Orthopaedics · Mobility

Why 1-in-8 Adults Over 55 'Buckle' on Stairs — and the 1865 Orthopaedic Principle That Stops It in 14 Days

A specific, documented orthopaedic condition explains the "wobble" that millions of adults over 55 have been told is simply aging. It isn't. And it can be addressed.

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The Later Life Report Health Desk · Mar 12, 2026

12 min read

It rarely starts with a fall.

In nearly every account, the first incident is small enough to dismiss. Turning around at the kitchen counter. Stepping off a kerb. Standing up from a low chair at the end of a meal. The knee, for half a second, is not there. The hand goes out. The breath catches. Nothing is said.

A few months later it happens on the stairs going down. The hand reaches for the rail. The next time, it stays there. Then it is both rails — then sideways down the cinema steps to hold the rail with both hands, an adaptation one 83-year-old described on the forum Patient.info that is now echoed, almost word for word, by people twenty years younger.

Each incident is small enough to file as nothing. The cumulative pattern is what older adults privately call the wobble.

The medical literature calls it something specific. The researchers who named it have spent the better part of two decades trying to get their colleagues to pay attention. Mostly, they have not.

The verdict

"it's just old age. there's nothing we can do about it."

That line is so widely repeated in GP surgeries across four countries that it has become a kind of folklore. On the Australian community site Starts at 60, it circulates as a joke. On Patient.info in the UK, it appears verbatim in thread after thread. One woman in her seventies summarised her entire experience of the medical system in a single sentence:

I was told it's normal.

She was describing her knee giving way on the stairs. The standard response, repeated surgery after surgery, is the same script. It is wear and tear. It is osteoarthritis. It is just age. Try a compression sleeve. Try paracetamol. Come back if the pain gets bad.

But here is the problem with that script: in many of these patients, the knee does not actually hurt — not in the way the question means. What is wrong with it is something the script does not name and the prescription pad cannot address. It is a mechanical problem. It has a clinical name. And it has been documented for twenty years.

The evidence

the quiet research that almost nobody reads

In 2007, the Annals of Internal Medicine published a paper by Dr David Felson and his colleagues that tracked 2,351 community-dwelling adults over the age of 60. The paper asked a simple question: how common is it for an older adult's knee to buckle?

The answer was not how many patients had buckled at some point. It was how many had buckled in the previous three months.

Stat Callout — Poppins

11.8%

in 3 months

Nearly one in eight adults over sixty had experienced the wobble in any given quarter. Of those, 78% had buckled more than once. Twelve and a half percent had fallen during an episode.

A second study — the Multicenter Osteoarthritis Study, or MOST — tracked the same question across a larger cohort. Adults who buckled at the five-year mark had up to 2.5 times the odds of falling repeatedly two years later, and three times the odds of fall injuries serious enough to limit their activity.

Its lead investigator, Dr Michael Nevitt of the University of California, San Francisco, made a remark to ScienceDaily in 2016 that should have provoked a quiet reckoning inside orthopaedics. It did not. What he said was this:

Pain is the predominant symptom of knee osteoarthritis, and symptoms of instability such as knee buckling and falls may be overlooked by treating professionals.

Read the second half of that sentence again. May be overlooked by treating professionals. The lead investigator on the largest American study of knee osteoarthritis is publicly stating that the instability his own research has documented is something his colleagues are routinely missing.

The patient voice

what the patients knew before the doctors did

What struck me most, reading the patient forums in detail, is that the patients themselves have always known. The same words recur so often they begin to feel like a clinical vocabulary the profession has refused to adopt.

A woman called Veronica posts on Patient.info in 2015: "Yesterday whilst coming downstairs one stair at a time… my leg gave way. The jolt of pain was dreadful — worse still, the carefully prepared sandwiches flew into the air."

Another, posting as Tucks, writes about her 83rd birthday meal: "The short distance from the car to the resturant had me clinging on to my son and grandsons arms, my legs were like a wobbly jelly and all through the beautiful meal I was worrying about that short walk back."

The defining experience isn't pain. It's the quiet hesitation — and the dread of the walk back.

Notice what Tucks describes. Not the pain. Not the fall. The worry about the walk back — a meal she was present for perhaps half of, the rest spent silently rehearsing the return journey. That is what an unstable knee feels like from the inside. Not pain. Anticipatory dread: a knee that can no longer be trusted on movements that once required no thought at all.

The mechanism

what is actually happening inside the joint

The clinical name is lateral ligament laxity: the gradual loosening — over years, accelerating from the fifties onward — of the medial and lateral collateral ligaments, the two cords of connective tissue that hold the knee in lateral alignment whenever weight is placed on it.

When they are tight, the knee tracks straight and the joint is quiet — it does its work without intruding on the patient's attention. When they slacken, the joint loses lateral containment. The femur can shift, briefly, off the tibia. The patient feels that shift as the wobble, the buckle, the giving way — the knee not quite being where it was supposed to be.

The collateral ligaments hold the knee in lateral alignment under weight. When they slacken — a normal consequence of ageing — the joint loses containment.

The shift is not large — a matter of millimetres. But the nervous system registers it instantly, and the next time the body has to descend a stair, it remembers. The quadriceps tense pre-emptively. The other leg takes the load. The hand reaches for the rail. Over months and years, the protective adaptation becomes the new baseline, and the slow inventory begins.

And it is not only the ligaments. Dr Jonathan Negus, a Sydney orthopaedic surgeon who writes publicly about why knees begin to feel unstable without any injury at all, points to the muscles that brace the joint — chiefly the quadriceps. "If these muscles are underused or fatigued… the knee may feel less supported," he writes. The two effects compound: slackening ligaments and deconditioning muscle both reduce the knee's lateral support, and each accelerates the other as activity quietly falls away.

Felson's group called it functional loss. A man on the forum BoneSmart, describing how he stopped wanting ten-mile hikes, then five-mile hikes, then noticed the five-mile hikes "getting steep," put it in a sentence that has become one of the most-quoted lines in all the patient writing on this subject:

Feature Quote — Poppins

Your life narrows before you know it.

That is the actual cost of lateral ligament laxity. Not the wobble itself. The slow, almost imperceptible inventory of activities that get quietly removed from a person's week, then their month, then their year — until one day they realise they have not knelt in the garden for two summers, and they cannot quite remember when they stopped.

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The dead ends

what has been tried, and why none of it has worked

If you ask an older adult with an unstable knee what they have tried, the list is usually long.

Most have worked through the chemist aisle and beyond: compression sleeves, hinged ACL braces, supplements, cortisone, sometimes surgery. For nearly all of them, the result is the same disappointment — not because the products are bad, but because none of them was built for the mechanical issue just described. Each targets a different tissue, a different symptom, or a different condition altogether.

Comparison Matrix — Poppins

Solution

What it's built for

Lateral instability?

Compression sleeves

Warmth & proprioception

✕

Hinged sport braces

Acute ACL recovery

✕

Cortisone injections

Inflammation & pain

✕

Glucosamine

Cartilage

✕

Surgery (TKR)

Advanced joint disease

✕

Curae Stability Brace

Lateral ligament laxity

✓

The sleeve "slides down by lunchtime." The hinged brace is bulky and obvious under trousers. Cortisone wears off in weeks. Glucosamine is aimed at the wrong tissue. Surgery is reserved for joint damage most of these patients do not yet have — which is why so many describe being told to "wait," or that they are "too old." None of them mechanically replaces the lateral support the ligaments have lost. That gap has sat in plain sight — in the literature, in the forums, in the GP notes — for the better part of two decades.

The heritage

a 160-year-old discovery, preserved by military medicine

What is most surprising is that the principle required to address lateral instability is not new. It has been documented since the mid-nineteenth century — simply confined, for most of that time, to acute orthopaedic injury rather than daily life.

In 1865, a Welsh orthopaedic surgeon named Hugh Owen Thomas, working out of his clinic in Liverpool, published a book titled Diseases of the Hip, Knee and Ankle Joints with Their Deformities Treated by a New and Efficient Method. In it, he described a device of his own design: a rigid metal frame, lined with leather, that wrapped around the upper thigh and ran down the outside of the leg on rods to a second ring at the ankle. He intended it, initially, for the treatment of tuberculosis of the knee.

The device became known as the Thomas splint.

The Thomas splint, designed in 1865, applied rigid lateral containment to the knee — the same mechanical principle behind the modern brace described below.

What Thomas understood — half a century before any modern study of ligament biomechanics — was that a knee in trouble does not need to be immobilised so much as laterally contained. The rigid rods did not stop the knee bending; they stopped it collapsing sideways under load. In a sentence: externalised lateral stabilisation.

For fifty years it remained a modestly useful piece of clinical kit. Then the First World War began. In the trenches between 1914 and 1916, compound fractures of the femur carried an 87% mortality rate — soldiers were dying in transit. In 1916, Sir Robert Jones ordered every femoral fracture in the British Army stabilised with the Thomas splint before transport.

Within two years, mortality from compound femoral fracture in the British Army had fallen from 87% to under 8%.

Stat Callout (Mortality) — Poppins

87→8

% mortality

The Thomas splint is, on the strength of that statistic alone, one of the most quietly important pieces of medical equipment of the twentieth century — and it has remained in continuous hospital use ever since.

It has, however, remained an acute injury device. Hospital-grade. Bulky. Worn for hours, not weeks.

The principle Thomas pioneered — rigid lateral containment of the knee, externally applied — has, until very recently, not been rebuilt at a scale a person could wear under their trousers on the school run, in the garden, or on the walk to the car park.

The modern application

the same principle, rebuilt for daily life

The brace now made under the name Curae is, in a single sentence, the Thomas principle rendered for daily wear. Not a sleeve, not a sport brace, not an unloader brace — a consumer-grade descendant of the 1865 device, built around the exact problem Felson, Nevitt, and the MOST cohort have spent twenty years documenting.

curae+ three components do the work.

Component 01

Dual flexible spring-steel side stabilisers

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Two slim spring-steel rods sit on the medial and lateral sides of the knee. They flex through the natural range of motion — walking, descending stairs, standing from a chair — but resist lateral collapse. They act, in effect, as external collateral ligaments: where the patient's own have slackened, the rods take over the containment work.

Component 2

The SLS micro-adjustable tension dial

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A one-handed dial on the front of the brace lets the wearer tighten or loosen it in real time. This is the single most important difference between Curae and every drugstore sleeve on the market. A standard sleeve has one fixed tension, set at the factory, usually wrong for at least half the day. Only an adjustable dial lets the wearer tighten for the walk to the car park and loosen for the meal, without removing the brace — the structural answer to the most common complaint in the category: "it slides down by lunchtime."

Component 3

The integrated patella gel cushion

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A soft pad sits directly over the kneecap, offloading pressure during bending. The kneecap takes approximately five times bodyweight on the descent of a single stair, which is why the wobble is felt most acutely on stairs and on standing up from low chairs. The gel cushion absorbs that load.

Three components. One principle. The principle is a hundred and sixty years old.

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What to expect

what begins to happen, and on what timeline

It is worth being honest about what to expect, because every other brace in this category has overpromised, and our reader has been promised quick results for forty years.

Recovery Timeline — Poppins

Week 1

The first descent of the stairs without reaching for the rail. The sensation, on standing up from a low chair, of the knee being quiet in a way it has not been for some time. A small, almost surprising thing — the wobble does not come.

Weeks 2–3

The activity audit that has run quietly in the background for years begins to run in reverse. The shortened dog walk gets a little longer. The supermarket trip stops requiring planning around the kerb. The garden bed gets knelt in for half an hour, then an hour.

Weeks 4–5

The bigger items return. The walk along the foreshore. The hike with the grandchildren on the easier paths. The wedding where the brace is worn under a suit and the walk back to the car at midnight, on a gravel drive, happens without a second thought.

The brace does not heal the ligaments. We want to be clear on that. What it does is take over the structural work the ligaments are no longer fully doing — which allows the patient, while wearing it, to use the leg the way they used to use the leg. The activities that come back, come back because the knee has stopped vetoing them.

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"I gave up kneeling in the garden about eighteen months ago. Getting down was fine, getting back up was the issue. Last weekend I was out there for two and a half hours without checking the time."

Michael R.

Verified Customer

"I've tried three braces before this. They either slipped by lunchtime or were so tight I took them off within the hour. The dial is the difference. I set it in the morning, it holds. Eleven hours today and I haven't thought about it since breakfast."

Rachel B.

Verified Customer

"My grandkids had started asking me to sit on the floor with them. I'd been saying no for two years — I could get down but the getting back up was unpredictable. Said yes last Sunday. Forty minutes on the floor. No drama."

Sarah T.

Verified Customer

"The first few steps of the morning were always the worst. I'd sit on the edge of the bed for a minute before committing. That's just gone now. I get up and walk."

Amanda K.

Verified Customer

60-day Money-back guarantee

sixty days to find out if it's yours

Curae offers a sixty-day money-back guarantee with free returns in Australia, the US, the UK, and Canada. Wear it for two months; if your knee feels no different and you have not begun adding things back to your week, send it back for a full refund.

Guarantee Panel — Poppins

Sixty-day money-back guarantee — wear it, test it, decide

Free returns across AU, US, UK and CA

No questionnaire, no restocking fee, no condition on the box

For a customer who has, by the time they reach this article, often spent the better part of a decade buying products that did not work, the sixty days is the meaningful part. It is the first time the risk of trying something has actually been taken off the customer's shoulders.

Whether the brace works for you specifically is, in the end, something only sixty days of wearing it will answer. But the mechanical principle it is built around — the one Hugh Owen Thomas described in 1865, the one that brought British Army femoral fracture mortality from 87% to 8%, the one that Felson, Nevitt, and the MOST cohort have spent two decades quietly documenting in older adults — that principle is not new, not unproven, and not in dispute.

It has simply, finally, been rebuilt at a scale you can wear under your trousers.

See the Curae

Stability Brace

Read the full specification, the sizing chart, and how the brace works in daily wear — then decide for yourself whether two months of trying it is worth the risk.

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Sixty-day money-back guarantee · Free returns in AU, US, UK & CA

A note from the editor. If you recognised yourself in this article — the rail, the kitchen, the worry about the walk back — please do not read it as a verdict on your own decline. In the available research, the patients who recognise themselves earliest in a piece like this are also the ones who recover most of what they had been quietly losing. The thing about the activity audit is that it runs in either direction.

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Sources & further reading

1. Felson DT, et al. "The Prevalence of Knee Buckling Among Older Persons." Annals of Internal Medicine, 2007; 147(8): 534–540.

2. Nevitt MC, Tolstykh I, Shakoor N, et al. "Symptoms of Knee Instability as Risk Factors for Recurrent Falls." Arthritis Care & Research, 2016; 68(8): 1089–1097.

3. Negus J. "Why Your Knee Feels Wobbly (Even Without a Fall)." drjnegus.com — Dr Jonathan Negus, orthopaedic surgeon, Sydney.

4. Robinson PM, O'Meara MJ. "The Thomas splint: its origins and use in trauma." Journal of Bone and Joint Surgery (Br), 2009; 91-B(4): 540–544.

5.Glenside Hospital Museum, Bristol. Archival records on Sir Robert Jones, the Thomas splint, and First World War femoral fracture mortality.

This is an advertorial and not an actual news article, blog, or consumer protection update.

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