Posterior Cruciate Ligament Injury

Introduction to posterior cruciate ligament injury The posterior cruciate ligament injury (injuryof posteriorcruciateligamentofknee) is caused by strong violence, and the posterior cruciate ligament injury accounts for 3% to 20% of all knee ligament injuries. Of these, 30% were separate injuries and 70% were combined with other ligament injuries. Because PCL is the most powerful in the knee ligament structure, biomechanical experiments prove that PCL is twice as strong as ACL against external force. It is the main stable structure of knee flexion and extension and rotation activity, which is equivalent to the rotation axis of knee joint. Therefore, after the PCL injury, not only the joint is not stable, but also the rotation of the knee joint is unstable. The degree of functional loss after posterior cruciate ligament injury can occur from almost no lifestyle to severe daily activities. The posterior cruciate ligament injury can lead to further relaxation of the secondary stability factor of the knee, causing local pain, swelling and instability. It has been demonstrated that in the medial and patellofemoral joints, the result of this injury is degenerative osteoarthritis. Appropriate treatment must be performed clinically. basic knowledge Sickness ratio: 0.1% Susceptible people: no specific population Mode of infection: non-infectious Complications: fracture osteoarthritis

Cause of posterior cruciate ligament injury

(1) Causes of the disease

The violent knee and the over-extension of the knee at the upper end of the humerus can cause damage.

(two) pathogenesis

1. The violent effect of the upper humerus of the knee flexion: the upper part of the lower leg is suddenly moved backward, causing PCL fracture. If the upper part of the humerus continues to move backward, the posterior capsule of the knee is also torn. This injury can also be combined with dislocation of the femur, tibia and fibula. At this time, the PCL injury is easily covered by the fracture and dislocation and missed diagnosis.

2. Knee overextension: Violence forces the knee to be overextended, first causing PCL to break. If the violence continues to stretch the knee, then the ACL is also damaged. The PCL fracture is mostly in the femoral condyle, and the incidence of injury in other parts. Lower.

3. Post-rotation violence: When the foot is fixed, the upper end of the humerus is subjected to violence from the front and rotates at the same time. This damage mechanism often causes compound injury, that is, the injury with lateral structure, the posterior subluxation of the tibia is more than the PCL injury alone. serious.

Posterior cruciate ligament injury prevention

Avoid trauma.

Posterior cruciate ligament injury complications Complications fracture osteoarthritis

Can be complicated by intra-articular fractures or avulsion fractures, and can be complicated by knee degenerative osteoarthritis in the late stage.

Symptoms of posterior cruciate ligament injury Common symptoms Severe pain and severe pain

When the knee is damaged, it often smells tearing or has a tearing sensation. The knee is severely painful and swollen quickly. It is initially confined to the joint. When the posterior capsule is ruptured, the swelling spreads to the armpit and involves the calf. On the posterior side, subcutaneous congestion spots appear gradually, indicating that intra-articular hemorrhage leaks in the back of the knee and the gastrocnemius muscle, and the soleus muscle gap. If the knee MCL or LCL injury is combined, abnormal movements of the inner and outer valgus and internal and external rotational instability may occur. Pain and swelling may occur locally, and the Jerk test is positive. The positive Jerk test indicates that the anterior lateral rotation of the knee is unstable, which proves that the MCL of the knee joint (including the MCL and the medial joint capsule ligament) is often inspected after the acute phase. The method is: Allow the patient to lie on his back, bend the hip 45°, bend the knee 90°, rotate the humerus at the same time, and apply the external stress to the upper end of the calf. Then gradually extend the knee joint to 20°30°, the lateral femoral and tibial articular surface can occur. Subluxation, if the knee joint is further straightened, the natural reset appears to have a sense of springiness and sound, it is positive, the other method is: stretch the knee position, the calf is externally rotated or neutral, and the knee joint is turned over. When force is gradually flexion to 20 ° ~ 30 ° position, sound bombs and positive sense of dislocation.

Drawer test

After the knee flexion 90°, the drawer test was positive after the examination, but due to the pain and muscle spasm caused by the knee flexion movement, the back drawer test is often difficult to perform, and some are misdiagnosed by the negative result, as shown in (Fig. 1), the knee bend is checked. After the calf was removed, the patient was lying on his knees and completely relaxed. The PCL was broken. The examiner slowly lifted the lower part of the lower thigh 10 cm from the knee. The upper part of the humerus slipped backward, and the lower part of the sac was obviously collapsed. The ACL was broken. The examiner slowly lifted the lower 10 cm of the upper part of the affected leg. The lower part of the femur slipped backward and the upper part of the sac was collapsed. Each case should be examined on the lap and the lower part. The two sides can be compared. No or PCL damage.

2. Step sign

When the knee is bent at 90°, the thumb slides down from the medial malleolus of the femur. If the stepped inner step of the tibia is smaller or disappears to the opposite side, it indicates a PCL injury.

3. Joint puncture

Whole blood can be drawn, and there are intra-articular fractures in the blood.

4. The tibia external rotation test (dial test)

In order to check the posterolateral instability of the injured knee joint, the external rotation of the tibia on the femur can be measured at 30° and 90° of the knee flexion, and the supine or prone position can be taken. When the knee is bent at 30°, the external rotation is increased by >10° compared with the contralateral side. There is pain, but this is not the case at 90°. The posterior external angle injury is more than 10° when the knee flexes 30° and 90°, which indicates that both PCL and posterolateral angle are damaged.

Examination of posterior cruciate ligament injury

X-ray inspection

The knee joint gap was widened, and the avulsion fracture was seen in the PCL iliac crest. For suspicious cases, the author used the femoral nerve and sciatic nerve block, knee flexion 90° before, and the rear drawer test, according to the knee lateral X-ray film, to measure From the center point of the femoral condyle to the horizontal line of the tibial plateau, the horizontal line is divided into two sections, and any section is longer than the same section of the healthy side by more than 5 mm, which is positive. The anterior segment is ACL tear, and the posterior segment is PCL damage.

2.MRI diagnosis

Acute PCL injury, the diagnosis rate is 100%, but for old injuries, there is a false negative.

Diagnosis and diagnosis of posterior cruciate ligament injury

diagnosis

According to the history of trauma, symptoms, signs, X-ray, MRI, most patients can be diagnosed clearly. When the drawer test is negative, it should be checked under anesthesia, and the above X-ray examination often results in a positive result.

Differential diagnosis

Erythematous limb pain

A disease caused by the paroxysmal expansion of small blood vessels at the extremities due to vasomotor dysfunction. More common in both lower extremities, manifested as severe pain in the extremities, local skin temperature increased, redness, sweating or mild depression. Pain in the cold water when the limb is attacked can be alleviated or relieved, and the vasodilatation can increase the symptoms after being heated.

2. Raynaud's disease

The disease is caused by intermittent contraction of small blood vessels in the extremities or spasm caused by spasm. The upper limbs are often seen as pale, chilly, numb, burning sensation on both sides, or blue-purple due to secondary telangiectasia. In the late stage, it can be cramped and ulcerated. Symptoms can worsen in the cold due to vasoconstriction.

3. Rickety limb numbness

Often caused by mental factors, limb numbness, duration varies, and there are other symptoms of rickets. The sputum reflex is more active, and the range of the sensory dysfunction often exceeds the elbow, knee joint, or the boundary changes.

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