|
|
Reliability of accelerometer placement at the sacrum for performing accelerometer based gait analysis Host Publication: Congres Kine & Ergo in de Geriatrie 2010 Authors: B. Jansen, I. Bautmans, B. Van Keymolen and T. Mets Publication Date: May. 2010
Abstract: Context
In accelerometer based gait analysis, a wide range of outcomes related to fall risk and mobility are calculated from data gathered with a tri-axial accelerometer, both in diagnostic as in revalidation settings. For most of these outcomes, the correct placement of the sensor at the sacrum is crucial (e.g. inverted pendulum models). Current research is often focusing on the validity and the reliability of various outcomes, both in very broad or very specific patient groups. However, reliability of the accelerometer placement at the sacrum itself is not investigated. Also, it is not clear whether inter and intra rater differences are bigger for elderly patients compared to young controls.
Methods
Eighty elderly (?70 years old) [E] and 40 young controls [Y] participated. All subjects walked 18m on a straight line. Each subject performed the test three times with at least five minutes of resting in between. Two of the three tests were observed by the same observer, one test was observed by a second observer. Before each test, the observer placed the sensor in a neoprene belt at the sacrum. Group differences were evaluated with a one way ANOVA test with a significance level of 0.05. Intra and inter rater reliability was analyzed using the intra class correlation coefficient ICC(3,1) and the coefficient of variation of the method error (CVME) using SPSS 17.0.
Results
The average intra rater absolute altitude difference was very small and not significantly different between both groups: 1.30(1.29) cm [E] vs. 1.32(1.20) cm [Y] neither was it for the inter rater case: 1.35(1.11) [E] vs. 1.44(1.40) cm [Y]. The maximum observed difference was 8.00 cm. Both the intra rater reliability (ICC 0.951, CVME 1.04) as well as the inter rater variability (ICC 0.913, CVME 1.31) were very high.
Conclusions
A tri-axial accelerometer can be placed reliably at the sacrum. Given the small intra and inter rater differences observed in this study, problems with reliability of outcomes in accelerometer based gait analysis, can probably not be attributed to differences in accelerometer placement.
|
|
