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Knee Dislocation

What Is a Knee Dislocation?

  • A knee dislocation occurs when the bones that form the knee are out of place. A knee dislocation, more specifically, is when the bones of the leg (the tibia and fibula) are moved in relation to the bone in the thigh (femur).
  • The bones of the knee are held together by strong bands of tissue called ligaments. Each ligament is responsible for stabilizing the knee in a certain position.
  • For a knee dislocation to occur, these ligaments must tear. A partial dislocation is referred to as a subluxation. In some injuries, the kneecap (patella) and its ligaments are also disrupted.
  • Inappropriate or delayed treatment of a knee dislocation may result in loss of the leg.
Picture of knee dislocations plus ligament and artery damages.
Picture of knee dislocations plus ligament and artery damages. SOURCE: Medscape

What Causes a Knee Dislocation?

Knee dislocations are rare. They usually happen only after major trauma, including falls, car crashes, and other high-speed injuries.

  • If the knee is dislocated, it will look deformed. The usual straight line of the leg will be crooked or angulated.
  • Sometimes, knee dislocations relocate (go back into place) on their own. In this case, the knee will be very swollen and painful. Even if the knee relocates, usually significant damage (tearing) of ligaments has occurred.
Medically Reviewed by a Doctor on 9/11/2017

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Patient Comments & Reviews

The eMedicineHealth doctors ask about Knee Dislocation:

Knee Dislocation - Follow-up

Tell us about any complications as a result of your knee dislocation and subsequent surgery or other treatment.

Knee Dislocation - Symptoms

What symptoms did you experience with your knee dislocation?

A dislocated knee is a rare injury that causes severe pain and deformity.

Causes of Knee Pain

Dislocated Knee

Knee dislocation

  • Description: Dislocation of the knee is a true limb-threatening emergency. This is also a rare injury. Dislocation of the knee is caused by a particularly powerful blow to the knee. The lower leg becomes completely displaced with relation to the upper leg. This displacement stretches and frequently tears not only the ligaments of the knee but also arteries and nerves. Untreated arterial injuries leave the lower leg without a blood supply. In this case, amputation may be required. Nerve injuries, on the other hand, may leave the lower leg viable but without strength or sensation.
  • This injury can be due to a motor vehicle accident where the patient's knee or leg hits the dashboard.
  • Symptoms and signs: Knee dislocations are severely painful and produce an obvious deformity of the knee. Many dislocations are reduced or put back into anatomic alignment spontaneously. As this occurs, many will report feeling a dull clunk.

Read What Your Physician is Reading on Medscape

Dislocations, Knee »

Knee dislocation is a relatively rare injury but an important one to recognize because coexistent vascular injury, if missed, often leads to limb loss.

Read More on Medscape Reference »


Medical Dictionary