SummaryBackground-Falls in elderly people are a major health burden, especially in the long-term care environment. Yet little objective evidence is available for how and why falls occur in this population. We aimed to provide such evidence by analysing real-life falls in long-term care captured on video.

No abstract

No abstract

A major determinant of the risk of hip fracture in a fall from standing height is the force applied to the femur at impact. This force is determined by the impact velocity of the hip and the effective mass, stiffness, and damping of the body at the moment of contact. We have developed a simple experiment (the pelvis release experiment) to measure the effective stiffness and damping of the body when a step change in force is applied to the lateral aspect of the hip. Results from pelvis release experiments with 14 human subjects suggest that both increased soft tissue thickness over the hip and impacting the ground in a relaxed state can decrease the effective stiffness of the body, and subsequently reduce peak impact forces. Comparison between our fall impact force predictions and in-vitro measures of femoral fracture strength suggest that any fall from standing height producing direct, lateral impact on the greater trochanter can fracture the elderly hip.

No abstract

This paper proposes a Kalman filter-based attitude (i.e., roll and pitch) estimation algorithm using an inertial sensor composed of a triaxial accelerometer and a triaxial gyroscope. In particular, the proposed algorithm has been developed for accurate attitude estimation during dynamic conditions, in which external acceleration is present. Although external acceleration is the main source of the attitude estimation error and despite the need for its accurate estimation in many applications, this problem that can be critical for the attitude estimation has not been addressed explicitly in the literature. Accordingly, this paper addresses the combined estimation problem of the attitude and external acceleration. Experimental tests were conducted to verify the performance of the proposed algorithm in various dynamic condition settings and to provide further insight into the variations in the estimation accuracy. Furthermore, two different approaches for dealing with the estimation problem during dynamic conditions were compared, i.e., threshold-based switching approach versus acceleration model-based approach. Based on an external acceleration model, the proposed algorithm was capable of estimating accurate attitudes and external accelerations for short accelerated periods, showing its high effectiveness during short-term fast dynamic conditions. Contrariwise, when the testing condition involved prolonged high external accelerations, the proposed algorithm exhibited gradually increasing errors. However, as soon as the condition returned to static or quasi-static conditions, the algorithm was able to stabilize the estimation error, regaining its high estimation accuracy.

Summary:The risk for hip fracture from a fall is known to decrease with increased body mass index (weight/height*), a relative measure of obesity. To explore whether this reduced risk is due to the protective effect of increased soft-tissue cushioning in obese individuals, we used an impact pendulum and surrogate human pelvis to conduct simulated fall impact experiments on trochanteric soft tissues harvested from the cadavers of nine elderly individuals. For each impact, the total applied energy was 140 J. Peak forces ranged from 4,050 to 6,420 N, and tissue energy absorption ranged from 8.4 to 81.6 J. Increased tissue thickness correlated strongly with both decreased peak force (r2 = 0.91) and increased tissue energy absorption (r2 = 0.76). However, peak forces in all cases were within 1 SD of previously reported average fracture forces for elderly cadaveric femora. This suggests that force attenuation in trochanteric soft tissues alone is insufficient to prevent hip fracture in falls in which an elderly person lands directly on the hip. In such falls, additional energy-absorbing mechanisms, such as breaking the fall with an outstretched hand and eccentric contraction of the quadriceps during descent, are likely to be involved if fracture does not occur.Several studies have shown that high body mass index (weight/height2) decreases the risk for hip fracture in a fall (4,7,11,24). However, the reason for this association is unknown. One possibility lies in the observed correlation between high body mass index and high regional bone density (2), which correlates with increased femoral fracture strength (3,12). A n alternative explanation is that high body mass indices may reflect decreased body height and thus lower potential energy and height of descent in a fall from standing. However, the above possibilities do not appear to explain fully the link between body mass index and fracture risk given that a recent study by Greenspan et al. (7) found that body mass index, femoral bone mineral density, and potential energy of the fall (calculated from body mass and fall height) all were significant and independent predictors of fracture risk. A final possibility is that individuals with high body mass indices are likely to possess a greater thickness of fat tissue over the greater trochanter (13), and this fat cushions the impact and reduces the energy that must be absorbed by the femur. It is this last possibility that we are interested in exploring here.Several previous studies have shown that considerable energy is absorbed by skin and subcutaneous tissues during impact to the human body. Nikolic et al. (15) conducted an in vitro study with a dual pendulum system to determine the energy required to cause fracture of the radius from an impact to the palmar side of the hand. By comparing fracture energies from specimens having various degrees of intact skin, adipose tissue, muscle, and ligament, they concluded that 30-55% of the total impact energy is absorbed by the skin and subcutaneous tissue, 25-40% is absorbed...

Background Fall-related injuries exert an enormous health burden on older adults in long-term care (LTC). Softer landing surfaces, such as those provided by low-stiffness “compliant” flooring, may prevent fall-related injuries by decreasing the forces applied to the body during fall impact. Our primary objective was to assess the clinical effectiveness of compliant flooring at preventing serious fall-related injuries among LTC residents. Methods and findings The Flooring for Injury Prevention (FLIP) Study was a 4-year, randomized superiority trial in 150 single-occupancy resident rooms at a single Canadian LTC site. In April 2013, resident rooms were block randomized (1:1) to installation of intervention compliant flooring (2.54 cm SmartCells) or rigid control flooring (2.54 cm plywood) covered with identical hospital-grade vinyl. The primary outcome was serious fall-related injury over 4 years that required an emergency department visit or hospital admission and a treatment procedure or diagnostic evaluation in hospital. Secondary outcomes included minor fall-related injury, any fall-related injury, falls, and fracture. Outcomes were ascertained by blinded assessors between September 1, 2013 and August 31, 2017 and analyzed by intention to treat. Adverse outcomes were not assessed. During follow-up, 184 residents occupied 74 intervention rooms, and 173 residents occupied 76 control rooms. Residents were 64.3% female with mean (SD) baseline age 81.7 (9.5) years (range 51.1 to 104.6 years), body mass index 25.9 (7.7) kg/m 2 , and follow-up 1.64 (1.39) years. 1,907 falls were reported; 23 intervention residents experienced 38 serious injuries (from 29 falls in 22 rooms), while 23 control residents experienced 47 serious injuries (from 34 falls in 23 rooms). Compliant flooring did not affect odds of ≥1 serious fall-related injury (12.5% intervention versus 13.3% control, odds ratio [OR]: 0.98, 95% CI: 0.52 to 1.84, p = 0.950) or ≥2 serious fall-related injuries (5.4% versus 7.5%, OR: 0.74, 95% CI: 0.31 to 1.75, p = 0.500). Compliant flooring did not affect rate of serious fall-related injuries (0.362 versus 0.422 per 1,000 bed nights, rate ratio [RR]: 1.04, 95% CI: 0.45 to 2.39, p = 0.925; 0.038 versus 0.053 per fall, RR: 0.81, 95% CI: 0.38 to 1.71, p = 0.560), rate of falls with ≥1 serious fall-related injury (0.276 versus 0.303 per 1,000 bed nights, RR: 0.97, 95% CI: 0.52 to 1.79, p = 0.920), or time to first serious fall-related injury (0.237 versus 0.257, hazard ratio [HR]: 0.92, 95% CI: 0.52 to 1.62, p = 0.760). Compliant flooring did not affect any secondary outcome in this study. Study limitations included the following: findings were specific to 2.54 cm SmartCells compliant flooring installed in LTC resident rooms, standard fall and injury prevention interventions were in us...