Hyperextended Knee

What is a hyperextended knee?

A hyperextended knee is an injury that happens when your knee is bent backward beyond its usual limit.

Sports injuries and other traumas apply a lot of force to your knee’s connective tissue (the tendons, ligaments and cartilage that hold it in place and help it move). Any force that pushes your knee further back than its usual limit can cause a hyperextension injury. After your knee is hyperextended, it might feel unsteady or “buckle” when you try to put weight on it.

Knee hyperextensions range from mild cases that you can treat at home to more severe injuries that will need surgery to repair.

Hyperextended knees vs. ACL, PCL MCL and LCL tears

Hyperextended knees, ACL tears and PCL tears are all different knee injuries. They’re all also most commonly caused by sports injuries.

Your ACL (anterior cruciate ligament) and PCL (posterior cruciate ligament) connect your thigh bone (femur) to your shin bone (tibia). They both cross the middle of your knee. Your ACL is at the front of your knee and your PCL runs along the back, behind your knee.

You MCL (medial collateral ligament) and LCL (lateral collateral ligament) are on the sides of your knee. They stabilize your knee and help it move sideways.

It’s possible that an injury can damage one or multiple ligaments in your knee, including during a hyperextension. Severe hyperextensions are common causes of ACL and MCL tears.

However, not all hyperextensions lead to ligament tears, and it’s possible to strain or tear ligaments without hyperextending your knee.

Who gets hyperextended knees?

Anyone can experience a hyperextended knee, but they’re most common in people who play sports.

How common are hyperextended knees?

Hyperextended knees are very common injuries, especially for athletes.

How does a hyperextended knee affect my body?

In addition to symptoms like pain and swelling, it might be hard to use your knee like you usually can after it’s hyperextended. This is especially true if you damaged other parts of your knee like tendons, ligaments or your meniscus when you were injured. Your knee might buckle (feel weak or unstable), and you might not be able to put weight on it like you’re used to.

Don’t “play through the pain” or try to “walk it off” if you hyperextend your knee. Ignoring symptoms can cause a mild injury to become worse, and can lead to more damage inside your knee.

See your healthcare provider if you’re in pain or have trouble moving your knee.

What are the symptoms of a hyperextended knee?

Symptoms of a hyperextended knee include:

• Pain.
• Swelling.
• Trouble moving your knee like you usually can.
• Instability or feeling like your knee is weaker than usual.
• Bruising or discoloration.

If you hear or feel a pop inside your knee during your injury, it’s more likely you’ve torn one of your ligaments. Torn ligaments can also be extremely painful and make it hard or impossible for you to use your knee.

What causes hyperextended knees?

Most hyperextensions are caused during sports or other physical activities. Traumas like falling can also cause your knee to hyperextend. Anything that forces your knee backward can cause a hyperextended knee. Picture a football player getting tackled by their legs, or a basketball player landing awkwardly after a jump.

How is a hyperextended knee diagnosed?

Your healthcare provider will diagnose a hyperextended knee with a physical exam and imaging tests. They’ll look at your knee, talk to you about your symptoms and see how limited your ability to use your knee is.

You’ll probably need at least one type of imaging test, including:

• X-rays.
• Magnetic resonance imaging (MRI).
• A CT (computed tomography) scan.

These will help your provider see the damage inside and around your knee. They’ll also show if you have a more serious injury like a torn ligament.

How are hyperextended knees treated?

How your hyperextended knee is treated depends on the severity of your injury. If you only have mild symptoms and didn’t damage anything inside your knee, you should be able to treat your hyperextended knee at home by the following RICE:

• Rest: Avoid the activity that caused your injury. Don’t overuse your knee while it heals.
• Ice: Apply a cold compress to your knee for 15 minutes at a time, four times a day.
• Compression: You can wrap your knee in an elastic bandage to help reduce swelling.
• Elevation: Prop your knee and leg up above the level of your heart as often as you can.

Over-the-counter NSAIDs like aspirin or ibuprofen can reduce pain and inflammation. Talk to your provider before taking NSAIDs for longer than 10 days. Your provider might suggest exercises to increase the strength and flexibility in the muscles around your knee to help prevent future injuries.

Hyperextended knee surgery

It’s rare to need surgery after a hyperextended knee. However, if the injury that caused your hyperextension damaged tendons like your ACL or PCL, you might need surgery to repair those tears.

Most of the time, surgery to repair damage in your knees is an outpatient procedure, which means you can go home the same day. Your surgeon will perform what’s called a knee arthroscopy, a minimally invasive technique to repair the ligaments inside your knee.

How long does it take to recover from a hyperextended knee?

How long it takes you to feel better depends on how severely your knee was hyperextended and any other injuries you experienced. If your hyperextension didn’t damage anything inside your knee and you don’t need surgery, it should take between a few weeks and a month to recover.

If you need surgery to repair more severe injuries it could take a few months before you can resume all your usual activities.

Talk to your healthcare provider or surgeon about a specific timeline for your recovery.

How can I prevent a hyperextended knee?

During sports or other physical activities:

• Wear the right protective equipment.
• Don’t “play through the pain” if your knee hurts during or after physical activity.
• Give your body time to rest and recover after intense activity.
• Stretch and warm up before playing sports or working out.
• Cool down and stretch after physical activity.

Follow these general safety tips to reduce your risk of an injury:

• Make sure your home and workspace are free from clutter that could trip you or others.
• Always use the proper tools or equipment at home to reach things. Never stand on chairs, tables or countertops.
• Use a cane, crutches or walker if you have difficulty walking or have an increased risk for falls.

What can I expect if I have a hyperextended knee?

You should expect to make a full recovery after hyperextending your knee. It’s a temporary injury that shouldn’t have long-term impacts on your health or your ability to play the sports you love.

If you experience a severe injury that requires surgery, you should expect to avoid the sport or activity that caused your hyperextension for at least a few months.

Do I need to miss work or school with a hyperextended knee?

If you can do your job or schoolwork seated or without putting additional stress on your injured knee you shouldn’t need to miss work or school while you heal.

Talk to your surgeon or healthcare provider before resuming any physical activities while you’re recovering.

What is the outlook for a hyperextended knee?

The outlook for people with hyperextended knees is very positive. Most injuries don’t require surgery, and you should be able to resume all your usual activities within a few weeks.

When should I see my healthcare provider?

Talk to your provider if you’re experiencing symptoms like pain or swelling that get worse after a few days or if you can’t move your knee like you usually can.

When should I go to the ER?

Go to the emergency room if you notice any of the following:

• Extreme pain.
• Swelling that’s getting worse.
• Discoloration.
• You can’t move your knee at all.

What questions should I ask my doctor?

• Will I need any imaging tests?
• Do I have an ACL or PCL tear?
• How long should I rest and avoid sports and other physical activity?
• Will I need surgery?

A note from Cleveland Clinic

How much time will I miss? Is this a serious injury? Am I done for the season?

These are all questions that run through your mind when you hyperextend your knee. Fortunately, most hyperextended knees don’t require surgery, and you’ll be able to recover at home with over-the-counter treatments and by giving your body time to rest and heal.

If you do experience a more severe injury — like a ligament tear — you should still make a full recovery and get back to the sports and activities you love.