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A hyperextended knee happens when the knee bends backwards beyond its normal range of motion.
Some are born with naturally hyperextended knees, while others may experience a specific hyperextended knee injury.
In either case, a hyperextended knee lacks the normal support and stability of an otherwise normally structured knee.
Let’s dive further into the nitty gritty of what a hyperextended knee is, the potential causes, symptoms and how to treat it.
Table of Contents
Types of Knee Hyperextension
Knee hyperextension can happen for three possible reasons:
- A specific knee hyperextension injury
- Naturally hyperextended knees
- Acquired knee hyperextension
A hyperextended knee injury is a specific event or condition that occurs to cause the knee to bend backwards beyond its normal limits.
This is considered a traumatic event that can range from mild to severe. The severity will then determine how to treat the injured knee.
When someone is born with naturally hyperextended knees, this is called genu recurvatum. While those with natural knee hyperextension could potentially never experience pain or injury, the possibility can’t be completely ruled out either.
Acquired knee hyperextension means that you weren’t born with naturally hyperextended knees, but a specific orthopedic injury didn’t cause them either.
Some medical conditions can lead to the development of knee hyperextension, such as after a stroke. In cases like this, the body has developed a lack of control around the knee joint (and likely other parts of the body), leading to knee hyperextension.
Regardless of the cause, knee hyperextension places the knee joint out of a neutral alignment. This can place excess stress and strain on the joint itself, along with the surrounding soft tissues, such as the ligaments, tendons and muscles.
This knee hypermobility can make the knee more susceptible to chronic instability. It can also increase your risk of injuring the knee if not properly controlled.
Exact Cause of Hyperextended Knee
While we’ve broken down the types of knee hyperextension, let’s take a closer look at some specific causes of a hyperextended knee injury.
We’ll exclude natural knee hyperextension from this, as we know in a case like that you were more simply born with this knee structure.
A hyperextended knee injury commonly occurs in athletes.
This is possible in any sport, especially those that involve high impact running, jumping, sudden stops or sharp turns. This may include athletes that play soccer, football, baseball, gymnastics, etc.
It’s not uncommon for athletes to experience other knee injuries when their hyperextension injury occurs.
This may involve a sprain or tear in any of the primary four ligaments that surround and stabilize the knee:
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
- Medial collateral ligament (MCL)
- Lateral collateral ligament (LCL)
There could even be combined knee ligament injuries involving the ligaments and other inner structures of the knee, such as the meniscus.
These combined knee injuries are considered more severe injuries and could require surgery to repair.
When an initial sports injury occurs, it’s important to be able to distinguish each of the above possible injuries from each other, or to identify a combined injury.
Athletes are not the only ones susceptible to a hyperextended knee injury.
Other types of traumas and impact to the knee can also cause an over extended knee joint:
- Direct blow to the front of the knee
- Jumping and landing incorrectly (can be sports related or non-sports related)
These hyperextension injuries, whether related to sports or not, are commonly accompanied by knee pain, especially pain behind the knee. The amount of pain will vary depending on how bad the injury is.
It’s important to understand that not all cases of knee hyperextension are natural or from an orthopedic injury.
Various medical conditions, particularly neurological conditions, can lead to a hyperextended knee on one or both legs.
The following is a list of a few common neurological conditions that could create a hyperextended knee:
- Traumatic brain injury
- Spinal cord injury
Some neurological conditions may further promote an already present hyperextended knee due to muscle weakness and nerve damage from the condition itself. This can occur in the following conditions:
- Myasthenia gravis
- Parkinsons disease
- Multiple sclerosis
- Amyotrophic lateral sclerosis (ALS)
The common thread among neurological disorders that may cause a hyperextended knee is that there has been a loss of neuromuscular control around the knee. The hyperextended knee will then develop as a compensation for the body to support itself in order to stand and walk.
Symptoms of a Hyperextended Knee
How will you know if you have a hyperextended knee?
From a structural standpoint, if the knee is hyperextended, you’ll notice that it’s capable of bending beyond a neutral position or 0 degrees when standing straight. You may or may not be capable of correcting this voluntarily, depending on the cause of your knee hyperextension.
Other symptoms of a hyperextended knee will depend on the exact cause of the knee hyperextension.
Those related to hyperextended knee injuries may experience one or more of the following:
- Knee pain at the time of the injury (pain location can vary, but at the time of injury may be directly behind the knee due to the pressure from the hyperextension)
- Inability to bear weight on the injured leg
- Difficulty standing and walking
- Knee instability or buckling
- Possible popping sound at the time of the injury (common with simultaneous ligament or meniscus injuries during knee hyperextension)
Those who have knee hyperextension from a specific medical condition will demonstrate a lack of control over their knee during standing and walking activities.
The knee hyperextension may be more noticeable when in mid stance with all of their weight on the leg. It may also be noticeable with other weight bearing activities, such as using stairs.
The knee hyperextension may improve with the use of a walking aid, such as a cane or walker. The hyperextension will commonly worsen and become more unstable the more fatigued the leg becomes.
Treatment of a Hyperextended Knee
Treatment recommendations for a hyperextended knee will vary depending on the exact cause of the problem.
If you’ve experienced a more minor hyperextension injury, especially related to a sports injury or minor incident, the first method you could try at home is the R.I.C.E. method.
It’s recommended to rest the affected knee. You can still get up periodically to move around but avoid any strenuous activities that could cause further injury.
Make sure to ice regularly (aim for up to 20 minutes of icing, as needed, but take at least a 30-minute break between icing sessions).
You may need to use some type of compression at first. This usually means using some type of knee brace or wrap. This will help with pain and swelling.
Once the knee starts feeling better, try to wean away from the compression so that your knee can begin to learn how to support itself again.
Try to keep the knee elevated while resting it to also help with knee swelling and inflammation.
Exercises for Hyperextended Knees
At some point when treating knee hyperextension, no matter the cause, exercise will usually be encouraged to help your symptoms.
If you’ve been referred to physical therapy, your physical therapist will guide you through the right kind of exercises to practice, depending on the cause of your knee hyperextension.
If your knee hyperextension has resulted from an injury, the type of exercise you can do will largely depend on what phase of healing you’re in and if a surgery was involved for more serious injuries.
Let’s go through a few basic exercises that can be helpful to address general knee joint laxity due to hyperextension.
These exercises will focus on gentle strengthening of the quadriceps muscles (located in the front of the thigh) in particular, which are key players in controlling knee stability.
1. Terminal Knee Extension
- Tie a resistance band (light, medium or heavy resistance) around something sturdy, such as a chair leg.
- Step through the loop with the working leg. Make sure the band is positioned on the back of the knee. Step back a little bit so that there is slight tension on the band.
- Begin with the working knee in a slightly bent or flexed position. Slowly straighten the knee, moving into the resistance of the band.
- Avoid straightening the knee to the point of hyperextension and simply move it to a neutral position.
- Hold this position for 5 seconds, then slowly return to your starting point.
- Repeat 10-15x for 2-3 sets.
It’s important to make sure you have full control over this motion and don’t allow the knee to push back into hyperextension.
If you’re having a hard time differentiating what it looks like to move to a neutral knee position versus hyperextension, take a look at the video demonstration below to see the difference.
2. Long Arc Quad
A long arc quad is a progression from the terminal knee extension exercise. This also targets the quadriceps muscles.
- For this exercise you can use either a small ankle weight (2-5#) or wrap a resistance band around the ankles (light, medium or heavy resistance).
- Begin sitting in an upright position with the feet flat on the floor.
- Kick the foot on the working leg off the floor, allowing the knee to straighten.
- Straighten the knee to a neutral position. Don’t allow it to move into hyperextension.
- Hold for 2-3 seconds, then return to your starting position.
- Repeat 10-15x for 2-3 sets.
3. Mini Squats
Mini squats will target the quadriceps and the glutes.
- Begin with the feet flat on the floor about hip width apart. In this position, make sure you begin with the knees neutral and not in hyperextension.
- Slowly sit the hips back towards the heels as the knees bend to about a 30-45 degree angle. As you do this motion, you should notice the torso will hinge forward to help counterbalance you sitting back towards the heels.
- Hold the position at the bottom of the mini squat for up to 5 seconds, then return to your starting position.
- Repeat 10-15x for 2-3 sets.
Remember, this motion should be slow and controlled.
If you’re concerned about balance, place a chair behind you while you practice this as a safety net. You can also stand in front of something sturdy to place your hands on, such as your countertop.
4. Forward Step Ups
Forward step ups will also target the quadriceps and glutes.
- You can use a 4-6″ step for this. If you don’t have a step available at home, you can substitute another firm surface, such as a book.
- You can position your step next to something sturdy, like the countertop, if you need additional balance support.
- Start with the foot of the working leg on the step directly in front of you.
- Step up onto the step strong and confident. Make sure when you step up that you don’t lock into knee hyperextension. You have to be able to control the movement.
- Once up on the step, slowly lower back down to where you began.
- Repeat 10-15x for 2-3 sets.
**Tip: If your glutes aren’t properly activated during a forward step up, it may accentuate your knee hyperextension while stepping up. Take a look at the following video that shows the right and wrong way to practice a forward step up when dealing with knee hyperextension.
It’s not common to need surgery for knee hyperextension; however, if you’ve had a serious hyperextension injury combined with other injuries to the knee (e.g., ligament or meniscus tear), then surgery may be necessary.
The exact type of surgery needed will depend on the specific injuries.
Hyperextended Knee Recovery Time
If your hyperextended knee is not something you were born with or the result of another medical condition, then recovery time will vary depending on the extent of the injury.
A mild knee hyperextension injury can take a few weeks or up to a month to heal.
A more serious injury, especially one that may require surgery, can take a few months or up to a year to recover from.
Prevention of a Hyperextended Knee Injury
There are measures you can take to help prevent a hyperextended knee injury in the first place.
Including a well-rounded home exercises program that promotes functional strength in the legs is a great start. Make sure to challenge your muscles but practice your exercises with the correct form.
If you’re an athlete, make sure to practice using the right body mechanics and landing techniques with any jumping motions. This is to be done in addition to the right kind of cross training.
If you’re naturally hyperextended or have a hyperextended knee related to another medical condition, these preventative measures still apply to you! Having already-present knee hyperextension can make you more prone for knee hyperextension injuries.
In cases like this, it’s still important to make sure you practice a good home exercises program. Another thing you can work on is how to stand and walk without falling into your natural knee hyperextension.
This is especially helpful to do with a physical therapist observing your walk.
If you have a hard time telling whether or not you’re resting in knee hyperextension, use of a mirror can be helpful to learn how to correct this.
Check out the following video that shows how you can use a mirror to check if you’re resting in knee hyperextension, as well as how to correct this.
Sometimes practicing going back and forth between the right and wrong position will better train your body to recognize when it’s doing something wrong and fix it immediately.
Having a hyperextended knee, regardless if related to an injury or not, is very easily managed. With a little practice and time, you’ll gain control over that knee hyperextension in no time!
What type of doctor can I see for a knee hyperextension injury?
An orthopedic surgeon, who specializes in knees, would be best. This doesn’t mean you need surgery, but this type of specialist will be the best to look at your knee hyperextension injury.
What will happen if I don’t treat my knee hyperextension?
If from a minor injury, it could recover on its own; however, without treating it you will increase your chances of further worsening the injury.
If you naturally have knee hyperextension and don’t try to strengthen the surrounding muscles, you are more susceptible to experiencing an injury.
How can I tell if my knee has been strained or torn during a hyperextension injury?
If you’ve had a serious injury and are concerned about a strain or tear, then you need to seek medical attention right away. They will assess your injury and likely order imaging (e.g., X-rays, CT scan, MRI) to determine what injuries you’ve sustained.