Elderly falls is one of the mechanisms that can trigger the downward spiral of independent living. Without the proper training and diet, osteoporosis may make it more likely to break a bone. Fracturing a hip can literally be a death sentence for some individuals. In 2010, 258,000 people age 65 or older had hip fractures. Within one year, 1 out 5 died because of complications dealing with the hip fracture.
Reading through Human Locomotion by Thomas Michaud, he mentions some worthwhile ideas as relating to the elderly.
Proprioception, (the sense of body awareness) just like muscles, gets weaker as we age. The foot itself has a ton of information to give the body. A few suggestions were vibrating insoles and also an irritating insole. Both combined to give more proprioception and lead to less falls by stimulating mechanoreception in the skin.
He goes on to state that most elderly and most recommendations suggest the opposite. I can verify this. Most of my elderly clients wear tanks on their feet. Well cushioned and heavy. This does the opposite of providing proprioception to the body. It actually takes information away.
Some things to remember. When your toes splay, (spread apart) there is a reflex that triggers your quadriceps to engage. This essentially helps support you further. If your big toe goes through adequate range of motion, your glute max engages more fully.
So, with a big, heavy shoe, chances are we are decreasing information to the body and stunting two of the largest muscles in the body. Doesn't seem like such a great idea to me.
Some concerns to deal with before putting your grandparents into minimalist shoes. As we age we lose our calcaneal fat pad, it atrophies, as well as the metacarpal fat pad. So the goal is to have the least amount of cushioning and not irritate the bones. This is individual. No cookie cutter answers there.
What can be done is test the proprioceptors. One should be able to stand on one foot with eyes closed for 10 seconds. If you can't pass, start some balance training. This is different then just strength training. Balance training activates the subcortical pathway, which when trained activates automatically.
Strengthen the flexor digitorum longus muscle. Weakness here has been shown to have higher prevalence of falling. Simply pointing the toes (minus the big piggie) against some form of resistance will strengthen these.
The best medicine is prevention. Don't wait for a fall to get someone into PT. Fire up the proprioception system and strengthen a few key muscles and perhaps wear a truck instead of a tank.