Hypermobile Knees: Why They Hurt and What Makes Them Steadier

If your knees bend backwards when you stand still, give way on stairs, and ache after a day that involved nothing but standing, the flexibility and the pain are the same story. Knees that go past straight are doing a different job from knees that stop at straight.

The version people recognise: you are waiting for a bus, weight settled back, knees locked. It is comfortable, it costs no effort, and you have stood that way your whole life. An hour later the fronts of your knees burn, and going downstairs feels unreliable, as though one of them might quietly fold.

🧬 What hanging on the ligaments actually costs

A knee that extends past straight is called genu recurvatum, and it is one of the features clinicians are taught to look for in hypermobility spectrum disorders, alongside flat feet, knees that angle inwards, and a kneecap that subluxes or dislocates.

Standing in that locked position feels efficient because it is: you are resting on the ligaments at the back of the joint rather than holding yourself up with muscle. The catch is that ligaments are not built to be load-bearing furniture. Hours spent parked at the end of range keep the joint under a kind of load it tolerates badly, while the muscles that should be sharing that work stay switched off.

Meanwhile the kneecap has its own problem. It has to track in a groove, guided largely by the quadriceps and the surrounding soft tissue. Where those tissues are lax, the tracking is less reliable, and the front of the knee ends up carrying uneven pressure. That is the ache that shows up after stairs, hills, driving, and sitting through a film.

🔍 The signs that point at hypermobility rather than a knee injury

• Both knees behave the same way, even if one is worse.

• Giving way happens on ordinary ground, on stairs or when turning, not after a tackle or a fall.

• Pain is worse after standing still than after walking, and worse going downstairs than up.

• Your kneecap has slipped sideways at least once, or feels as if it might.

• Scans are clean, and you have been told the knee is structurally fine while it keeps letting you down.

If your ankles roll and your arches drop as the day goes on, the knees are rarely working in isolation. That chain is the subject of our article on hEDS and your feet, which is often where the problem starts.

🛠️ What helps, and what the evidence actually shows

Strength work is not off-limits, and it may be the main event. In a case series of sixteen women with knee pain and knee hypermobility, a supervised heavy resistance programme was tolerated and every participant reported less knee pain afterwards. Knee proprioception improved in all sixteen, by an average of around half. It is a small, uncontrolled study, so it proves tolerability rather than superiority, but it contradicts the widespread assumption that hypermobile knees must be handled gently forever.

The word doing the work in that sentence is supervised. Loaded exercise done badly, into the hyperextended range and without progression, is how people end up sorer. Getting the programme from someone who understands hypermobile joints matters more than the exercises themselves, which is why we wrote a guide to what an hEDS-literate physiotherapist looks like.

Learning where straight is. Most people with recurvatum cannot feel the difference between straight and locked, because the position sense is part of what is affected. Standing with a soft knee feels wrong before it feels normal. This is retrainable in a way the ligaments are not, and it is the same principle at work in proprioception training elsewhere in the body.

Breaking up standing. Shifting weight, moving every few minutes, and keeping a foot forward rather than locking both knees costs almost nothing and removes the most common source of the ache.

Supports, used for a purpose. A brace that blocks the last few degrees of extension during a specific activity can be genuinely useful. A brace worn all day so that the muscles do less is a step backwards, a trade-off covered in our guide to braces and supports.

🗣️ How to raise it

Name the instability, both sides and the function: "Both my knees hyperextend and give way on stairs, without any injury, and the front of the knee hurts after standing. My joints are generally hypermobile. Could I be referred to a physiotherapist for knee stability work?"

If your kneecap has ever slipped out of place, say so explicitly, including roughly how many times. Patellar instability is a recognised feature in this population and it changes what a clinician considers.

⚠️ Worth medical attention rather than patience

A knee that locks and will not straighten, one that swells rapidly after an episode, or a kneecap that has visibly moved and stayed out needs urgent assessment rather than a wait-and-see approach. Pain accompanied by redness and heat is also a reason to be seen promptly.

❓ Frequently asked questions

📚 Sources & further reading

The information in this article is drawn from the following sources. We encourage you to explore them, and to always discuss your own symptoms and diagnoses with a qualified healthcare professional.

• Journal of the American Board of Family Medicine (2021): Diagnosis and Management of Hypermobility Spectrum Disorders in Primary Care (genu recurvatum and patellar instability as recognised features)

• Case series in Journal of Clinical Medicine: Supervised, Heavy Resistance Training Is Tolerated and Potentially Beneficial in Women with Knee Pain and Knee Joint Hypermobility

• Systematic review: The relationship between joint hypermobility and patellar instability