Bulk movement included in multi-channel mechanomyography: similarity between mechanomyography of resting muscle and that of contracting muscle.

Although mechanomyography (MMG) reflects local vibrations from contracting muscle fibers, it also includes bulk movement: deformation in global soft tissue around measuring points. To distinguish between them, we compared the multi-channel MMG of resting muscle, which dominantly reflected the bulk movement caused by arterial pulsations, to that of the contracting muscle. The MMG signals were measured at five points around the upper arms of 10 male subjects during resting and during isometric ramp contraction from 5% to 85% of maximal voluntary contraction (MVC) of the biceps brachii muscle. The characteristics of bulk movement were defined as the amplitude distribution and phase relation among the five MMG signals. The bulk movement characteristics during the rest state were not necessarily the same among the subjects. However, below 30 Hz, each subject's characteristics remained the same from the rest state (0% MVC) to the contracting state (80% MVC), at which the bulk movement mainly originates from muscle contraction activity. Results show that the MMG of the low frequency domain (<30 Hz) includes bulk movement depending on the mechanical deformation characteristics of each subject's body, for a wide range of muscle contraction intensities.

Lateral translation of the lumbar spine: in vitro biomechanical study.

A biomechanical study of lateral translation in lumbar spine with human cadavers was performed in order to explore the direction of the force increasing lateral translation and the contributions of discs and facet joints to lateral translation. Whole lumbar spines from 12 fresh cadavers were attached to a specially designed loading apparatus whose five cables simulated the muscles of the trunk without restricting natural movement. Three-dimensional positions of each vertebra were recorded with position-sensitive detectors. Force in the anterolateral direction increased the lateral translation more than force in the posterolateral direction. Lateral translation was increased to a significantly greater extent when the facet joints were removed than when the discs were removed at L4-5 at the levels of shear loading applied in this study.

Gait analysis of patients with neurogenic intermittent claudication.

STUDY DESIGN: The gait of patients with neurogenic intermittent claudication was analyzed before and after surgery using a ground reaction force plate. OBJECTIVES: To analyze the gait characteristics of patients with neurogenic intermittent claudication, to evaluate quantitatively their gait improvement after surgical treatment, and to examine the differences in gait characteristics and postoperative improvement among different types of neuropathy. SUMMARY OF BACKGROUND DATA: A number of reports have been published on the pathophysiology or treatment of neurogenic intermittent claudication. However, almost no detailed reports exist on the gait abnormalities associated with this condition. METHODS: The subjects were 60 lumbar canal stenosis patients with intermittent claudication who underwent surgery at the authors' hospital. A ground reaction force plate was used for the analysis, and factors related to time and distance (speed, stride, interval, and pitch) were analyzed, as well as factors related to the style of walking (symmetry, reappearance, smoothness, sway, rhythm, and impact). RESULTS: Before surgery, there were abnormalities of various factors related to the style of walking soon after the patients began to walk. Gait analysis also showed that the pattern of gait abnormality and its improvement after surgery varied depending on the type of neuropathy. CONCLUSIONS: Gait analysis permits objective and quantitative evaluation of the gait characteristics of patients with lumbar canal stenosis and is useful for evaluating responses to surgical treatment in these patients.