When the knee gives way.
In a study of 1,842 older adults with or at high risk of knee osteoarthritis, one in six said a knee had buckled. Those who had fallen during a buckling episode had 4.5 times the odds of repeated falls two years later.
It usually happens on an ordinary step. Stepping off a kerb, turning to answer the door, coming down the last stair with a bag in one hand. For a fraction of a second the knee stops holding. It folds a little, then catches. Most people grab a rail or a wall, carry on, and say nothing about it.
Clinicians call this buckling, or giving way. In the moment it often seems minor. But a steady body of research suggests that a knee you cannot quite trust is one of the quieter routes into a problem that ends a great deal of independent living: falling.
Falls are already common. In the United States, the Centers for Disease Control and Prevention reports that “over 14 million, or 1 in 4 older adults” say they fall every year, and that falls are the leading cause of injury for adults aged 65 and over.1 The age-adjusted death rate from falls among older Americans rose by 21% between 2018 and 2024, from 64.7 to 78.4 per 100,000.1 Worldwide, the World Health Organization estimates that 684,000 people die from falls each year, the second leading cause of death from unintentional injury, and that 37.3 million falls a year are severe enough to need medical care.2
How often a knee gives way
One of the first large counts came from the Framingham Osteoarthritis Study. In a paper published in 2007, David Felson and colleagues reported on 2,351 adults aged 36 to 94 who were asked whether a knee had buckled in the previous three months. Some 11.8% said it had. Of those, 78.1% had experienced more than one episode, and 12.6%, roughly one in eight, had fallen during one.3
Two details stand out. Buckling was independently linked to knee pain and to weakness of the quadriceps, the large muscle at the front of the thigh. And over half of the people whose knees buckled had no osteoarthritis visible on an X-ray.3 This is not only a problem of worn joints. A painful knee with weak muscles around it can give way long before an image shows much damage.
It also showed up in daily life. Among people with buckling, 46.9% reported limitations in their work, against 21.7% of those without (adjusted odds ratio 2.0), and their poorer physical function persisted after the authors took knee pain and weakness into account.3
From one stumble to a pattern
A snapshot cannot say what happens next. The Multicenter Osteoarthritis Study, known as MOST, could. Michael Nevitt, Felson and colleagues followed 1,842 adults who had knee osteoarthritis or were at high risk of it, with an average age of 67. At the five-year visit, 16.8% reported buckling. By seven years, 14.1% had fallen two or more times.4
People who reported buckling at five years had 1.6 to 2.5 times the odds of recurrent falls, fear of falling and poor balance confidence two years later.4 The strongest signal came from people who said, at the five-year visit, that they had fallen when a knee buckled. Two years on, they had 4.5 times the odds of recurrent falls, twice the odds of a significant fall injury and three times the odds of an injury that limited their activity, and they were four times as likely to have poor balance confidence.4
After a fall when the knee gave way
Increased odds two years later, as reported by the authors, for MOST participants who said at the five-year visit that they had fallen when a knee buckled
Source: Nevitt et al., Arthritis Care and Research (2016)
The authors concluded that treatments which reduce knee buckling may help prevent falls and their physical and psychological consequences in people with knee osteoarthritis.4 That is a hypothesis to test, not a proven remedy. But it changes how buckling looks: less a nuisance, more an early warning.
Does arthritis itself raise the risk?
Buckling is one route. A broader question is whether knee osteoarthritis on its own makes falls more likely. A 2023 systematic review and meta-analysis by Youyou Zhang and colleagues pooled 17 studies with 862,849 participants.5 Radiographic knee osteoarthritis was associated with higher odds of falling (odds ratio 1.28, 95% CI 1.03 to 1.59).5
The picture for symptoms was narrower. Symptomatic knee and hip osteoarthritis were linked to recurrent falls rather than to falls in general, and the review found no statistically significant link between knee or hip osteoarthritis and fractures.5 The evidence is observational, so it shows association rather than cause. Still, the direction is consistent: an unreliable knee and repeated falls tend to travel together. (We have written separately about how knee osteoarthritis unfolds over decades.)
The world gets smaller
Falling is half of the story. The other half is what people do to avoid it. In a study of 4,031 community-living people aged 70 and over, published in Age and Ageing in 2007, 54.3% reported a fear of falling.6 Across studies of older people living in the community, reported rates of fear of falling range from 20% to above 60%, and avoidance of activity because of that fear from 15% to above 55%.7
In the 2007 study, avoiding activity was independently associated with being 80 or older, with poor perceived health and with having fallen more than once.6
The avoidance makes sense, one decision at a time. If your knee let you down on the stairs, you use the stairs less. If it gave way on the walk to the shops, someone else does the shopping. Each choice is reasonable. Together they shrink a life: fewer trips out, fewer visits, fewer steps. The MOST findings fit that pattern: buckling was linked not only to more falls but to more fear of falling and less confidence in balance.4
Why this matters at home
For most people, the place a knee gives way is not a clinic. It is the bathroom, the kitchen, the front step. That is where the fear settles too, and where independence is negotiated quietly, one avoided staircase at a time. We have also looked at why standing up gets harder and at what happens when someone cannot get up after a fall.
Veema works on mobility at home because the moments that decide whether someone keeps living independently are small, physical and mostly unseen. Whether an exoskeleton can reduce buckling, falls or the fear of falling is a question only studies with older adults can answer.
These figures describe the need. They are not results or claims about Veema.
Sources
- Centers for Disease Control and Prevention, Older Adult Falls Data (updated 2026): Over 14 million, or 1 in 4, older adults report falling every year; falls are the leading cause of injury for adults 65 and over; fall death rate rose 21%, from 64.7 to 78.4 per 100,000 (2018 to 2024).
- World Health Organization, Falls fact sheet (2021): 684,000 fall deaths a year globally; falls are the second leading cause of unintentional injury death worldwide; 37.3 million falls a year need medical attention.
- Felson et al., Annals of Internal Medicine (2007): 2,351 adults aged 36 to 94; 11.8% buckled in 3 months, 78.1% of them more than once, 12.6% fell during an episode; over half had no radiographic OA; work limitation 46.9% vs 21.7% (adjusted OR 2.0); worse function after adjustment for knee pain and weakness.
- Nevitt et al., Arthritis Care and Research (2016): 1,842 adults aged 55 to 84, mean age 66.9; 16.8% buckling at 60 months; 14.1% recurrent falls by 84 months; 1.6 to 2.5 fold odds of recurrent falls, fear of falling and poor balance confidence; among those who fell when a knee buckled at the 60-month visit, 4.5, 2 and 3 fold odds of recurrent falls, significant fall injuries and injuries limiting activity, and 4 times as likely to have poor balance confidence.
- Zhang et al., Arthritis Research and Therapy (2023): 17 observational studies, 862,849 participants; radiographic knee OA and falls OR 1.28 (95% CI 1.03 to 1.59); symptomatic knee and hip OA linked to recurrent falls, not falls or fractures; no significant OA and fracture associations.
- Zijlstra et al., Age and Ageing (2007): 4,031 community-living people aged 70 and over; 54.3% reported fear of falling; avoidance of activity independently associated with age 80 and over, poor perceived health and multiple falls.
- Kempen et al., BMC Public Health (2009): Background: fear of falling prevalence in community-living older persons ranges from 20 to above 60%, and avoidance of activity due to fear of falling from 15 to above 55%.
