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Session: Movement Sensing - Balance - Fall Detection
Session starts: Friday 25 January, 10:30
Presentation starts: 10:30
Room: Lamoraalzaal

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Josien van den Noort (VU medisch centrum, afdeling revalidatiegeneeskunde, Amsterdam)
Suzanne Wiertsema (VU medisch centrum, afdeling revalidatiegeneeskunde, Amsterdam)
Karin Hekman (VU medisch centrum, afdeling revalidatiegeneeskunde, Amsterdam)
Casper Schonhuth (VU medisch centrum, afdeling orthopedie, Amsterdam)
Joost Dekker (VU medisch centrum, afdeling revalidatiegeneeskunde, Amsterdam)
Jaap Harlaar (VU medisch centrum, afdeling revalidatiegeneeskunde, Amsterdam)

Abstract:
People with shoulder pathologies often show scapular dyskinesis, i.e. alterations in scapular position and motion [1]. To direct interventions aimed at improving scapular position, motion and muscle forces, an objective and reliable measurement of scapular dyskinesis in clinical setting is important. However, currently available measures are not reliable, not objective, clinically not suitable, invasive, or limited to static positions (e.g. visual based scapular dyskinesis tests, optoelectronic markers, scapula locators or bonepins). An inertial and magnetic measurement system (IMMS: small, wireless sensors containing gyroscopes, accelerometers, and magnetometers) could be a good alternative to measure scapular motion in clinical routine [2]. The aim of this study is to evaluate the intra- and inter-observer reliability (i.e. the precision) of the measurement protocol using IMMS for of scapular motion in 20 healthy subjects. For intra-observer reliability, scapular motion of 20 healthy subjects without shoulder problems (age 36±11, BMI 22±2) were measured with the IMMS by a physical therapist on two different days (T0 and T1). For inter-observer reliability, a second physical therapist also measured the scapular motion with the IMMS at T1. Four IMMS sensors were placed on the body: scapula (edge of spina), thorax, upper and lower arm. The subjects repeatedly elevated their arm in the sagittal plane (anteflexion) and in the frontal plane (abduction). Kinematics of the scapula with respect to the thorax were measured. Reliability was assessed by calculating the intraclass correlation coefficient (ICC), the standard error of measurement (SEM) and the smallest detectable difference (SDD) of scapular kinematics at 0, 30, 60, 90, 120 and 150 deg of arm elevation [3]. Furthermore, the differences in range of motion (dROM) and the mean differences (to determine the offset) over the entire movement curves were calculated. The intra- & inter-observer reliabilities of the 3D scapular motion were equal for both the anteflexion and abduction movement (SEM 4±1deg, dROM 4±3deg), and similar movement patterns were observed between the measurements. ICC’s were 0.73±0.12. The highest SDD was found for the inter-observer reliability (17±2deg) in the transversal plane (scapular re/protraction), mainly caused by an offset, i.e. a constant difference between the curves (range 0-22deg, average 8±6deg). Using the IMMS, measurement could be performed objectively and easily during dynamic tasks as part of clinical routine. Measurement errors are similar to studies using wired IMMS (SEM 1-5deg [2]) or optoelectronic markers (SEM 3-8deg [4]). The use of a scapula locator for optimization of anatomical calibration of the scapular IMMS-sensor might reduce the offset. In the near future, patients measurements will be performed to assess reliability and validity of the IMMS for scapular dyskinesis. This will show whether measurement errors are small enough to enable scapular dyskinesis assessment. REFERENCES [1] Warner et al., Clinical Orthopaedics and Related Research 285 (1992) 191-199 [2] Parel et al., Gait & Posture 35 (2012) 636-640 [3] de Vet et al., Journal of Clinical Epidemiology 59 (2006) 1033-1039 [4] Van Andel et al., Gait & Posture 29 (2009) 123–128