Cruciate ligaments of the knee have been described as early as ancient Egyptian times, but it is only in recent years that the management of cruciate ligament injuries has received sufficient attention. in 1900, Battle was the first to report on anterior cruciate ligament repair surgery. In 1912, Giertz was the first to try to reconstruct the cruciate ligament with autologous grafts, and two weeks after osteotomy in a patient with ankylosis in 45 degrees of knee flexion, he reconstructed the anterior cruciate ligament using the patient’s own broad fascia strips. In 1932, Major zur Verth reconstructed the anterior cruciate ligament with the patellar ligament, and in 1938, Ivar Palmer of Sweden published the classic principles of management of knee ligament injuries. In that article the anatomy, physiology, pathology and treatment of the cruciate ligament were discussed. He even invented the drill locator that we still use today.Ivar Palmer’s research work was excellent but was not recognized until 30 or 40 years later. Wang Hong, Department of Orthopedics, Wuhan Union Medical College Hospital
In 1963, Jones first proposed the method of reconstructing the ACL with a patellar ligament with a bone block and treated 38 patients with this method. This technique was similar to the method we apply now, except that he placed the ligament under the subpatellar fat pad. in 1966, H. Bruckner reported the tibial tunneling technique in cruciate ligament reconstruction, in the context of an unknown study by Jones. The first report of arthroscopic ACL reconstruction appeared in 1980, when Dandy performed ACL reconstruction using an artificial ligament made of carbon fibers, and Ckancy et al. greatly developed the technique of ACL reconstruction using autologous materials. Nowadays, the rapid development of arthroscopic techniques has made microscopic ACL reconstruction a routine procedure of choice.
I Anterior cruciate ligament injury
Anterior cruciate ligament (ACL) injuries are common in the knee, with an incidence of 38/100,000 per year in the general population, 600/100,000 per year in soccer, and 70/10,000 per year in skiing. In the United States, 2 million patients seek medical attention for knee injuries each year, with 25,000 of those diagnosed as ACL injuries. On the world’s largest sports field, the soccer field, an athlete playing 1000 hours has the potential for 4-7.6 ACL injuries. This means that on a soccer team, there will be 1-2 ACL injuries per year. The incidence of ACL injuries among professional athletes in China is 0.71% for women and 0.29% for men, 2.37 times higher for women than for men. 78% of ACL injuries occur in non-contact sports, often during landing, stopping, twisting or shearing movements. Awareness of the ACL stems from the difficulty of returning athletes with ACL deficits to play. With this increased understanding, the techniques for diagnosis and treatment of ACL injuries have gradually improved.
(A) Functional anatomy and physiological function of the ACL
The parenchyma of the ACL is a dense connective tissue that is both elastic and rigid, located within the joint but surrounded by the synovial membrane, and is an intra-articular extra-synovial structure. The ligament begins in a semicircular area on the posterior medial aspect of the lateral femoral condyle and travels inferiorly and anteriorly, crossing the intercondylar fossa and ending between the anterior tibia and the intercondylar spine. It is approximately 30-38 mm in length and 10-12 mm in width. the parenchyma is the thinnest, with an area of 44 and 36 mm2 in men and women, respectively (approximately 7.5 mm and 6.8 mm in diameter, based on a circle), and the stop is approximately 3.5 times larger than the parenchyma. The ACL is connected from the femoral attachment area to the tibial attachment area by a number of fibrous bundles of distinct orientation. It consists mainly of the anteromedial bundle (AMB) and the posterior lateral bundle (PLB). The AMB starts from the posterior femoral condyle and ends at the anterior medial tibial intercondylar spine, while the PLB starts from the anterior femoral condyle and ends at the posterior lateral tibial intercondylar spine. The AMB is located on the proximal side of the medial wall of the femoral epicondyle, with an area of 47±13 mm2, while the PLB is located on its distal side near the cartilaginous surface of the distal femoral epicondyle, with an area of 49±13 mm2. The angle with the tibia is 500 and with the femur in the coronal plane is 21 0. The long axis of the femoral stop follows the long axis of the femur and the long axis of the tibial stop follows the anterior-posterior diameter of the tibial plateau, forming a ligament that twists around itself. The ACL at the tibial stop forms a “footprint”, which increases the attachment area and prevents the ACL from impinging on the intercondylar fossa during knee extension. When the knee is flexed at 900, the AMB is tense with ligament torsion and the PLB is relaxed and approximately horizontal. The AMB was 22-41 mm long (mean 32 mm) and the PLB was 17.8 mm long and 6.6-8.3 mm wide in extension; the AMB and PLB lengths varied in different degrees of flexion and tension, with the AMB length increasing by 3.3-3.6 mm in flexion at 900. In addition, internal rotation of the tibia also increases the ligament length. In flexion 900 with internal rotation. the ACL length can increase by 1.7-2.7 mm.
The ACL is an avascular tissue and is nourished by synovial tissue and synovial fluid. The synovial wall is rich in blood vessels, and the proximal portion of the ligament is nourished by the middle knee artery and the distal portion by the internal and external infrapatellar arteries. The distal and proximal vessels are formed in the synovial membrane on the surface of the ligament. The ACL is innervated by the tibial nerve, which branches to the synovial wall of the ligament and sends axons to the interior of the ligament. The nerve fibers are mainly located in the subsynovial and attachment sites of the ACL. A large number of Golgi-like tensor receptors are present at the attachment points and on the surface of the ligament. There are also a few mechanoreceptors within the ligament, which are located in the proximal tibial portion of the ligament and are involved in proprioceptive transmission to the knee joint. there are few free nerve endings in the ACL, which are only located within 5 mm of the ligament stop.
The ACL has an ultimate tensile strength of (2020±264)N and a maximum deformation of (15.9±3.5) mm, a stiffness of 240 N/mm, a modulus of elasticity of 278 MPa, and an ultimate tensile strength of 35 MPa. The ACL stress variation varies between different external forces, flexion angles, and fascicles. The tension in the ACL is minimal at 40°-50° of flexion. The primary function of the ACL is to prevent anterior displacement of the tibia, as well as to limit internal rotation of the tibia, prevent hyperextension, and limit internal and external rotation. These functions are adapted to this need throughout flexion and extension, and the ACL is structurally divided into several functional units. The anterior medial bundle, which starts at the proximal part of the femoral stop and ends at the anterior medial part of the tibial stop, plays a greater role in flexion, while the posterior lateral bundle, which starts at the distal part of the femoral stop and ends at the posterior lateral part of the tibial stop, plays a greater role in extension and limits tibial rotation and resists internal and external rotation stresses on the limb. Selective severance of the anterior cruciate ligament has shown that in the flexed knee the anteromedial bundle of the ligament is tense, whereas in the extended knee the majority of the postero-lateral bundle of the ligament is tense.
This is what we see when the AMB is ruptured with a positive 900 anterior drawer test in flexion and a positive lachman test with a 300 knee in flexion with a PLB rupture. In the extended knee position, the anterior medial and middle portions of the ACL are in direct contact with the roof of the intercondylar fossa (intercondylar shelf) and rupture often occurs in the middle 1/3 of this ligament when the knee is hyperextended with violence.
(b) Mechanism of injury to the anterior cruciate ligament
Injury to the ACL accompanied by significant rupture of other ligaments of the knee is one of the most common types of major knee injuries in athletes. The mechanism of injury is usually a noncontact, decelerated valgus and external rotation injury. The common mechanisms of ACL rupture alone are deceleratory internal rotation forces and extreme hyperextension. In principle, there are four mechanisms that can cause an ACL injury. External rotation violence of the knee can damage the medial portion of the ACL and the meniscus. This injury is seen when the ski sled is blocked and the knee is externally rotated in combination with external rotation of the tibia. The second mechanism of injury is the inversion-inside rotation violence of the knee commonly seen in handball or basketball. The third mechanism of injury is internal tibial rotation violence during knee extension, which may cause the anterior cruciate ligament to impact the anterior aspect of the medial femoral condyle and injure the former. Recently, a fourth mechanism of injury has been described in which a skier falling backwards with the foot on the ground to bear weight tries to stay upright by contracting the quadriceps muscle, which together with the posterior aspect of the ski boot pushes the tibia forward, causing an isolated injury to the ACL. This injury is also called ski boot injury.
(C) the type of injury
1, ACL parenchymal rupture: can be divided into partial rupture and complete rupture. Partial rupture is less common than complete rupture. dragan observed a group of 66 patients with acute ACL rupture, found that 62% of complete rupture, 38% of partial rupture, of which 16% of the remaining is the anterior internal part of the ligament tissue.
2, ACL tibial stop avulsion fracture
(1) Tibial intercondylar spine avulsion fracture: because this injury also causes symptoms of ACL deficiency. So some people regard it as a special type of ACL injury. karola et al. reported 60 patients with acute ACL rupture, 8.3% were tibial intercondylar spine avulsion fractures.
2) Avulsion fracture of the femoral stop of the ACL: This injury causes similar results to the former and can also be considered as a specific type of ACL injury. This type of injury is extremely rare. A review of the literature by Harukazu et al. shows that prior to 2002, there were only a total of 3 cases of this injury reported in the English literature, with the age of onset ranging from 7 to 13 years.
(iv) Clinical presentation and diagnosis
History and physical examination: First, the patient has a clear history of trauma, with sports injuries being the most common, commonly occurring during sports when the knee joint is sprained during jumping and landing. The second is a car accident injury, a fall from a moving object, often combined with injury to the multiple knee ligaments.
Acute symptoms of ACL injury: patients suddenly experience severe pain in the knee joint, hear a loud cracking sound in the knee joint, sometimes feel a sense of joint movement, and due to the injury of the ligament intra-articular bleeding and obvious joint swelling and affect joint movement and walking.
Symptoms of chronic ACL injury: After the acute phase, the typical symptom is knee instability, knee joint misalignment when doing a sharp turn or a sharp stop, and even some movements in daily life, such as turning, will have the feeling of knee joint misalignment, and the frequency will gradually increase. There is a feeling of knee dislocation during running. In long-standing ACL ruptures, there are often symptoms of joint locking or interlocking secondary to a tear of the medial and lateral meniscus. Chronic pain in the knee is present secondary to degenerative joint degeneration or cartilage damage.
Signs of ACL injury: anterior drawer test, Lachman test, positive pivot shift test.
1. Anterior drawer test (Figure).
Method: bend the knee at 90°, the examiner sits on the patient’s foot to keep it fixed, hold the proximal part of the calf with both hands and pull it forward to observe the degree of anterior tibial shift. The examination was performed in the internal rotation, neutral and external rotation positions of the lower leg. In the internal rotation position, the lateral ligament structure is tight, and the anterior cruciate ligament and the lateral ligament structure are mainly examined; conversely, in the external rotation position, the anterior cruciate ligament and the medial ligament structure are mainly examined; in the neutral position, the anterior cruciate ligament is mainly examined. When the tibia is internally rotated, the cruciate ligament is spirally twisted and tightened, and when the tibia is externally rotated, the cruciate ligament is spirally untwisted, therefore, under normal circumstances, the amplitude of internal rotation of the tibia is smaller than that of external rotation, and the amplitude of tibial anterior displacement in the internal rotation position is smaller than that in the external rotation position when the anterior drawer test is performed. The anterior drawer test can be performed in different tibial rotation positions to indirectly examine the structural integrity of the medial and lateral ligaments.
The anterior drawer test has three drawbacks.
1. in patients with acute injuries, the patient is often unable to flex the knee and cannot perform this test due to pain, intra-articular hematoma, etc.
2. the anterior drawer test is performed in the flexed knee position and often results in false negative results due to the posterior horn of the meniscus blocking the posterior femoral condyle.
3. It is not possible to differentiate between complete rupture of the ligament, partial rupture, and capsular laxity without ligament rupture due to the blockage of the meniscus and the incomplete fixation of the thigh.
2. Lachman’s test (Figure).
The Lachman test is the anterior drawer test with the knee flexed at 30°. The advantages of the Lachman test are: it can be performed on both acute and old injuries; the positive rate of the test is increased because there is no meniscal interference; the termination point of the ligament can be accurately observed; a positive Lachman test with a soft termination point indicates a complete rupture of the ligament; and a positive Lachman test with a soft termination point indicates a complete rupture of the ligament. A positive Lachman test with a hard termination point indicates partial damage to the ligament or simple laxity of the joint capsule; a negative Lachman test with a hard termination point indicates a normal ligament.
3. Axial shift test (pivot shift) test (Figure).
Method: Fully straighten the knee joint, hold the affected foot with one hand, place the other hand on the lateral side of the knee joint and apply external stress and flexion at the same time, gradually flex the knee joint, at 20° of knee flexion, the popping sound of the lateral tibial plateau moving forward can be felt, continue to flex the knee joint, at close to 40° the popping sound of the lateral tibial plateau can be felt, this is a positive axis shift test axis shift test is used to check the anterior cruciate The axial shift test is used to check for damage to the anterior cruciate ligament.
A positive axial shift test can be divided into four degrees.
First degree – positive axial shift test when internal rotation stress is applied to the calf, and negative when the calf is rotated in neutral position.
Second degree – positive axial shift test when the calf is in neutral rotation position and negative when external rotation stress is applied.
Third degree – positive axial shift test when external rotation stress is applied to the lower leg.
Fourth degree – positive axial shift test with significant lateral composite instability.
A first degree positive only indicates ACL laxity, while a second degree positive or higher indicates ACL rupture.
2. Imaging tests for ACL injury.
1. routine frontal and lateral radiographs of the knee to rule out knee fractures, assess pre-existing degenerative joint changes, and record lower extremity force lines.
2. CT plus three reconstructions, from which the presence of intra-articular fracture with intercondylar fossa stenosis can be detected. It is helpful to determine if intercondylar fossa molding is needed during surgery.
3. MRI – most helpful in diagnosing ACL injury.
Normal ACL MRI presentation: On coronal, sagittal, and cross-sectional MRI images of various sequences, the ACL is a band of low signal shadow. On TI-weighted images of the attachment points (mainly the tibial attachment points), a wired, streaked moderate to high signal shadow is seen separating them, representing fat and synovium.
MRI manifestations of anterior cruciate ligament injury: direct MRI signs of complete anterior cruciate ligament tears: ① interruption of anterior cruciate ligament continuity; ② uninterrupted anterior cruciate ligament continuity, but twisted fibers with wavy changes; ⑧ formation of pseudotumor within the anterior cruciate ligament with low signal on T1-weighted images and high signal on T2-weighted images and proton images, and no intact fiber bundles are seen; ④ on T2-weighted images, the diffuse high-signal changes within the anterior cruciate ligament.
Indirect signs of a complete ACL tear include: (1) the angle between the ACL and the tibial plateau is less than 45°; (2) bone contusion or osteochondral fracture of the lateral part of the knee, i.e., contusion or osteochondral fracture of the lateral tibial plateau and lateral femoral condyle; (3) the posterior cruciate ligament becomes vertical; (4) the anterior tibial displacement is greater than 7 mm; and (5) the lateral meniscus is posteriorly displaced.
MRI manifestations of partial tears of the anterior cruciate ligament: ① increased signal within the ligament is seen on T1-weighted images, T2-weighted images, and proton images, but continuity or intact fiber bundles are still seen, ② thinning of the anterior cruciate ligament, ③ indirect signs of an anterior cruciate ligament tear are seen in one MRI sequence, while an intact anterior cruciate ligament is seen in another sequence (Fig.)
3. Knee ligament checker (KT-1000, KT-2000) examination: used to measure anterior-posterior laxity of the knee joint, compared with the healthy side, anterior-posterior laxity difference >5mm can be initially diagnosed anterior cruciate ligament injury.
4. Diagnostic arthroscopy.
Diagnostic arthroscopic exploration is essential. The intra-articular space is observed in a certain order with the knee arthroscope and probe hook so that all intra-articular lesions can be clearly understood and missed. The sequence is: suprapatellar capsule, medial intercondylar sulcus, lateral intercondylar sulcus, patellofemoral joint surface, medial intercondylar compartment, posterior medial compartment, intercondylar fossa, lateral intercondylar compartment, and posterior lateral compartment.
Articular cartilage softening of the patellofemoral and tibiofemoral joints was recorded, and meniscal tears were evaluated. There was also intercondylar fossa bone formation, vertical collision between the ACL and PCL, and cartilage damage to the lateral femoral condyle. arthroscopic images of ACL rupture (Figure)
Treatment The goal is to restore normal mechanical function of the ACL and maintain knee stability. Conservative treatment can be used for those with incomplete ACL rupture and those without acute instability, and surgical treatment is used for complete ruptures, all of which are currently done arthroscopically.
1. Conservative treatment: For acute ACL injuries of the knee, if the joint is significantly swollen and painful, immediate icing and knee brace braking is required. Due to the swelling and pain of the joint during the acute phase, the patient usually refuses to be examined by the physician. As a result, the anterior drawer test, the Lachman test, and the pivot shift test are often negative. X-ray and MRI can be followed by 3 weeks of observation before examining the knee for ACL injury to determine if arthroscopic surgery is needed. This will avoid missing the ACL attachment point avulsion fracture. Conservative treatment can be used in older patients with simple ACL injuries with minimal sporting requirements, and it is aimed at restoring most daily activities without meeting the demands of strenuous exercise. Conservative treatment, on the other hand, aims at rehabilitation. The process consists of two steps: the first step is to eliminate the inflammatory response and restore joint mobility and muscle control. Ice may be applied to reduce pain and swelling and to move the joint and patella, while muscle strength training is performed to avoid muscle atrophy. The second step is to emphasize N-cord and quadriceps strength training, and once the patient returns to normal gait to perform open and closed chain exercises, ranging from high frequency and low intensity to low frequency and high intensity. Balance training and proprioceptive training are then performed.
Conservative treatment should use a functional brace, which provides full range of knee stability and allows a range of motion for patients with ACL injuries. The functional brace serves two purposes: first, to improve proprioception and second, to avoid re-injury.
2. ACL repair: for avulsion fractures with the ACL attachment point can be fixed arthroscopically by tunneling on both sides of the bone block by wearing a wire or using a Lovejoy Gang #5 suture. Screw fixation may also be used. For avulsion fractures of the femoral end attachment point fixation with suture anchor technique is available (Fig.)
3. arthroscopic ligament reconstruction for ACL rupture: The current classical surgical treatment for ACL rupture is arthroscopic ACL reconstruction. Autologous, allograft tendons and artificial ligaments can be used to replace the ruptured ACL. The autologous ligaments used to reconstruct the ACL are, autograft tendons: 1/3 bone-patellar tendon-bone, bone-quadriceps, N cord (semitendinosus and thin femoral muscle). Allograft tendons: 1/3 bone-patellar tendon-bone, bone-quadriceps, N cord (semitendinosus and femoralis), tibialis anterior, tibialis posterior. Artificial tendons are currently available in the LARS ligament. Autologous tendon graft grafts are quick to shape, but the diameter of the tendon is difficult to control and requires harvesting from other sites, which may leave complications in the donor area. Allogeneic tendons have poor histocompatibility, immune rejection and the potential for disease transmission. Artificial ligaments must also be observed over time.
Single band is the reconstruction of the isometric point of the ACL, i.e. the length of the reconstructed ligament remains the same during knee flexion and extension. double band is the reconstruction based on the anatomical points of the AMB and PLB of the ACL. double band Reconstruction is beneficial for ACL rupture with knee rotation instability (Fig.)
Methods of fixation: femoral end has Endobutten, absorbable interface screws and ligament beads, cross pins (Cross pin, Rigifix). The tibial end has absorbable interface screws, portal nails, 4.5 mm cortical bone screws, Intrifix. button plates from Snake are also available (Fig.).
Indications for surgery: Surgery should be considered for complete rupture of the ACL, combined with meniscal or other ligament injuries, participation in sports at a high level of play, and in young patients. The vast majority of studies have shown that conservative treatment leads to reinjury, meniscal damage, and increased osteoarthritis in both children and adults. Although the surgical results of ACL reconstruction are still not as satisfactory as one might expect, the vast majority of physicians believe that surgery is the best option for continued participation in high-risk sports or for other injuries such as meniscal injuries, other ligament injuries, cartilage injuries, and significant anterior instability. For the selection of the timing of surgery for acute ACL injuries, doctors recommend surgery after the joint effusion disappears and joint mobility and quadriceps strength are restored.
Post-operative rehabilitation: functional exercises such as straight leg raising can be started on the 1st day after surgery, while starting to practice passive knee flexion and extension activities, and try to control knee flexion within 500 before 4 weeks. 4 weeks to move within the range of 0° to 90°, and 6-8 weeks to return to normal. After surgery, a brace should be worn for 8 weeks for protection, and the affected limb can be partially weight-bearing under the protection of the brace. 12 weeks after resuming normal walking, fixed bicycle and lower limb muscle strength recovery exercises can be started. After six months after surgery, you can deep pedal and resume simple sports. 8 months after surgery, you can start jogging exercise, and one year after surgery, you can basically resume normal sports activities.
Posterior cruciate ligament injury
The posterior cruciate ligament PCL is another important structure to keep the knee joint stable. Its rupture will cause posterior instability and rotational instability of the knee joint, and lead to a series of secondary knee injuries, and may even cause serious osteoarthritis of the knee joint and joint replacement. Only 10-22% of posterior cruciate ligament injuries are isolated, and the majority are combined with injuries to other structures, such as the ACL and meniscus. Its avulsion from the bony end is more frequent than that of the ACL, with 16-22% tearing from the middle segment.Schulz et al. reported that traffic accidents (45%) and sports injuries (40%) were the most common causes of PCL injury. With the in-depth research on PCL anatomy, important biological features and physiological roles, natural post-injury regression and effects on knee function, selection of reconstructive substitutes and biological regression of reconstructed ligaments, there has been a new development in the understanding of PCL injuries and a significant improvement in their clinical diagnosis and treatment.
(A) Functional anatomy and physiological function of PCL
The PCL starts from the posterior non-articular surface of the intercondylar crest of the tibia and becomes 70-800 toward the medial femoral condyle and ends obliquely at the lateral aspect of the medial femoral condyle through the medial aspect of the anterior cruciate ligament, with an average length of 38 mm and a width of 13 mm, and can be divided into two bundles: the anterolateral bundle and the posterior medial bundle. The two bundles alternate in posterior and rotational stabilization during knee motion, with the anterolateral bundle tense in the flexed position and the posterior medial bundle tense in the extended position (Figure).
Covey divided the posterior cruciate ligament into four bundles, namely the anterior, middle, posterior oblique, and posterior longitudinal bundles, based on the location and morphology of fiber attachment to the femur, and concluded that these four bundles are not independent of each other but are a unified functional whole. the PCL is the strongest ligament of the knee, being twice as strong as the ACL. after studying age-matched cadaveric specimens, Prietto et al. reported that the maximum rupture of the posterior cruciate ligament stresses were not significantly different from those of the anterior cruciate ligament. The posterior cruciate ligament had a maximum rupture stress of 1,627±491 N compared to 1,725±660 N for the anterior cruciate ligament. The posterior cruciate ligament is more vertical and is the axis of rotational motion production in the knee joint, and it appears to direct the “rotation termination locking” mechanism during the end femoral internal rotation of the knee joint at the end of extension. When the posterior cruciate ligament is lost, the displacement of the posterior drawer test increases while the anterior drawer sign remains unchanged; the stability of rotation remains unchanged in knee extension but changes in flexion. Because the attachment point of the femur is closer to the axis of rotation of the knee, changes in the position of the graft on the femur have a greater effect on isometric properties. The distance between each fiber attachment site is sensitive to changes in position within the larger area of the femoral attachment, but is not sensitive to changes at the tibial attachment site.
The PCL, as the main stabilizing structure of the knee joint, acts as the axis of motion throughout the knee joint activity. Its main role is to limit the posterior stability of the tibia and ensure the posterior stabilizing role of the knee joint. It can also limit tibial hyperextension and has a certain degree of limiting the role of internal rotation, adduction and abduction of the lower leg. Under normal conditions, the PCL is intact and the knee joint does not become unstable. If the PCL is ruptured, the knee joint loses its rotational role on the axis of the PCL, and posterior rotational instability may occur in addition to posterior instability of the knee joint.
(B) Mechanism of injury to the posterior fork ligament
The injury mechanism of the PCL is summarized in two points: (l) anterior-posterior injury: direct posterior violence to the proximal tibia during knee flexion is a common injury mechanism, mostly simple injury. This mechanism of PCL tear has 70% occurred in the tibial end, 15% in the femoral end, l5% occurred in the middle of the ligament; (2) hyperextension injury: PCL most of the fibers in the extension position tension, knee hyperextension often leads to PCL is an isolated injury, especially when the point of force in front of the upper tibia both hyperextension and posterior displacement of the force. (3) Severe valgus injury: With the rupture of the medial collateral ligament and ACL, the PCL is also ruptured, commonly at the site of separation or avulsion of the femoral attachment (Fig.)
(C) Types of posterior cruciate ligament injury
1. PCL parenchymal rupture: it can be divided into partial rupture and complete rupture.
2. PCL tibial stop avulsion fracture. The avulsed bone block may not be separated and detached.
3. avulsion fracture of PCL femoral stop. Usually the femoral bone block is separated.
(IV) Clinical manifestations and diagnosis
PCL injury mainly manifests as functional posterior instability and lateral rotational instability of the knee joint, as well as symptoms caused by damage to the internal structures of the knee joint secondary to the instability of the knee joint. Early knee instability can occur soon after the injury and is due to the loss of ligamentous posterior stabilization of the knee joint. Late instability of the knee joint can appear longer after the injury and is due to a combination of loss of posterior stabilizing structures in the knee joint and loss of stabilization of the muscle ligaments around the knee joint.
Clinical diagnosis.
1, medical history: all have a history of knee injury, mostly seen in sports injuries and block injuries.
Acute symptoms of posterior cruciate ligament injury: pain, swelling and bleeding in the N fossa after the injury. Severe injury may result in blood accumulation in the joint cavity and limitation of knee movement.
Chronic symptoms of posterior cruciate ligament injury: posterior instability of the knee joint that affects joint motion. Due to the appearance of knee instability secondary to the manifestation of structural damage in the knee joint and joint interlocking.
2. Signs: signs of quadriceps atrophy, cartilage damage and meniscal damage. Tests of significance for the diagnosis of PCL rupture.
(1) Positive posterior drawer test:The method is basically the same as the anterior drawer test, except that the proximal segment of the lower leg is pushed backward with both hands. There are also three positions, internal and external rotation and neutral position, with the same meaning as before. The posterior drawer test is the most reliable method to check for posterior cruciate ligament injury. However, in the presence of a combined anterior cruciate ligament rupture, errors in judgment can sometimes occur. The posterior drawer test is the most reliable method to examine posterior cruciate ligament injury, but in combination with anterior cruciate ligament rupture, it can sometimes be misjudged.
(2) Sag sign: the tibia sinks due to gravity, resulting in a significant depression of the upper tibia and a significantly lower tibial tuberosity than the healthy side (Figure).
3. Imaging examinations.
(1) Conventional frontal and lateral x-ray of the knee joint: it is of great diagnostic value for injuries with partial avulsion of the bone from the starting or stopping point, but has no direct diagnostic significance for other types of injuries. A lateral radiograph of the posterior drawer of the knee shows a significant posterior displacement of the tibia (Figure).
(2) CT plus three reconstructions, from which the presence or absence of intra-articular fractures can be detected, and there are guidelines for the presence or absence of displacement of tibial stop avulsion fractures and the need for surgery.
3). MRI of posterior cruciate ligament: normal signal changes of PCL, thickening, fracture tortuosity or disappearance and other changes.
(1) Normal posterior cruciate ligament MRI performance: in various sequences of coronal, cross-sectional and sagittal planes, the posterior cruciate ligament is low signal; in cross-sectional planes, its cross-section gradually becomes thinner; in sagittal planes, the posterior cruciate ligament is bowed in a convex posterior direction with smooth edges. 5 mm layer thickness of the sagittal plane can show its entire length on 1-2 consecutive images, and the posterior cruciate ligament, which was bowed when the knee joint was flexed, can become a straight line. The posterior cruciate ligament can become a straight line when the knee is flexed.
(2) MRI manifestations of posterior cruciate ligament injury.
Signs of complete posterior cruciate ligament tears: ① the continuity of the posterior cruciate ligament is interrupted, and the residual cruciate ligament is retracted and twisted: ② it cannot show all parts of the posterior cruciate ligament, which is mostly seen in old injuries: ③ the posterior cruciate ligament shows irregular high signal on T1-weighted images and T2-weighted images, and the posterior edges of its inner layers are fused with each other as fibrous strips.
Signs of partial tears of the posterior cruciate ligament: no signs of complete tears as described above, but abnormal signal changes within the posterior cruciate ligament, or disruption of fiber continuity in part of the posterior cruciate ligament on MRI images while the rest of the fibers are intact (Fig.)
(4) Knee arthroscopy: it can clearly examine and diagnose the PCL injury, and the microscopy can show that the tension of the injured PCL is significantly reduced or the absorption disappears. In acute injury, a severed end can be found (Figure).
Treatment Whether to operate for PCL injury depends on the degree of PCL injury, the presence of other structural injuries and the age and occupation of the patient. In symptomatic posterior cruciate ligament-deficient knees, the goal of surgery is to re-establish the primary function of the posterior cruciate ligament as the basic static limiting structure against posterior tibial migration.
1. Conservative treatment
Most studies have shown good results with non-operative management of I° or II° injuries, at least in the short term. These reports suggest that only minor short-term functional instability occurs with nonoperative management, and that function is often consistent with objective stability. Despite the encouraging reports of nonoperative management, it is clear that not all simple posterior cruciate ligament tears of the knee have a good prognosis. Recent long-term studies have shown that knee function tends to deteriorate over time, with most patients eventually experiencing varying degrees of functional impairment. Common criteria for nonoperative treatment are: a posterior drawer sign of less than 10 mm (grade II) in neutral tibial rotation (reduced displacement of the posterior drawer sign with internal rotation of the tibia on the femur); abnormal rotational laxity of less than 5° (especially abnormal external rotation of the tibia in the 30° flexed knee position, indicating postero-lateral instability); and no significant abnormal laxity of the inversion a valgus (without significant other ligamentous injury). Patients with non-operative treatment should be closely followed up to observe whether degenerative symptoms and functional decompensation occur.
2. Surgical treatment: Patients with posterior cruciate ligament laxity with obvious bone block avulsion at the tibial attachment are recommended for surgical fixation. For posterior cruciate ligament injury with significant other ligament tears (including knee dislocation), posterior cruciate ligament reconstruction is required.
1) Repair of acute tears of the posterior cruciate ligament
Posterior cruciate ligament tears alone may be extremely difficult to diagnose in the acute phase unless the patient is examined under anesthesia or arthroscopy is performed, or there is a bone mass that is avulsed from the posterior tibial stop and is visible on x-ray.MRI is more reliable for the diagnosis of posterior cruciate ligament tears than for anterior cruciate ligament tears.
Posterior cruciate ligament injury with tibial avulsion fracture: clinically, it presents as a simple acute posterior cruciate ligament rupture and should be repaired. The methods are: arthroscopic or trans-N fossa approach to the avulsed bone block with internal fixation by wearing wires or love handles 5 wires on both sides, arthroscopic 4.5 mm hollow screw internal fixation, trans-N fossa approach with the aid of arthroscopy for absorbable screws or suture anchor technique internal fixation.
Posterior cruciate ligament femoral end avulsion: can be fixed by arthroscopic suture anchor technique. The torn ligament can also be fixed by using the LoveHelp 5 wire through the torn ligament, but the efficacy is not always reliable.
(2) Posterior cruciate ligament reconstruction.
(1) Indications: Posterior cruciate ligament rupture alone and grade III instability should be considered for reconstruction, especially for acute injuries. In compound forms of instability (both medial and lateral) or knee dislocation, surgical treatment to repair and reconstruct all necessary ligament defects in the acute phase is preferable. In knees with complete rupture of the posterior cruciate ligament in combination with other ligament injuries, posterior tibial dislocations are difficult to avoid and the surrounding torn capsule structures are difficult to restore to their normal anatomic position, especially in the posterior lateral horn. These structures, which could have been repaired in the acute phase, will require reconstruction if they reach the chronic period of joint instability.
(2) Surgical approaches: single-bundle reconstruction of the posterior cruciate ligament, double-bundle reconstruction of the posterior cruciate ligament and tibial Inlay technique to reconstruct the posterior cruciate ligament. As for the selection of graft and fixation, see ACL reconstruction.
(1) Single-bundle reconstruction of the posterior cruciate ligament mainly reconstructs the anterolateral bundle and is a functional reconstruction. The aim is to restore the stability of the knee joint, not to fully restore the physiological anatomy of the PCL. However, some scholars are exploring the isometric reconstruction of the PCL. It is the graft that remains intact during knee motion.
② Double bundle reconstruction of the posterior cruciate ligament is the reconstruction of both the anterolateral bundle and the posterior medial bundle. It is a reconstruction based on the normal anatomy of the PCL and is closer to the anatomy and biomechanics of the PCL.
(iii) The tibial Inlay technique for reconstruction of the posterior cruciate ligament is an inlay technique based on avoiding the “killer turn” and fixing the tibial side of the graft directly in the bone socket, while abandoning the tibial tunnel technique. It is a combination of arthroscopic and open surgery. A ligament with a bone block is used for the graft.
Postoperative rehabilitation.
The principle of rehabilitation after posterior cruciate ligament reconstruction alone is that restoration of function begins with reduction of pressure on the healing graft and avoidance of tibial posterior displacement or protection against gravity and limitation of posterior leg muscle activity. As these processes improve, it is necessary to restore knee mobility in a protective manner to the quadriceps muscle. Patients must be counseled about the expectations and limitations of the procedure prior to surgery. The operator, patient, and physical therapist, as well as the patient’s parents and even the athletic trainer, should recognize that full recovery from posterior cruciate ligament reconstruction is slower and return to sports later than from anterior cruciate ligament reconstruction. The following rehabilitation guidelines are based on the records of a trial designed by Pittsburgh University.
Phase I The first month postoperatively, including the first week in the extended position using a brace and column abduction for weight bearing is Phase I. Assisted passive mobility exercises were started during this period, with caution to maintain strength in the anterior leg. Avoid exercises that cause posterior displacement of the tibia. Exercises for the quadriceps and hip are performed together with the calf. Cold compresses are started and maintained throughout the rehabilitation period.
Phase II Continues through the third month after surgery. 8 weeks after removal of the brace, begin off-bed mobility exercises to improve all activities. As quadriceps control and gait return to normal, crutches are discontinued. Work on gaining full extension or greater flexion mobility and begin early strengthening exercises to decrease posterior leg muscle activity, including stationary bike and stair climbing apparatus exercises. But increase flexibility of the posterior leg muscles.
Phase III Continues until the ninth month after surgery. Mobility has returned, with full flexion occasionally as late as the fifth month post-surgery. Therapeutic exercises and proprioceptive training are initiated as functional strengthening improves and continued attention is given to the quadriceps. Phase IV continues until until the patient returns to desired activity. Specialized exercise training ends at the end of phase III and before the start of phase IV. Maximize strength and durability, and the patient reviews the maintenance program.