Patella Fracture

A patella fracture is a break in your kneecap, the bone that covers your knee joint. It’s usually caused by a traumatic injury, such as a fall or a blow to your kneecap. A patella fracture can be simple or complex. Some fractures require surgery to repair. Recovery can be long, and side effects are common.


What is a patella fracture?

A patella fracture is a break in your kneecap — the small, flat bone that covers and protects your knee joint like a shield. It’s usually caused by direct injury like a fall on your knee, a blow to your knee or a collision, lik with the dashboard in a car accident. A patella fracture is a serious injury, which can impact your ability to bend or straighten your knee. Some patella fractures are simple, but this small bone is also capable of breaking into many pieces.


Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

What happens when the patella fractures or breaks?

A patella fracture is usually caused by a direct impact to your knee. Depending on the force applied, it may create a hairline crack, break into two pieces or it may break into many small pieces. Patella fractures can cause the extensor mechanism of your knee to no longer function properly. The quadriceps and patellar tendon attach to your patella, which normally allows you to flex and extend your knee. The patella is covered with cartilage, which provides a cushion for your knee joint. The cartilage can be injured with this type of fracture, which can lead to post-traumatic arthritis.

What are the different types of patella fracture?

  • Stable patella fracture: In a stable fracture, also called a “nondisplaced” fracture, the broken pieces of your bone remain essentially in the right place. They may still be connected to each other, or they may be separated by a millimeter or two. This type of fracture usually heals well without surgery. If your healthcare provider determines that you don’t need surgery, they will immobilize your knee in extension with either a knee immobilizer, a hinged knee brace or a cast. You’ll be allowed to bear as much weight as you’re comfortable.
  • Displaced patella fracture: In a displaced fracture, your broken bone pieces have been displaced from their correct position and don’t line up with each other as they should. These pieces often need to be fixed with surgery in order to heal and allow your knee to function properly.
  • Transverse patella fracture: A transverse fracture is a fracture where your patella breaks into two pieces. These breaks are often fixed with surgery. Various surgical techniques can be used to fix these injuries. Your surgeon will decide which is best for you.
  • Comminuted patella fracture: In a comminuted fracture, your bone has shattered into three or more pieces. A comminuted fracture can be stable or unstable. When a comminuted fracture is unstable, some of your bone pieces may be too small to reconnect and may need to be removed in surgery.
  • Open patella fracture: In an open fracture, your skin over your bone has been broken. Either your bone pieces themselves have penetrated through your skin, or something has penetrated your knee from the outside. An open fracture requires prompt treatment with antibiotics and surgery to thoroughly clean the wound. Open fractures tend to have a higher rate of infection, so it’s important to seek urgent medical treatment. Your surgeon will decide which surgical treatment will best fix your fracture.


How common is a patella fracture?

Patella fractures are not common. They represent only 1% of all fractures. They are twice as likely to occur in men as in women.

Symptoms and Causes

What causes the patella to fracture?

A patella fracture is usually caused by a direct blow to your kneecap, such as in a fall, from a sports injury or from a car accident. More rarely, it can also be caused by a sudden muscle contraction in your knee.


What are the signs and symptoms of a fractured patella?

  • Pain.
  • Swelling.
  • Bruising.
  • Palpable patellar defect (a change in your kneecap that you can feel through your skin).
  • Inability to straighten your leg.
  • Inability to raise your extended leg.
  • Inability to walk.

Can you still walk on a fractured patella?

A patella fracture will often leave you unable to walk. If you think you can, but it is still painful, it’s probably best not to try until you have been diagnosed. Once you have been diagnosed and treated for a patella fracture, you’ll be allowed to bear weight in a knee immobilizer, hinged knee brace or cast locked in full extension. Your orthopaedic surgeon will let you know how much you can bend your knee. At first, you won’t be allowed to flex your knee, but flexion will be allowed slowly, over time. You’ll be allowed to bear as much weight as you feel comfortable.

Diagnosis and Tests

How is a patella fracture diagnosed?

Your healthcare provider will ask about your symptoms and what happened at the time of the injury. Then they’ll examine your knee. They might have you try to extend your leg. If you can’t, that will likely necessitate surgical intervention. They may also be able to feel the edges of the fractured bone pieces through your skin.

They will check for open wounds and for signs of hemarthrosis — blood from the broken bone pieces collecting in your joint, which can cause excessive swelling. They will take X-rays or even a CT scan to define the fracture.

Management and Treatment

How is a patella fracture treated?

  • Examination: The treatment for a patella fracture depends on the nature of your break. Your healthcare provider will begin by physically examining your knee and checking for signs of hemarthrosis. They may need to treat the hemarthrosis first by draining some of the blood. Then they will take X-rays to determine the type of fracture you have. If it is a stable fracture, your bone can be expected to heal without surgery.
  • Surgery: If your bone pieces are displaced, they will need to be put back together in surgery. Bone pieces that are too far apart from each other have a hard time coming back together on their own because the strong muscles attached to your knee tend to pull the bone pieces apart. Orthopaedic surgeons can use screws, pins, plates or wires to reconnect your bone pieces. If your pieces of bone are too small, your surgeon may remove them. They may also need to reattach your tendon to your bone.
  • Rest: You’ll be sent home with a cast, splint or brace to keep your knee in position and limit movement while it is healing. Your healthcare provider will let you know how much weight you can bear and how much you can bend your knee. Your healthcare provider will recommend over-the-counter pain medication with periodic ice and elevation to keep the swelling down.
  • Rehabilitation: Physical therapy will be very important to restore the mobility of your knee. This injury can cause stiffness and muscle weakness, and you may need to retrain your knee to move as it did prior to your injury. Physical therapy may be ordered, which will focus on strengthening, stretching and range-of-motion exercises.

Outlook / Prognosis

How long does it take to recover from a patella fracture?

The healing process for a patella fracture can vary, depending on the severity of your break and whether you had surgery or not. Most people will be feeling good in about six weeks, and able to return to all of their normal activities within three to six months. Some people report long-term symptoms of pain or stiffness, and some choose to continue wearing a knee brace for support.

What’s the long-term outlook for a fractured patella?

While most fractures are done healing within three to six months, it’s not uncommon for people to report long-term complications. These can include:

  • Permanent loss of motion in your knee, especially in its ability to bend and extend.
  • Chronic knee pain. Doctors aren’t sure why, but it seems to be related to stiffness and muscle weakness.
  • Post-traumatic arthritis. This occurs when the cartilage that cushions your kneecap in the joint has been damaged. Up to 50% of people report some arthritis after about eight years.

Living With

How should I take care of my knee after a patella fracture?

  • Make sure to follow through with physical therapy after your fracture has healed, in order to restore your muscle strength and range-of-motion.
  • Your healthcare provider may recommend trying to avoid stairs, squatting and bending, when possible, to limit stress on your knee and prevent future complications.
  • If you suffer from chronic stiffness or weakness in your joint, you may want to continue wearing a knee brace for support.
  • Non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin or ibuprofen, can help manage pain and inflammation flare-ups.

A note from Cleveland Clinic

Patella fractures are not common, but traumatic injuries do happen. If you’ve fractured your patella, you may have a long recovery ahead. Pain is usually moderate and manageable with over-the-counter medications. Meanwhile, it’s very important to be patient and committed to the healing process. Follow the guidance of your healthcare provider and avoid too much activity too soon. When the time is right, be diligent with your physical therapy exercises. Your healthcare provider will guide you through the process to ensure that you restore as much mobility as possible to your knee.

Medically Reviewed

Last reviewed on 11/12/2021.

Learn more about our editorial process.

Appointments 216.444.2606