Knee Dislocation Symptoms, Causes, and Treatment

A knee dislocation is an uncommon but extremely serious injury in which the thigh bone (femur) and shin bone (tibia) lose contact with each other. A knee dislocation is different from a patellar dislocation in which only the kneecap is detached from its groove at the end of the femur.

Soccer player in pain and holding his knee
Terje Rakke / Getty Images


The most common symptoms of knee dislocation are the visible swelling and deformity of the knee joint. The lower extremity will often look shortened and misaligned, and any movement of the joint will cause extreme pain.

About half of all knee dislocations are repositioned prior to arrival at the hospital. This is problematic as it may result in even greater injury and an increased risk of complications, including:

  • Compression or damage of the peroneal nerve that runs along the outer edge of the calf
  • Rupture or obstruction the popliteal artery and vein located at the back of the knee
  • The development of deep venous thrombosis (DVT)

If a vascular obstruction is left untreated for more than eight hours, the chance of amputation is 86 percent compared to 11 percent if treated within eight hours.


Knee dislocations are often the result of a high-impact injury such as an automobile crash, severe fall, and sports injuries.

A knee dislocation should not be confused with a subluxation, a partial dislocation in which the knee "gives out" due to a damaged ligament. A knee dislocation is a far more severe injury in which the misaligned bones must be reset to their proper position. With a subluxation, the bones will "slip back" into place.

A knee dislocation can also occur from an unusual twist or misstep. With that being said, the same concerns exist whatever the cause.

Rapid response is required without exception to prevent serious and even devastating damage to the knee and lower extremity.


If a knee dislocation has occurred, the joint will usually be repositioned upon arrival at the emergency room (a procedure referred to as "reducing the joint"). Once reduced, the healthcare provider will carefully evaluate the surrounding tissues, nerves, and blood vessels.

Because of the extreme nature of the injury, the surrounding ligaments will invariably be damaged. In almost every case, both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) will be torn or ruptured. In addition, the collateral ligaments, cartilage, and meniscus (the membrane between the bone and cartilage) may also experience damage.

X-rays or computed tomography (CT) scan would be used to evaluate the nature and position of the misaligned bones. Magnetic resonance imaging (MRI)—a technique far better at visualizing soft tissues—may be ordered to characterize the damage done to ligaments, cartilage, and tendons prior to surgery.

To evaluate vascular obstruction, your healthcare provider 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.

Nerve damage, experienced in about 25 percent of knee dislocations, can be initially assessed with a physical exam to check for abnormal sensations (numbness, radiating pain) or the impairment of foot movement either internally (inversion) or externally (eversion).


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 almost all cases, surgery will be required, often to repair multiple ligament injuries, meniscus tears, and cartilage damage. Arterial injuries may require the direct repair of the affected vessel (with a synthetic patch, graft, or transplanted vein), an arterial bypass, or an embolectomy to remove a clot.

The surgery may be performed as an open operation (using a scalpel and large incision) or arthroscopically (using a scope, tube-like instrument, and keyhole incisions).

Nerve damage may require the expertise of a neurologic surgeon. It is not uncommon, in fact, for a knee dislocation to require multiple surgeries. Efforts may also be made to restore lost cartilage with such advanced techniques as cartilage implantation or cartilage transfer.

Complications of knee dislocation surgery, include chronic stiffness , instability, and postoperative nerve pain. Joint malformation and infection are also possible.

Adhering to an extensive physical therapy and rehabilitation program is considered essential to restoring near-normal to normal knee function.

A Word From Verywell

Knee dislocation, while serious, is extremely rare, representing less than 0.5 percent of all joint dislocations. While most people with knee dislocation will seek emergency care due to the extreme nature of the injury, any efforts to self-treat should be avoided without exception.

Delayed treatment can lead to tissue atrophy, resulting in the shortening of severed ligaments. This not only makes repair difficult, but it can also end up severely restricting the range of motion of your knee.

Furthermore, waiting until morning to "see if things improve" can lead to extensive tissue death (necrosis) due to the restriction of blood flow. By the stage, the damage may be so severe as to require an above-the-knee amputation.

To this end, any knee injury should be seen without delay if there is severe pain, swelling, redness, bleeding, or a restriction of movement.

Frequently Asked Questions

  • Is a knee dislocation the same as a patellar subluxation or dislocation?

    No. A dislocated knee occurs when the femur and tibia no longer connect at the knee joint. A patellar subluxation is when the knee cap slides slightly out of its normal place. This is considered a partial dislocation of the knee cap. A patellar dislocation is when the knee cap slides completely out of place. 

  • How common is a dislocated knee?

    A dislocated knee is a relatively rare injury. Less than 1% of knee injuries are dislocations and less than 0.5% of all dislocated joints occur in the knee.

  • What can cause a dislocated knee?

    A knee dislocation is a serious injury that is often the result of a high-impact blow, such as a car accident, sports injury, or severe fall.

  • Can you walk on a dislocated knee?

    No, a dislocated knee is an extremely painful injury. If your knee is dislocated, you will not be able to put weight on the joint or be able to walk.

  • How long does it take a dislocated knee to heal?

    A dislocated knee is a serious injury that can take up to a year to heal. In most cases, surgery is needed to repair the knee and surrounding ligaments and cartilage. After surgery, physical therapy is needed to rehabilitate the knee and work to restore normal knee functioning. 

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Bonnevialle P, Dubrana F, Galau B, et al. Common peroneal nerve palsy complicating knee dislocation and bicruciate ligaments tears. Orthop Traumatol Surg Res. 2010;96(1):64-9. doi:10.1016/j.rcot.2009.12.004

  2. Medina O, Arom GA, Yeranosian MG, Petrigliano FA, Mcallister DR. Vascular and nerve injury after knee dislocation: a systematic review. Clin Orthop Relat Res. 2014;472(9):2621-9. doi:10.1007/s11999-014-3511-3

  3. Hanley J, Westermann R, Cook S, et al. Factors Associated with Knee Stiffness following Surgical Management of Multiligament Knee Injuries. J Knee Surg. 2017;30(6):549-554. doi:10.1055/s-0036-1593624

  4. Pardiwala DN, Rao NN, Anand K, Raut A. Knee Dislocations in Sports Injuries. Indian J Orthop. 2017;51(5):552-562. doi:10.4103/ortho.IJOrtho_229_17

Additional Reading

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.