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 a direct injury like a fall on your knee, a blow to your knee, or a collision, like 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.

What happens when the patella fractures or breaks?

A patella fracture is usually caused by a direct impact on 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?

• A hairline kneecap fracture is a simple crack in the bone (the patella is still in one piece). Hairline fractures are also known as stress fractures and are rare in the kneecap. They can occur in athletes, such as marathon runners, and may be due to overuse. A stress fracture of the patella may be difficult to see on an X-ray. The main symptom is a pain in the front of the knee that gets worse over time.

• 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 with.
• 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.

What is a hairline fracture?

A hairline fracture, also known as a stress fracture, is a small crack or severe bruise within a bone. This injury is most common in athletes, especially athletes of sports that involve running and jumping. People with osteoporosis can also develop hairline fractures.

Hairline fractures are often caused by overuse or repetitive actions when microscopic damage is done to the bone over time. Not allowing yourself enough time to heal between activities is often a factor in the probability of getting this injury.

The bones of the foot and leg are especially prone to hairline fractures. These bones absorb a lot of stress during running and jumping. Within the foot, the second and third metatarsals are most commonly affected. This is because they’re thin bones and the point of impact when pushing off on your foot in order to run or jump. It’s also common to experience a hairline fracture in your:

• heel
• ankle bones
• navicular, a bone on the top of the midfoot

What are the symptoms of a hairline fracture?

The most common symptom of a hairline fracture is pain. This pain can gradually get worse over time, especially if you don’t stop the weight-bearing activity. Pain is usually worse during activity and lessens during rest. Other symptoms include:

• swelling
• tenderness
• bruising

What causes a hairline fracture?

Most hairline fractures are caused by either overuse or repetitive activity. An increase in either the duration or frequency of activity can result in a hairline fracture. This means that even if you are used to running, suddenly increasing either your distance or the number of times per week you run can cause this injury.

Another similar cause of a hairline fracture is changing the type of exercise you do. For example, if you’re an excellent swimmer, it’s still possible to sustain an injury from suddenly engaging in another intense activity like running, no matter how good of shape you may be in.

Bones adapt to increased forces put on them through various activities, where new bones form to replace old bone. This process is called remodeling. When the breakdown happens more rapidly than new bone can form, you increase your likelihood of a hairline fracture.

Who’s most at risk for developing a hairline fracture?

• Certain sports: Participants in high-impact sports, such as track and field, basketball, tennis, dance, ballet, long-distance runners, and gymnastics, increase their chances of getting a hairline fracture.
• Sex: Women, especially women with absent menstrual periods, are at increased risk of hairline fractures. In fact, female athletes may be at a greater risk because of a condition called the “female athlete triad.” This is where extreme dieting and exercise may result in eating disorders, menstrual dysfunction, and premature osteoporosis. As this develops, so does a female athlete’s chance of injury.
• Foot problems: Problematic footwear can cause injuries. So can high arches, rigid arches, or flat feet.
• Weakened bones: Conditions such as osteoporosis, or medications that affect bone density and strength, can cause hairline fractures even when performing normal, daily activities.
• Previous hairline fractures: Having one hairline fracture increases your chances of having another.
• Lack of nutrients: Lack of vitamin D or calcium can make your bones more susceptible to fracture. People with eating disorders are also at risk for this reason. Additionally, there can be a greater risk of this injury in the winter months when you may not be getting enough vitamin D.
• Improper technique: Blisters, bunions, and tendonitis can affect how you run, altering which bones are impacted by certain activities.
• Change in a surface: Changes in playing surfaces can cause undue stress to the bones of the feet and legs. For example, a tennis player moving from a grass court to a hard court may develop injuries.
• Improper equipment: Poor running shoes can contribute to your likelihood of getting a hairline fracture.

How’s a hairline fracture diagnosed?

Your doctor will ask about your medical history and general health. They’ll also ask questions about your diet, medications, and other risk factors. Then, they may perform several exams, including:

• Physical examination: Your doctor will inspect the painful area. They’ll probably apply gentle pressure to see if it causes pain. Pain in response to pressure is often the key for your doctor to diagnose a hairline fracture.
• MRI: The best imaging test for determining hairline fractures is an MRI. This test uses magnets and radio waves to provide images of your bones. An MRI will determine a fracture before an X-ray scan. It’ll do a better job of determining the type of fracture as well.
• X-ray: Hairline fractures often aren’t visible on X-rays immediately after the injury. The fracture may become visible a few weeks after the injury takes place when a callus has formed around the healing area.
• Bone scan: A bone scan involves receiving a small dose of radioactive material through a vein. This substance accumulates in areas where bones are repaired. But because this test will indicate an increased blood supply to a particular area, it won’t specifically prove there’s a hairline fracture. It’s suggestive but not diagnostic of a hairline fracture, as other conditions can cause an abnormal bone scan.

How are hairline fractures treated?

If you suspect you have a hairline fracture, there are a number of first aid treatments you can perform before you go to the doctor.

Home treatments

Follow the RICE method:

• rest
• ice
• compression
• elevation

Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) and aspirin (Bayer) can help with pain and swelling.

It’s important to seek further treatment from your doctor if the pain becomes severe or doesn’t get better with rest. How your doctor chooses to treat you will depend on both the severity and location of your injury.

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.

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.

• Sudden contractions (pulling) of the quadriceps muscle causes the tendon to pull on the kneecap and break it apart

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 orthopedic 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.

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.

Nonsurgical Treatments

Nonsurgical treatment is typically recommended for more stable patellar fractures or less severe breaks and may include:

• A cast or splint to hold the leg in place while the bone heals
• Preventing or reducing weight-bearing
• Pain medications (opioid pain medication may be appropriate for the first few days after a severe kneecap fracture, followed by non-opioid options)
• Physical therapy and walking aids help you regain strength and independence.

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. Orthopedic 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.

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.

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.

*Disclaimer: This information is not intended to be a substitute for professional medical advice. You should not use this information to diagnose or treat a health problem or disease without consulting with a qualified healthcare provider.
Please consult your healthcare provider with any questions or concerns you may have regarding your condition.
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