Canes and walkers, obviously. And, if the user begins to fall, they can often stop the fall. It's hard to see how a less obtrusive wearable device could do that.

I think OP is asking for any alternatives that are more fullproof than simply holding into a cane or walker. It can only take one stumble or slip and fall for someone at 80-90 to break a bone, never completely recover, and lose their ability live independently and be forced to go to a nursing home or other assisted care facility.

Though more intrusive to wear/use, I would imagine there are some bionic leg braces that could keep legs stable 99% of the time.

I don't think there's anything that could stop them from falling, but maybe it could warn them about how slippery the area is, based on the accelerations sensed by similar devices in the same spot. But I don't know of anything that does it.

What about shoes with active vacuum gripping? What causes the falls? Is it just an extreme version of how the young fall but with more dire consequences?

What about a device to rapidly and objectively measure if things are too slippery? Or a laser that can burn a decorative anti slip micro pattern into hardwood?

Maybe an accelerometer that can males sound of you tip over, if the problem is inner ear and not noticing you aren't upright.

Glasses with an artificial horizon to help low vision people who rely on sight to balance?

Does the presence or absence of sharp lines on wallpaper and the like do anything to help one balance with visual cues?

One thing Atul Gawande writes about in Being Mortal is podiatry as a simple intervention to reduce the rate of falls amongst the elderly. I don't have the book to hand and don't know if it had a corresponding citation, but worth a look.

A device that uses a gyroscope to force stability of the subject through angular momentum, and a shock collar to make sure they stay within acceptable bounds.

First one's been done already: https://m.youtube.com/watch?v=RhOrwjPkes0

Better first improve their diets. Quoted from linked article: "Tryptophan is among the nine amino acids our body can't make and we must consume in foods like turkey and soybeans so we can perform essentials like making protein." https://scienmag.com/major-research-initiative-explores-how-...

One of the biggest problems is perceived intrusiveness of whatever tech you propose. My mother, who has Alzheimers and is in a memory care facility, sometimes just refuses to use her walker. She's not all that prone to falls, but she seems to hang on to more able people a lot when she walks. If she was in better command of her own mind, she would probably see the logic of using mechanical assistance, but as it is now, if she's made up her mind that she doesn't want to do something, often no amount of persuasion will help.

Apple Watches and iPhones measure stability when walking. https://support.apple.com/en-us/HT212503

Flat surfaces and shoes, IMHO, reduce the amount of work it takes to stay balanced and thus makes it easier to fall. If you’re walking on uneven ground and need to be careful where and how you step your balance and the amount of attention you pay to it improve quickly.

Ask physical therapists. There is a whole subspecialty there about Gait and Balance. They would be familiar with devices and technology.

Four year olds -

> a group of older retirement home residents are brought together with a group of preschoolers, to see if this inter-generational contact can improve the health and well-being of the older people

Before and after testing demonstrated significant improvement in mental health, mobility, and balance (in both AU and UK).

[1] https://thetvdb.com/series/old-peoples-home-for-4-year-olds

[2] https://thetvdb.com/series/the-old-peoples-home-for-4-year-o...

[3] https://www.youtube.com/watch?v=13_rJVvxx_g

Staying active.

Would companies who make cycling airbags/protection be useful?

See helmets[0] or for hip guards [1]

[0] https://hovding.com/

[1] https://en.helite.com/hipguard/