Patella Fractures Overview

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A patella fracture is an injury to the kneecap. The kneecap is one of three bones that make up the knee joint. The patella is coated with cartilage on its undersurface and is important in providing the strength of extension (straightening) of the knee joint.

Common Symptoms of Patella Fracture
Verywell / Gary Ferster

Patella Fracture Symptoms

Patella fractures can cause severe pain and difficulty walking. Some of the more common symptoms of this injury include the following.

  • Pain: Patella fractures are generally quite uncomfortable. Keeping the knee straight can help significantly with discomfort, and bending the joint is typically very painful.
  • Swelling: Swelling and bruising around the front of the knee is typical of a patella fracture. As days go by, it is not uncommon for the swelling to extend down the leg, into the calf, and even into the foot.
  • Inability to lift leg: The most common test to diagnose this injury is called a straight leg raise test. This test finding may be present with other injuries but can help determine when treatment is necessary.
  • A palpable defect in the kneecap: Depending on the type of fracture, the damage to the kneecap can sometimes be felt through the skin. The ability to feel the patella fracture is easiest soon after the injury, before swelling has become more significant.

Causes

A patella fracture most often occurs from a fall directly onto the kneecap. When the fracture occurs due to this type of direct trauma, there is often damage to the overlying skin, and because of the limited amount of soft tissue, this can sometimes become an open fracture.

Patella fractures can also occur when the quadriceps muscle is contracting but the knee joint is straightening (a so-called "eccentric contraction"). When the muscle pulls forcefully in this manner, the patella can fracture.

There are certain situations when the kneecap may fracture even with minor injuries. Sometimes these injuries are pathologic fractures—bone fractures that occur as a result of weak bone. Pathologic fractures can be caused by osteoporosis (thin bone), bone infection, or tumors.

Treatment

Patella fractures should be seen in the emergency room. X-rays will determine the type of fracture and the amount of displacement (separation) of the fracture. One of the critical factors in determining treatment is a thorough examination.

Specifically, doctors will check if the patient can perform a straight leg raise. A straight leg raise test is done by having the patient lie flat on a bed. With the leg straight, the patient should then raise his or her foot off the bed and hold it in the air.

This tests the function of the quadriceps muscle and its attachment to the shin bone (tibia). A disruption of the quadriceps tendon, patella, or patellar tendon can lead to the inability to perform a straight leg raise. If a straight leg raise can be done, then non-operative treatment may be possible in the setting of a patella fracture.

One of the common symptoms of a patella fracture is knee swelling. The swelling is caused by bleeding from the fractured bone ends into the knee joint. Patients with a large amount of blood in the knee may benefit from draining the blood for pain relief. Immobilizing the knee with a knee brace will also help minimize discomfort.

Patella Fracture Surgery

Patients with nondisplaced (not separated) or minimally displaced fractures who can perform a straight leg raise (as described above) can usually be treated without surgery. A long leg cast or a knee immobilizer will be used for the treatment of these types of patellar fractures.

When surgery is necessary, an incision is made over the front of the knee joint. The fractured ends of the bone are realigned and held in place with some combination of pins, screws, and wires. In some cases, a portion of the patella can simply be removed, but this is usually done for smaller fracture fragments.

Rehab After Surgery

Following surgery, you will need to keep your knee in a straight position to allow for initial healing. You will be given a hinged brace, cast, or splint to wear immediately after surgery that will help with immobilization. Exactly when the knee can begin moving depends on your surgeon's protocol, which is specific to your surgery. Gentle motion can usually begin in the first days to weeks following surgery.

In some cases, early motion of the knee may help to achieve the best results after surgery, but check with your doctor for what is best and safest for your type of injury.

The most common complication of patella fracture surgery is stiffness of the knee. Another complication is that the metal implants can become painful over time—especially when kneeling.

It is not uncommon for a second procedure to be needed to remove the metal implants. This procedure is usually done at least a year after the initial surgery.

Other possible complications include:

  • Infection
  • Non-healing fractures
  • Failure of the fixation to hold the fragments in place
  • Kneecap pain (chondromalacia)
  • Knee arthritis

One of the important aspects of surgery is to realign the bones and cartilage surface of the kneecap to minimize the development of arthritis of the knee joint. Because of damage to the knee joint cartilage when a fracture occurs, there is a higher chance of the development of arthritis of the joint.

If kneecap arthritis becomes severe, some people may ultimately need a knee replacement or a partial knee replacement of the kneecap.

Frequently Asked Questions

How do you sleep with a broken patella?

Since you’ll be wearing a hinged brace, cast, or splint to keep your knee immobile, sleeping on your back is likely to be most comfortable while recovering from patella
surgery. Icing the knee a half-hour to an hour before bed, and taking any
painkillers you’ve been prescribed, such as NSAIDs, at the same time, can help you get to sleep. You may also want to use pillows underneath the knee to keep it slightly elevated, as well as on either side of your body to ensure you don’t roll over and inadvertently damage or cause pain in your knee during sleep. When you’re cleared by your surgeon to go without a brace or other supportive technology, the same guidelines will still apply until your knee is fully on the way to recovery.

What is the average healing time of a broken patella?

It can take three to six months, on average, to return to prior activity levels after treatment for a patellar fracture. Your recovery time will depend on your physical therapy goals, whether you had surgery or nonsurgical treatment, and the seriousness of your injury.

How do you exercise with a broken patella?

Exercise with a broken patella will be difficult to impossible. After your patellar fracture repair, exercise options will vary depending on your stage of recovery. Whether you’ve had surgical or nonsurgical treatment—both of which involve a period of knee immobilization—you’ll initially be limited to non-weight-bearing exercise that does not stress your knee. As you heal, you’ll begin weight-bearing, knee-extension, and quadriceps-strengthening exercises in physical therapy, which is an essential part of the recovery process. Your therapist can help you find ways to stay active without impeding your recovery. In later stages of recovery, swimming and exercising in water can be great options as you regain strength and mobility in your knee.

Can you still walk with a fractured patella?

The patella connects the quadriceps muscle of the thigh to the bones of the lower leg, and it is essential to walking. Since you will likely not be able to place any weight on a knee with a fractured patella, it will be difficult, if not impossible, to walk until it is repaired.

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  1. American Academy of Orthopaedic Surgeon. OrthoInfo. Patellar (kneecap) fractures. Updated January 2017.

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