Priorities in lower limb prosthetic service delivery based on an international survey of prosthetists in low- and high-income countries.

BACKGROUND: Prosthetic services, including the provision of an appropriate prosthesis, are a crucial part of the rehabilitation process for individuals with lower limb amputations. However, globally there exist unique challenges in the delivery of prosthetic services that are limiting rehabilitation outcomes and consequently the well-being and socio-economic status of individuals with lower limb amputations. OBJECTIVES: The objective of this work was to explore the issues related to the provision of appropriate prosthetic technologies and to compare these across different economies of the world. STUDY DESIGN: Cross-sectional survey. METHODS: An online survey was developed and distributed to prosthetic practitioners providing services in countries around the world. An open-coding thematic content analysis procedure was applied to extract key themes from the data. RESULTS: The response codes defined three overall themes of lower limb prosthetic delivery, and several key differences between higher and lower income countries emerged. Namely, a higher emphasis on part/material availability, practitioner training and durability in lower income countries was found. High costs were an issue raised by practitioners in all countries. CONCLUSION: Practitioners around the world share many of the same concerns; however, some lower income countries face important and pressing issues that limit their ability to provide adequate prosthetic services. CLINICAL RELEVANCE: This work highlights the most crucial service and technology-related needs, as perceived by trained prosthetic practitioners, of populations requiring lower limb prosthetic treatment around the world. Additionally, the results may be used to prioritize prosthetic-related health-care initiatives led by other researchers, governments and organizations working to improve services internationally.

Improving the gait performance of non-fluid-based swing-phase control mechanisms in transfemoral prostheses.

A prosthetic swing-phase control mechanism simulates the action of leg musculature, aiding gait function by controlling the duration of swing, extent of heel-rise, and by allowing the shank to smoothly decelerate into full knee extension without excessive impact. Non-fluid-based mechanisms have the potential to provide a durable and affordable solution as required in many parts of the world, but the design variables that lead to improved performance of non-fluid-based swing-phase control technologies are not well established. Seven transfemoral amputees were fitted with a prosthetic knee joint and different non-fluid-based swing-phase setups were systematically assessed. Clinical testing included walk tests utilizing a potentiometer (to measure knee flexion angles) and accelerometer (to measure terminal impact decelerations) mounted on the prosthetic limb. As hypothesized, the friction and spring systems improved gait function. This includes an increased walking speed that closely matched high-end hydraulic prosthetic knee joints, decreased and more normal maximum prosthetic knee flexion, decreased flexion duration, and lower terminal impact. Further improvements were obtained using a dual spring system, two springs in series, over the more conventional single spring system. Non-fluid-based swing-phase control mechanisms are simple and significantly improve the performance of prostheses. Their application is ideal where size, weight and cost may be constrained.

Design and quantitative evaluation of a stance-phase controlled prosthetic knee joint for children.

The aims of this study were to demonstrate a theoretical basis for the design of a stance-phase controlled paediatric prosthetic knee joint, clinically test prototypes of the knee, and use a questionnaire to evaluate its efficacy. Biomechanical models were used to analyze the stance-phase control characteristics of the proposed knee, and those of three other commonly prescribed paediatric knee joint mechanisms, which were also the conventional knee joints used by the six participants of this study (mean age 10.8 years). A questionnaire pertaining to stance-phase control was designed and administered twice to each child; once for the evaluation of the prototype knee joint and once for the conventional knee joint. Stance-phase modeling results indicated decreased zones of instability for the new knee as compared to other paediatric knee joints. Questionnaire results revealed a decrease in the frequency of falls with the prototype compared to other knees, especially in highly active children. The children also reported worrying less about the knee collapsing during walking. No differences were evident for stance-phase stability during running, walking on uneven terrain, ambulating up and down stairs and inclines, fatigue, and types of activities performed.

Design characteristics of pediatric prosthetic knees.

We examined whether pediatric prosthetic single-axis knees can theoretically provide the beneficial functional characteristics of polycentric knees and the design considerations needed to realize this. Five children and their parents provided subjective opinions of the relative importance of functional requirements (FRs) for the knee. FRs related to comfort, fatigue, stability, and falling were found to be of high importance, while sitting appearance and adequate knee flexion were of lower importance. Relationships were drawn between these FRs and deductions were made regarding the importance of associated design parameters. Stance-phase control was rated to be of greatest importance followed by toe clearance. Models were developed for five knees including four- and six-bar knees, corresponding to two commercially available components, and for three configurations of a single-axis knee. Stance-phase control, specifically stability after heel-strike and swing-phase initiation at push-off, and toe clearance were simulated. The results suggest that a single-axis knee design incorporating stance-phase control will mutually satisfy the identified set of highly and moderately important FRs.

Estimating bone conduction transfer functions using otoacoustic emissions.

A technique for estimating the nonparametric bone conduction transfer function using distortion product otoacoustic emissions (DPOAEs) is presented. Individual transfer functions were obtained using DPOAEs recorded from a single ear of five normal-hearing adults. Repeatability of the technique was investigated by performing measurements on at least three dates. Functions were reasonably repeatable, and were unique to each individual as expected from subjective measurements. Input force and DPOAE measurements were made for each individual, and a model of the auditory periphery representative of an average person was employed. The technique is objective and requires only passive cooperation, but robust DPOAEs are needed and the measurement time can be onerous for a wide frequency band or fine frequency resolution. With appropriate adjustments to the model of the auditory periphery, the method could be applied with animal models.