intermuscular septum and the capsule, which may be associated with some morbidity), and for this reason using the AM portal seems more appropriate.

The AM femoral tunnel is made first. With the knee flexed to at least 120 degrees, a 4-mm offset femoral guide (Acufex, Smith & Nephew) is introduced through the AM portal. The 2.4-mm guidewire is placed at the 1-o’clock position in the left knee (the 11 o’clock position in the right knee). The 4.5-mm Endobutton-CL reamer is then run over the guidewire in order to pierce the lateral cortex. The tunnel is then reamed up to the corresponding graft size using the cannulated dilators.

After drilling the AM tunnel, a femoral PL bundle drill guide (Fig. 23-2) is used. The appropriate size guide is introduced into the AM tunnel and then rotated so that the PL bundle tunnel is positioned lower, more shallow, and more laterally (using notch navigation terminology) in the intercondylar notch at the 2:30 position (the 9:30 position in right knees). The drill guide allows the PL tunnel to be pierced with a 4.5-mm drill (again piercing the lateral cortex) so that the two femoral tunnels diverge at 15 degrees. With the knee flexed, the AM tunnel is more vertical, measuring 45 to 50 mm in length compared with the more oblique PL tunnel, which varies between 30 and 35 mm long. The PL tunnel should breach the cortex proximal to the tibial insertion of the lateral collateral ligament such that the cortical bone is sufficient to support the Endobutton. As with the AM bundle, the PL bundle is then dilated to the appropriate diameter. The drill guide is designed so that an approximate 2-mm bony bridge is left between the tunnels as they emerge into the intercondylar notch. This corresponds to the anatomical positions of the two tunnels in the femoral ACL attachment.