Using wearable sensors to characterize gait after spinal cord injury: evaluation of test-retest reliability and construct validity.

STUDY DESIGN: Quantitative cross-sectional study. OBJECTIVES: Evaluate the test-retest reliability and the construct validity of inertial measurement units (IMU) to characterize spatiotemporal gait parameters in individuals with SCI. SETTING: Two SCI rehabilitation centers in Canada. METHODS: Eighteen individuals with SCI participated in two evaluation sessions spaced 2 weeks apart. Fifteen able-bodied individuals were also recruited. Participants walked 20 m overground under five conditions that challenged balance to varying degrees. Five IMU were attached to the lower-extremities and the sacrum to collect the mean and the coefficient of variation of five gait parameters (gait cycle time, double-support percentage, cadence, stride length, stride velocity). Intra-class correlation coefficients (ICC) were used to evaluate the test-retest reliability. Linear mixed-effects models were used to compare the five walking conditions to evaluate known-group validity while Spearman's correlation coefficients were used to characterize the level of association between gait parameters and the Mini BESTest (MBT). RESULTS: Cadence was reliable across all walking conditions. Reliability was higher for the mean (ICC = 0.55-0.98) of the parameters compared to their coefficient of variation (ICC = 0.16-0.97). Cadence collected with IMU had construct validity as their values differed across walking conditions and groups of participants. The coefficient of variation was generally better than the mean to show differences across the five walking conditions. The MBT was moderately to strongly associated with mean cadence (ρ ≥ 0.498) and its coefficient of variation (ρ ≤ -0.49) during most walking conditions. CONCLUSIONS: IMU provide reliable and valid measurements of gait parameters in ambulatory individuals with SCI.

Perspectives of individuals with chronic spinal cord injury following novel balance training involving functional electrical stimulation with visual feedback: a qualitative exploratory study.

BACKGROUND: Individuals with an incomplete spinal cord injury (iSCI) are highly susceptible to falls during periods of walking or standing. We recently reported the findings of a novel intervention combining functional electrical stimulation with visual feedback balance training (FES + VFBT) on standing balance abilities among five individuals with motor iSCI. However, the previous publication did not report the perceived impact of the intervention on the participants' lives. In this report, the experiences of these five individuals with incomplete spinal cord injury (iSCI) who had recently completed the four-week balance training program are described. METHODS: Five individuals with a motor iSCI took part in this study. Each individual was at least 12 months post-injury, capable of unassisted standing for 60 s and had a Berg Balance Scale Score < 46. Participants completed twelve sessions of a novel balance intervention combining closed-loop functional electrical stimulation with visual feedback balance training (FES + VFBT). Participants received visual feedback regarding their centre of pressure position as they completed balance-training exercises while FES was applied to the ankle plantarflexors and dorsiflexors bilaterally. Semi-structured interviews were conducted after completion of the balance training intervention and eight-weeks post-training to understand participant's experiences. Categories and themes were derived from the transcripts using conventional content analysis. RESULTS: Three themes were identified from the collected transcripts: (1) Perceived benefits across International Classification of Functioning, Disability and Health levels; (2) Change in perceived fall risk and confidence; (3) Motivation to keep going. CONCLUSIONS: Participation in the FES + VFBT program resulted in perceived benefits that led to meaningful improvements in activities of daily living. Following completion of the training, individuals felt they still had the capacity to improve. Individuals felt they had increased their balance confidence, while a few participants also reported a decrease in their risk of falling. The inclusion of qualitative inquiry allows for the evaluation of the meaningfulness of an intervention and its perceived impact on the lives of the participants. TRIAL REGISTRATION: NCT04262414 (retrospectively registered February 10, 2020).

Functional Electrical Stimulation Plus Visual Feedback Balance Training for Standing Balance Performance Among Individuals With Incomplete Spinal Cord Injury: A Case Series.

Individuals with an incomplete spinal cord injury (iSCI) are highly susceptible to falls during walking or standing. Our objective was to evaluate a therapeutic tool for standing balance that combined functional electrical stimulation, applied bilaterally to the plantarflexors and dorsiflexors, with visual feedback balance training (FES+VFBT). Five adults with iSCI completed 12 FES+VFBT sessions over 4 weeks. During the training sessions, participants completed each of the four balance exercises twice. Visual feedback of the center-of-pressure (COP) location was provided as participants completed the balance exercises and received FES to assist with performance of the exercises. A closed-loop FES system was used in which the COP was continually monitored and the level of electrical current administered was automatically adjusted. Balance abilities were assessed pre- and post- training using clinical balance scales (i.e., Berg Balance Scale, Mini-Balance Evaluation Systems Test, and Activities-specific Balance Confidence Scale) and biomechanical assessments (i.e., postural sway measures and limits of stability test during standing). User acceptability was explored through semi-structured interviews. Improvements were seen for four of the five participants on at least one of the clinical scales following completion of the training intervention. All participants showed greater maximal COP excursion area during the limits of stability test after the training intervention, whereas only one participant demonstrated a reduction in postural sway. Specific components of FES+VFBT, including the ability to safely practice challenging balance exercises, were deemed important by the participants. These results suggest that FES+VFBT has potential as an intervention for standing balance after iSCI.

Motorcyclist fatality rates and mandatory helmet-use laws.

Using cross-sectional time series data for the 50 states and Washington, DC, covering the period 1975-2004, we estimate fixed effects regression models that examine the effects of universal and partial helmet laws on three different motorcyclist fatality rates, while controlling for other state policies and characteristics. Depending on the particular measure that is employed, states with universal helmet laws have motorcyclist fatality rates that are on average 22-33% lower in comparison to the experience with no helmet law. Additionally, partial coverage helmet laws are associated with reductions in motorcyclist fatality rates of 7-10%, on average.

Motorcycle safety and the repeal of universal helmet laws.

OBJECTIVES: We assessed the implications for motorcyclist safety of recent repeals of universal helmet laws in 6 US states. METHODS: We examined cross-sectional time-series data from the 50 states and the District of Columbia for the period 1975 through 2004. RESULTS: On average, when compared to state experience with no helmet mandate, universal helmet laws were associated with an 11.1% reduction in motorcyclist fatality rates, whereas rates in states with partial coverage statutes were not statistically different from those with no helmet law. Furthermore, in the states in which recent repeals of universal coverage have been instituted, the motorcyclist fatality rate increased by an average of 12.2% over what would have been expected had universal coverage been maintained. Since 1997, an additional 615 motorcyclist fatalities have occurred in these states as a result of these changes in motorcycle helmet laws. CONCLUSIONS: Motorcyclist safety has been compromised in the states that have repealed universal coverage and is likely to be compromised in other states that abandon these statutes.

Are helmet laws protecting young motorcyclists?

PROBLEM: The trend in state mandatory motorcycle helmet laws is away from universal coverage to partial coverage statutes that require only young riders to wear a helmet. Among partial coverage states substantial variation exists in this age requirement. How effective are motorcycle helmet laws at reducing young motorcyclist fatalities? METHOD: The dependent variable is the number of motorcyclist fatalities 15-20 years of age. Fixed effects negative binomial regression models are estimated using panel data for all 50 states and Washington DC, for the period 1975-2004. RESULTS: Universal helmet laws are associated with fatality rates that are 31% lower among motorcyclists 15-20 years of age. In contrast, partial coverage laws targeting young motorcyclists are statistically unrelated to a reduction in the fatality rates of this age group. DISCUSSION: The long-term consequence of the move away from universal helmet laws will be an increased level of risk faced by young motorcyclists. In many states, mandatory motorcycle helmet laws are not protecting even young riders.

Safety belt use and the switch to primary enforcement, 1991-2003.

State seat belt laws have increased use rates and have reduced traffic fatalities, but tremendous variation exists in the laws. New Hampshire does not have a law, and 30 states have only secondary enforcement laws. Whereas primary enforcement allows an officer to issue a citation for any infraction, secondary enforcement permits a citation only if a motorist is stopped for another infraction first. We performed a cross-sectional time-series analysis of the impact of upgrading to primary enforcement on belt use rates for 47 states and the District of Columbia from 1991 to 2003. Our results suggest that states with secondary enforcement laws could increase belt use by 10 percentage points and improve public safety considerably by upgrading to primary enforcement.

Getting Americans to buckle up: the efficacy of state seat belt laws.

Annual state observed safety belt use rates over the period 1991-2001 are examined using time-series cross-section regression analysis. It was found that seat belt laws are associated with higher use rates and that the enforcement provision matters. Primary states experience belt use rates that on average are 9.1 percentage points higher than their secondary counterparts. In addition, the level of the fine imposed by statute has an effect on safety belt use apart from that attributable to the enforcement provision. The current median fine of 25 US dollars is associated with an additional 3.8 percentage points increase in belt use. To further increase safety belt use, it is recommended that states adopt primary enforcement and impose fines of at least $50 for violating a seat belt law.

Malaria on a military peacekeeping operation: a case study with no cases.

BACKGROUND: Malaria continues to be a disease of importance to travelers and the military is no exception. Individual protection measures based on advice, bite avoidance, chemoprophylaxis, and diagnosis are advocated for protection against the disease. However, the military has an additional strand to malaria protection--the chain of command. AIM: To describe the experience of a British military deployment where the Force Commander took a proactive approach to malaria protection. RESULTS: In 512 person-weeks of exposure in a theater with high rates of transmission of malaria, with an enduring threat of asymmetric military action and with a proactive approach by the chain of command to the implementation of malaria protection policy, no malaria cases developed. CONCLUSION: The chain of command can have a significant impact on compliance with malaria protection measures, which might reduce incidence of the disease in the deployed population.

Traffic safety and the switch to a primary seat belt law: the California experience.

This study explores whether the change of an existing seat belt law from secondary to primary enforcement enhances traffic safety. In particular, we examine traffic fatalities and injuries in California from 1988 to 1997. During the first half of this period, California law provided for secondary enforcement of its mandatory seat belt law, but in 1993 it upgraded the law to primary enforcement. Controlling for the number of motor vehicle collisions, a Box-Tiao intervention analysis of the time series is used to compare the monthly fatalities and injuries before and after the change in the enforcement provision. The results show that California experienced an improvement in traffic safety in terms of a significant reduction in injuries, but the change in enforcement provision had no statistically significant impact on fatalities.