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Anterior cruciate ligament (ACL) injury is one of the most common injuries to the knee joint. Often resulting in anterior and rotational laxity of the proximal tibia relative to the distal femur, a large number of patients with ACL rupture will develop symptomatic knee osteoarthritis in young and middle-aged adults. There are approximately 250,000 new patients with ACL injuries in the United States every year, of which 125,000 to 175,000 patients require anterior cruciate ligament reconstruction (ACLR).
Currently, ACLR is still the gold standard for the treatment of ACL injuries. Its purpose is to maintain the stability of the knee joint, prevent further damage to articular cartilage and meniscus, and restore the patient’s function in daily life and sports activities to the maximum extent. With the deepening of ACL anatomy, ACLR technology has made great progress in the past 30 years. However, ACLR technology is not uniform in clinical work, and different ACLR technologies may bring different prognoses to patients. Based on existing research, comparing the advantages and disadvantages of various surgical options, and selecting an appropriate surgical option based on patient characteristics is crucial to the long-term prognosis of patients with ACL injury.
Tendon Selection
Clinically, ACLR grafts must not only have similar structural and mechanical properties to the original ACL, but must also have minimal antigenicity and sufficient biological potential to integrate into the host bone. Graft selection may directly affect surgical prognosis. Currently, ACLR grafts include autologous tendons, allogeneic tendons, and artificial ligaments. Each graft has its advantages and disadvantages. However, there is no unified consensus on the selection of grafts and there is controversy.
Bone-Patellar Tendon-Bone Complex From a biological healing perspective, autografts are preferred because they contain viable autologous tissue, avoid the risk of disease transmission, and maximize biointegration of the graft-host junction. Speed and possibility. Among autologous tendons, BPTB complex was the first autologous tendon to be utilized. Compared to the tendon-bone interface, the bone connection is more capable of healing than soft tissue bone. Although the BPTB graft has a higher ultimate tensile load than the native ACL, the BPTB graft has the disadvantages of fixed tendon length and smaller graft cross-sectional area.
Hamstring tendon HT grafts are mainly gracilis tendon and semitendinosus tendon. In recent years, HT has gradually become the mainstream choice for ACLR grafts due to its smaller incision, lower infection rate and postoperative complications. Although the healing speed of HT is far slower than that of the bone interface healing of BPTB graft, it also has a higher early re-tear rate. However, it has greater biomechanical ultimate tensile load, stiffness and cross-sectional area after healing. And some studies have shown that choosing BPTB is associated with worse mid- and long-term knee joint functional outcomes and more donor-site complications while choosing HT only increases short-term knee laxity. Of course, this graft also has shortcomings. The size of the HT autograft varies greatly between individuals. Many studies have shown that HT diameter <8 mm means a higher surgical failure rate. Therefore, many studies have used the patient’s general characteristics such as height, weight and age or imaging information such as CT and magnetic resonance to predict the size of HT to select an appropriate graft for ACLR before surgery.
Artificial ligaments Many artificial ligaments were developed and transplanted in the early days, but their long-term prognosis appears to be unsatisfactory, with high rates of complications and failure of artificial ligaments. Although many early artificial ligaments have been withdrawn from the market, ligament-augmented reconstruction systems (LARS) are still used as an alternative to autografts in some parts of the world, and some studies have shown better clinical results. However, the controversy over the LARS ligament has never stopped. Many studies believe that the LARS ligament can cause synovitis and do not recommend it as a potential graft for ACLR. However, some studies believe that there is no direct evidence that it is related to postoperative complications.
Choice of Reconstruction Method
1. Single and Double-Bundle Reconstruction
The most commonly used clinical ACLR is single-bundle (SB) reconstruction or double-bundle (DB) reconstruction. However, so far, there is no consensus on whether DB technology is superior to SB technology. As we all know, the ACL can be divided into 2 functional bundles, the anteromedial bundle and the posterolateral bundle. The two bundles play different roles at different angles of the knee joint. The anteromedial bundle and the posterolateral bundle prevent the translation of the anterior tibia at higher and lower flexion angles respectively. Many studies believe that DB reconstruction is closer to the original ACL bioanatomy and biomechanics than SB reconstruction. Moreover, DB reconstruction can increase the bone-tendon contact area, increase the rotational stability of the knee joint, and share the load on the knee joint. However, there are also studies suggesting that DB reconstruction may not provide more significant advantages than SB reconstruction. Therefore, most surgeons perform ACL repair with SB reconstruction.
2. Bone Canal Positioning
Bone tunnel selection is critical for ACLR, in the past few decades, surgeons have transformed the previous open surgery into arthroscopic minimally invasive surgery. At the same time, ACLR has gradually transformed from traditional isometric reconstruction to anatomical reconstruction.
3. Isometric Reconstruction
The popular method of ACLR in the early days was the overhead technique proposed by Macintosh, which pursued the equal length of the ACL within the joint and tried to maintain the continuous tension of the ACL and the stability of the knee joint during flexion and extension through isometric techniques. The isometric point of the tibial tunnel has always been considered to have less influence on the effect of ACLR, while the femoral positioning point is particularly important. The femoral positioning point is parallel to the most prominent point of the posterior condyle 60% anterior to the Blumensaat line, located at the clock positions of 1:00-1:30 on the left knee and 10:30-11:00 on the right knee. With the in-depth study, it was found that isometric reconstruction mainly limits the anterior translation of the tibia, but its effect on the rotational stability of the knee joint is poor, making it difficult to satisfy patients who return to high-intensity sports and have higher requirements for knee joint stability. In addition, this surgery requires high tendon length and often causes impact due to positional issues.
4. Anatomical Reconstruction
Due to the above disadvantages of isometric reconstruction, more doctors are beginning to pay attention to anatomical reconstruction. The tibia is positioned in the ACL footprint. The footprint area of the femoral end is located below the resident’s ridge and the lateral bifurcation ridge of the intercondylar notch is the center of the bone tunnel. It can also be located in the area below 30% to 35% of the lateral wall of the intercondylar notch when the knee joint is flexed 90°. Its positioning relies more on the clinician’s experience than isometric reconstruction, but it brings better knee rotation stability. Due to the complex anatomy of the ACL, anatomical reconstruction cannot be performed. Currently, only quasi-anatomical reconstruction can be performed.
5. Complete Reconstruction
Total internal reconstruction technology is a “no-tunnel” technology. If allogeneic tendons are used, it is also a “no-incision” technology. It can minimize surgical trauma and complete the establishment of a femoral tunnel while preserving bone mass. These advantages increase the number of surgical procedures. It is beautiful and is conducive to the renovation and saving of inhibitors. Both total internal reconstruction and traditional single-bundle ACLR have better functional prognoses, but the laxity increased in the total internal ACLR group.
6. I. D. E. A. L Positioning
In recent years, with in-depth research on ACL anatomy, some scholars have proposed the femoral footprint tunnel I. D. E. A. L positioning. Its positioning points are designed to determine the optimal positioning point for ACLR femur from several aspects: anatomy, histology, isometric, biomechanical and clinical data. I. D. E. A. L The L anchor point is located off-center in the anterior (high) and proximal (deep) areas of the footprint, histologically covering the directly inserted fibers and anatomically within the footprint. This anchor point connects the femoral tunnel to It is placed at equidistant points from the original ACL and allows the reconstructed ACL to replicate the low tension-flexion pattern of the original ACL throughout the entire range of flexion and extension. The I.D.E.A.L anchor points have a better early prognosis than traditional anchor points. So far, regarding I. D. E. A. L. There are few studies on L concept reconstruction, and there is a lack of comparative studies with anatomical reconstruction. But as far as the current research is concerned, based on I. D. E. A. L. The single-bundle reconstruction of L concept may become the trend of ACL reconstruction in the future.
Conclusion
In summary, there are currently diversified surgical methods for ACLR, but the impact of these surgical methods on ACL outcomes is still controversial. I believe that with the continuous progress of ACLR research and the increasing understanding of ACL injuries, it will Clinicians develop an individualized surgical plan for each patient.