How Is a Dislocated Kneecap Treated?

Although the knee bone structure is unstable, there are stronger ligaments and muscle protection around and inside the joint, so knee dislocations are rare. Occasional dislocation is also caused by strong direct violence hitting the upper end of the tibia or indirect violence causing the knee joint to be rotated or overextended, causing the upper end of the tibia to dislocate backward and forward. When completely dislocated, not only the rupture of the joint capsule, tears of the cruciate ligament, the medial and lateral collateral ligaments, the meniscus, and the surrounding muscles; even the tibial spine, tibial tubercle avulsion fracture, and femoral condyle fracture. Severe medial dislocation can cause stretch injuries to the common peroneal nerve. Severe post-dislocation can cause throbbing, venous rupture, embolism, compression, causing limb necrosis and ischemic contracture.

Basic Information

English name

dislocation of knee joint

Visiting department

orthopedics

Common causes

Strong direct violence hits the upper end of the tibia or indirect violence causes rotation or hyperextension of the knee joint

Common symptoms

Swelling of the knee joint, hemorrhage, pain, loss of function

Causes of knee dislocation

The upper end of the tibia is subjected to strong direct or indirect violence, causing injuries to the knee when it is rotated and overextended.

Clinical manifestations of knee dislocation

According to the degree of dislocation and whether there is a fracture, knee dislocations are divided into the following three categories.

1. Knee joint (full) dislocation

According to the relative position of the tibial condyle and the distal femur during dislocation: anterior dislocation of the knee joint; posterior dislocation of the knee joint; lateral dislocation of the knee joint; medial dislocation of the knee joint; rotational dislocation of the knee joint.

The frequency of joint displacement in the dislocation of the knee joint is generally arranged in the following order: anterior dislocation, posterior dislocation, lateral dislocation, rotational dislocation and medial dislocation. The incidence of anterior dislocation of the knee joint is twice as high as that of posterior dislocation, and about 1/8 of the cases of medial dislocation are anterior dislocation.

2. Knee fracture and dislocation

Usually during the formation of the dislocation, the impact of the femoral condyle on the tibial condyle can cause the fracture of the tibial condyle and cause the displacement of the fracture with the continued external force; of course, the muscle contraction at the attachment also plays an important role. Clinically, avulsion of the bone mass at the attachment point of the ligament can also be regarded as joint dislocation with fracture.

3. Subluxation of the knee joint

The tibia is usually moved forward, backward, or rotated due to the fracture of the corresponding ligament structure of the knee joint. Some scholars do not advocate the classification of subluxation as a dislocation of the knee joint and suggest that it be regarded as a type of knee instability.

After the knee joint is injured, the pain is severe, and the calf may be displaced or deformed forward, backward, medial, lateral, and lose its normal connection. The local tenderness is obvious, there is a sense of vacancy under the skin, and there is a large congestion spot. The front and back drawer test, varus stress test, and hyperextension stress test are all positive. Pay attention to vascular injury or nerve injury. Carefully check the dorsal and posterior tibia. Arterial pulsation and feeling in the distal limbs.

Knee dislocation examination

Imaging examination: Standard positive and lateral X-ray films are helpful for diagnosis and differential diagnosis. If you need to further clarify the ligament damage, you can use MRI examination; CT scan can help determine the fracture situation.

Diagnosis of knee dislocation

1. There are many typical trauma histories, which should be inquired in detail to determine and estimate the injury and injury of the ligament.

2. The clinical manifestations are mainly swelling and pain of the knee joint, and if the deformity caused by dislocation is easier to diagnose. Should pay attention to whether there is neurovascular injury. Local anesthesia compression test of the knee joint under and under the anterior and posterior drawer tests are helpful for clear diagnosis, classification and treatment choice.

Knee Dislocation Treatment

After dislocation of the knee joint, closed reduction can often be used to obtain satisfactory rehabilitation. Hematomas in the joints should be aspirated by aseptic manipulation. Then, thigh plaster is used to fix the knee joint flexion by 15 ° -20 °. This is a temporary good treatment because it can prevent the knee joint from being damaged in other ways. Thigh plaster is temporarily fixed for 5 to 7 days. During this time, a thoughtful and appropriate surgical solution for ligament repair can be carefully selected. If the knee joint is unstable after manual reduction, especially the knee joint is dislocated posterolaterally, if the knee joint shows instability after rehabilitation, other tissues may be embedded in the joint.