Fractured Kneecap

What is a fractured kneecap?

The kneecap (the patella) is a triangular bone at the front of the knee. Several tendons and ligaments connect to the kneecap, including ones attached to the upper leg (femur) and lower leg (tibia) bones.

Though the kneecap is not needed for walking or bending your leg, it makes your muscles more efficient and absorbs much of the stress between the upper and lower portions of the leg. Climbing stairs and squatting can put up to seven times your normal body weight on the kneecap and the joint behind it.

Kneecap fractures account for about 1 percent of all skeletal injuries. The kneecap can fracture in many ways: partially or completely, into a few or into many pieces. Sometimes when the kneecap is fractured, the ligaments or tendons attached to it can be sprained or torn.

What causes a fractured kneecap?

In most cases, a broken kneecap is caused by a direct blow to the front of the knee from a car accident, sports or a fall onto concrete.

Most kneecap fractures occur in people between the ages of 20 and 50.

What are the symptoms of a fractured kneecap?

Symptoms may include:

  • Severe pain in and around the kneecap
  • Swelling
  • Pain when moving the knee in both directions
  • Difficulty extending the leg or doing a straight-leg raise
  • A deformed appearance of the knee due to the fractured pieces
  • Tenderness when pressing on the kneecap

How is a fractured kneecap diagnosed?

A doctor can often diagnose a fractured kneecap by asking you about the details of your accident and examining you. Your doctor will look at your knee, focusing on where it is tender, swollen or misshapen. Your doctor may also ask you to raise your leg or extend your knee, possibly after giving you a local anesthetic to eliminate pain. This helps the doctor see if there are other injuries in and around your knee.

X-rays, taken from several angles, are the best way to learn the extent of a fractured kneecap and to check for other injuries. If other injuries are suspected, a computed tomography or magnetic resonance imaging scan may be done.

How is a fractured kneecap treated?

Two types of surgery may be done to repair a fractured kneecap:

Open reduction-internal fixation (ORIF) surgery: The surgeon opens the skin and puts the broken bones back together with metal wires, pins or screws. Broken pieces of bone too small to be fixed are removed. If the kneecap is so severely fractured that it cannot be repaired, it may be partially or totally removed.

After the bones have been joined, the opening is closed, a sterile dressing is put over the area and the knee is put in a cast or other device so it cannot move while it heals.

Sometimes, especially in patients who are thin, the wires, pins or screws can be irritating. In this case, the devices will be removed after the kneecap has fully healed.

Full or partial patellectomy: This two-hour procedure removes all or part of the kneecap. If your surgeon finds that the break is too severe to repair, they will remove the damaged pieces of bone.

The surgery preserves the quadriceps tendon above the kneecap, the patellar tendon below and other soft tissues around the kneecap. After this surgery, you will be able to extend your knee, but the extension will be weaker.

Once your kneecap has healed, making the muscles around your knee stronger can help avoid further injury. Playing contact sports or doing other activities that put stress on your knee can increase the risk of another injury to the kneecap. You should avoid these activities or use a kneepad to cushion the blow when playing contact sports.

Physical therapy, learning ways to spare your knee stress and strengthening and conditioning your leg muscles on an on-going basis can help prevent more injuries to the knee.

Your best exercise options are low-impact and non-weight-bearing, like stationary bikes and certain weightlifting programs, so that the knees do not have to absorb shock.

Key points

  • Though the kneecap is not needed for walking or bending your leg, it makes your muscles more efficient and absorbs much of the stress between the upper and lower portions of the leg.
  • In most cases, a broken kneecap is caused by a direct blow to the front of the knee from a car accident, sports or a fall onto concrete.
  • Kneecap fractures account for about 1% of all skeletal injuries.
  • Two types of surgery may be done to repair a fractured kneecap.
  • Once your kneecap has healed, making the muscles around your knee stronger can help avoid further injury.
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