ACL reconstruction allows the patients to return to sporting activities and improves the functional outcomes [48]. However, one study found that half of patients operated 10–20 years ago, showed signs of osteoarthritis (OA) with associated pain and functional impairment. The same authors found inconclusive evidence to support the protective role of repair or reconstructive surgery of the ACL or meniscus against osteoarthritis development [49]. A comparison of conservative and reconstructive ACL surgery found similar physical activity levels for both groups at 11 years follow-up. ACL reconstruction led to higher stability but also increased risk for osteoarthritis. Nonetheless, the risk of secondary meniscal tears is reduced after reconstruction, which indirectly reduces the negative effects of OA [50]. The extraarticular augmentation procedure from the Rizzoli Institute of Bologna, Italy only demonstrated progressive joint narrowing for patients having concomitant medial meniscal surgery [51]. A retrospective evaluation performed in Pittsburg identified an almost 40 % incidence of radiographic OA approximately 8 years after ACL surgery. Prior medial meniscectomy, 2 or greater medial chondrosis and obesity were the best predictors for OA development [52]. An analysis of the MOON (Multicenter Orthopaedic Outcomes Network) cohort found patients were able to perform sports function at 6 years, but the activity level continued to decline from baseline evaluation. In addition, lateral meniscus treatment, allograft, smoking and obesity were negative predictors for long-term outcomes [53]. More than a 3-fold increase prevalence of OA was found after ACL reconstructed knees compared with the contralateral. The prevalence of OA was similar between the B-PT-B and hamstrings grafts. A meniscus resection was also a strong predictor of symptomatic degeneration [54]. In the Swedish ACL register, older aged patients (over 40 years) recorded lower preoperative KOOS scores. These patients exhibited the greatest improvement in for all subscales up to 5 years, even though they had more cartilage and meniscus injuries and longer intervals from injury to reconstruction [55]. Fourteen years after operative or nonoperative management of ACL injury, the reconstructed cohorts had less need for subsequent meniscal surgery and less decline of functional scores. The difference in pivot-shift results was not significant, as well as final outcome scores (Tegner – Lysholm, International Knee Documentation Committee – IKDC) or the rate of radiographically evident degeneration [56, 57].

The transtibial technique (TT) has been the first widely used arthroscopic reconstruction technique, with favorable outcomes reported in the late ’80. In the late ’90, the works of Professor Freddie Fu from Pittsburg and others have raised concern regarding the graft placement and function using this surgical procedure. In addition, the clock dial referencing was considered an inappropriate single plane description of a three dimensional position. More research into the biomechanics of the ACL saw the advent of the double bundle technique (DB).

The over-the-top position of the graft on the femur was anterior and medial to the native ACL insertion [9, 17]. In knees with hyperextension and a vertical notch roof, the TT technique required notchplasty and a more posteriorly placed tibial tunnel to prevent impingement [94]. This led to extremely vertical and nonphysiological grafts that were found to have less resistance to anterior translation and especially less rotational stability compared to double bundle anatomic reconstruction [95]. The current switch to anatomic reconstruction has greatly limited the need for notchplasty, mainly to osteophyte removal from the lateral condyle border (Fig. 3.12). Experimental studies have repeatedly showed that the femoral attachment of the native ACL is on the lateral femoral condyle and never on the notch roof. A correctly positioned tibial tunnel will never allow for a correct placement of the femoral aperture in the native insertion [96]. Further research provided additional data to support femoral tunnel drilling through the antero-medial portal. When compared to the TT technique, it offered better function and closer obliquity to the native contralateral ACL [97, 98]. With regard to the tibial tunnel aperture, the results are somewhat inconclusive between the two techniques. It has been shown that trans tibial technique places the tibial tunnel in the same position as the trans antero-medial portal or more posterior in order to achieve better placement of the femoral tunnel [97–99].

It is now universally accepted that ACL reconstruction via transtibial technique fails to accurately position femoral and tibial tunnels within the natural insertion site [100]. In addition, freedom of femoral drilling through the AM portal will also allow for a more anterior placement of the tibial tunnel [99]. This in turn will lead to a more oblique and natural graft placement with improved restoration of anatomy and stability with ACL reconstruction compared with conventional transtibial drilling techniques [101].

The introduction of the anatomic ACL reconstruction technique changed the way surgeons drill the femoral tunnel, by using an antero-medial portal instead of the traditional tibial tunnel. This subsequently changed the positioning of the tunnels and the resulting obliquity of the graft. One of the first materials that evaluated neoligament obliquity in ACL reconstructed patients found a continuous and homogeneous graft similar to the native ACL, but with a more vertical position that does not recreate the normal sagittal obliquity. Nevertheless, these more vertical grafts were still found to control anterior posterior knee displacement [102].

Ahn et al. compared the antero-medial and TT techniques and found a significant vertical angle in the coronal and sagittal plane for the TT reconstructions compared with the native ACL. In addition, the more horizontally the angle of the tibial tunnel can be the closer will be the result compared to the native ACL [103] When the tibial remnant stump was preserved, magnetic resonance imaging showed significantly larger grafts with progressive remodeling and no increase in the incidence of cyclops lesions [104]. MRI proves to be the most useful imaging method in determining outcome after ACL reconstruction. It gives reliable information on graft healing, integrity, length, position, inclination angle, obliquity, impingement syndromes and potential associated lesions. It may even identify ACL impingement against PCL (posterior cruciate ligament) with the knee extended, which cannot be detected by conventional arthroscopy [105].

Three dimensional (3D) volume rendered (VRT) computed tomography (CT) is a useful tool for planning accurate femoral tunnel positioning when aiming for anatomic ACL reconstruction. The direct insertion of the ACL is located in the depression between the resident’s ridge and the articular cartilage margin on the lateral femoral condyle [106]. 3D CT reconstructed volumes (VRT) are reliable and can be used to assess the tunnel position regarding stability and outcome [107]. Although not as widely used, 3D MR imaging were proved accurate and can also be used for preoperative templating in anatomic ACL reconstruction (Figs. 3.13 and 3.14) [108].

The anatomic single bundle technique appeared initially as a therapeutic alternative in cases where anatomic DB technique could not be performed (small knees, narrow notch) and later gained increased use by surgeons due to easier technique, shorter operating room time and comparable results to the DB technique. The anatomic single bundle (SB) reconstruction technique has been found to more accurately reproduce the femoral footprint and the orientation of the graft. By comparison, with the classical TT technique the tibial tunnel placement resulted in a more vertical graft than native ACL. It has thus been underlined the importance of thorough knowledge of the anatomical landmarks of the ACL [109]. Nonetheless, in many cases normal graft obliquity is not restored with either technique. This may be caused by the single bundle technique itself [110].

The senior authors have been performing ACL reconstructions for more than a decade, with almost 1,000 treated cases each. In the beginning, we used the TT single bundle technique with autologous ipsilateral bone-patellar tendon-bone (B-PT-B) graft fixed with 2 interference screws. Presently, our most versatile and recommended procedure is the anatomic SB reconstruction with autologous ipsilateral quadrupled hamstring graft, cortical button femoral and interference screw tibial fixations. Nonetheless, many types of grafts and fixations can be used equally successful. This technique was applied to both professional and amateur athletes with excellent functional outcomes. A knee MRI is performed on a regular basis to investigate for possible associated ruptures of the menisci, lesions of the cartilage or lesions of the collateral ligaments even though clinical tests (Lachmann, anterior drawer test) are sufficient for the diagnosis of the ACL rupture (Fig. 3.15).

The femoral and tibial insertion sites of the native ACL were extensively studied for landmarks, shape and normal variation (see Sect. 3.​1.​2). This was translated technically in the advent of “anatomic” techniques. The first to emerge was the anatomic double bundle (DB) technique that aimed not only to replicate the number of anatomical bundles of the ACL but also their insertion sites in order to restore knee kinematics to preinjury level [119]. There are several variations in the technique for DB reconstruction. Two standard portals are most commonly used, although some surgeons use a third central or accessory anteromedial to aid visualization. Transtibial DB is possible but the femoral aperture of the PL bundle is very unlikely to be accurately positioned through this approach [120]. A four tunnel approach is therefore recommended and used by the majority of surgeons. The patient is positioned in the same manner as for SB reconstruction. After a brief examination of instability under anesthesia, a standard exploration of the joint is performed (see Sect. 1.​2.​4).

By far the best graft choices for DB reconstruction are double looped hamstrings or tendon allograft with lateral cortical button fixation. Ideally, the grafts should be larger than 6 mm for the AM and 5 mm for the PL bundle respectively. We harvest the semitendinosus and gracillis tendons through a 3 cm oblique incision centered over their ‘pes anserinus insertion’. The semiT is used for the AM bundle which is thicker and longer and the gracilis for the PL (see Sect. 3.​1.​2).

While the grafts are prepared on the backtable, any associated lesions are addressed. We always try to preserve as much as possible from the menisci. Although we most commonly treat meniscal ruptures by partial meniscectomy, we try to perform limited excisions and whenever possible suture. Outside in techniques are cheaper but require more effort (see Sect. 2.​3.​1). Small, stable longitudinal ruptures, especially when located on the posterior horn of the lateral meniscus can be successfully left in situ [121]. The ACL remnants and especially the tibial are trimmed just enough to allow for footprint identification and prevent impingement. The medial side of the lateral condyle is gently debrided of soft tissues with a mechanical or radiofrequency shaver.

With the knee flexed at 110–120° the location of the AM and PL bundles are judged and their centers marked with an awl or a small pin (see Sect. 3.​5.​2.​1). If only two portals are used, the position should also be assessed by switching the camera to the anteromedial portal. The AM bundle is placed higher and deeper in the footprint (see Sect. 3.​1.​2). The tunnel is reamed to the appropriate size and the corresponding guide is placed into the tunnel and rotated so that the PL is located positioned lower and more shallow. By using the guide seen in Fig. 3.25 the two femoral tunnels diverge at 15° and are separated by a 4 mm bonebridge. This is sometimes to wide and will force the tunnels to be located outside the anatomic landmarks. Smaller offset guides are currently available on the market. The tunnel is drilled through the lateral cortex with a 4 or 4.5 guide pin, depending on the fixation system. The AM tunnel is longer and wider and exits more proximal through good cortex. The PL tunnel is shorter and exits more lateral. Care should be taken when reaming because the lateral cortical bone is thin and can easily be reamed through.

The tibial insertion is wider than for SB. The AM bundle aiming device is positioned just medial to the tuberosity, in a more anterior position than for SB and is passed at 55° to the horizontal. It is enlarged to the corresponding size and the appropriate PL drill guide is inserted through the AM tunnel and advanced until it becomes visible on the articular surface. The barrel has a mark on its head that indicates the direction of the PL guide pin. By rotating the guide’s handle this line will point toward the native PL bundle attachment (see Sect. 3.​1.​2). Using this guide, the PL aperture is placed 9 mm posteriorly and laterally to the center of the AM bundle tunnel (Fig. 3.26). The tunnel is then reamed to the graft size. Two different leading sutures are pulled through each femoral tunnel and brought distal from the articular side through the tibial tunnels using a grasp.

The PL bundle graft is pulled first and the AM second, through their corresponding tibial and then femoral tunnels, and the cortical buttons are secured. The small size of the femoral tunnels and their proximity on the lateral condyle makes interference screw fixation more difficult. The knee is then extended and flexed whilst individually manually tensioning the grafts. This assures a comfortable fit of the grafts in the tunnels. The AM bundle should be relatively isometric whereas the PL bundle should exhibit a perceptible amount of variation during the range of motion. The AM bundle is secured first at 50° of flexion. The angle for the PL bundle depends on the length change throughout the knee flexion. If this is less than 3 mm, the bundle should be fixed in 20° of flexion. The more variation is seen, the closer to full extension the fixation is performed. The tibial fixation is made using absorbable interference screws, one size larger than the tunnel diameter. The tension applied to the grafts should be between 5 and 8 kg of force. When in doubt, the tension can be measured using the coil dynamometer from the graft preparation bench. The remainder of the grafts can be cut flush to the cortex or the pulling sutures tight one to another over the bone bridge between the tunnels.

The management of a ruptured ACL can differ depending on the patient age, past and future level of activity and the type of injury. For the elderly, sedentary patient conservative treatment and physiotherapy leads to a satisfactory outcome [122]. On the other hand, ACL deficient knees exhibit rotational instability even during activities of daily living. Gait analysis found these patients rotated their tibia internally during the initial swing phase. This abnormal movement might lead to articular degeneration and is attenuated after ACL reconstruction [123].

For the high demand patients such as athletes that wish to return to their previous level of exercise the primary goal is achieving a stable knee, avoiding further damage to the internal structures of the knee (menisci) and early start of rehabilitation and return to sports. Professional athletes are also one of the groups most exposed to the accidental rupture of the ACL. This injury is of the outmost importance to them because the ACL is the primary stabilizer of the knee. Injuries to this ligament can seriously alter an athlete’s physical activity level or even end their sporting career. The focus on restoring the native ACL landmarks has led to the popularization of the anatomic double-bundle technique. Recent data however has somewhat failed to show definitive superior outcomes with the double bundle approach. Nonetheless, the anatomic reconstructions, weather single or double bundle have proved superior to the transtibial technique.

The team led by Professor Freddie Fu from Pittsburgh, USA, have devised a flowchart individually tailor ACL surgery. The authors define anatomic reconstructions as the ‘functional restoration of the ACL to its native dimensions, fiber orientation, and insertion sites’ [73]. This guide requires large footprints to be restored by double bundle procedure in order to provide a closer resemblance to the native architecture. Nevertheless, for smaller knees and footprints the double-bundle is no longer considered superior [124]. An award winning paper based on a comparative study between techniques found that anatomic SB reconstruction resulted in better antero-posterior and rotational stability than classic SB reconstruction but the results of the anatomic DB were superior to both. However, the difference was significant only between anatomic DB and conventional SB, but in this particular study, the authors did not account for the individual footprint variability [125].

Hence, the most commonly listed indications for DB ACL reconstructions according to Musahl et al. are [126]:

Established contraindications for double-bundle ACL reconstruction are:

To perform individualized reconstruction, the footprints of the insertion are measured (Fig. 3.27). These can also be sized on the preoperative MRI so that adequate graft choices can be made (Fig. 3.28)

).

The individualized approach takes into account each ACL footprint size [127]. Depending on the tibial insertion length, the recommended reconstruction technique is either SB, DB or both:

If clinically important instability is absent, partial tears usually have favorable outcomes with conservative treatment (Fig. 3.29). Approximately one-quarter will develop a positive pivot shift and might require reconstruction. When arthroscopic confirmation of the partial tear is obtained, selective bundle reconstruction can be successfully performed, although it can be challenging with a torn PL and preserved AM (Fig. 3.30) [128]

].