Falls among seniors are a major cause of disability and death, but learning what led to a tumble can often be difficult after a person is found sprawled on the ground.
With the goal of better prevention, researchers in British Columbia used video cameras in long-term care facilities to capture spills among residents so they could analyze the mechanics of falls.
"We've known for a long time that falls are the No. 1 cause of injury in older adults, including 90 per cent of hip fractures and 60 per cent of head injuries. They're also the No. 1 cause of injury-related deaths," said Stephen Robinovitch, a researcher at Simon Fraser University who specializes in injury prevention and mobility biomechanics.
"So there's been a great deal of research focusing on the cause of falls, prevention of falls and fall-related injuries," Robinovitch said from Burnaby, B.C. "But really up until now, we've had no objective evidence on how and why these events occur."
To get a better sense of what happens when someone takes a tumble, researchers set up video cameras in public hallways, dining halls and lounges in two B.C. long-term care residences. They analyzed recordings of 227 falls involving 130 individuals, separating the spills into three stages: initiation, descent and impact.
"So what we found was that about 20 per cent of falls were due to trips and 10 per cent were due to being bumped or nudged by someone else, or hit by a door closing," said Robinovitch, who led the study published in this week's issue of the Lancet.
"But the remaining 70 per cent – and the reason why we think falls are so common in this population of frailer individuals in long-term care – they basically occurred during a failed attempt at performing daily activities like walking, sitting down and even just standing quietly."
These falls were most often caused by incorrect weight shifting, Robinovitch said, explaining that the person leaned too far past their centre of gravity, losing their base of support between the feet and the ground.
"So this might occur when you're turning or reaching. It also occurred when people stood up from sitting, but failed to achieve a stable final position."
Although not discussed in the Lancet paper, Robinovitch said the research shows 37 per cent of falls involved hitting the head, even though three-quarters of these elderly residents did get their arms out in an attempt to break their fall. "But this didn't affect their risk for head impact," he said.
"In a sense it's not bad news. We see people getting their arms out to protect themselves. But perhaps it's the lack of strength that is making it ineffective. And strength is one thing that we actually can target successfully through exercise, through resistance training. So maybe that's a future avenue to explore."
Geoff Fernie, director of the Toronto Rehab Research Institute, said the B.C. study reinforces and expands on similar work done by his group that was published in the early 1990s.
That research found that tipping past the centre of balance because of incorrect weight shifting was the most common cause of falls among the elderly. However, the study only analyzed about 25 falls using less sophisticated videotaping equipment, Fernie said.
The B.C. study also found that 25 per cent of trips occurred when a person's foot got caught on a table or chair leg, suggesting that designing furniture for long-term care facilities with a central base rather than legs could prevent seniors from tripping.
Fernie said walkers can also be a problem because when people begin leaning past their centre of gravity, they tend to step sideways to steady their base of support. But the legs of a walker get in the way, preventing a sidestep and leading to a fall that can leave a senior tangled up in the supportive device, which could conceivably cause even greater injury.
In a commentary accompanying the Lancet study, Dr. Clemens Becker of the Robert Bosch Hospital in Stuttgart, Germany, said many assumptions about falls and prevention strategies have been based on subjective information. "This absence of understanding is one of the reasons why efforts to prevent falls have had little success, although some progress has been achieved."
Although the Canadian study provides objective analyses of the mechanics of falling, Becker said one limitation is that researchers looked only at falls in public areas, which are thought to account for just half of all falls among long-term care residents.
Figuring out how to prevent falls among seniors is an important public health goal, Robinovitch said. Almost a third of older people who live independently, and about half of those residing in long-term care facilities, fall at least once each year.
"Falls are often the thing that breaks the camel's back," he said. "Someone who's at risk for falls could have multiple conditions. They could be taking medications, they could have diabetes or Parkinson's, or a history of stroke that put them at risk.
"But having said that, individuals will often be functioning perfectly well, living independently in the community or functioning well in residential care, and it is the fall that causes a downward spiral," Robinovitch said, adding that even fear of falling can lead to health problems because people become less active and their muscles weaken.
"When you think about it, any fall from standing is a life-threatening event for anyone."