Gait Features Assessment in Hip Osteoarthritis and Total Hip Replaced Patients Based on an ambulatory System (Physilog)

Osteoarthritis is the most frequent joint pathology throughout the world. Obtaining objective, dynamic and quantified data allowing the evaluation of patients’ progress before and after hip arthroplasty is crucial. Gait analysis can be used for evaluating improvement in such patients, since walking is the principal human physical activity. Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. Recently, we have proposed a new ambulatory system for gait analysis (Physilog) and validated its performances for normal and abnormal walking (Aminian et al., 2002). The aim of this study is to show the efficacy of Physilog system for clinical gait analysis in orthopaedics

ESMAC-SIAMOC 2001 Joint Congress: Gait Events in Hip Osteoarthritis and Total Hip Replaced Patients Evaluated by Two different Gait Analysis Systems

Kamiar Aminian, Bijan Najafi, Philippe Robert

Comprehensive gait analysis usually includes kinematics, kinetics, and electromyography. A complex instrumentation is thus required that only can be installed in a dedicated laboratory. These techniques are valuable to support clinical decisions and to evaluate the results. However, in several instances, a simplified analysis, concentrated on few selected gait parameters, can be valuable as well. One problem, however, is to ascertain that the computed parameters are correct and correspond to what could be measured by other, more complicated methods. A second point is to verify the feasibility of the measurement in pathologic cases. A third point is to understand the validity and the usefulness of the computed parameters to demonstrate the benefit for the clinical practice. In this study we describe an ambulatory system for temporal parameters estimation using gyroscopes. The accuracy of the measurement was assessed using a standard provided by an Elite system. To show the effectiveness of the method, gait parameters were obtained in patients with hip osteoarthrosis and after arthoplasty

2001

Ambulatory system for human motion analysis using a kinematic sensor: Monitoring of daily physical activity in the elderly

Kamiar Aminian, Anisoara Ionescu, Bijan Najafi, Philippe Robert

A new method of physical activity monitoring is presented, which is able to detect body postures (sitting, standing, and lying) and periods of walking in elderly persons using only one kinematic sensor attached to the chest. The wavelet transform, in conjunction with a simple kinematics model, was used to detect different postural transitions (PTs) and walking periods during daily physical activity. To evaluate the system, three studies were performed. The method was first tested on 11 community-dwelling elderly subjects in a gait laboratory where, an optical motion system (Vicon) was used as a reference system. In the second study, the system was tested for classifying PTs (i.e., lying-to-sitting, sitting-to-lying, and turning the body in bed) in 24 hospitalized elderly persons. Finally, in a third study monitoring was performed on nine elderly, persons for 45-60 min during their daily physical activity. Moreover, the possibility-to-perform long-term monitoring over 12 h has been shown. The first. study revealed a close concordance between the ambulatory and reference systems. Overall, subjects performed 349 PTs during this study. Compared with the reference system, the ambulatory system had an overall sensitivity of 99% for detection of the different PTs. Sensitivities and specificities were 93% and 82% in sit-to-stand, and 82% and 94% in stand-to-sit, respectively. In both first and second studies, the ambulatory system also showed a very high accuracy (> 99%) in identifying the 62 transfers or rolling out of bed, As well as 144 different posture changes to the back, ventral, right and left sides. Relatively high sensitivity (> 90%) was obtained for the classification of usual physical activities in the third study in comparison with visual observation. Sensitivities and specificities were, respectively, 90.2% and 93.4% in sitting, 92.2% and 92.1% in "standing + walking," and, finally, 98.4% and 99.7% in lying. Overall detection errors (as percent of range) were 3.9% for "standing.+ walking," 4.1% for sitting, and 0.3% for lying. Finally, overall symmetric mean average errors were 12% for "standing + walking," 8.2% for sitting, and. 1.3% for lying.

2003

Ambulatory system for the quantitative and qualitative analysis of gait and posture in chronic pain patients treated with spinal cord stimulation

Kamiar Aminian, Anisoara Ionescu, Bijan Najafi

The physical activity in normal daily life is determined to a large extent by the functional ability of a subject. As a result, the measurement of the physical activity that a subject performs spontaneously could be a useful and objective measurement of disability, particularly in patients with disease-related functional impairment. The aim of this study is to provide an accurate method for the measurement and analysis of the physical activity under normal life conditions. Using three kinematical sensors strapped to the body, both the posture and the gait parameters can be assessed qualitatively and quantitatively. A detailed description of the algorithms used to analyse both the posture and the gait are presented in this paper. Two methods, based on different sensor configurations and signal processing, are proposed for the detection of sitting and standing postures (Methods P1 and P2). Two other methods are used for the quantitative assessment of walking (Methods W1 and W2). The performance of the algorithms (expressed in terms of sensitivity, specificity and error) is based on the comparison of data recorded simultaneously by a non-interfering observer (reference data) with the data provided by the recording system (21 patients, 61 h). Sensitivity and specificity are respectively 98.2% and 98.8% (P1), 97.8% and 98.1% (P2) for sitting; 98.0% and 98.5% (P1), 97.4% and 97.8% (P2) for standing; 97.1% and 97.9% (W1), 92.4% and 94.9% (W2) for walking; and finally, 99.2% and 98.6% for lying. Overall detection errors (as a percent of range) are as follows: 1.15% (P1) and 1.20% (P2) for sitting, 1.36% (P1) and 1.40% (P2) for standing, 1.20% (W1) and 1.60% (W2) for walking and 0.40% for lying. The error for the estimated walking distance and the speed is 6.8% and 9.6%, respectively. We conclude that both methods can be used for the accurate measurement of the basic physical activity in normal daily life. Measurements performed before and after the delivery of a treatment can therefore provide information of unprecedented accuracy and objectivity on the ability of a procedure, in this case spinal cord stimulation, to restore functional capabilities. (C) 2003 Elsevier B.V. All rights reserved.