1, the role of the cruciate ligament The cruciate ligament is an important stabilizing structure of the knee joint, which plays a role in the normal or abnormal rotational movement of the joint. The anterior cruciate ligament maintains the anterior direct stability and rotational stability of the knee joint in flexion and limits the excessive forward movement of the tibia. The primary function of the posterior cruciate ligament is to prevent the tibia from moving backward during knee motion and, to a lesser extent, to limit external rotation. The anterior and posterior cruciate ligaments of the knee joint work together to maintain the stability and normal motion of the tibiofemoral joint. 2, the causes of cruciate ligament injury ACL injuries are mostly seen in sports injuries. In particular, sports such as rugby, skiing, basketball and soccer are all dangerous sports. The common mechanisms of ACL injury are: knee hyperextension; foot fixation but body rotation, such as ball players controlling the ball and turning sharply; sudden deceleration movement, such as speed ski landing or shoveling directly from the front of the leg; knee extension inversion injury and knee flexion under the external rotation injury can cause ACL rupture. The clinical incidence of ACL injuries is much higher than that of posterior cruciate ligament injuries. Posterior cruciate ligament injury is mostly seen in sports injuries and car accident injuries, most sports injuries knee in flexion, inversion or valgus position, suddenly encounter the force of the lower leg backward, such as basketball sports emergency stop, soccer sports shovel; car accident injuries are mostly seen in the injury knee hyperextension or flexion position from front to back violent impact. 3, the clinical manifestations after the cruciate ligament injury cruciate ligament injury are a history of knee trauma. According to the time of injury can be divided into acute injury and old injury of the cruciate ligament injury. After an acute injury to the cruciate ligament, the knee joint is obviously swollen, painful and limited in activity, sometimes the patient can feel a tearing sensation or hear a ringing sound in the knee joint when injured, sometimes there is a transient “misalignment feeling” and then reset on its own, after the injury can no longer play sports. The main symptom of an old ACL injury is knee instability. If the patient goes up and down the stairs and walks with a knee and a sense of joint looseness and instability, sometimes complaining of a sense of joint misalignment, but also can be manifested as jumping up and down when the affected limb does not dare to force the ground, thigh muscle (quadriceps) atrophy, daily life can not do a sharp turn, emergency stop and other movements, the original can do sports now can not or dare not do. Also complained of swelling, pain and discomfort in the knee after too much activity. 4.What damage will be caused to the joint after cruciate ligament injury With the understanding of the importance of the function of the cruciate ligament, we know that the knee joint will be seriously unstable after the injury, in addition to affecting daily life and sports, it can also cause secondary damage to the meniscus and articular surface cartilage in the injured knee joint, and this injury is often not recoverable once it occurs. Therefore, cruciate ligament injuries must be treated promptly. Stable incomplete injuries can be treated conservatively by wearing a brace, but most cruciate ligament injuries are complete ruptures and require ligament reconstruction to restore knee joint stability. The structural characteristics and function of the cruciate ligament determine its importance in maintaining the stability of the knee joint. Therefore, it can be said that cruciate ligament injury is the beginning of the loss of knee function, which directly causes joint instability, secondary cartilage damage, and eventually leads to osteoarthritis, osteophytes, narrowing of the joint space, joint deformity, and eventually necessitates an artificial knee replacement. Therefore, timely cruciate ligament reconstruction is needed to restore joint stability. At present, arthroscopic cruciate ligament reconstruction has become the main method of treating cruciate ligament injuries. 5, what are the repair methods of cruciate ligament injury Cruciate ligament injury includes the following specific common surgical repair and reconstruction methods: there are two surgical methods, namely single-tract reconstruction and double-tract reconstruction. The specific choice of surgery depends on the patient’s age, occupation and individual situation. Generally, people with low sports requirements, adolescents in the growth period, older and smaller bone and joint structures choose single-tract reconstruction surgery. For patients who participate in more strenuous sports and have high sports requirements, double reconstruction is more appropriate. Single tract reconstruction, i.e. single bundle reconstruction, can restore the anterior straight stability of the knee joint, eliminate the phenomenon of playing soft leg and relieve the symptoms, and restore most of the pre-injury motor functions, but it is difficult to perform certain movements that require knee rotation in sports, such as the step-back defense in blue ball and soccer. In contrast, the postoperative reconstruction of the ligament is closer to the anatomical structure of the original ligament, and the postoperative straight and rotational stability are well restored, basically restoring the pre-injury level of motion. The above two surgical methods have their own advantages and disadvantages. Single tract reconstruction is less invasive and less expensive, while double tract reconstruction is more invasive and more expensive. Patients need to choose the appropriate surgical method for their own body according to their individual conditions. 6.How to choose the material for reconstruction of cruciate ligament injury There are three main types of tissues used for reconstruction of cruciate ligament: the first one is homogeneous allogeneic tendon, including allogeneic N cord tendon, patellar ligament, Achilles tendon and anterior tibial tendon, allogeneic tendon has the possibility of immune reaction and infectious disease (the ratio is about 1/1.6 million), which is relatively expensive; however, it is less traumatic than autologous tendon, and the recovery is relatively fast, which can avoid further damage to the autologous tendon due to taking the tendon. Further damage to the autologous body can be avoided. The second type is to take autologous tendon tissue, including autologous patellar ligament, quadriceps tendon and N cord tendon (semitendinosus and thin femoral tendon), with N cord tendon being the most commonly used, which has the characteristics of low cost and no rejection reaction, but has certain trauma and may have potential effects on certain movements of the lower leg (internal rotation, knee flexion, etc.) after the graft tendon is cut; the third type is artificial ligament, which has the advantage of early activity, but expensive, and the long-term effect is not completely certain. 7. What is the difference in cost between different surgical methods of cruciate ligament reconstruction? After reconstruction, the tibial and femoral ends of the cruciate ligament are fixed, and currently the femoral end is often fixed with Endobutton, bio-transverse rod or bio-extrusion nail, while the tibial end is often fixed with bio-extrusion nail and portal nail. In cruciate ligament reconstruction surgery, there are several options for fixation on the bone tract, each with its own advantages and disadvantages and different costs, especially double tract reconstruction, which can be much more expensive compared to single tract reconstruction because it requires twice as much fixation material. Because of the different surgical methods of cruciate ligament reconstruction and different fixation methods, the hospitalization cost will also vary greatly. 8.How about the rehabilitation procedure after the repair and reconstruction of cruciate ligament injury Rehabilitation training for patients after cruciate ligament reconstruction can avoid knee adhesions and stiffness, improve muscle strength and enhance joint stability. However, before complete healing between the graft and the bone tract, premature weight-bearing activities of the affected limb will affect the healing of the reconstructed ligament, thus affecting the stability of the joint. Therefore, a reasonable, standardized and scientific rehabilitation exercise program is of great importance to restore the function of the affected limb after cruciate ligament reconstruction. The following points should be noted in the rehabilitation exercise process: ① Except for the braking protection of the operated limb, the rest of the body parts should be practiced as much as possible to ensure the physical quality, improve the overall circulatory metabolic level and promote the recovery of the operated local area. ②Early joint mobility (flexion and extension) exercises should be performed only once a day, and it is sufficient to strive for an improvement in the angle, avoiding repeated flexion and extension and multiple exercises. If the flexion angle does not progress for a long time (>2 weeks), there is a possibility of joint adhesions, so we should pay great attention to this and insist on completing the exercises. ③Ice packs should be applied for 20-30 minutes immediately after the mobility exercises. If you usually feel swelling, pain and fever in the joint, you can apply ice again, 2-3 times a day. ④The exercises should be completed according to the requirements of the rehabilitation program and should not exceed the prescribed angles or fail to reach the prescribed angles. After the cruciate ligament reconstruction, it is usually necessary to wear an external fixation support for 2-3 months, while walking with the aid of crutches. 2 days after surgery, you can help crutches to go down, generally wash your face, brush your teeth, go to the bathroom and other daily life can be self-care, 2 weeks later, you can be competent to sit in the office, 6 months after surgery, you can do jump rope, swimming, jogging and other sports, 1 year after surgery to participate in strenuous sports. 9.Can you restore the pre-injury sports level after the cruciate ligament injury repair and reconstruction surgery Patients after the cruciate ligament repair and reconstruction surgery can restore most of their sports ability, and some can also restore all. Basically, it is possible to perform strenuous sports again as long as it is cured, but strenuous sports cannot be performed during the recovery period of the reconstructed ligament, otherwise it will lead to the relaxation of the cruciate ligament or even the possibility of re-rupture. Strain and strenuous sports should be avoided within 3-6 months after surgery, recovery training can be carried out after 7 months, and only after 1 year can we participate in strenuous sports. 10.Introduction of cruciate ligament injury repair and reconstruction surgery ①Simple anterior and posterior cruciate ligament reconstruction ②Cruciate ligament reconstruction and meniscus repair ③Cruciate ligament reconstruction and chondroplasty ④Cruciate ligament reconstruction and lateral collateral ligament repair ⑤Cruciate ligament reconstruction and posterior lateral structure repair and reconstruction ⑥Anterior and posterior cruciate ligament and posterior lateral structure repair and reconstruction at the same time. Surgical methods include single-tract reconstruction and double-tract reconstruction.