Stride count and frequency measured with a wrist-worn inertial sensor

This study proposes three simple approaches to estimate the stride count and frequency during walking and running using an inertial measurement system on the wrist. The approaches were based on a time-domain, frequency-domain and autocorrelation analysis, respectively. They were compared and validated against a reference on walks and runs of 16 participants in different conditions (different speeds, over ground and on treadmill). Results showed that the three methods provided an accurate and precise measure of the stride count and frequency: the median stride count error was 1 stride with a 90% confidence interval of 4 strides and the stride frequency presented a median error of 0.03 strides/min with a 90% confidence interval lower than 1.5 strides/min for all three methods. The approach, based on a wrist-worn inertial sensor, offers an effective and simple way to quantify the strides of healthy subjects in various conditions

Heightened clinical utility of smartphone versus body-worn inertial system for shoulder function B-B score

Background The B-B Score is a straightforward kinematic shoulder function score including only two movements (hand to the Back + lift hand as to change a Bulb) that demonstrated sound measurement properties for patients for various shoulder pathologies. However, the B-B Score results using a smartphone or a reference system have not yet been compared. Provided that the measurement properties are comparable, the use of a smartphone would offer substantial practical advantages. This study investigated the concurrent validity of a smartphone and a reference inertial system for the measurement of the kinematic shoulder function B-B Score. Methods Sixty-five patients with shoulder conditions (with rotator cuff conditions, adhesive capsulitis and proximal humerus fracture) and 20 healthy participants were evaluated using a smartphone and a reference inertial system. Measurements were performed twice, alternating between two evaluators. The B-B Score differences between groups, differences between devices, relationship between devices, intra- and inter-evaluator reproducibility were analysed. Results The smartphone mean scores (SD) were 94.1 (11.1) for controls and 54.1 (18.3) for patients (P < 0.01). The difference between devices was non-significant for the control (P = 0.16) and the patient group (P = 0.81). The analysis of the relationship between devices showed 0.97 ICC, -0.6 bias and -13.2 to 12.0 limits of agreement (LOA). The smartphone intra-evaluator ICC was 0.92, the bias 1.5 and the LOA -17.4 to 20.3. The smartphone inter-evaluator ICC was 0.92, the bias 1.5 and the LOA -16.9 to 20.0. Conclusions The B-B Score results measured with a smartphone were comparable to those of an inertial system. While single measurements diverged in some cases, the intra- and inter-evaluator reproducibility was excellent and was equivalent between devices. The B-B score measured with a smartphone is straightforward and as efficient as a reference inertial system measurement.sch_phy12pub4727pub

Effect of ACL rupture on knee biomechanics: in vivo measurements and finite element analyses

Ce projet met en commun les connaissances de deux laboratoires de l'Institut de Biomécanique Translationnelle (IBME) : la mesure de la cinétique et de la cinématique du genou (LMAM), ainsi que l'analyse biomécanique de l'articulation en éléments finis (LBO). Dans une première étape, une plateforme de force sera combinée avec des systèmes de capture du mouvement afin de mesurer si- multanément les forces et rotations tridimensionnels du fémur et du tibia pendant la marche. Pour la suite, un modèle en éléments finis du genou sera adapté pour reproduire le mouvement mesuré, afin de calculer les efforts intra- articulaires. Finalement, une étude clinique sera réalisée avec des patients présentant des pathologies ligamentaires du genou

Objective evaluation of cervical spine mobility after surgery during free-living activity

Background: Evaluation of cervical spine mobility after surgery is mainly based on the measurement of the range of motion during imposed movements. It can thus be questionable if this assessment represents the mobility experienced during daily life. The goal of this study was to propose a new evaluation tool based on the monitoring of cervical spine movement during daily activities. Methods: The detection of cervical movement and the determination of primary motion component (lateral bending, axial rotation or flexion-extension), using two inertial sensors, were first validated in laboratory settings. Fifteen patients who underwent a cervical arthrodesis and nine healthy control subjects were monitored during their daily activity for half a day. The frequency of cervical movement was quantified according to posture, i.e. static and walking periods. The amplitude and velocity of cervical movement were evaluated using the median and cumulative distribution function. Findings: The movement detection and classification showed an excellent performance (sensitivity and specificity > 94%). For the daily monitoring, the patients presented a movement frequency similar to controls, whereas the amplitude and velocity in patients were lower than in controls (P b 0.05). The differences between patients and controls were larger for the velocity parameters (effect sizes > 0.37 and >0.54 for static and walking periods respectively) than for the amplitude parameters. Interpretation: Body-worn inertial sensors enable the quantitative evaluation of global cervical movement. The movement amplitude and velocity during free-living conditions can be used as objective parameters to evaluate the cervical spine mobility after treatment. © 2013 Elsevier Ltd. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

A wearable inertial system to assess the cervical spine mobility: comparison with an optoelectronic-based motion capture evaluation

In clinical settings, the cervical range of motion (ROM) is commonly used to assess cervical spine function. This study aimed at assessing cervical spine mobility based on head and thorax kinematics measured with a wearable inertial system (WS). Sequences of imposed active head movements (lateral bending, axial rotation and flexion-extension) were recorded in ten controls and 13 patients who had undergone an arthrodesis. Orientation of the head relative to the thorax was computed in terms of 3D helical angles and compared with the values obtained using an optoelectronic reference system (RS). Movement patterns from WS and RS showed excellent concurrent validity (CMC up to 1.00), but presented slight differences of bias (mean bias < 2.5 degrees) and dispersion (mean dispersion < 4.2 degrees). ROM obtained using WS also showed some differences compared to RS (mean difference < 5.7 degrees), within the range of those reported in literature. WS enabled the observation of the same significant differences between controls and patients as RS. Moreover, ROM from WS presented good test-retest repeatability (ICC between 0.63 and 0.99 and SEM < 6.2 degrees). In conclusion, WS can provide angles and ROM comparable to those obtained with RS and relevant for the cervical assessment after treatment. (C) 2013 IPEM. Published by Elsevier Ltd. All rights reserved

Arm velocity distribution during daily activity: objective outcome evaluation after shoulder surgery

This study proposed a new metric to assess the arm mobility based on the monitoring of daily activity using inertial sensors. Forty-one healthy participants and 21 patients suffering from rotator cuff tear disease were evaluated using a clinical questionnaire and one day measurement of the arm kinematics. Arm movements were detected from inertial data, and characterized by their velocity. Cumulative distribution of the velocities of each patient was compared to the reference distribution of controls, using the Kolmogorov-Smirnov distance. This distance was significantly correlated to clinical score. Moreover, it was used to compute the probability of "healthiness of arm movement" for each patient. The approach, based on the mobility of daily activity, offers an effective way to quantify the deviation of one patient from the group of controls

Concurrent validity of three measurement systems for the evaluation of cervical spine mobility

In this study, we compared the cervical range of movement (ROM) and range of angular velocity (RAV) measured simultaneously using a 3-dimensional electrogoniometer, the CA6000-OSI (OSI), an optoelectronic motion capture system (MCS), the VICON® and a wearable system (WS) composed of inertial measurement units, the Physilog®. Measurement of primary and associated cervical movement during active lateral bending (LB), axial rotation (AR) and flexion-extension (FE) were compared from those systems in 10 healthy subjects according to two tasks of movement: with the best amplitude possible (BEST) and the fastest possible (FAST). For primary components of movement, ROM absolute differences between respectively WS and MCS, MCS and OSI and WS and OSI were 5%, 3% and 7% of mean ROM for the BEST task and 7%, 4% and 11% for the FAST task. RAV absolute differences were 6%, 11% and 13% respectively for BEST task and 11%, 20% and 20% for FAST task. ICC between 0.96 and 0.99 were obtained. CMC for angular and velocity patterns were between 0.95 and 0.99. The three systems must be considered as usual and confident tools to assess the normal and fast cervical motion. A better correlation between the different systems is observed during the BEST task