Anatomical Double-Bundle Anterior Cruciate Ligament Reconstruction Procedure Using the Semitendinosus Tendon

Introduction

The anterior cruciate ligament (ACL) is composed of the anteromedial bundle (AMB) and the posterolateral bundle (PLB), each with a different function. The author reported the first practical double-bundle procedure to anatomically reconstruct the AMB and the PLB using the transtibial technique in 2004, and the first clinical results compared with a conventional single-bundle procedure in 2006. Then, in 2008, our prospective comparative study using 328 patients demonstrated that the postoperative anterior and rotational stability after the anatomic double-bundle ACL reconstruction was significantly better than that after the conventional single-bundle reconstruction. In addition, our biomechanical study showed advantages of this double-bundle procedure in terms of restoration of knee stability, in comparison with a conventional single-bundle procedure. In this chapter, the surgical theory and the practical procedure of our anatomical double-bundle ACL reconstruction are explained.

Theory of the Procedure

In this procedure, we intend to reconstruct the midsubstance fibers of the anteromedial (AM) and posterolateral (PL) bundles at each anatomical location in the intercondylar space. To reconstruct such fibers, we should create four independent tunnels at the center of each attachment of the AM and PL midsubstance fibers, respectively ( Fig. 36.1 ). This is a basic theory of this procedure.

To understand the basic theory, it is important to precisely know functional anatomy of the femoral ACL attachment. The ACL attachment is composed of two different shapes of fibers, the attachment of the midsubstance fibers and the fan-like extension fibers. The thin fan-like extension fibers extend from the midsubstance fibers and broadly spread out on the posterior condyle, while all fascicles that make up the midsubstance of ACL attach to the relatively narrow oval area on the lateral condyle. Recently, we discovered that a deep fold is formed at the border between the midsubstance and the fan-like extension fibers during knee flexion. This fact implies that a force in the midsubstance fibers is considered to be hardly distributed to the fan-like extension fibers across the fold, when the knee is flexed. To confirm this presumption, we performed a biomechanical study to clarify the role of the midsubstance fibers and the fan-like extension fibers in the femoral attachment of the ACL in resisting tibial displacement, using the sequential cutting method. As for the results, the narrow attachment of the midsubstance fibers resisted 82%–90% of the anterior drawer force, and the fan-like extension fibers contributed very little ( Fig. 36.2 ). These results suggest that, first, it is essential to anatomically reconstruct the midsubstance fibers and the attachment of the ACL, while it is of less value to reconstruct the fan-like extension fibers. Second, specifically in double-bundle ACL reconstruction, two femoral tunnels should be created at the center of the combined areas G and H and the center of the combined areas E and F, which are in the ACL midsubstance fiber attachment. These facts supported the previously described original theory.

This theory has been justified by several biomechanical studies. Previously, Yagi et al. and Petersen et al. concluded that the anatomic double-bundle reconstruction produces a better biomechanical outcome, especially during rotatory loads, compared with the conventional single-bundle reconstruction, using a robotic manipulator. Yasuda et al. measured tension in the simulated AM and PL bundle grafts during the clinical surgery described later in the chapter, and showed that the tension-versus-flexion curve of each reconstructed bundle is similar to that of the native bundle. Furthermore, Recently, Kondo et al. performed an arthroscopic double-bundle procedure in the cadaver knees (described later), and compared the knee stability with that after a conventional single-bundle procedure. There were significant reductions of anterior laxity and internal rotational laxity in the anatomic double-bundle reconstruction, as compared with the single-bundle reconstruction. These biomechanical facts have shown that the original theory of this procedure is appropriate.

Theory of the Procedure

In this procedure, we intend to reconstruct the midsubstance fibers of the anteromedial (AM) and posterolateral (PL) bundles at each anatomical location in the intercondylar space. To reconstruct such fibers, we should create four independent tunnels at the center of each attachment of the AM and PL midsubstance fibers, respectively ( Fig. 36.1 ). This is a basic theory of this procedure.

To understand the basic theory, it is important to precisely know functional anatomy of the femoral ACL attachment. The ACL attachment is composed of two different shapes of fibers, the attachment of the midsubstance fibers and the fan-like extension fibers. The thin fan-like extension fibers extend from the midsubstance fibers and broadly spread out on the posterior condyle, while all fascicles that make up the midsubstance of ACL attach to the relatively narrow oval area on the lateral condyle. Recently, we discovered that a deep fold is formed at the border between the midsubstance and the fan-like extension fibers during knee flexion. This fact implies that a force in the midsubstance fibers is considered to be hardly distributed to the fan-like extension fibers across the fold, when the knee is flexed. To confirm this presumption, we performed a biomechanical study to clarify the role of the midsubstance fibers and the fan-like extension fibers in the femoral attachment of the ACL in resisting tibial displacement, using the sequential cutting method. As for the results, the narrow attachment of the midsubstance fibers resisted 82%–90% of the anterior drawer force, and the fan-like extension fibers contributed very little ( Fig. 36.2 ). These results suggest that, first, it is essential to anatomically reconstruct the midsubstance fibers and the attachment of the ACL, while it is of less value to reconstruct the fan-like extension fibers. Second, specifically in double-bundle ACL reconstruction, two femoral tunnels should be created at the center of the combined areas G and H and the center of the combined areas E and F, which are in the ACL midsubstance fiber attachment. These facts supported the previously described original theory.

This theory has been justified by several biomechanical studies. Previously, Yagi et al. and Petersen et al. concluded that the anatomic double-bundle reconstruction produces a better biomechanical outcome, especially during rotatory loads, compared with the conventional single-bundle reconstruction, using a robotic manipulator. Yasuda et al. measured tension in the simulated AM and PL bundle grafts during the clinical surgery described later in the chapter, and showed that the tension-versus-flexion curve of each reconstructed bundle is similar to that of the native bundle. Furthermore, Recently, Kondo et al. performed an arthroscopic double-bundle procedure in the cadaver knees (described later), and compared the knee stability with that after a conventional single-bundle procedure. There were significant reductions of anterior laxity and internal rotational laxity in the anatomic double-bundle reconstruction, as compared with the single-bundle reconstruction. These biomechanical facts have shown that the original theory of this procedure is appropriate.

Practical Procedure

Preparation for Arthroscopic Surgery

Surgery is performed with an air tourniquet in the standard supine position. 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. This setup is also critical to appropriately create two femoral tunnels later using the transtibial tunnel technique. A short oblique incision is made in the anteromedial portion of the proximal tibia. The semitendinosus tendon is harvested using a tendon stripper. An arthroscope is inserted through the lateral infrapatellar portal. A remnant tissue 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 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 . 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. 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 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. Keeping the tibial indicator on this point, we aim the femoral indicator at the center of the PLB footprint on the femur ( Fig. 36.3A ), which is precisely explained in the next section, and the proximal end of the extra-articularly located wire sleeve is fixed on the anteromedial aspect of the tibia. The proximal end and the direction of the wire sleeve are automatically determined depending on the direction of the intra-articular navi-tip. A guidewire is drilled through the sleeve in the tibia. The insertion point of the wire on the anteromedial aspect of the tibia is located several millimeters anterior to the medial collateral ligament. The first tunnel is made with a cannulated drill, which corresponds to the measured diameter of the prepared substitute (commonly 6 mm).

Next, a guidewire 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 8 mm anterior to the center of the first tunnel. Keeping the tibial indicator on this point, we then aim the femoral indicator at the center of the femoral footprint of the AMB (see Fig. 36.3B ). The wire sleeve is fixed on the anteromedial cortex of the tibia. A guidewire is then drilled through the sleeve in the tibia. The second tunnel is drilled with a cannulated drill, which corresponds to the measured diameter of the prepared substitute (commonly 7 mm).

Creation of Femoral Tunnels

To insert a guidewire at the averaged center of the femoral footprint of the native AMB midsubstance through the second tibial tunnel, we developed a clinically available quantitative technique ( Fig. 36.4 ). In this technique, we intend to insert a guidewire into the lateral wall of the intercondylar notch at the point with “1:30” or “10:30” clock orientation and at a distance D of 5 mm from the proximal outlet. The “1:30” orientation, an eighth of a circle, can be easily detected by a surgeon in the arthroscopic visual field. In the actual procedure, we introduce a 5-mm offset guide into the joint cavity through the tibial tunnel, and set the hook-shaped tip of this guide at the “over-the-top” portion of the lateral condyle at 90–100 degrees of knee flexion. Keeping the hook at this point, the offset guide should be rotated so that the tip of a guidewire inserted through the guide is aimed at the “1:30” or “10:30” clock orientation in the arthroscopic visual field. Using this wire as a guide, a tunnel is created with a 4.5-mm cannulated drill. The length of the tunnel is measured with a scaled probe.