• Classification of elderly as fallers and non-fallers using centre of pressure velocity

      Hewson, David; Singh, Neeraj Kumar; Snoussi, Hichem; Duchêne, Jacques (IEEE, 2010-11-11)
      Falls are a leading cause of death in the elderly. One of the most common methods of predicting falls is to evaluate balance using force plate measurement of the Centre of Pressure (COP) displacement. This signal, known as a stabilogram, can be decomposed into movement in anteroposterior (AP) and mediolateral (ML) directions. It has been suggested that studying the velocity of COP displacement could lead to new insights into fall risk. The aim of this study was to attempt to classify elderly fallers and non-fallers, as well as control subjects based on COP velocity measurements. Three groups of 10 subjects (controls, elderly fallers, and elderly non-fallers) were compared. Discriminant function analysis was able to correctly classify 90% of the subjects based only on COP velocity measurements. Further work is needed to determine whether this parameter might be of use in longitudinal measurement of fall risk in home-dwelling elderly.
    • Evaluation of the risk of falling in institution-dwelling elderly: clinical tests versus biomechanical analysis of stepping-up

      Michel-Pellegrino, Valerie; Hewson, David; Drieux, Michele; Duchêne, Jacques (IEEE, 2007-12-31)
      Falls in the elderly constitute a major socio-economic problem for modern healthcare. The aim of the study was to extract biomechanical parameters to indicate balance level and the risk of falling in the elderly. It is a preliminary work as part of the development of a home-test based on force-plate technology. Seven faller and 12 non-faller elderly subjects performed stepped up onto a forceplate. Each subject was tested once per weekday for three weeks. Tinetti, Mini Mental Scale test (MMS) and the Geriatric Depression Scale (GDS) scores were measured before the experimentations. Temporal and ground reaction force parameters were measured. The Tinetti test was not correlated with falls in the following six-month period. In contrast, the biomechanical parameters related to the forces measured at foot-contact and to the durations of the phases of the stepping-up were correlated with fall, as well as with MMS and GDS. These results demonstrated that biomechanical parameters could be used as indicators of balance and risk of fall.
    • Identification of the period of stability in a balance test after stepping up using a simplified cumulative sum

      Safieddine, Doha; Chkeir, Aly; Herlem, Cyrille; Bera, Delphine; Collart, Michèle; Novella, Jean-Luc; Dramé, Moustapha; Hewson, David; Duchêne, Jacques; University of Technology of Troyes; et al. (Elsevier, 2017-09-19)
      Falls are a major cause of death in older people. One method used to predict falls is analysis of Centre of Pressure (CoP) displacement, which provides a measure of balance quality. The Balance Quality Tester (BQT) is a device based on a commercial bathroom scale that calculates instantaneous values of vertical ground reaction force (Fz) as well as the CoP in both anteroposterior (AP) and mediolateral (ML) directions. The entire testing process needs to take no longer than 12 s to ensure subject compliance, making it vital that calculations related to balance are only calculated for the period when the subject is static. In the present study, a method is presented to detect the stabilization period after a subject has stepped onto the BQT. Four different phases of the test are identified (stepping-on, stabilization, balancing, stepping-off), ensuring that subjects are static when parameters from the balancing phase are calculated. The method, based on a simplified cumulative sum (CUSUM) algorithm, could detect the change between unstable and stable stance. The time taken to stabilize significantly affected the static balance variables of surface area and trajectory velocity, and was also related to Timed-up-and-Go performance. Such a finding suggests that the time to stabilize could be a worthwhile parameter to explore as a potential indicator of balance problems and fall risk in older people.
    • The PARAChute project: remote monitoring of posture and gait for fall prevention

      Hewson, David; Duchêne, Jacques; Charpillet, François; Saboune, Jamal; Michel-Pellegrino, Valerie; Amoud, Hassan; Doussot, Michel; Paysant, Jean; Boyer, Anne; Hogrel, Jean-Yves (Springer, 2007-01-01)
      Falls in the elderly are a major public health problem due to both their frequency and their medical and social consequences. In France alone, more than two million people aged over 65 years old fall each year, leading to more than 9 000 deaths, in particular in those over 75 years old (more than 8 000 deaths). This paper describes the PARAChute project, which aims to develop a methodology that will enable the detection of an increased risk of falling in community-dwelling elderly. The methods used for a remote noninvasive assessment for static and dynamic balance assessments and gait analysis are described. The final result of the project has been the development of an algorithm for movement detection during gait and a balance signature extracted from a force plate. A multicentre longitudinal evaluation of balance has commenced in order to validate the methodologies and technologies developed in the project.
    • Reconstructed phase spaces of intrinsic mode functions : application to postural stability analysis

      Snoussi, Hichem; Amoud, Hassan; Doussot, Michel; Hewson, David; Duchêne, Jacques (IEEE, 2006-12-31)
      In this contribution, we propose an efficient nonlinear analysis method characterizing postural steadiness. The analyzed signal is the displacement of the centre of pressure (COP) collected from a force plate used for measuring postural sway. The proposed method consists of analyzing the nonlinear dynamics of the intrinsic mode functions (IMF) of the COP signal. The nonlinear properties are assessed through the reconstructed phase spaces of the different IMFs. This study shows some specific geometries of the attractors of some intrinsic modes. Moreover, the volume spanned by the geometric attractors in the reconstructed phase space represents an efficient indicator of the postural stability of the subject. Experiments results corroborate the effectiveness of the method to blindly discriminate young subjects, elderly subjects and subjects presenting a risk of falling.