Hyperextended Knee

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Suffering a knee injury can really disrupt your movement and capability to perform exercise normally.

Knee injuries are so disruptive as they are required to carry your full weight and are an integral part of carrying your body weight during exercise.

Knee injuries also disrupt your ability to perform your simple day to day tasks and can also be known to affect comfort when sitting and trying to sleep.

Your knee mostly moves in flexion and extension and is also capable of a small amount of rotation.

One of the most common injuries you can suffer to the knee joint is a hyperextension injury.

Put simply – this is when the knee is forced backwards on its self and over extends. There are many ways you can do this and there are various injuries which can happen as the result of a hyperextension injury to the knee.

If you have had a hyper extension injury to the knee then you will know how troublesome these injuries can be, if you haven’t suffered one then you are one of the lucky ones.

This article looks to give you guidance on the anatomy involved with a hypertension injury, symptoms that may happen and all of the best ways to manage the injury.

As a word of safety, please seek the help of a physiotherapist or health professional if you have had a hyperextension injury – this will help get you an accurate diagnosis and ensure a safe rehabilitation.

Anatomy of the Knee

Hyperextension injuries affect the whole knee, but we are going to list the specific structures involved and what injuries may be possible to happen to these structures which cause the pain and dysfunction during a knee hyperextension injury.



The kneecap is the small bone that sits on the front of the thigh in a small groove in the end of the femur. Because it is a small bone and it is mobile, a direct impact to the patella can cause discomfort, swelling and sometimes possible dislocation.


Tibiofemoral joint

This is the main joint of the knee and this is what makes it go forwards and backwards. When the knee is forced backwards the joint locks out against itself and this causes pain and aggravation to the joint when it happens.


Posterior Cruciate Ligament

This is the ligament that joins the back of the femur to the back of the tibia. It is designed to attach the bones but also it is the last line of defence in a hyperextension injury. If your muscles and joints are unable to take the impact and hyperextension is caused – then the ligament will be placed under stress. It is common for PCL injuries to occur with hyperextension injuries.



The hamstrings are the main flexors of the knee joint. They begin at the pelvis but attack beneath the knee on to the tibia. When hyperextend they become overstretched and this can cause pain in the hamstring tendon.



The meniscus is the cartilage tissue that sits within the knee joint and provides shock absorption and smooth movement of the knee. Hyperextension can lead to joint and meniscus aggravation due to the sudden compressive force applied.

Symptoms of a Hyperextended Knee

Each hyperextension injury to the knee will be unique.

Your symptoms will depend on the person involved and the forces involved. If someone has a stronger knee taking an equal force to someone who has a weaker knee then there will likely be a difference in the symptoms that will be experienced.

With almost all hyperextension injuries there will be some trauma to the knee joint and capsule. The capsule is the lining which sits around the knee and contains synovial fluid which helps to keep the knee lubricated. When stress is applied to the knee joint as a whole you will see an increase in swelling.

This is a protective mechanism from the body to protect the knee whilst it deals with the injury and heals. If there have been other structures injured such as the posterior cruciate ligament, then you will see more swelling and sometimes this can be due to a bleed caused by the trauma.

If there has been a ligament injury you will see instability of the knee. Patients often report difficulty with securing the knee and often say that it may buckle underneath them causing it to flop backwards. Whilst this is commonly caused by ligament injury, shock to the knee and hamstrings can often replicate this symptom as the knee has taken an unexpected impact and tendons also help to stabilise the knee.

Changes in how a person walks after a hyperextension injury will be common – as just mentioned, stability issues are common but general limping due to pain will be present.

Loss off normal function and ability to exercise in the immediate period afterwards will be a certainty, even with the most minor of hyperextension injuries.

Management of an injury like this is key – take a read of the next section to see how we recommend you deal with this problem in a stage by stage guide.

Causes of a Hyperextended Knee

Hyperextension injuries simply mean that the joint is extended forcefully past its end range, causing trauma. When the joint and its associated structures are forced against their usual capability, this then causes pain and potential structural failure.

How do hyperextension injuries to the knee happen, let’s take a closer look.

This can be divided in to 2 main categories, contact and non contact.


Non Contact Knee Hyperextension Injury

Examples of knee hyperextension injury without contact would involve the knee falling backwards on itself, locking out and then hyperextending.

In clinic – patients have provided such as examples as:



Missing a step, stepping too far forward or changes in the surface of the ground causing them to plant their foot sooner or later than they thought. This then takes them by surprise and the knee can fall backwards and because they were not expecting this to happen the knee will lock backwards against the joint and hyperextend.


Weather Related

When it is cold and there is ice and snow and unstable surfaces – this can cause slipping and the inability for us correct our footing, again there have been incidents in clinic where patients have described their knee locking out because they’ve slipped.


Stair Related

Commonly reported is missing a step at home or work, thinking they were going to land on the next step and it’s either come sooner or later than they expected, causing the heel to plant and the knee to fall backwards.


Contact Hyperextension 

This one is relatively straight forward and self explanatory. During sport the knee can become impacted by other participants causing knee hyperextension.

In football / soccer – goal keepers suffer these most commonly but outfield players are also prone to them due to the contact nature of the game. Typically the foot becomes planted, being unable to move then another player will often collide and impact the shin or the knee causing the knee joint to be forcefully hyperextended.

It isn’t always player to player contact but sometimes player to object collisions such as goal posts or any surrounding fencing / equipment that the lower limb can impact against.

Treatment & Rehabilitation for a Hyperextended Knee

Early Stage

Immediately after a hyperextension injury it is important to self assess the extent of the injury and perform the right actions.

Ensure you limit your activity and remove yourself from any danger – this could be stopping the activity you were doing and resting, or calling for assistance.

Try and walk, see how stable your knee feels and try to walk as normally as possible. If the knee is swollen then a good regime of compression and elevation is recommended.

If your knee is unstable and extremely swollen then a recommendation to see someone is advised – such as a physio who can help to diagnose and provide a management plan.

If there has been significant damage to the knee such as a ligament rupture or any meniscus damage then this should be passed to the appropriate department such as orthopaedics for further reinvestigation.

Exercises in the early stage should be kept simple, use crutches to walk if you are unsafe or unstable on your feet, if not, simply slow your walking down and shorten your step length to avoid limping and excess pain.

Move your knee in flexion and extension gently whilst off your feet and things such as static cycling can be good to get the knee moving again and reduce pain. Access to a swimming pool is a great way to mobilise the knee in the early stages.

Apart from good diagnosis – a physiotherapist can provide you with treatment such as mobilisation and massage to help the knee move more freely.

If there is instability, swelling or just simply discomfort, a knee brace or sleeve might be helpful to provide security and comfort to the knee.


Mid Stage Management

Once some of the early symptoms have started to disappear, it’s time to get some strength back in to the knee.

Quadriceps and hamstring exercises should be a main part of the focus when doing this rehab. The quads are what help to secure the knee and keep it extended. The hamstrings will need strengthening as they may have been damaged by the injury.

In the gym using quadriceps extension machines and hamstring curl machines are the best and most safe way to do this. Strengthening the glutes is also an important part of the rehab as they assist with the extension of the leg backwards and assist with securing the knee. Glute bridges are another good exercise to strengthen the knee back.

In the early stages, gentle cycling and swimming was advised but now a progression to adding resistance on would be recommended.


Late Stage

If the knee is improving as expected, then it can be progressed to further exercise that is in line with the activities you want to return to.

By this stage, a knee support should not be needed, however if you do feel that you need the security of a support, then choose a sleeve with less support as you want your knee to support itself rather than it being artificially supported.

The knee should be moving fully and strength should be increasing. Walking style should also be regulating and there shouldn’t be a limp.

If all of the above is in check – progress on to starting a return to sport or exercise. If it is running based then think about performing small sessions of running with good rest periods between sessions.

Jumping and landing practice is highly recommended as this will help you gain confidence in the knee but also recondition the knee to absorbing force and improving control to prevent further hyperextension. Landing practice should also be performed landing on to a ‘soft knee’ which means having it slightly bent. Never land on to a straightened leg as this increases the chances of lower limb injury.


That concludes our guide to hyperextended knee injury – we hope that it has been helpful and that you have enjoyed reading it. If you think this article could help someone you know then, please let them know and share it with them!

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