Characterizing the demands of backward balance loss and fall recovery during stair descent to prevent injury

The Effect of Handrail Cross-Sectional Design and Age on the Speed and Quality of Reach-To-Grasp Reactions to Recover Balance

OBJECTIVE

To determine the effect of handrail cross-section on the speed and quality of reach-to-grasp movements following balance loss in younger and older adults.

BACKGROUND

Grasping a handrail is a common strategy for balance recovery. For handrails to be effective, the design must enable fast and accurate reactive grasping. Little is known about the effect of handrail cross-section on the timing or quality of the reach-to-grasp movement following balance loss.

METHODS

Twenty-four younger and 16 older adults experienced incrementally increasing magnitudes of perturbations in the forward and backward direction until they were no longer able to recover balance. We analyzed the last trial where the participant could recover using only the handrail, without stepping or relying on the harness, the maximum withstood perturbation (MWP). Seven handrail cross-sections were tested.

RESULTS

Handrail cross-section did not affect the speed or timing of the reach-to-grasp reaction for younger or older adults. However, handrail cross-section affected the MWP, the grip types used, and the likelihood of making an error or adjustment when grasping. The greatest MWP and fewest errors occurred with 1.5" round handrails.

CONCLUSION

The absence of common strategies for accurately grasping complex shapes (reaching more slowly), combined with the higher frequency of errors with larger handrails, suggests that both older and younger adults prioritized quickly reaching the handrail over prehension during reach-to-grasp balance reactions.

APPLICATION

This work provides new insights on the effect of age and handrail cross-sectional design on reach-to-grasp reactions to recover balance, which can inform safer handrail design standards.

Outcomes after stairway falls in a rural Appalachian trauma center

BACKGROUND

Injuries due to falls represent one of the most common etiologies of traumatic injury in the United States. Stairway-related falls in particular can lead to significant morbidity, mortality, and concomitant long-term disability and economic costs. Our study aims to evaluate the outcomes of patients presenting to a rural academic trauma center after experiencing a fall down stairs.

METHODS

This was a single institution retrospective analysis of data extracted from our trauma registry. The study was considered exempt by Ballad Health Institutional Review Board. The data included patients aged 18 years or older who presented to the emergency department after a fall down stairs between January 1, 2017, and June 17, 2022. Patients who experienced falls other than those involving stairs were excluded.

RESULTS

Of the 439 patients evaluated for falls down stairs, 259 (58.9%) were aged ≥65 years. Compared with younger patients, older patients required significantly longer hospital admissions (4.8 vs 3.6 days, P < .003), had significantly higher injury severity scores (9.1 vs 6.8, P < .05), and were more likely to be discharged to a posthospital care facility (51% vs 14.9%, P < .05). There was no difference in length of intensive care unit stay (3.8 vs 3.6 days, P < .72), ventilator days (3.3 vs 3.3 days, P < .97), or mortality (7% vs 3%, P < .08). When considering sex, male patients had significantly worse outcomes in injury severity score (9.0 vs 7.6, P < .02) and mortality (10% vs 2%, P < .0002) but no difference in hospital (4.5 vs 4.0 days, P < .20), intensive care unit (3.8 vs 3.5 days, P < .59) or ventilator days (2.8 vs 4.3 days, P < .27) when compared with female patients.

CONCLUSION

Patients aged 65 years or older who experience a fall down stairs are more severely injured and require more posthospital care. Our findings demonstrate that males have an elevated risk of mortality and increased injury severity compared to female patients. Previous findings from our institution examining injuries from falls, including a sub-analysis on ground-level falls, have shown similar sex disparity. This study shows the necessity of preventing stair-related falls, especially in the older population.

Risky behavior during stair descent for young adults: Differences in men versus women

Injuries commonly occur on stairs, with high injury rates in young adults, especially young women. High injury rates could result from physiological and/or behavioral differences; this study focuses on behaviors. The purposes of this observational study were (1) to quantify young adult behaviors during stair descent and (2) to identify differences in stair descent behavior for young adult men versus women. Young adult pedestrians (N = 2,400, 1,470 men and 930 women) were videotaped during descent of two indoor campus staircases, a short staircase (2 steps) and a long staircase (17 steps). Behaviors during stair descent were coded by experimenters. Risky behaviors observed on the short staircase included: No one used the handrail, 16.1% used an electronic device, and 16.4% had in-person conversations. On the long staircase: 64.8% of pedestrians did not use the handrail, 11.9% used an electronic device, and 14.5% had in-person conversations. Risky behaviors observed more in women included: less likely to use the handrail (long staircase), more likely to carry an item in their hands (both staircases), more likely to engage in conversation (both staircases), and more likely to wear sandals or heels (both staircases) (p≤0.05). Protective behaviors observed more in women included: less likely to skip steps (both staircases), and more likely to look at treads during transition steps (long staircase) (p≤0.05). The number of co-occurring risky behaviors was higher in women: 1.9 vs 2.3, for men vs women, respectively (p<0.001). Five pedestrians lost balance but did not fall; four of these pedestrians lost balance on the top step and all five had their gaze diverted from the steps at the time balance was lost. The observed behaviors may be related to the high injury rate of stair-related falls in young adults, and young women specifically.

Effect of Handrail Height and Age on Trunk and Shoulder Kinematics Following Perturbation-Evoked Grasping Reactions During Gait

OBJECTIVE

To characterize the effect of handrail height and age on trunk and shoulder kinematics, and concomitant handrail forces, on balance recovery reactions during gait.

BACKGROUND

Falls are the leading cause of unintentional injury in adults in North America. Handrails can significantly enhance balance recovery and help individuals to avoid falls, provided that their design allows users across the lifespan to reach and grasp the rail after balance loss, and control their trunk by applying hand-contact forces to the rail. However, the effect of handrail height and age on trunk and shoulder kinematics when recovering from perturbations during gait is unknown.

METHOD

Fourteen younger and 13 older adults experienced balance loss (sudden platform translations) while walking beside a height-adjustable handrail. Handrail height was varied from 30 to 44 inches (76 to 112 cm). Trunk and shoulder kinematics were measured via 3D motion capture; applied handrail forces were collected from load cells mounted to the rail.

RESULTS

As handrail height increased (up to 42 inches/107 cm), peak trunk angular displacement and velocity generally decreased, while shoulder elevation angles during reaching and peak handrail forces did not differ significantly between 36 and 42 inches (91 and 107 cm). Age was associated with reduced peak trunk angular displacements, but did not affect applied handrail forces.

CONCLUSION

Higher handrails (up to 42 inches) may be advantageous for trunk control when recovering from destabilizations during gait.

APPLICATION

Our results can inform building codes, workplace safety standards, and accessibility standards, for safer handrail design.

Underlying mechanisms of fall risk on stairs with inconsistent going size

Serious falls occur frequently on stairs with inconsistent dimensions. Inconsistent smaller goings are thought to reduce user's foot clearances and foot contact lengths since individuals do not detect and alter their behaviour prior to the inconsistency, increasing the risk of a trip, heel-catch or over-step and potential slip on the stairs. So far, these mechanisms for a stair fall remain theoretical only. The aim of this paper was to identify the underlying mechanisms by which steps with inconsistent going size increase the risk of falls. For this study twenty-seven younger adults (24 ± 3 y, 1.74 ± 0.09 m, 71.41 ± 11.04 kg) and thirty-three older adults (70 ± 4 y, 1.68 ± 0.08 m, 67.90 ± 14.10 kg) ascended and descended a seven-step instrumented staircase in two conditions: 1) consistent dimensions with 200 mm risers and 250 mm goings and 2) inconsistent going dimensions where the going of the third step was reduced by 10 mm, and consequently the going of the second step was larger by 10 mm. Five repeated trials on the inconsistent stairs were performed to assess if there was an adaptation effect after first exposure. In descent in the first inconsistent trial, foot contact lengths were not significantly different between conditions for the younger and older adults on the inconsistently shorter step (∼1%, p = .121). Foot trajectories were pulled further back in the last 22% of swing before contact (p = .025), contradicting previous expectations. Younger adults then had reduced clearances over the next step (∼5 mm, p = .027), which was inconsistently longer, increasing the risk of a heel-catch, whereas foot clearances for older adults were not different. With repeated inconsistent trials the foot contact length of older adults reduced on the shorter step (p = .024). In ascent, in the first inconsistent trial, interaction effects were detected between groups and conditions on three steps: the inconsistently longer step (p = .003), the shorter step (p = .004), the next step (p = .006), as well as on the walkway (p = .048). Older adults positioned themselves further away from the stairs on the walkway compared to younger adults and then had a reduced foot contact length on the inconsistently shorter step (∼2.8%, p = .026), increasing the chances of under-stepping and slipping off the shorter step. Whereas younger adults were positioned closer to the stairs on the walkway, had increased foot contact lengths on the inconsistently longer step and contact lengths that were not different on the inconsistently shorter step. With repeated inconsistent trials, foot contact lengths were reduced on the longer step (p = .006) and then on the shorter step (p = .018). These findings contradict previous assumptions that individuals do not adapt to inconsistent goings on stairs. In descent on the first trial, both groups adjusted their stepping behaviour late in the swing prior to contact with the first inconsistent step. In ascent younger adults made changes to their position and stepping behaviour before stepping on the stairs. These behaviours to mitigate the risk of the inconsistent step, did not persist in the repeat trials. Future investigations should establish the magnitude at which inconsistencies are detectable and can be acted upon and should include a wider range of individuals. This type of research could help inform future initiatives to prevent serious stair falls.

Injuries from falls by older adults in long-term care captured on video: Prevalence of impacts and injuries to body parts

Background

Falls are the leading cause of injuries in older adults. However, most falls in older adults do not cause serious injury, suggesting that older adults may fall in a manner that reduces the likelihood of impact to body sites that are most vulnerable to injury. In this observational study of falls in long-term care (LTC), we tested whether body parts differed in their probability of impact and injury.

Methods

We recorded and analyzed videos of 2388 falls by 658 LTC residents (mean age 84.0 (SD = 8.1); 56.4% female). We used Linear Mixed Models to test for differences between body parts in the probability of impact and injury, and injury when impacts occurred.

Results

Injuries were reported in 38.2% of falls, and 85.9% of injuries involved direct impact to the injured body part. Impact occurred most often to the hip/pelvis (probability (standard error) = 0.95 (0.01); p < .001 relative to other body parts), and least often to the head (0.35 (0.01)). Conversely, injury occurred most often to the head (p < .001 relative to other body parts). The probability of injury when impacts occurred was 0.40 (0.01) for the head, and 0.11 or less for all other body parts.

Conclusion

Our results help to explain why most falls by older adults in LTC do not cause serious injury: residents land on body parts that are the most resilient to injury. The high susceptibility of the head to injury reinforces the need to enhance upper limb protective responses for fall arrest. The dominant role of direct impact as the mechanism of injury supports approaches to attenuate impact forces through strategies like protective clothing and compliant flooring.

The effect of handrail cross-sectional design and age on applied handrail forces during reach-to-grasp balance reactions

Handrails have been shown to reduce the likelihood of falls. Despite common use, little is known about how handrail shape and size affect the forces that people can apply after balance loss, and how these forces and the corresponding ability to recover balance depend on age. Following rapid platform translations, 16 older adults and 16 sex-matched younger adults recovered their balance using seven handrail cross-sections varying in shape and size. Younger adults were able to withstand higher perturbations, but did not apply higher forces, than older adults. However, younger adults achieved their peak resultant force more quickly, which may reflect slower rates of force generation with older adults. Considering handrail design, the 38 mm round handrails allowed participants to successfully recover from the largest perturbations and enabled the highest force generation. Conversely, tapered handrails had the poorest performance, resulting in the lowest force generation and withstood perturbation magnitudes. Our findings suggest that the handrail cross-sectional design affects the magnitude of force generation and may impact the success of recovery. Our findings can inform handrail design recommendations that support effective handrail use in demanding, balance recovery scenarios.

A kinematic analysis of balance recovery following an unexpected forward balance loss during stair descent

Falls during stair descent pose a major health concern. A stronger understanding of recovery from balance loss during stair descent is needed to guide fall prevention strategies and environmental design. We characterized balance recovery strategies, trunk and center-of-mass (COM) kinematics, and handrail use following unexpected forward balance loss during stair descent, and the effect of perturbation magnitude on these outcomes. Eighteen young adults experienced a rapid platform translation during stair descent to disrupt balance. Deception was used to reduce anticipation. All participants used compensatory stepping to recover balance, and most applied forces to the handrail in multiple directions. Higher perturbation magnitude resulted in higher COM velocity and handrail forces, more frequent incomplete steps, and quicker step contact time. Our findings provide a foundation for understanding balance recovery on stairs. The findings emphasize the importance of designing stairways that enable compensatory stepping, and handrails that permit adequate force generation in multiple directions to facilitate balance recovery on stairs.

Negotiating stairs with an inconsistent riser: Implications for stepping safety

Stairs are associated with falls, especially when step dimensions are inconsistent. However, the mechanisms by which inconsistencies cause this higher risk are mostly theoretical. In this experimental study we quantified the effect of inconsistent rise heights on biomechanical measurements of stepping safety from younger (n = 26) and older adults (n = 33). In ascent, both groups decreased foot clearance (~9 mm) over the inconsistently higher step (F(1,56) = 48.4, p < 0.001). In descent, they reduced foot contact length on the higher step by 3% (F(1,56) = 9.1, p < 0.01). Reduced clearance may result in a toe-catch potentially leading to a trip, while reduced foot contact lengths increase the risk of overstepping which may also lead to a fall. These effects occurred because participants did not alter their foot trajectories, indicating they either did not detect or were not able to adjust to the inconsistent rise, increasing the likelihood of a fall. Consistent stair construction is vital, and existing inconsistencies should be identified and safety interventions developed.

Effect of Holding Objects on the Occurrence of Head Impact in Falls by Older Adults: Evidence From Real-Life Falls in Long-Term Care

BACKGROUND

Falls cause approximately 80% of traumatic brain injuries in older adults, and nearly one third of falls by residents in long-term care (LTC) result in head impact. Holding objects during falls, such as mobility aids, may affect the ability of LTC residents to avoid head impact by arresting the fall with their upper limbs. We examined the prevalence of holding objects and their effect on risk for head impact during real-life falls in older adults living in LTC.

METHODS

We analyzed videos of 1105 real-life falls from standing height by 425 LTC residents, using a validated questionnaire to characterize the occurrence of head impact and whether the resident held objects during descent and impact. We classified objects as either "weight-bearing" (via contact to the fixed environment, eg, chairs and walkers) or "non-weight-bearing" (eg, cups) and tested their effect on odds for head impact with generalized estimating equations.

RESULTS

Residents held objects in more than 60% of falls. The odds for head impact were reduced for falls where weight-bearing objects were held or grasped during descent (odds ratio = 0.52; 95% confidence interval = 0.39-0.70) or maintained throughout the fall (odds ratio = 0.34; 95% confidence interval = 0.23-0.49). The most commonly held objects were chairs/wheelchairs (23% of cases), tables/counters (10% of cases), and walkers/rollators (22% of cases); all reduced the odds of head impact when held during descent. Holding non-weight-bearing objects did not affect the odds of head impact (odds ratio = 1.00; 95% confidence interval = 0.64-1.55).

CONCLUSION

Our results show that older adults in LTC use held, weight-bearing objects to reduce their risk for head impact during falls.

Effect of handrail height and age on the timing and speed of reach-to-grasp balance reactions during slope descent

We investigated the effect of handrail height on the timing and speed of reach-to-grasp balance reactions during slope descent, in fourteen younger and thirteen older adults. Participants walked along an 8° slope mounted to a robotic platform. Platform perturbations evoked reach-to-grasp reactions. Handrail height did not significantly affect handrail contact time (i.e., time from perturbation onset to handrail contact) or movement time (i.e., time from EMG latency to handrail contact). Participants appeared to compensate for the increased hand-handrail distance with higher rails via increased peak upward hand speed, and decreased vertical handrail overshoot. Aging was associated with slower EMG latency, reduced hand acceleration time, and increased hand deceleration time. Our findings suggest that participants were not disadvantaged by higher handrails from reach-to-grasp timing or speed perspectives, and that other metrics (e.g., center-of-mass control after grasping) may be more important when evaluating handrail designs for balance recovery.