So researchers used strategically placed video cameras in long-term care facilities to capture spills among residents so they could analyze the mechanics of various falls, with the goal of improving prevention.
"We've known for a long time that falls are the number 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 number 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, who led the study published in this week's issue of the Lancet, 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 hallways, public dining halls and lounges in two B.C. long-term care residences. They analyzed recordings of 227 falls involving 130 individuals, separating the falls 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," he said.
"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.
"And they were most often due to what we call incorrect weight shifting," he 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 who toppled over 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 is important because it reinforces and expands on similar work done by his group published in the early 1990s.
That research found that tipping past the centre of balance due to incorrect weight shifting was the most common cause of falls among the elderly. However, the study analyzed only about 25 falls using less sophisticated videotaping equipment, he 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 furniture in long-term care facilities could be designed with a central base rather than legs to prevent tripping falls.
Fernie said walkers can also be a problem because when an individual begins leaning past their centre of gravity, they tend to step sideways to steady their base of support. But the legs of the walker are in the way, preventing a sidestep and leading to a fall tangled up in the supportive device, a spill that 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."
The Canadian study provides objective analyses of the mechanics of falling. However, 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.
"To study falls in the community, we will need a technological shift," he writes. "Evidence provided by Robinovitch and colleagues of the movement patterns that lead to falls is helpful in guiding the design of sensor-based fall monitoring systems.
"The next step will require co-ordinated action and possibly an open-access database that would allow real-world fall data, obtained through different sensors, to be shared."
Figuring out how to prevent falls among seniors is an important public health goal, said Robinovitch. 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," he said, adding that even fear of falling can lead to diminished health because people become less active and their muscles weaken.
"So it really is a serious problem. When you think about it, any fall from standing is a life-threatening event for anyone."