Validity and reliability of inertial measurement units for gait assessment within a post stroke population.

BACKGROUND: The ability to objectively measure spatiotemporal metrics within individuals post-stroke is integral to plan appropriate intervention, track recovery, and ultimately improve efficacy of rehabilitation programs. Inertial measurement units (IMUs) provide a means to systematically collect gait-specific metrics that could not otherwise be obtained from clinical outcomes. However, the use of IMUs to measure spatiotemporal parameters in stroke survivors has yet to be validated. The purpose of this study is to determine the validity and reliability of IMU-recorded spatiotemporal gait metrics as compared to a motion capture camera system (MCCS) in individuals post-stroke. METHODS: Participants (n = 23, M/F = 12/11, mean (SD) age = 50.2(11.1) spatiotemporal data were collected simultaneously from a MCCS and APDM Opal IMUs during a five-minute treadmill walking task at a self-selected speed. Criterion validity and test-retest reliability were assessed using Lin's concordance correlation coefficients (CCCs) and intraclass correlation coefficients (ICCs), respectively. Spatiotemporal values from MCCS and IMU were used to calculate gait asymmetry, and a t-test was used to assess the difference between asymmetry values. RESULTS: There were fair-to-excellent agreement between IMU and MCCS of temporal parameters (CCC 0.56-0.98), excellent agreement of spatial parameters (CCC >0.90), and excellent test-retest reliability for all parameters (ICC >0.90). CONCLUSIONS: Compared to motion capture, the APDM Opal IMUs produced accurate and reliable measures of spatiotemporal parameters. Findings support the use of IMUs to assess spatiotemporal parameters in individual's post-stroke.

Validity and Responsiveness of Floor Sitting-Rising Test in Post-Total Knee Arthroplasty: A Cohort Study.

OBJECTIVES: To assess the construct validity and responsiveness of the floor sitting-rising test (SRT) in individuals with total knee arthroplasty (TKA). DESIGN: Cohort study with 6-month follow-up. Secondary analysis using data from a randomized controlled trial. SETTING: An outpatient rehabilitation research center. PARTICIPANTS: Participants (N=240) enrolled in the parent study who had unilateral primary TKA. INTERVENTION: Participants in the parent study underwent 12 weeks of exercise programs. MAIN OUTCOME MEASURES: Validity analysis correlated baseline data of participants who completed the SRT and measures of knee motion, muscle strength, performance-based tests, and patient-reported outcomes of physical and psychosocial function. Responsiveness analysis used the 3- and 6-month follow-up data. Effect sizes were calculated using changes from baseline. Areas under the receiving operating characteristics curve were calculated using a global rating of change as the external anchor. RESULTS: Of the 240 participants (148 women; age, 70±7y), 180 (75%) were able to perform the SRT at baseline. Performers scored significantly better in all physical function tests (P<.0001) than nonperformers. SRT scores generally converged with measures of knee impairment and performance-based tests (associations ranged from small [r=0.15; P=.0516] to moderate [r=0.52; P<.0001]). SRT scores associated with self-efficacy for function (r=0.34; P<.0001) and fear of falls (r=-0.25; P=.001). At 3 (n=174) and 6 months (n=160), SRT effect sizes were 0.38 (95% confidence interval, 0.25-0.52) and 0.42 (95% confidence interval, 0.25-0.60), and areas under the curve were 0.59 (95% confidence interval, 0.49-0.69) and 0.62 (95% confidence interval, 0.52-0.73), respectively. CONCLUSIONS: The results add evidence to the validity of the SRT in patients after TKA. The strength of the associations suggests that the SRT measures a physical function construct not captured by the other tests. The magnitude of indices of responsiveness for the SRT were similar to other performance-based tests, indicating comparable responsiveness to more widespread tests of functional performance.