Knee Dislocation

Overview

Knee dislocation occurs when the leg bones, which meet at the knee joint, are forced out of alignment. This misalignment often results from a high-impact trauma to the knee joint, such as from a fall, car accident or sports injury.

Symptoms of a dislocated knee include hearing a “pop” at the time of the injury, and experiencing extreme pain, bruising and swelling in the affected knee.

A dislocated knee is a serious injury that requires immediate medical attention. Seek emergency medical care if you have extreme pain in the knee following an injury, if there is a noticeable deformity, or if your foot is numb. 

Knee dislocation causes

Knee dislocations occur when the leg bones become misaligned at the knee joint.

Common causes of dislocated knees include:

• Falling
• Contact sports
• Car accidents

Knee dislocation risk factors

You may be at an increased risk of dislocating a knee if you:

• Have had a previous knee dislocation
• Experienced direct trauma to the knee
• Have weak or imbalanced muscles in the leg
• Are a woman
• Are particularly tall

Knee dislocation symptoms

Signs and symptoms of a dislocated knee include:

• Hearing a “pop” when the injury occurs
• Severe pain
• Swelling and bruising in the affected knee
• An inability to move the knee

Knee dislocation complications

A dislocated knee can lead to blood vessel and nerve damage.

If left untreated, a dislocated knee can lead to:

• Limited range of motion in the knee
• Tissue atrophy and tissue death, which can ultimately require an amputation above the knee, in severe cases

Knee dislocation diagnosis

When evaluating a dislocated knee, your doctor will assess the extent of the damage by examining the knee and its surrounding area, including the:

• Nerves
• Tissues
• Blood vessels

Your doctor will also order one or several of the following imagine procedures, to further assess the nature of the injury:

• X-ray to visualize bone damage
• CT scan to visualize bone damage in detail
• MRI scan to visualize soft tissue damage

Knee dislocation treatment

When receiving treatment for a dislocated knee, the first line of treatment is to minimize and prevent any further damage to the nerves and blood vessels surrounding the knee.

Once a doctor has taken measures to prevent further damage, the next line of treatment is to address the existing damage. Most dislocated knees will require surgery, to repair damaged:

• Ligaments
• Meniscus
• Cartilage
• Arteries
• Nerves

The type and extent of the surgery will vary depending upon the nature of the injury.

When to seek care

Seek emergency medical care if you think you may have a dislocated knee.

Next Steps

After receiving treatment for a dislocated joint, your doctor will provide a recovery timeline and rehabilitation program. This program will include physical therapy exercises to help restore a full range of motion and full strength in the knee.