Knee dislocations are uncommon orthopedic injuries and occur when the bones that form the knee are out of place. A knee dislocation involves damage to multiple ligaments, resulting in severe instability. Knee dislocations also often occur with injuries to the meniscus and the nerves and vessels that surround the knee. A knee dislocation occurs when the femur (thigh bone) and tibia (shin bone) lose contact with each other. In some injuries, the knee cap (patella) also is disrupted. Most knee dislocations are the result of high-energy traumatic injury, such as a motor vehicle accident or severe fall or impact.
What happens when the knee dislocates?
When the knee dislocates, there is serious damage to the soft-tissues that surround and stabilize the joint. Often the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL) are torn with this type of injury. In addition, the collateral ligaments and cartilage can be damaged.
What are the symptoms of a knee dislocation?
There will be a significant amount of pain in the knee area with a dislocation. Many times, there is loss of feeling below the knee. Swelling and bruising are also common symptoms.
How is a knee dislocation diagnosed?
If the orthopedic specialist suspects a knee dislocation, he will order x-rays of the joint. Once a dislocation is identified, the joint will have to be repositioned (called reduction). To reduce the joint the doctor gently repositions the bones into normal alignment. The doctor will then evaluate the nerves and blood vessels of the area and may order an angiogram, MRI, or CT scan to assess the damage.
Examination of Pulses – Because injury to the arteries is common with knee dislocation, the doctor will evaluate the pulses in your foot.
Examination of Arteries – An arteriogram is an x-ray of an artery. This is done to evaluate artery injuries. Some facilities also use ultrasound or Doppler machines to assess the blood flow in your leg.
Examination of Nerves – Because nerves run through the knee joint, they could be damaged. The doctor will evaluate your nerves by checking for your ability to turn your foot inside (inversion), and checking for your ability to turn your foot outside (eversion). Your doctor will also test the sensation below the knee.
What is the treatmentof a knee dislocation?
If the blood vessels and nerves are stable, the orthopedic specialist will focus on correcting the damage to the ligaments, cartilage, and soft tissues of the knee. It is usually necessary to surgically reconstruct these structures. Once the doctor has put the structures of the lower leg back into position, he will then immobilize the leg to prevent further injury and allow the joint to heal. This is done with a splint or cast.
What can I do to help my knee heal?
The knee will be immobilized with bracing or a cast for a determined period of time. During this time, you will be given crutches and given instructions as to how much weight you can put on the healing joint. Elevate your leg as often as you can.
What is the prognosis of a knee dislocation?
While a knee dislocation is a serious injury, recovery is possible. Most people do not regain full capacity of the knee, however. Your orthopedic specialist may suggest some type of supportive device or wrap to protect your knee and reduce stress on it. Some knee injuries are so severe that the doctor advises against sporting activities. With appropriate treatment and surgery, the prognosis is best.