What is a dislocation of the tibiofemoral joint?

The tibiofemoral joint is commonly called the knee joint. A tibiofemoral dislocation is the formal name for a dislocated knee. It’s a fairly rare injury, but a serious one.

A tibiofemoral dislocation can cause damage to the structures that support your knee. This may result in joint instability, which can be a long-term problem. As well, damaged tibial nerves and tendons within your knee can cause long-term pain.

It’s also possible that the popliteal artery, one of the arteries of the knee, could be affected. If left untreated, the artery may become blocked. This serious complication can keep other tissues from getting blood, which could lead to amputation. Popliteal artery injuries occur in about 20 to 40 percent of all knee dislocations and in 65 percent of high-energy traumas.

The most obvious symptom of a tibiofemoral dislocation will be severe pain in your knee. Other symptoms may include:

  • swelling of your knee
  • knee deformities, such as your knee looking like it’s been knocked out of place
  • bruising
  • limited ability to bend your knee
  • a knee that can’t bear weight or is unstable

Try not to bend your knee if you suspect it’s dislocated.

A swollen popliteal fossa — the shallow indentation at the back of the knee — may indicate a popliteal arterial injury.

Tibiofemoral dislocations are caused by a direct, hard impact to the knee. This commonly happens in car accidents. Other trauma can happen during an injury sustained during contact sports or a hard fall.

The two most common types of tibiofemoral dislocations are posterior and anterior dislocations.

A posterior dislocation occurs when something strikes the front of the knee and pushes the tibia, or shinbone, back. This can happen during falls or in some car accidents.

Hyperextension of the knee, which is extension beyond its usual range, causes an anterior dislocation. About 30 degrees of hyperextension can lead to this type of dislocation.

Less common is what’s called a rotary dislocation. It can occur when your body rotates in a direction that’s different from your standing foot.

See your doctor immediately if you suspect a tibiofemoral dislocation. It can’t be treated without medical intervention.

During the diagnosis process, your doctor will confirm the dislocation and its severity. This will determine treatment, as well as check for the other complications a kneecap dislocation could cause.

Your doctor will first do a physical exam, where they look at your knee for signs of deformity, bruising, swelling, and instability. They may move the knee to look for limitations in mobility. They’ll ask about your medical history and how the injury was sustained.

Your doctor will also order an X-ray or an MRI scan. X-rays will give your doctor a clearer look at the joint. An MRI scan will help them view ligaments, tendons, or cartilage that may have also been damaged.

Your doctor will use these tests to make sure that you have a tibiofemoral dislocation. They’ll look for signs of fractures of bones in the area — your tibia, patella, and femur. The imaging tests will be able to offer a differential diagnosis. That is, it allows your doctor to rule out other conditions that may cause the same symptoms.

Your doctor will order other tests to look for additional complications. This may include a doppler ultrasound to look for impaired blood flow.

Unlike other dislocations, most tibiofemoral dislocations require surgery for complete treatment. This is because there’s a higher incidence of damage that needs to be repaired, often occurring in these structures in the area of the injury:

  • ligaments
  • tendons
  • arteries
  • blood vessels

Surgery typically doesn’t happen immediately. Your surgeon may wait up to three weeks after the injury. This allows the swelling time to go down. They may recommend taking nonsteroidal anti-inflammatory drugs, applying ice, and keeping the leg elevated first.

If your knee is filled with fluid, your doctor may order joint aspiration. In this procedure, your doctor uses a syringe to remove excess fluid from the joint.

After surgery, your doctor will likely recommend rehabilitation therapy. A physical therapist will teach you stretches and exercises to improve the mobility, strength, and function of your knee. You may also be required to wear knee braces during physical activity to keep your knee in place.

Both before and immediately after surgery, your doctor will recommend you use crutches and reduce pressure on the affected leg. During the treatment and recovery process, your doctor may also prescribe pain medications.

With reconstructive surgery and physical therapy, many people make a full or near-full recovery. Some people may experience chronic pain or arthritis later as a result of the injury.

While treatment is available for a tibiofemoral dislocation, it’s preferable to avoid such an injury altogether. The best method of prevention is to always wear the proper protective gear, like knee pads, when engaging in high-contact sports. You should also wear your seat belt while riding in a car.