Knee Dislocation

ExitCare ImageKnee dislocation is the displacement of the bones that make up the knee. These bones are the thigh bone (femur), the lower leg bones (tibia and fibula), and the kneecap (patella). Strong, fibrous tissues that connect bones to each other (ligaments) support the knee and keep the bones together. Typically, at least 2 of the 4 major ligaments of the knee are torn before a dislocation of the knee can occur.

CAUSES

Knee dislocation is the result of a force that causes an excessive extension of the knee joint (hyperextension) that is greater than the ligaments can withstand. This is often caused by a direct hit (trauma). In rare cases, it is caused by a noncontact injury, such as stepping in a hole in the ground and twisting your knee. Typically, it is associated with vehicular trauma or contact sports.

RISK FACTORS

Knee dislocations are not common. However, some people are at greater risk of these injuries, including:

  • People who participate in sports that involve pivoting, jumping, cutting, or changing direction (basketball, gymnastics, soccer, volleyball).

  • People who participate in contact sports (football, rugby, lacrosse).

  • People with poor leg strength and flexibility.

  • People born with greater looseness in their joints.

SYMPTOMS

  • One or more "pops" heard or felt at the time of injury.

  • Knee swelling within 1 to 2 hours after the injury.

  • Deformity of your knee.

  • Loss of motion in your knee.

  • A sensation that your knee is "giving way" or "buckling."

  • Numbness, weakness, discoloration, or coldness of your foot and ankle. This may occur if you also have nerve or blood vessel injury.

DIAGNOSIS

Knee dislocation is diagnosed using results of a physical exam. Usually, an X-ray exam and an MRI scan (magnetic resonance imaging) are done to see any cartilage or ligament injuries.

TREATMENT

Knee dislocations require emergency realignment of the bones (reduction). Once your knee is realigned, it is held in position by a splint or pins drilled into the bones of your upper and lower legs and connected to metal rods outside the leg to hold your knee in position (external fixator). Often, an exam such as an ultrasound exam or angiography will be done to be sure that a major blood vessel has not been damaged. Most often, surgery to repair damaged blood vessels is done when your torn ligaments are repaired.

HOME CARE INSTRUCTIONS

The following measures can help to reduce pain and hasten the healing process:

  • Rest your injured joint. Do not move it. Avoid activities similar to the one that caused your injury.

  • Apply ice to your injured joint for 1 to 2 days after your reduction or as directed by your caregiver. Applying ice helps to reduce inflammation and pain.

  • Put ice in a plastic bag.

  • Place a towel between your skin and the bag.

  • Leave the ice on for 15 to 20 minutes at a time, every couple of hours while you are awake.

  • Elevate your leg above your heart as instructed by your caregiver.

  • Move your ankle and toes as instructed by your caregiver.

  • Take over-the-counter or prescription medicine for pain as directed by your caregiver.

SEEK IMMEDIATE MEDICAL CARE IF:

  • Your splint or external fixator becomes damaged.

  • Your pain becomes worse rather than better.

  • You lose feeling in your foot, or you cannot move your ankle and toes.

MAKE SURE YOU:

  • Understand these instructions.

  • Will watch your condition.

  • Will get help right away if you are not doing well or get worse.