Simple Tests Can Predict Amputees’ Fall Risk

Falls are a frustrating reality for people living with limb loss. If you use a lower-limb prosthesis, you probably know someone who’s taken a tumble—or maybe you’ve experienced it yourself. The statistics are sobering: More than half of people who use a leg prosthesis fall at least once a year, and these falls often result in serious injuries (such as fractures or head trauma) that land people in the hospital.

But what if your prosthetist could identify your fall risk and suggest preventive measures before you ever hit the ground? New research published in Clinical Biomechanics suggests that a few quick, simple tests performed in the clinic might make that possible—and the specific tests that matter most depend on whether you use a below-knee or above-knee prosthesis.

Healthcare providers have traditionally focused on treating injuries after falls occur rather than preventing them in the first place. Part of the problem has been a lack of clear guidelines about which clinical measures actually predict who will fall in the future. Previous research examining fall risk has generally lumped all lower-limb amputees together, regardless of whether they used a transtibial (below-knee) or transfemoral (above-knee) prosthesis.

This study, conducted by prosthetists and rehab specialists from North Texas University and the University of Washington, took a different approach. The research team recruited 21 adults with unilateral limb loss (14 below-knee, seven above-knee) and had them complete seven tests during a single clinical session. These weren’t elaborate exercises requiring expensive equipment—they were straightforward measures that any prosthetist or physical therapist can perform in about 30 minutes.

Participants completed familiar assessments such as the Timed Up and Go (TUG), where you stand from a chair, walk to a cone, turn around, and sit back down. They also did the Four Square Step Test (FSST), which involves quickly stepping forward, sideways, and backward over low canes arranged in a cross pattern. The team measured walking speed on level ground and collected questionnaires about socket comfort, mobility confidence, anxiety, and other factors.

In addition, rather than asking participants to recall falls from the past year (a common feature of previous studies), the research team followed them forward in time. Over a six-month period, participants checked in every two weeks and reported whether they had fallen. This prospective approach captures falls as they happen and, crucially, measures people’s baseline abilities before any falls occur.

The findings reveal that fall risk screening isn’t one-size-fits-all. The most accurate test depends on your level of amputation. For transtibial prosthesis users, two tests emerged as strong predictors, beginning with the FSST. Below-knee amputees who took 12.83 seconds or longer to complete the test were significantly more likely to fall within the next six months, compared to those who finished the exercise in fewer than 12.83 seconds. This factor identified future fallers with 83 percent accuracy.

Walking speed also proved valuable. Below-knee amputees who walked slower than 1.28 meters per second (about 2.9 miles per hour) faced higher fall risk than those with a faster pace. Interestingly, this threshold is faster than the typical fall-prediction cutoff used for older, nondisabled adults, suggesting that prosthesis users need different standards.

For transfemoral prosthesis users, the TUG test provided the clearest forecast of fall risk. Every study participant who took 9.44 seconds or longer to complete the TUG experienced a fall within the next six months. Given the small sample size, it’s not reasonable to conclude that this predictor is truly 100 percent accurate. But it seems clear that the TUG is particularly relevant for above-knee prosthesis users.

Why the difference? The authors speculate it relates to the unique challenges of transfemoral prosthesis use. Above-knee amputees tend to use ambulatory motions such as sound-side vaulting and affected-side hip hiking) that below-knee amputees don’t. They also experience greater gait asymmetry. The TUG’s specific tasks—rising from a chair, turning around a cone, sitting back down—seem to capture the extra risk involved in positioning a prosthetic knee joint for stability.

What makes these findings potentially game-changing is their simplicity. The FSST takes about 15 seconds to complete. The TUG takes less than a minute. Walking speed can be measured in a hallway. None require specialized equipment or extensive training.

“Clinicians’ ability to prospectively identify people who are at higher risk of falling could support targeted interventions to reduce fall risk, subsequently reducing fall-related health costs and increasing quality of life,” the authors write.

One unexpected finding challenges common assumptions about fear and falls. Among transtibial users, people who later fell actually reported less anxiety before their falls than those who didn’t fall. This aligns with an idea that’s emerged in other fall research: People who fall might actually be more active and engaged in their communities, giving them more opportunities to lose their balance. It’s worth noting that both fallers and nonfallers reported similar balance confidence levels, suggesting that confidence in your abilities doesn’t necessarily predict whether you’ll actually fall.

This was only an exploratory study with 21 participants (and just seven above-knee amputees), so the authors are cautious about their findings. They acknowledge that larger studies are needed to confirm whether these specific cutoff times hold true across diverse populations. Additionally, several participants who fell during the six-month follow-up period had also fallen in the previous year. Since people sometimes change how they walk after experiencing a fall, this could have influenced the results.

Even with those caveats, this research represents an important step toward proactive fall prevention in the limb loss community. It points the way toward specific, actionable tools rather than one-size-fits-all recommendations. If the screening identifies you as having high fall risk, your care team can intervene proactively—perhaps recommending balance training, adjusting your prosthetic components, or addressing environmental hazards at home before a fall occurs.

The next step is to validate these findings in larger, more diverse groups of prosthesis users. If the cutoff times hold up, they could eventually become standard screening tools—as routine as measuring blood pressure or checking socket fit.

For now, if you use a prosthesis, consider asking your prosthetist or physical therapist about incorporating these simple tests into your care. Even without official cutoff scores, tracking your performance over time could provide valuable insights into your fall risk and mobility changes.

After all, the best fall is the one that never happens.

The post Simple Tests Can Predict Amputees’ Fall Risk appeared first on Amplitude.