Biomedical subjects

Stéphane Bouilland

Publications and source records attributed to Stéphane Bouilland.

3 recordsLinked to original sources

PubMed2006

A support method for the contextual interpretation of biomechanical data.

In the clinical field, biomechanical data provided by advanced technical devices are still underexploited. Data analysis usually consists of extracting attributes or computing synthetic values from temporal data and exploiting them by means of a monovariable statistical method. This article proposes a method to support clinicians, especially those in orthopedics, in the contextual interpretation of biomechanical data. We propose to characterize temporal biomechanical data by means of fuzzy space-time windows and to induce fuzzy decision trees to map the biomechanical and clinical data related to patients. Then, we present a method for objectively explaining a given clinical characteristic of a particular patient; this method is derived using the fuzzy rule base generated from the trees and a satisfiability measure. We have applied our method to real data in order to provide an objective explanation of the subjective self-evaluation of the functional status of patients with a shoulder prosthesis, and evaluate it by means of the stratified tenfold cross validation method. The mean explanation rate--which corresponds to the mean proportion of the patients belonging to test sets whose functional state is explained by the proposed method--exceeds 80% for more than half of the decision trees, and exceeds 70% for 94% of the trees. By supporting clinicians during the biomechanical data interpretation process, our method helps them take the objective biomechanical measurements in the medical practice into account, particularly in orthopedics. It can also make subjective evaluations more objective by mapping subjective and objective data.

Algorithms↗

PubMed2003

Intrathecal baclofen in subjects with spastic hemiplegia: assessment of the antispastic effect during gait.

OBJECTIVE: To determine whether leg muscle stiffness is measurably reduced after intrathecal baclofen (ITB) in subjects with spastic hemiplegia. DESIGN: Nonrandomized trial. SETTING: Inpatient multidisciplinary rehabilitation unit in France. PARTICIPANTS: Seven consecutive subjects with spastic hemiplegia having Ashworth Scale scores for their quadriceps and triceps greater than 2. INTERVENTION: Subjects were given ITB by lumbar puncture after a dose-selecting test period. MAIN OUTCOME MEASURES: Triceps and quadriceps Ashworth scores, gait analysis at preferred and maximal speed measured by a motion analysis system with 2 forceplates, and electromyographic recording of leg muscles before and 4 hours after ITB. The slopes of the moment-angle curves were measured on the hemiplegic side at the onset of ankle and knee flexion to assess muscle stiffness during walking. Pre- and post-ITB spatiotemporal, kinetic, and kinematic data were compared by using a nonparametric test (Wilcoxon signed-rank test). RESULTS: Ashworth scores of the quadriceps and triceps of all subjects decreased significantly after ITB. Maximal walking speed increased significantly, with a significant increase in stride length, but the preferred walking speed was unchanged. Minimal knee extension and maximal ankle flexion were the only kinematic data significantly different (increased) after ITB. The slope of the ankle moment-angle curve decreased significantly after ITB at preferred gait speed; it also decreased at maximal gait speed in all but 1 subject. Of the 4 available moment-angle curves, 3 showed decreased knee extensor muscle stiffness. The duration of the bursts of spastic muscles decreased after ITB. CONCLUSION: Acute ITB improved walking and reduced muscle stiffness at both the ankles and knees on the spastic hemiplegic side of our subjects. Electromyographic findings suggest that some of the post-ITB reduction in muscle stiffness might be attributed to decreased spasticity.

Adult↗

PubMed2003

Multidimensional signal exploration using multiple correspondence analysis. An example of a load lifting study.

Most empirical studies concerning rehabilitation yield numerous multidimensional signals (dozens of time variables are obtained for dozens of empirical situations). The purpose of this paper is to suggest a statistical analysis procedure based on: 1) space-time fuzzy windowing; 2) signal behavior characterization within the windows using membership value averages (MVA); and 3) MVA analysis using the multiple correspondence analysis (MCA). A load lifting study provided an example of 78 multidimensional signals including 89 time variables (forces, energy indicators, linear and angular positions, speeds, and accelerations). The main goal of MCA was to compare and contrast biomechanical signals from two lifting modes: "free" and "isokinetic." In the first mode, three loads were tested--light, medium, and heavy. In the second, three speeds were tested--slow, medium, and fast. Thirteen male individuals without disabilities participated in this study. The MCA showed that most of the free load-lifting strategies cannot be used in isokinetic lifting because the constraints of the subject and the environment are different. In addition, as the level of difficulty increases, free lifting became more economical while isokinetic lifting became less economical. These results would appear to indicate that movement strategies used for free lifting cannot be learned using an isokinetic machine during rehabilitation sessions for chronic low back pain. MCA was also suggested as a tool for comparing patients with control individuals. To achieve this aim, the notion of "supplementary data" was introduced.

Adult↗