Hyperextended Knee

Quick answer: A hyperextended knee is one that straightens past its normal range, bending slightly backward. The term covers two different things: a sudden injury, where the knee is forced backward (often in sport), and a standing posture where the knees habitually lock back, called genu recurvatum. This entry focuses on the posture. A knee injury with pain, swelling or instability needs a doctor.

Maybe you’ve noticed your knees look slightly bowed backward in side-on photos, or that you stand by “locking” your knees and resting on them. Maybe your knees ache after standing for long periods, or feel unstable on stairs. Knowing which kind of hyperextension you’re dealing with is the place to start.

What Is a Hyperextended Knee?

When you stand, your knee would ideally be straight, with the muscles around it sharing the work of holding you up. With postural hyperextension (genu recurvatum), the knee pushes back past straight and locks, so you’re resting on the joint and its ligaments rather than your muscles. It often travels with sway back, where the hips drift forward and the knees lock back to balance them.

Hyperextension Injury vs. Hyperextended Posture

• Hyperextension injury: a sudden force bends the knee backward, such as a bad landing or a blow to the front of the knee. It can strain or tear ligaments. Pain, swelling, instability or difficulty bearing weight all need a doctor, promptly.
• Hyperextended posture: a habit of standing with the knees locked back. It develops gradually, usually without a single injury, and it’s the kind posture work addresses.

Do I Have Hyperextended Knees?

1. Side-view photo. Have someone photograph you from the side while you stand relaxed. Imagine a line from your hip to your ankle. Does your knee sit behind that line, curving backward?
2. Locking check. Stand normally and notice your knees. Are they pushed back and locked? Can you soften them slightly without feeling like you’re crouching?
3. Standing check. Do your knees ache, or your legs tire, when you stand for a long time? Do you tend to shift from leg to leg, or rest on one?

What Causes a Hyperextended Knee Posture?

• Standing on autopilot. Locking the knees lets you rest on your joints instead of your muscles. It’s easy, so it becomes habit.
• What’s happening above and below. Hips drifting forward (sway back), a tucked pelvis, or feet rolling in (overpronation) all change how the knee sits between them.
• Muscle balance. The muscles around the hips, thighs and calves may not be sharing the work of holding the knee, so the ligaments take over.
• Naturally flexible joints. Some people’s joints simply move further than most. Generalized hypermobility can also be part of a connective-tissue condition such as Ehlers-Danlos syndrome, which is diagnosed by a physician, often with input from a geneticist or rheumatologist.
• Past injuries. An earlier hyperextension injury or ligament damage can leave the knee less stable.

What Are the Symptoms?

Many people with hyperextended knees have no symptoms. When there are symptoms, people commonly describe:

• Aching at the front or back of the knee after standing
• Tired legs when standing still for long periods
• Feeling unsteady on stairs or uneven ground
• Lower back discomfort, often alongside sway back

See a doctor if you have knee swelling, locking, giving way, significant pain, or trouble bearing weight, or if your knee hyperextended during an injury.

How Do You Fix Hyperextended Knees?

The first advice most people hear is “don’t lock your knees.” It’s good advice, but hard to follow for more than a few minutes, because locked knees are where your body has learned to rest. Keeping them soft by effort alone is tiring.

What tends to help is giving the knees a better position to rest in: bringing the hips back over the ankles, getting the glutes and thigh muscles to share the load, and addressing how the feet carry weight. How much your knees change varies from person to person; naturally hypermobile joints won’t change their range, but better muscle control can still help how they handle load.

Exercises for Hyperextended Knees

Two starting points that teach the knees to work slightly bent rather than locked. Stop anything that causes pain.

1. Airbench

Stand with your back against a wall and walk your feet forward until you can slide down into a sitting position, knees bent to about 90 degrees and heels under or slightly in front of your knees. Keep your feet and knees hip-width apart and pointing straight ahead, with your weight in your heels. Hold for 1 to 2 minutes, and sit higher on the wall if your knees feel strained.

2. Standing Glute Contractions

Stand tall with your feet hip-width apart and pointing straight ahead, and your knees soft, not locked. Squeeze your glutes firmly, then release. Repeat 20 times. Then turn your toes out slightly, heels a few inches apart, and do 20 more. Notice how your knees want to lock as you squeeze, and keep them soft.

Choosing Your Next Step

There’s no single right path. It depends on how you like to work:

• You’d like to start on your own. If your knees aren’t injured, the checks and exercises above are a sensible place to begin.
• You’d like someone to find what’s driving it. A free 30-minute consultation includes a postural assessment of how you stand and walk. We have clinics in Newton, Gloucester, Santa Monica, Beverly Grove and Middletown, RI.
• You’re not near a clinic. Virtual posture therapy brings the same assessment approach to you.

Frequently Asked Questions About Hyperextended Knees

Is it bad to stand with locked knees?

Occasionally, no. As a habit, it puts more load on the joint and ligaments and less on the muscles, which many people find leads to aching after standing. Learning to stand with soft knees usually feels better over time.

How long does a hyperextended knee take to heal?

That depends on whether it’s an injury or a posture. A hyperextension injury’s recovery depends on what was damaged, which a doctor should assess. A postural habit isn’t something that “heals”; it changes gradually as you retrain how you stand.

Should I see a doctor for a hyperextended knee?

Yes, if you injured it, or if you have significant pain, swelling, instability, locking, or trouble bearing weight. These can mean a ligament injury.

What is genu recurvatum?

It’s the medical name for knees that bend backward past straight when standing, the postural form of knee hyperextension.

This article is general education, not medical advice. If you injured your knee or have pain, swelling, instability, locking, or trouble bearing weight, see a physician first. If you have widespread joint hypermobility, ask your physician about assessment. Posture therapy works alongside medical care, never instead of it.

Related reading: Leg and Knee Alignment: the complete guide.