The movement of the center of mass (COM) during human walking has been hypothesized to follow a sinusoidal pattern in the vertical and mediolateral directions. The vertical COM displacement has been shown to increase with velocity, but little is known about the mediolateral movement of the COM. In our evaluation of the mediolateral COM displacement at several walking speeds, 10 normal subjects walked at their self-selected speed and then at 0.7, 1.0, 1.2, and 1.6 m/s in random order. We calculated COM location from a 15segment, full-body kinematic model using segmental analysis. Mediolateral COM displacement was 6.99 +/-1.34 cm at the slowest walking speed and decreased to 3.85 +/-1.41 cm at the fastest speed (p < 0.05). Vertical COM excursion increased from 2.74 +/-0.52 at the slowest speed to 4.83 +/-0.92 at the fastest speed (p < 0.05). The data suggest that the relationship between the vertical and mediolateral COM excursions changes substantially with walking speed. Clinicians who use observational gait analysis to assess walking problems should be aware that even normal individuals show significant mediolateral COM displacement at slow speeds. Excessive vertical COM displacement that is obvious at moderate walking speeds may be masked at slow walking speeds.Abbreviations: ANOVA = analysis of variance, COM = center of mass, fps = frames per second, SS = self-selected.
Prosthetic liners exist to improve amputee safety and comfort by adding a cushioning layer between the residual limb and the prosthetic socket. Many choices in liner technology are available, and clinicians often rely on personal intuition and experience to choose which liners are appropriate for which patients. The purpose of this study was to examine the literature to find what scientific evidence exists to inform prescription practices. 'Prosthetic liner' was used as a search term in the Web of Science and PubMed research databases. Fourteen scientific articles met the eligibility criteria and are discussed in this review. The results of this review suggest that there is little scientific evidence to inform prosthetic liner prescription practices. Liner material properties have been well-studied, but their influence on in vivo performance is not well understood. Understanding liner effect on function would be an area of great usefulness.
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