Preparation for Arthroscopic Surgery

Surgery is performed with an air tourniquet in the standard supine position. An approximately 3-cm-long oblique incision is made in the anteromedial portion of the proximal tibia. The semitendinosus and gracilis tendons are harvested using a tendon stripper in the figure-four knee position. When the semitendinosus tendon is thick and long enough, the gracilis tendon is not harvested. At the beginning of arthroscopic surgery, a surgeon sits beside the knee joint of the patient. An edge of a drape is attached to a lumbar portion of the surgeon so that the patient’s leg hanging beside the table can be put on the surgeon’s knee in a sterile condition. This setup allows the surgeon to control the patient’s knee position using the surgeon’s own knee. An arthroscope is inserted through the lateral infrapatellar portal. After a routine arthroscopic examination, a remnant of the torn ACL is resected, leaving 1-mm-long ligament tissue at the femoral and tibial insertions, which can be used as landmarks for inserting guidewires.

Creation of Tibial Tunnels

In ACL reconstruction procedures with the transtibial tunnel technique, the greatest key to success is to create a tibial tunnel with an appropriate three-dimensional (3D) direction. In other words, a tibial tunnel should be created so that a guidewire for femoral tunnel creation can be easily inserted at a targeted point on the lateral condyle through the tibial tunnel. To create such a tibial tunnel, we use a specially designed wire guide, called a wire navigator (Fig. 22-1, A), which was developed in our previous study.^7,8 This device is composed of a navi-tip and a wire sleeve. The navi-tip consists of sharp tibial and femoral indicators. The axis of the wire sleeve passes through the tip of the tibial indicator (Fig. 22-1, B). First, a tibial tunnel for the PLB is created. The navi-tip is introduced into the joint cavity through the medial infrapatellar portal. The surgeon holds the tibia at 90 degrees of knee flexion, keeping the femur horizontal. The tibial indicator of the navi-tip is placed at the center of the PLB footprint on the tibia, which is located at the most posterior aspect of the area between the tibial eminences and 5 mm anterior to the posterior cruciate ligament (Fig. 22-2). Keeping the tibial indicator on this point, we aim the femoral indicator at the center of the PLB footprint on the femur (Fig. 22-3, A), which is precisely explained in the next section, and the proximal end of the extraarticularly located wire sleeve is fixed on the anteromedial aspect of the tibia through the skin incision made for the graft harvest. The proximal end and the direction of the wire sleeve are automatically determined depending on the direction of the intraarticular navi-tip (see Fig. 22-1, B). A Kirschner wire of 2 mm in diameter is drilled through the sleeve in the tibia. According to our basic studies, this tunnel does not injure this ligament because the insertion point of the wire on the anteromedial aspect of the tibia is located several millimeters anterior to the medial collateral ligament.⁴ The first tunnel is made with an approximately 6-mm cannulated drill corresponding to the measured diameter of the prepared substitute.

Fig. 22-1 The wire navigator (A) and the concept of wire navigation for the tibia (B). The wire navigator is composed of a navi-tip (A) and a wire sleeve (B). The navi-tip consists of the tibial indicator (C) and femoral indicator (D). The axis of the wire sleeve is passed through the tip of the tibial indicator. Keeping the tibial indicator at the targeted point on the tibia, we aim the femoral indicator at the targeted point (TP) on the femur. Subsequently, the direction and the insertion point of the wire are automatically determined.

Fig. 22-2 Two tibial tunnel outlets are shown. They are created at the center of the normal attachment of the anteromedial bundle (AMB) and posterolateral bundle (PLB).

Fig. 22-3 The navi-tip of the wire navigator in an arthroscopic visual field. First (A), keeping the tibial indicator at the center of the posterolateral bundle (PLB) footprint on the tibia, a surgeon aims the femoral indicator at the center of the PLB footprint on the femur. Then (B), keeping the tibial indicator at the center of the anteromedial bundle (AMB) footprint on the tibia, a surgeon aims the femoral indicator at the center of the AMB footprint on the femur.

Next, a Kirschner wire for the AMB reconstruction is drilled using the same wire navigator. The tibial indicator is placed at the center of the tibial footprint of the AMB, which is located at a point approximately 7 mm anterior to the center of the first tunnel (see Fig. 22-2). Keeping the tibial indicator on this point, we then aim the femoral indicator at the center of the femoral footprint of the AMB (Fig. 22-3, B). The wire sleeve is fixed on the anteromedial cortex of the tibia. A Kirschner wire is then drilled through the sleeve in the tibia. The knee should be extended to ensure that the tip of the second wire is located at a point 5 mm posterior to the anterior edge of the roof in the intercondylar notch. The second tunnel is drilled with an approximately 7-mm cannulated drill corresponding to the measured diameter of the prepared substitute. Subsequently, two intraarticular outlets are aligned in the sagittal plane (see Fig. 22-2).

Creation of Femoral Tunnels

In the anatomical double-bundle procedure, it is essential to precisely understand the attachment of the main ACL fibers that should be reconstructed in ACL reconstruction. Although the normal ACL has a wide footprint on the lateral condyle,^9–11 the author has found that the main ACL fiber attachment that should be reconstructed in ACL reconstruction is in the form of an egg, with its long axis inclined toward the posterior direction by 30 degrees to the long axis of the femur on the medial surface of the lateral femoral condyle⁴ (Fig. 22-4).

Fig. 22-4 Attachment of the anterior cruciate ligament (ACL) on the femur. The dotted lines show the attachment of the main fibers of the ACL. When we drew a vertical line (VL) through the contact point (C) between the femoral condyle and the tibial plateau on a picture taken at 90 degrees of flexion, this line and the long axis of the ACL attachment (AX) was crossed at the point (PL) on the vertical line 5 to 8 mm anterior to the edge of the joint cartilage. The center (AM) of the attachment of the anteromedial bundle was located at the point 5 to 6 mm distal from the back of the femur as measured using the offset guide. AFS, A parallel line with an axis of the femoral shaft.

First, a Kirschner wire is drilled at the center of the femoral footprint of the AMB through the second tibial tunnel, using the offset guide system (Transtibial Femoral ACL Drill Guide, Arthrex, Naples, FL). This point is located at the point 5 to 6 mm distal from the back of the femur (see Fig. 22-4). This point is consistent with the 1:30 (or 10:30) orientation for the left (or right) knee. Using this wire as a guide, a tunnel is made with a 4.5-mm cannulated drill. The length of the tunnel is measured with a scaled probe. Then, to precisely observe the lateral condyle in the arthroscopic visual field, the portal for the arthroscope is changed to the medial infrapatellar one. We have developed a reproducible method to identify the targeted point in the arthroscopic visual field.⁴ When the surgeon holds the tibia at 90 degrees of knee flexion, keeping the femur horizontal, we can draw an imaginary vertical line through the contact point between the femoral condyle and the tibial plateau in the arthroscopic visual field (see Fig. 22-4). The center of the attachment of the PLB is located approximately at the crossing point between the vertical line and the long axis of the ACL attachment. Therefore, when the remnant of the ACL is observed on the lateral condyle, this point can be easily determined. If the remnant of the ACL is not identified on the lateral condyle, the center of the attachment of the PLB can be determined as the point 5 to 8 mm anterior to the edge of the joint cartilage on the imaginary vertical line (see Fig. 22-4). The femoral tunnel that has been created already for the AMB reconstruction can be used as a good landmark to determine the center of the attachment of the PLB. To insert a guidewire at this point, the surgeon manually holds a Kirschner wire and aims it at the center of the attachment of the PLB on the femur through the tibial tunnel, keeping the femur horizontal at 90 degrees of knee flexion. Then the surgeon lightly hammers the wire into this point and drills it (Fig. 22-5, A). A 4.5-mm diameter tunnel is drilled using this wire as a guide. Our cadaveric study showed that this technique provides some benefits for Endobutton fixation, including easy passage of the graft and easy flip of an Endobutton.⁴ The tunnel length is measured in the same manner.

Fig. 22-5 Insertion of a guidewire for the posterolateral bundle (PLB) into the femur using the transtibial tunnel technique (observed through the medial portal). A, First, a surgeon drills a Kirschner wire into the center of the PLB attachment on the femur. B, Two tunnels are independently created within the anterior cruciate ligament (ACL) remnant on the lateral condyle. C, Each wire is inserted through a tibial tunnel to a femoral tunnel at 90 degrees of knee flexion demonstrates the position and direction of a pair of tunnels. Note that the directions of the anteromedial bundle (A) and PLB (P) wires are different.

Finally, two sockets are created for the AMB and PLB reconstruction with cannulated drills in the Endobutton fixation system (Acufex Microsurgical, Mansfield, MA), the diameter of which is matched to the two grafts prepared with the technique described in the following section. Thus, two tunnels are created inside the ACL remnant on the lateral condyle (Fig. 22-5, B). The different directions of the two pairs of tunnels are demonstrated by inserting two wires through the tibial tunnel to the femoral tunnel at 90 degrees of knee flexion (Fig. 22-5, C).

Graft Fashioning

The harvested semitendinosus is cut in half. Regarding the gracilis tendon, both ends are resected so that the thickest portion is used for the graft, and the length is matched to half the length of the semitendinosus tendon. One-half of the semitendinosus tendon and the resected gracilis tendon are doubled and used for AMB reconstruction. The remaining half of the semitendinosus tendon is also doubled and used for the PLB reconstruction. Using these tendon materials, the hybrid grafts are fashioned (Fig. 22-6). At the looped end of each doubled tendon graft, an Endobutton-CL (Acufex Microsurgical, Mansfield, MA) is attached. The length of the Endobutton-CL is determined such that a 15- to 20-mm long tendon portion can be placed within the bone tunnel. A commercially available polyester tape (Leeds-Keio Artificial Ligament, Neoligament, Leeds, United Kingdom) is mechanically connected in series with the other end of the doubled tendons, using the original technique⁵ (see Fig. 22-6). This tape is strong, soft, meshed, 10 mm wide, and 15 cm long. In our experience, the diameter of the tendon portion ranges from 6 to 8 mm for the AMB graft and from 5 to 6 mm for the PLB graft. The first advantage of the hybrid graft is that it is stronger and stiffer than the tendon-suture composite.^12,13 The second advantage is that the tape portions of the two grafts can be simultaneously fixed to the tibia with an initial tension.The latter feature is specifically important for anatomical double-bundle reconstruction.

Fig. 22-6 The hybrid grafts. At the looped end of each doubled tendon graft, an Endobutton-CL is attached. A polyester tape is mechanically connected in series with the other end of the doubled tendons, using the original technique. An absorbable suture marker is attached to each graft to show the point of flip of the Endobutton. The diameter of this tendon portion shows 7 to 8 mm for the anteromedial bundle (AMB) graft and 5 to 6 mm for the posterolateral bundle (PLB) graft.

Graft Placement

The graft for the PLB reconstruction is introduced through the tibial tunnel to the femoral tunnel using a passing pin and is fixed on the femur by an Endobutton. Then the graft for the AMB is placed in the same manner. Thus, the two bundles having different directions are intraarticularly grafted (Fig. 22-7). The grafts rarely impinge to the femur. Notchplasty is performed only in knees with an extremely narrow notch due to osteochondral spar formation or a similar problem.

Fig. 22-7 The reconstructed two bundles as observed through the lateral portal. The posterolateral bundle (P) is observed behind the anteromedial bundle (A).

Graft Tensioning and Fixation

For graft fixation, the knee is flexed to 10 degrees with a sterilized thin pillow placed beneath the thigh, keeping the heel in contact with the operating table (Fig. 22-8). A spring tensiometer (Meira, Nagoya, Japan) is attached at each end of the polyester tape portion of the graft. An assistant surgeon simultaneously applies tension of 30N to each graft for 2 minutes at 10 degrees of knee flexion, and a surgeon simultaneously secures the two tape portions onto the anteromedial aspect of the tibia using two spiked staples in the turn-buckle fashion.⁵

Fig. 22-8 A surgeon simultaneously secures the two tape portions onto the anteromedial aspect of the tibia using two spiked staples, applying a 30N tension to each graft for 2 minutes using tensiometers (TM) at 10 degrees of knee flexion.

The mechanism of our tensioning technique is explained as follows¹⁴: According to our in vivo measurement studies, when we applied the same initial tension on each bundle at 10 degrees of knee flexion, each tension pattern was similar to that of the normal bundle. This fact suggested that the slight flexion position (10 degrees of knee flexion) is recommended as the most appropriate knee flexion angle for easy graft tensioning. On the other hand, the full extension position may be clinically recommended to avoid flexion contracture of the knee after surgery. However, our previous studies^13,15 showed that the initial graft tension in the hamstring tendon graft was dramatically reduced in the early phase after surgery. Therefore, the slight flexion position is again recommended as the most appropriate knee flexion angle for graft tensioning, when we take into account the postoperative graft relaxation. Another important question about graft tensioning is whether we should separately fix the two grafts at different flexion angles. According to our in vivo measurement studies, if we apply a tension to the AMB after fixing the PLB at the extension position, the initial tension applied to the PLB is reduced to an unknown degree. A surgeon cannot sufficiently control the graft tension in this technique. Therefore, in anatomical double-bundle ACL reconstruction, it is important to simultaneously fix the two bundles, applying appropriate initial tensions to the two grafts.

Postoperative 3D computed tomography shows that each tunnel outlet was created at the center of the anatomical attachment of the AMB or the PLB (Fig. 22-9).

Fig. 22-9 Postoperative three-dimensional computed tomography showing that each tunnel outlet was created at the center of the anatomical attachment of the anteromedial bundle (A) or the posterolateral bundle (P).