The anterior cruciate ligament (ACL), located in the knee joint, connects the femur to the tibia, and its main function is to limit the excessive forward displacement of the tibia, which works together with other structures in the knee joint to maintain the stability of the knee joint and enable the body to perform a variety of complex and difficult lower limb movements.
1. Causes of morbidity
Trauma is an important cause of ACL injury. the main cause of ACL fracture is sports injury, which accounts for about 70% or more. The most affected sports are basketball and soccer, in addition to professional athletes engaged in judo, wrestling and track and field, and in the general population who love skiing, badminton and volleyball, ACL rupture is more common. Non-sports injuries, including traffic injuries, productive life accidental injuries, account for about 27%. Li Shuzhen, Department of Bone and Extremity, Ruikang Hospital, Guangxi University of Traditional Chinese Medicine
2.Pathogenesis
The basic function of the ACL is to prevent excessive anterior displacement of the tibia relative to the femur, and indirect violence causes ACL injuries. These common injuries occur in soccer when the opponent’s foot is turned, in basketball when the supporting leg twists sharply when the ball is crossed, in basketball when the single leg falls to the ground after a sprain, in skiing when the skis are inserted into the snow at high speed and the athlete trips and falls, all of which can easily lead to ACL injuries. Some mass sports, such as tug of war, vaulting, and box jumping, are also prone to ACL injuries. Pedestrians in high-energy traffic accidents, falls on motorized bicycles or inadvertent falls in some weak individuals may also lead to ACL injuries. However, slip injuries are often complained of as “kneeling injuries”, which are actually injuries in the flexed knee valgus position.
3.Pathophysiology
The ACL begins in the posterior medial portion of the intercondylar recess of the femoral epicondyle and ends between the intercondylar eminence of the tibia and its anterior slope and the medial and lateral menisci; the ACL can be broadly divided into the anterior medial bundle (AM) and the posterior lateral bundle (PL) depending on the course of the fibers. The anterior medial bundle is tense during knee flexion, while the posterior external bundle is tense during knee extension, and some scholars have also divided it into three bundles.The ACL is essential for maintaining knee stability, and the main mechanical stabilization functions include: limiting excessive tibial anterior translation; limiting knee hyperextension; limiting rotation of the tibia; and limiting lateral movement in the extended knee position. Theoretically, injury to one bundle alone is called a partial rupture, injury to both bundles at the same time is called a complete rupture, and there is also an ACL tibial stop that is torn up along with the bone called an intercondylar spine avulsion fracture. After a complete rupture of the ACL in clinical practice, adhesions after a certain period of time can easily cause the illusion of partial rupture.
4. Clinical manifestations
4.1. Preferred groups
(1). Professional athletes within 25 years of age, non-athletes between 18-35 years of age;
(2). The incidence of males is about twice that of females, but the incidence of females among athletes is higher than that of males;
(3). Some special occupations such as military, dancers and acrobats have a higher incidence than the general population.
4.2. Disease symptoms.
Fresh and old ACL ruptures differ in clinical manifestations.
4.2.1. Fresh ACL rupture mainly manifests as.
(1). Patients often hear or feel a “pop” sound during exercise, followed by knee pain, limited extension and flexion, joint swelling, and in most cases, inability to continue with the original exercise, or even limited extension and hyperflexion;
(2). On examination, the patella test is positive, and the Lachman examination is flaccid and non-resistant;
(3). Nuclear magnetic examination of the knee suggests intra-articular blood accumulation, swelling or interrupted continuity of the anterior cruciate ligament, visible stump, lateral wall of the intercondylar fossa of the femur or the posterior aspect of the femoral epicondyle and corresponding bone contusion manifestation of the tibial plateau.
4.2.2. Old ACL ruptures mainly present as.
(1) If the acute ACL injury is not treated in time and gradually develops into the chronic phase, the blood accumulation in the joint is absorbed, joint movement can be gradually restored, and the patient’s subjective sensation improves. However, since ACL is the main stabilizing mechanism of the knee joint, whether the knee joint can still remain stable after injury is closely related to the compensatory capacity of the muscles around the knee joint and the level of function that the patient is required to meet. The main manifestation is joint laxity and instability. Patients have the feeling of knee joint misalignment or playing soft leg in sports, unable to stop and turn sharply, unable to use the affected leg for single leg support, or obviously feel the knee joint instability when supporting with one leg;
(2) The knee joint is easily and repeatedly sprained and painful during sports, and even repeatedly interlocked after causing meniscus injury;
(3) Physical examination: Lachman’s examination for relaxation without resistance, positive front drawer test;
(4) Knee MRI suggests: disruption of ACL continuity, stumps can be seen, epicondyles of femur and tibial plateau bone contusion manifestation. In case of prolonged time, the morphology of the ligament disappears and osteophyte manifestations appear.
(5) KT1000 and KT2000 can quantitatively check the degree of anterior displacement of the knee joint, which is greater than 3mm compared to the contralateral side;
(6) Patients with repeated sprains often have secondary articular cartilage and meniscal injuries.
5. Disease treatment
5.1. Acute treatment
(1) Apply ice to the knee joint to reduce swelling and pain;
(2) Braking of the joint, with compression bandaging if necessary, to reduce rebleeding;
(3) If surgery is not available in the near future, knee mobility exercises and lower extremity muscle strength exercises should be performed after the swelling and pain have subsided;
(4) In the case of combined medial collateral ligament injury, emergency surgery should be performed within 10 days of the injury. If there is a joint mobility disorder, surgery should be performed after the range of motion of the joint is close to normal.
5.2. Conservative treatment
Early in the injury there will be an accumulation of blood in the joint, which should be extracted promptly to reduce discomfort and adhesions in the knee. The knee should be braked with a brace. In addition, anti-inflammatory and analgesic drugs and physical therapy can be given to reduce knee pain and swelling, facilitate early restoration of joint mobility, and avoid knee stiffness. For patients treated conservatively, muscle rehabilitation and muscle strength training of the affected limb should be strengthened to restore knee function as soon as possible.
This part of the patients is only a minority. That is, patients with partial ACL injury have good knee stability. Most of the completely ruptured ACL still cannot restore the normal stability after non-surgical treatment, so it is usually difficult to restore the motor function.
5.3. Surgical treatment
The main goal of surgery is to reconstruct a new ACL to restore stability of the knee joint. The surgical methods are mainly divided into direct repair, extra-articular reconstruction and intra-articular reconstruction. The latter is the mainstream method at present. Active post-operative rehabilitation should be adopted, and general daily activities can be resumed within a few months, and it usually takes more than 10 months to participate in competitive events.
(1) The best time for surgery is within one month after surgery;
(2) Arthroscopic ACL reconstruction surgery is a mature technique with minimal trauma and quick recovery;
(3) The current surgical methods for ACL reconstruction include: single bundle reconstruction, double bundle reconstruction, etc.; there is no significant difference between the clinical results of the two procedures.
(4) The graft materials that can be used to reconstruct the ACL include: autologous materials, such as N cord tendon, autologous patellar tendon, etc., with the best results. If multiple ligaments are injured at the same time, additional allograft tendons or artificial ligaments can be considered;
(5) Reconstruction of the anterior cruciate ligament requires fixation materials including: metal interface screws, absorbable interface screws, EndoButton, Introfix, etc;
(6) In case of combined medial collateral ligament injury or meniscal interlocking, emergency surgery should be performed for a limited period of time.
6.Disease prevention
(1) Prevention of fatigue training and competition.
(2) Increase the lower limb muscle strength exercises and coordination exercises;
(3) wear the necessary game protective gear;
(4) Keep the field lights and ground free of safety hazards;