A knee dislocation occurs when the bones that form your knee are out of place.
The bones of your calf (the tibia and fibula) get moved in relation to the bone of your thigh (femur). The bones of your knee are held together by strong bands of tissue, called ligaments. For a knee dislocation to happen, these bands have to tear.
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Knee dislocations are rare. They usually happen only after major trauma, which could result from falls, car crashes, and other high-speed injuries.
If the knee is dislocated, it will look deformed. The usual straight line of your leg will be crooked.
Sometimes, knee dislocations relocate (go back into place) on their own. In this case, the knee will be very swollen and painful.
Knee Dislocation Symptoms
With a knee dislocation, You'll feel a lot of pain in the knee. Sometimes, there will be no feeling below the knee. If the knee relocates, it will become swollen. You may not be able to feel a pulse (your heartbeat) in your foot.
When to Seek Medical Care
If you think you dislocated your knee, go to the nearest hospital's emergency department for medical care. Seek medical help for any of the following:
Extreme pain or swelling after a serious injury (such as a car crash)
An obvious deformity of your knee
Numbness in your foot
No pulse in your foot
Exams and Tests
Depending on how your knee looks, you can expect the doctor to check the injury in the following ways:
X-rays: X-rays will be taken to make sure there are no breaks in the bone.
Examination of pulses: Injury to the arteries in the knee is common with this injury. The doctor will make sure there are pulses in your foot (the place the artery in your knee runs to).
An arteriogram (x-ray of the artery): This x-ray may need to be done to make sure there are no injuries to the artery. Some medical centers may also use special ultrasound or Doppler (sound wave) machines to assess the blood flow in your arteries.
Examination of nerves: Nerves also run through your knee, so it is possible that they may have been damaged. Checking to see whether you feel touch and can move certain muscle groups are the main ways nerves are tested. Specifically, the doctor will check your ability to move your foot up and down and to turn it in and out. Any feeling of numbness is a concern for nerve injury.