The more common types of multiple ligament injuries in the knee are anterior cruciate ligament (ACL) combined with medial collateral ligament injury, posterior cruciate ligament combined with posterior posterolateral horn injury (PLC), anterior and posterior cruciate ligament combined with medial and lateral collateral ligament injury, etc. The diagnosis and treatment of these injuries have been reported extensively in the literature. Recently, Jeffrey et al[1] analyzed the causes of failure after surgical reconstruction of ACL injuries and concluded that unrepaired posterior external horn injury was one of the causes. However, ACL injury combined with posterior external horn injury is rare, and Ross et al [2] summarized more than ten years of patients with knee ligament injury, only 13 cases were diagnosed with ACL injury combined with posterior external horn injury, and there are no other reports in the literature. From December 2003 to May 2004, two cases of ACL injury combined with posterior external horn injury were treated in our department and are described as follows.
Typical cases
Case 1: female, 22 years old, 6 years ago, the left knee was hit by a car, the left knee swollen, painful, limited activity, X-ray did not see the knee fracture dislocation, in the local hospital to give a cast braking 6 weeks after the start of functional exercise, can walk after the discovery of road surface irregularities obviously feel the left knee instability, repeatedly playing soft leg, with a knee brace instability feeling slightly better, 6 years has not been able to participate in confrontational sports. He was admitted to the hospital for physical examination: positive anterior drawer test, positive Lachman test, positive axial shift test, positive medial stress test, obvious tension, positive dial test, MRI showed discontinuity of the anterior cruciate ligament and lateral collateral ligament of the left knee. The tendon was tracted into the femoral tract, and the lateral femoral button was turned over successfully to complete the fixation of the lateral femoral tendon, after which the tendon was tensioned in the 30° flexed knee position, and the tendon was fixed in the lateral tibial tract with absorbable soft tissue interface screws through a guide pin to complete the ACL reconstruction. A 2mm Kirschner pin was drilled superiorly, and the fibular head tract was drilled with a 6mm hollow drill to pass the semitendinosus tendon through the fibular head, followed by a 2mm Kirschner pin drilled into the femoral epicondyle to test the isometric point, and the femoral tract was drilled through this guide pin to introduce the tendon into the femoral tract, and the tendon was tensioned in a 30° flexed knee position, and the femoral end was fixed with absorbable interface screws. The lateral collateral ligament was reconstructed with one ligament anteriorly and the N-fibular ligament was reconstructed with one ligament posteriorly. Rehabilitation plan: The patient had multiple ligament injuries, so the rehabilitation was relatively conservative, the first four weeks were spent in the knee extension position with braking, during which the patient strengthened the quadriceps isometric exercise and pushed the patella; after four weeks, the patient started to practice knee flexion under the protection of a chain brace, and the knee flexion reached 90° at 6 weeks, and the knee flexion returned to normal at 8 weeks, and the brace protected the crutches to walk on the ground before 8 weeks, and after 8 weeks, the brace was removed and the patient walked freely. The patient could jog in a straight line after 3 months, and could run in the opposite direction after 4 months, and participate in antagonistic sports after 6 months. After 6 months of follow-up, the knee stability was completely restored, with negative anterior drawer test, negative Lachman test, negative medial stress test, negative dial test, complete knee extension and flexion up to 135°, and no joint instability during walking and straight-line running.
Case 2: Male, 54 years old, was admitted to the hospital with a 4h injury to the upper anterior medial aspect of the right knee by a car. He was admitted with swelling of the right knee, subcutaneous bruising and pressure pain above and below the lateral joint space, subcutaneous bruising and pressure pain above the anterior medial, positive floating patella test, positive anterior drawer test, positive medial stress test, significant tension, and positive dial test. x-ray and CT film showed a fracture of the medial femoral condyle, and MRI showed discontinuity of the anterior cruciate ligament and lateral collateral ligament of the right knee. On arthroscopic exploration, there was a compression fracture of the medial femoral condyle, widening of the lateral joint space, rupture of the N tendon, rupture of the lateral joint capsule, and rupture of the anterior cruciate ligament. Posterior lateral structures were repaired in one stage, and the lateral collateral ligament, N fibular ligament, N tendon, part of the lateral head of the gastrocnemius muscle and the lateral joint capsule were seen to be completely ruptured intraoperatively, and these structures were sutured in situ with AICK 5, and the anterior cruciate ligament was not reconstructed. After 8 months of follow-up, the case felt joint instability, even in the knee in the straight position with the road uneven, and the medial stress test and anterior drawer test were positive.
I. Mechanism of injury
Hughston et al[3] highlighted for the first time the complex nature of instability involving the lateral space of the knee and classified lateral instability into six categories, of which the most studied is posterior lateral rotational instability, i.e., posterior rotational subluxation of the lateral tibial plateau relative to the femoral epicondyle, with the mechanism of injury being external forces acting on the anteromedial tibia, causing damage to the posterior cruciate ligament and posterior lateral structures, which is the most common mode of injury[4] . . Anterolateral rotational instability refers to the forward subluxation of the lateral tibial plateau relative to the femoral epicondyle, which may occur for two reasons: first, ACL injury combined with posterior external angle injury, which is less common and the mechanism of injury is unclear, while anteromedial rotational instability produced by ACL combined with medial collateral ligament injury is more common; second, it is caused by laxity of the lateral structures after chronic injury to the ACL, which mainly manifests The second is due to the laxity of the lateral structures after chronic injury to the ACL, mainly manifested by a positive anterior drawer test and a positive axial shift test. From the analysis of one old and one fresh case of anterolateral rotational instability treated by us, the traumatic violence is large, and the external force acts on the anteroinferior and superior femoral condyles, resulting in the femur moving backward, relatively causing the tibia moving forward, and increasing the ACL stress, when the violence exceeds the ACL yield point, it can cause ACL rupture, and due to the outward force at the same time, it causes the knee joint to invert, and when the violence is large, it causes the posterior lateral structure injury, in which the rotational restriction of the tibia disappears after the rupture of the N-fibular ligament, and the anterior subluxation of the tibia will be more obvious when the femur is subjected to postero-lateral violence, further aggravating the anterior cruciate ligament injury.
II. Anatomy of the posterior lateral horn
The anatomy of the posterior external horn (PLC) is complex, and the posterior external horn ligament is closely related structurally. seebacher et al [5] divided it into three layers, the first layer mainly contains the biceps femoris tendon and the iliotibial bundle, the second layer mainly contains the lateral collateral ligament, the N tendon and the N fibular ligament, and the third layer contains the joint capsule and the lateral head of the gastrocnemius muscle. Its main function is to limit internal rotation of the knee joint, external rotation and to limit posterior external rotation of the tibia relative to the femur. Of these three layers, the most studied structure is the second layer, especially the recognition of the importance of the N muscle tendon and the N fibular ligament, which starts posteriorly from the proximal tibia and ends just below the lateral collateral ligament attachment point of the femoral epicondyle, with the N fibular ligament connecting it to the fibular head in its stroke and the tendonous portion forming a connection with the lateral meniscus via the intra-articular. The N muscle is currently considered to be an important dynamic structure in the lateral structures of the knee, and the N fibular ligament restricts the external rotation of the tibia relative to the femur [6].LaPrade et al [7] concluded from a cadaveric anatomical study that the main structures maintaining posterior lateral stability are the lateral collateral ligament, the N tendon, the N fibular ligament and the lateral head of the peroneal muscle.
III. Diagnosis and treatment
The incidence of anterior cruciate ligament injury combined with posterior external horn injury is low, and Ross et al [2] summarized more than ten years of patients with knee ligament injury, only 13 cases confirmed anterior cruciate ligament combined with posterior external horn injury. In the clinical often due to lack of awareness, and the acute phase of the patient’s knee pain, signs are more difficult to detect, the diagnosis has some difficulties; and old injury is generally more obvious, the main positive physical evidence are positive anterior drawer test, positive Lachman test, positive medial stress test, obvious tension, dial test is mostly positive at 300 position. ross believes that MRI examination is the most sensitive auxiliary examination, sagittal position The anterior cruciate ligament injury sign is understood in the sagittal position, and the posterior external horn structure injury can be seen in the coronal position. MRI in our two patients showed the injured structures and is an indispensable test for a definite diagnosis. MRI is recommended for patients with joint hemorrhage after knee trauma. The combination of clinical manifestations and MRI images can provide an early diagnosis of ACL injury combined with posterior external horn injury.
The timing of treatment of ACL injury combined with posterior external horn injury is very important, Ross et al [2] concluded that anatomical repair of the posterior external horn is most important within two weeks after trauma, and fresh trauma of the posterior external structure is fixed with in situ reinforced sutures, the ligament can heal and its stability can be completely restored, while direct suture repair after 2 weeks is poor and requires reconstruction of the posterior external horn structure with a ligament graft; Stannard et al [8] compared Stannard et al [8] compared the effect of posterior posterolateral complex repair and reconstruction and concluded that one-stage lateral collateral ligament reconstruction was effective in restoring lateral stability, while simple in situ repair of the lateral structures resulted in a failure rate of 37%, so for patients with tears of the lateral collateral ligament and the parenchyma of the N tendon, lateral collateral ligament reconstruction was performed, and the bony attachment point of the lateral collateral ligament was stripped and fixed with early in situ repair.Noyes et al [9], while reconstructing the lateral collateral ligament Noyes et al [9] required simultaneous reconstruction of the anterior cruciate ligament while reconstructing the lateral collateral ligament; if the anterior cruciate ligament is not repaired, laxity of the posterolateral structures will occur secondary to the repair of the anterior cruciate ligament. There are several methods to reconstruct the ACL and posterior external horn reconstruction during surgery in old injury cases [10], but the better result is to reconstruct the lateral collateral ligament and the N fibular ligament respectively in order to better restore the internal rotation and external rotation instability of the knee.
The more common types of multiple ligament injuries of the knee are anterior cruciate ligament (ACL) combined with medial collateral ligament injury, posterior cruciate ligament combined with posterior posterolateral corner injury (PLC), anterior and posterior cruciate ligament combined with medial and lateral collateral ligament injury, etc. The diagnosis and treatment of these injuries have been reported extensively in the literature. Recently, Jeffrey et al[1] analyzed the causes of failure after surgical reconstruction of ACL injuries and concluded that unrepaired posterior external horn injury was one of the causes. However, ACL injury combined with posterior external horn injury is rare, and Ross et al [2] summarized more than ten years of patients with knee ligament injury, only 13 cases were diagnosed with ACL injury combined with posterior external horn injury, and there are no other reports in the literature. From December 2003 to May 2004, two cases of ACL injury combined with posterior external horn injury were treated in our department and are described as follows.
Typical cases
Case 1: female, 22 years old, 6 years ago, the left knee was hit by a car, the left knee swollen, painful, limited activity, X-ray did not see the knee fracture dislocation, in the local hospital to give a cast braking 6 weeks after the start of functional exercise, can walk after the discovery of road surface irregularities obviously feel the left knee instability, repeatedly playing soft leg, with a knee brace instability feeling slightly better, 6 years has not been able to participate in confrontational sports. He was admitted to the hospital for physical examination: positive anterior drawer test, positive Lachman test, positive axial shift test, positive medial stress test, obvious tension, positive dial test, MRI showed discontinuity of the anterior cruciate ligament and lateral collateral ligament of the left knee. The tendon was tracted into the femoral tract, and the lateral femoral button was turned over successfully to complete the fixation of the lateral femoral tendon, after which the tendon was tensioned in the 30° flexed knee position, and the tendon was fixed in the lateral tibial tract with absorbable soft tissue interface screws through a guide pin to complete the ACL reconstruction. A 2mm Kirschner pin was drilled superiorly, and the fibular head tract was drilled with a 6mm hollow drill to pass the semitendinosus tendon through the fibular head, followed by a 2mm Kirschner pin drilled into the femoral epicondyle to test the isometric point, and the femoral tract was drilled through this guide pin to introduce the tendon into the femoral tract, and the tendon was tensioned in a 30° flexed knee position, and the femoral end was fixed with absorbable interface screws. The lateral collateral ligament was reconstructed with one ligament anteriorly and the N-fibular ligament was reconstructed with one ligament posteriorly. Rehabilitation plan: The patient had multiple ligament injuries, so the rehabilitation was relatively conservative, the first four weeks were spent in the knee extension position with braking, during which the patient strengthened the quadriceps isometric exercise and pushed the patella; after four weeks, the patient started to practice knee flexion under the protection of a chain brace, and the knee flexion reached 90° at 6 weeks, and the knee flexion returned to normal at 8 weeks, and the brace protected the crutches to walk on the ground before 8 weeks, and after 8 weeks, the brace was removed and the patient walked freely. The patient could jog in a straight line after 3 months, and could run in the opposite direction after 4 months. After 6 months of follow-up, the knee stability was completely restored, with negative anterior drawer test, negative Lachman test, negative medial stress test, negative dial test, complete knee extension and flexion up to 135°, and no joint instability during walking and straight-line running.
Case 2: Male, 54 years old, was admitted to the hospital with a 4h injury to the upper anterior medial aspect of the right knee by a car. He was admitted with swelling of the right knee, subcutaneous bruising and pressure pain above and below the lateral joint space, subcutaneous bruising and pressure pain above the anterior medial, positive floating patella test, positive anterior drawer test, positive medial stress test, significant tension, and positive dial test. x-ray and CT film showed a fracture of the medial femoral condyle, and MRI showed discontinuity of the anterior cruciate ligament and lateral collateral ligament of the right knee. On arthroscopic exploration, there was a compression fracture of the medial femoral condyle, widening of the lateral joint space, rupture of the N tendon, rupture of the lateral joint capsule, and rupture of the anterior cruciate ligament. Posterior lateral structures were repaired in one stage, and the lateral collateral ligament, N fibular ligament, N tendon, part of the lateral head of the gastrocnemius muscle and the lateral joint capsule were seen to be completely ruptured intraoperatively, and these structures were sutured in situ with AICK 5, and the anterior cruciate ligament was not reconstructed. After 8 months of follow-up, the case felt joint instability, even in the knee in the straight position with the road uneven, and the medial stress test and anterior drawer test were positive.
I. Mechanism of injury
Hughston et al[3] highlighted for the first time the complex nature of instability involving the lateral space of the knee and classified lateral instability into six categories, of which the most studied is posterior lateral rotational instability, i.e., posterior rotational subluxation of the lateral tibial plateau relative to the femoral epicondyle, with the mechanism of injury being external forces acting on the anteromedial tibia, causing damage to the posterior cruciate ligament and posterior lateral structures, which is the most common mode of injury[4] . . Anterolateral rotational instability refers to the forward subluxation of the lateral tibial plateau relative to the femoral epicondyle, which may occur for two reasons: first, ACL injury combined with posterior external angle injury, which is less common and the mechanism of injury is unclear, while anteromedial rotational instability produced by ACL combined with medial collateral ligament injury is more common; second, it is caused by laxity of the lateral structures after chronic injury to the ACL, which mainly manifests The second is due to the laxity of the lateral structures after chronic injury to the ACL, mainly manifested by a positive anterior drawer test and a positive axial shift test. From the analysis of one old and one fresh case of anterolateral rotational instability treated by us, the traumatic violence is large, and the external force acts on the anteroinferior and superior femoral condyles, resulting in the femur moving backward, relatively causing the tibia moving forward, and increasing the ACL stress, when the violence exceeds the ACL yield point, it can cause ACL rupture, and due to the outward force at the same time, it causes the knee joint to invert, and when the violence is large, it causes the posterior lateral structure injury, in which the rotational restriction of the tibia disappears after the rupture of the N-fibular ligament, and the anterior subluxation of the tibia will be more obvious when the femur is subjected to postero-lateral violence, further aggravating the anterior cruciate ligament injury.
II. Anatomy of the posterior lateral horn
The anatomy of the posterior external horn (PLC) is complex, and the posterior external horn ligament is closely related structurally. seebacher et al [5] divided it into three layers, the first layer mainly contains the biceps femoris tendon and the iliotibial bundle, the second layer mainly contains the lateral collateral ligament, the N tendon and the N fibular ligament, and the third layer contains the joint capsule and the lateral head of the gastrocnemius muscle. Its main function is to limit internal rotation of the knee joint, external rotation and to limit posterior external rotation of the tibia relative to the femur. Of these three layers, the most studied structure is the second layer, especially the recognition of the importance of the N muscle tendon and the N fibular ligament, which starts posteriorly from the proximal tibia and ends just below the lateral collateral ligament attachment point of the femoral epicondyle, with the N fibular ligament connecting it to the fibular head in its stroke and the tendonous portion forming a connection with the lateral meniscus via the intra-articular. The N muscle is currently considered to be an important dynamic structure in the lateral structures of the knee, and the N fibular ligament restricts the external rotation of the tibia relative to the femur [6].LaPrade et al [7] concluded from a cadaveric anatomical study that the main structures maintaining posterior lateral stability are the lateral collateral ligament, the N tendon, the N fibular ligament and the lateral head of the peroneal muscle.
III. Diagnosis and treatment
The incidence of anterior cruciate ligament injury combined with posterior external horn injury is low, and Ross et al [2] summarized more than ten years of patients with knee ligament injury, only 13 cases confirmed anterior cruciate ligament combined with posterior external horn injury. In the clinical often due to lack of awareness, and the acute phase of the patient’s knee pain, signs are more difficult to detect, the diagnosis has some difficulties; and old injury is generally more obvious, the main positive physical evidence are positive anterior drawer test, positive Lachman test, positive medial stress test, obvious tension, dial test is mostly positive at 300 position. ross believes that MRI examination is the most sensitive auxiliary examination, sagittal position The anterior cruciate ligament injury sign is understood in the sagittal position, and the posterior external horn structure injury can be seen in the coronal position. MRI in our two patients showed the injured structures and is an indispensable test for a definite diagnosis. MRI is recommended for patients with joint hemorrhage after knee trauma. The combination of clinical manifestations and MRI images can provide an early diagnosis of ACL injury combined with posterior external horn injury.
The timing of treatment of ACL injury combined with posterior external horn injury is very important, Ross et al [2] concluded that anatomical repair of the posterior external horn is most important within two weeks after trauma, and fresh trauma of the posterior external structure is fixed with in situ reinforced sutures, the ligament can heal and its stability can be completely restored, while direct suture repair after 2 weeks is poor and requires reconstruction of the posterior external horn structure with a ligament graft; Stannard et al [8] compared Stannard et al [8] compared the effect of posterior posterolateral complex repair and reconstruction and concluded that one-stage lateral collateral ligament reconstruction was effective in restoring lateral stability, while simple in situ repair of the lateral structures resulted in a failure rate of 37%, so for patients with tears of the lateral collateral ligament and the parenchyma of the N tendon, lateral collateral ligament reconstruction was performed, and the bony attachment point of the lateral collateral ligament was stripped and fixed with early in situ repair.Noyes et al [9], while reconstructing the lateral collateral ligament Noyes et al [9] required simultaneous reconstruction of the anterior cruciate ligament while reconstructing the lateral collateral ligament; if the anterior cruciate ligament is not repaired, laxity of the posterolateral structures will occur secondary to the repair of the anterior cruciate ligament. There are several methods to reconstruct the ACL and posterior external horn reconstruction during surgery in old injury cases [10], but the better result is to reconstruct the lateral collateral ligament and the N fibular ligament separately in order to better restore the internal rotation and external rotation instability of the knee.