Specialized prostheses for activities. An update

Deformable link segment analysis for prosthetic foot-ankle components: Kinematics

Approaches in the literature for estimating prosthetic foot-ankle power typically require calculating the segment deformation velocity. This, in turn, necessitates approximating the segment angular velocity. Methods can be distinguished by the way in which a segment is defined and the assumptions used for estimating the segment angular velocity. However, isolating foot-ankle performance from overall prosthetic system performance is limited by uncertainties in the definition of angular velocity of a deformable segment. A deformable link segment (DLS) analysis is proposed that provides a means for estimating deformation velocity of a deformable segment without first approximating the angular velocity: the deformation velocity and angular velocity are solved simultaneously at each instant during the stance phase of gait. DLS analysis was compared to two approaches in the literature: the distal foot (DF) model and the unified deformable (UD) segment model during over-ground walking for three trans-tibial prosthesis users. DLS and UD segment estimates of deformation velocity were comparable when applied to the UD segment. Furthermore, DLS analysis enables modelling of deformable prosthetic foot-ankle components separately from other prosthetic componentry. The method is proposed as a rigorous approach to estimating angular velocity and deformation velocity of passive prosthetic foot-ankle components for subsequent calculation of deformation power and energy performance of these devices.

The effects of a controlled energy storage and return prototype prosthetic foot on transtibial amputee ambulation

The lack of functional ankle musculature in lower limb amputees contributes to the reduced prosthetic ankle push-off, compensations at other joints and more energetically costly gait commonly observed in comparison to non-amputees. A variety of energy storing and return prosthetic feet have been developed to address these issues but have not been shown to sufficiently improve amputee biomechanics and energetic cost, perhaps because the timing and magnitude of energy return is not controlled. The goal of this study was to examine how a prototype microprocessor-controlled prosthetic foot designed to store some of the energy during loading and return it during push-off affects amputee gait. Unilateral transtibial amputees wore the Controlled Energy Storage and Return prosthetic foot (CESR), a conventional foot (CONV), and their previously prescribed foot (PRES) in random order. Three-dimensional gait analysis and net oxygen consumption were collected as participants walked at constant speed. The CESR foot demonstrated increased energy storage during early stance, increased prosthetic foot peak push-off power and work, increased prosthetic limb center of mass (COM) push-off work and decreased intact limb COM collision work compared to CONV and PRES. The biological contribution of the positive COM work for CESR was reduced compared to CONV and PRES. However, the net metabolic cost for CESR did not change compared to CONV and increased compared to PRES, which may partially reflect the greater weight, lack of individualized size and stiffness and relatively less familiarity for CESR and CONV. Controlled energy storage and return enhanced prosthetic push-off, but requires further design modifications to improve amputee walking economy.

Limb deficiency and prosthetic management. 1. Decision making in prosthetic prescription and management

This self-directed learning module highlights decision making in prosthetic management in pediatric and adult patients. This chapter reviews classification of congenital limb deficiency and management of congenital pediatric upper-extremity amputees. Differences in management of amputees of various ages from infancy to old age is discussed. Case examples are used to formulate prosthetic prescriptions for transradial limb deficiency as well as knee disarticulation and transtibial level amputations. Common prosthetic gait deviations and anticipated functional levels are evaluated.

OVERALL ARTICLE OBJECTIVE

To discuss prosthetic prescription and management in congenital limb deficiency and acquired amputations for patients of various ages.

Componentry for lower extremity prostheses

Prosthetic components for both transtibial and transfemoral amputations are available for patients of every level of ambulation. Most current suspension systems, knees, foot/ankle assemblies, and shock absorbers use endoskeletal construction that emphasizes total contact and weight distribution between bony structures and soft tissues. Different components offer varying benefits to energy expenditure, activity level, balance, and proprioception. Less dynamic ambulators may use fixed-cadence knees and non-dynamic response feet; higher functioning walkers benefit from dynamic response feet and variable-cadence knees. In addition, specific considerations must be kept in mind when fitting a patient with peripheral vascular disease or diabetes.

Energy storage and return prostheses: does patient perception correlate with biomechanical analysis?

The development and prescription of energy storage and return prosthetic feet in favor of conventional feet is largely based upon prosthetist and amputee experience. Regretfully, the comparative biomechanical analysis of energy storage and return and conventional prosthetic feet is rarely a motivation to either the technical development or clinical prescription of such devices. The development and prescription of prosthetic feet without supportive scientific evidence is likely due to the conflicting or non-significant results often presented in the scientific literature. Despite the sizeable history of comparative prosthetic literature and continued analysis of prosthetic components, the link between clinical experience and scientific evidence remains largely unexplored.A review of the comparative analysis literature evaluating energy storage and return and conventional prosthetic feet is presented to illustrate consistencies between the perceptive assessments and the objective biomechanical data. Results suggest that while experimental methodologies may limit the statistical significance of objective gait analysis results, consistent trends in temporal, kinetic, and kinematic parameters correlate well with perceptive impressions of these feet. These correlations provide insight to subtle changes in gait parameters that are deemed neither clinically nor statistically significant, yet are perceived by amputees to affect their preference for and performance of prosthetic feet during locomotion. Acknowledging and targeting areas of perceptive significance will help researchers develop more structured protocols for energy storage and return prosthesis evaluation as well as provide clinicians with information needed to enhance the appropriateness of their clinical recommendations. Expanding test environments to measure activities of perceived improvement such as high-velocity motions, stair ascent/descent, and uneven ground locomotion will provide a more appropriate assessment of the conditions for which energy storage and return prosthetic feet were designed. Concentrating research to specific test populations by age or amputation etiologies can overcome statistical limitations imposed by small study samples. Finally, directing research toward the areas of gait adaptation, heel performance, and the temporal release of energy in energy storage and return feet may reinforce the selection and utilization of advanced prosthetic components. These enhancements to current biomechanical analyses may serve to reduce the boundaries of perceptive significance and provide clinicians, designers, and researchers with the supportive data needed to prescribe, design, and evaluate energy storage and return prosthetic feet.

Lower limb amputation. Part 3: Prosthetics--a 10 year literature review

This paper is intended as a follow-up to the ISPO Consensus Conference on Amputation Surgery. It reviews all the literature on lower limb prosthetics published after 1990. The review was considered under six categories: feet, knees, hips, thermoplastics, liners/suspension and computers.