What Are Cruciate Ligaments?

Cruciate ligament, also called cruciate ligament, is an important stable structure in the knee joint. The stability of the knee joint is maintained by four ligaments: two medial and lateral ligaments and two cruciate ligaments. The medial and lateral ligaments are on the medial and lateral sides of the knee joint; the cruciate ligaments are on the inside of the knee joint, and are called the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL).

Chinese name: Torn cruciate ligament

Foreign name: Cruciate ligament laceration

Torn cruciate ligament 1. Causes and common diseases:

(A) anterior cruciate ligament tear:

The anterior cruciate ligament starts from the back of the medial side of the femoral condyle, travels forward, medial, and inferior, and ends at the anterior angle of the tibia intertrochanteric and the lateral meniscus. In normal conditions, Witte's knee joint is stable front and back, and is involved in limiting knee overextension, coordinating joint rotation activities, and limiting varus and varus activities. Due to overextension or abduction of the knee joint, excessive flexion, adduction, and rotation can cause injury and tear.

Secondary signs of ACL tears are instability of the knee joint, including tibia advancement and arched anterior posterior cruciate ligament. Some scholars believe that about 70% of ACL tears are accompanied by intra-articular injuries, the most common is the tear of the medial meniscus. Some scholars have proposed that recessive fractures of the posterolateral tibial plateau with or without fractures are a feature of acute ACL tears.

(2) Torn posterior cruciate ligament:

The posterior cruciate ligament starts from the posterior portion of the medial condyle of the femur and travels downward, posterior, and posterior. It normally restricts the backward movement of the upper end of the tibia, overextension and rotation of the knee joint, and participates in limiting the varus and knee varus activities. The posterior cruciate ligament is thicker than the anterior cruciate ligament, and it is damaged and torn under violence such as torsion, impact, fall, and crush.

Torn cruciate ligament 2. Differential diagnosis:

After the torn ligament of the cruciate ligament is torn and pulled, the joint's movement function will be reduced, bending or straightening will be limited, and there will be a localized stiffness.

Torn cruciate ligament

(1) Anterior Cruciate Ligament (ACL):

1. Drawer test:

The patient lies in bed. Bend your knees 90 degrees and place your feet flat on the bed to keep them relaxed. The examiner sat on the bed, holding the patient's feet to fix it, holding the tibia end of the knee joint with both hands, and pulling the calf forward. If the tibia moved 5mm larger than the healthy side, it was positive, and it was anterior straight instability.

2.Lachman test:

The patient is supine or prone with knees bent at an angle of about 30 °. The examiner fixed the thigh with one hand and the other hand tried to move the tibia forward. Positive results suggest anterior cruciate ligament.

This test can be performed not only for old injuries, but also for acute injuries; due to the absence of meniscus interference, the positive rate of examination is significantly improved; the termination point of the ligament can be accurately detected.

A positive Lachman test with a soft termination point indicates a complete rupture of the anterior cruciate ligament; a positive Lachman test with a hard termination point indicates a partial anterior cruciate ligament injury or a single joint capsule ligament relaxation; a negative Lachman test must be accompanied by a hard termination Point, indicating that the anterior cruciate ligament is normal.

3.MRI examination:

On MRI, the normal ACL is a clear, smooth low-signal band that passes through one or more of the intercondylar fossa, starting from the medial side of the femoral margin, diagonally forward and medial, and ending at the tibial spine. There are three bundle fibers in ACL anatomy: posterolateral bundle, anterior medial bundle, and intermediate bundle. Each fiber bundle has its own function and can be individually damaged to cause partial tearing. According to the time and degree of ACL injury, MRI has different manifestations. Acute ACL injury can manifest as irregular ligament edges, wavy, and / or discontinuous ligaments. A typical tear is usually in the middle of the ligament or the attachment point of the femoral ligament, often accompanied by fluid in the ligament injury area.

(B) posterior cruciate ligament:

1. Back drawer test:

In the supine position, bend your knees 90 degrees, put your hands behind the knee joint, put your thumbs on the extended side, and repeatedly push and pull the proximal end of the lower leg.

2. Anti-Lachman test:

The patient is supine or prone with knees bent at an angle of about 30 °. The examiner held the thigh in one hand and tried to move the tibia backward with the other hand. A positive result indicates a posterior cruciate ligament injury.