Knee Dislocations


What is a knee dislocation?

A knee dislocation is an uncommon but extremely serious injury in which the femur (thigh bone) and tibia (shin bone) lose contact with each other. A dislocated knee is different than a dislocated kneecap, which occurs when the kneecap slips out of place. Knee dislocation can damage several important ligaments, blood vessels, and nerves, and the entire health and integrity of the joint and leg may be at risk. 

A knee dislocation typically happens after a traumatic fall, high-speed motor vehicle accident, or a severe sports-related injury. Sometimes, a dislocated knee will go back into place on its own or with assistance, but this is a very painful and complex process. Patients will often need to be put under anesthesia or given a pain block in order to reduce the dislocated knee.


What are the symptoms of a dislocated knee?

  • Hearing a “popping” sound at the time of injury
  • Visible deformity and swelling of the knee joint
  • Severe pain with any movement of the joint
  • Numbness below the knee
  • Absent or diminished pulses in some cases


What happens during a knee dislocation? 

Most knee dislocations involve injuries to three or four of the major knee ligaments, including the ACL, PCL, MCL, and posterolateral corner  (PLC). In addition, there may also be injuries to the medial or lateral meniscus, the articular cartilage, fractures, or patellar tendon injury. It is very important to carefully assess the injury.

It is also extremely important to examine vascular and nerve function at the time of injury. To evaluate vascular obstruction, your doctor may order a CT angiogram in which an iodine-based dye is injected into a vein to map the blood flow. A Doppler ultrasound can also be used to assess arterial blood flow.


What is the treatment for a dislocated knee? 

Reduction, or repositioning of the injured joint, is the first and most crucial step in treating a knee dislocation in order to in order to reduce any further damage to blood vessels, nerves, or any other internal structures. In almost all cases, surgery will be required – often to repair multiple ligament injuries, meniscus tears, and cartilage damage. In the early stages of treatment, the medical priority is to minimize any damage caused to the blood vessels or nerves. When these issues have been addressed and stabilized, attention can be turned to the structural tissue damage. In general, the results of a dislocated knee are best if they are treated as soon as possible.