Quality benchmark for trans-tibial prostheses in low-income countries

Pioneering low-cost 3D-printed transtibial prosthetics to serve a rural population in Sierra Leone - an observational cohort study

BACKGROUND

There is a huge unmet global need for affordable prostheses. Amputations often happen in Sierra Leone due to serious infections, complex wounds, traffic accidents and delayed patient presentation to the hospital. However, purchasing a prosthesis is still beyond reach for most Sierra Leonean amputees.

METHOD

We applied computer-aided design (CAD) and computer-aided manufacturing (CAM) to produce low-cost transtibial prosthetic sockets. In February and March 2020, eight participants received a 3D printed transtibial prosthesis in the village of Masanga in Tonkolili district, Sierra Leone. Research was performed using questionnaires to investigate the use, participants' satisfaction, and possible complications related to the prostheses. Questionnaires were conducted prior to production of the prosthesis and five to six weeks after fitting the prosthesis. A personal short-term goal was set by the participants.

FINDINGS

Competitively priced and fully functional prostheses were produced locally. After six weeks, all participants were still wearing the prosthesis and six of the eight participants reached their personal rehabilitation goals. Using their prostheses, all participants were no longer in need of their crutches.

INTERPRETATION

We have come a step closer to the production of low-cost prostheses for low-and middle-income countries (LMICs). The goal of our project is to perform long-term follow-up and to refine our concept of 3D printed prostheses for LMICs to provide practical solutions for a global health need unmet to date.

FUNDING

€ 15,000 was collected during a crowdfunding campaign in collaboration with the Dutch Albert Schweitzer Fund. Internship allowance for MvdS was obtained from the University of Twente. 3D-scanner, 3D-printer, and printing material were donated by Ultimaker BV and Shining 3D.

Sustainable Development: A Below-Knee Prostheses Liner for Resource Limited Environments

This research sought to develop a fabricable prosthetic liner that could be fabricable, intuitive, and a cost-effective means of providing advanced prosthetics in developing settings. An affordable ethyl-vinyl-acetate roll-on (AERO) liner for permitting a total surface bearing suction socket design was created and provided to a single participant for in vivo outcome measurements. The liner was fabricated from locally produced low-density ethyl-vinyl-acetate (EVA) foam. A liner fabrication process was developed and described, and one participant was provided 3 mm and 6 mm AERO liner variants for outcome evaluations. Six-minute walk test, residual limb temperature, and socket comfort score (SCS) while in AERO liner were collected. Thirty-day step counts of AERO liner with prosthesis and thermoplastic elastomer (TPE) liner with prosthesis were collected. The results of in vivo evaluations indicate increased speed, slightly higher residuum temperature, and increased comfort of the 6 mm AERO liner. Pedometer tallied step counts for the AERO liner and TPE liner prostheses were similar. The 6 mm AERO liner provided the best comfort and function of the two thicknesses in liners, and step count data indicated that the volume of patient activity was similar to when wearing the TPE liner prosthesis. Roll-on fabricable low-cost liners offer an affordable means of providing total surface bearing suction prostheses for resource limited environments (RLE). A prosthetist or technician can use the existing skills and lab to create liners.

Transtibial Prosthetic Socket Shape in a Developing Country: A study to compare initial outcomes in Pressure Cast hydrostatic and Patella Tendon Bearing designs

This study compared the physical function and comfort level of patients with unilateral transtibial amputation after being fitted with a hand-cast Patella Tendon Bearing (PTB) socket and a pressure-cast (PCAST) hydrocast socket. The latter technique aims to reduce the skill dependency currently required for socket manufacture and fit. The study was conducted at the Vietnamese Training Centre for Orthopaedic Technologies and involved seventeen Vietnamese participants with unilateral transtibial amputation, all of whom were long term users of prosthetics. All participants were fitted with two sockets manufactured using both hand-cast and PCAST techniques with International Committee of the Red Cross components. Walking tests (timed up and go test and six-minute-walk-test), spatio-temporal gait analyses and subjective comfort assessments were completed after a short acclimatisation period with each socket. The participant-preferred socket was also noted. No significant differences were found for the measures of mobility, functional capacity, spatio-temporal gait parameters, gait symmetry, perceived comfort or participant socket preference. The results show the initial patient outcomes are similar when participants are fitted with a hand-cast PTB socket and a PCAST hydrocast sockets. Future work should confirm these findings in a longer trial.

The development and testing of a modified natural rubber CR solid ankle-cushion heel prosthetic foot for developing countries

Background

Durable and locally fabricated prosthetic feet are important for developing countries. Modifications to the current CR solid ankle–cushion heel prosthetic foot could enhance current foot characteristics and reduce costs. The goal of this project was to modify the keel and rubber outer foot shell to enhance features and reduce costs of the current CR solid ankle–cushion heel offering.

Methods

The prosthetic foot was designed, fabricated and then tested mechanically for strain and displacement in a cyclic testing machine according to a component of the ISO-10328 testing protocol. Dynamic cyclic testing of both forefoot and heel portions of the foot was conducted.

Findings

Dynamic mechanical cyclic testing of the forefoot and heel at 1.28 kN for two million cycles at a rate of 1 Hz was successfully achieved. The final cost of producing the foot was roughly $16 USD. Limitations include the inability to perform the full battery of ISO-10328 foot testing, UV testing and a limitation to laboratory testing. Clinical studies examining practical application of the modified foot should be conducted.

Patients' Satisfaction with Lower-limb Prosthetic and Orthotic Devices and Service delivery in Sierra Leone and Malawi

BACKGROUND

People with disabilities have the right to personal mobility and available and affordable assistive technology, according to the Convention of Rights of Persons with Disabilities. The aims were to investigate similarities and differences between Sierra Leone and Malawi concerning participants' mobility and satisfaction with their lower-limb prosthetic or orthotic device and related service delivery, and to identify variables associated with patients' satisfaction with assistive devices and associated services in the entire study group from these two low-income countries.

METHODS

Questionnaires, including QUEST, were answered by 222 patients in Sierra Leone and Malawi.

RESULTS

Eighty-six per cent of assistive devices were in use, but half needed repair. One third of participants reported pain when using their assistive device. A higher percentage (66%) of participants in Sierra Leone had difficulties or could not walk at all on uneven ground compared with 42% in Malawi. The majority in both countries had difficulties or could not walk at all up and down hills, or on stairs. Participants in both countries were quite satisfied (mean 3.7-3.9 of 5) with their assistive device. Participants were most dissatisfied with: comfort (46%), dimensions (39%), and safety (38%) of their assistive device. In Sierra Leone participants were less satisfied than in Malawi with service delivery (mean 3.7; 4.4, p < .001). Access to repairs and servicing of their assistive device was considered the most important item. In Sierra Leone patients were less satisfied with follow-up services (41%) than patients in Malawi were (22%). The strongest association with satisfaction with assistive device was pain, and for satisfaction with service, country. The general condition of devices and the ability to walk on uneven ground were associated with both satisfaction with assistive devices and service received.

CONCLUSIONS

Participants reported high levels of use and mobility with their assistive device, in spite of pain and difficulties walking on uneven ground, which were also associated with the level of satisfaction with the assistive device. Access to repairs and follow-up services were the most important to patients, and should be addressed. Country was associated with satisfaction with service, with participants in Sierra Leone significantly less satisfied.

A scoping literature review of the provision of orthoses and prostheses in resource-limited environments 2000-2010. Part two: research and outcomes

BACKGROUND

Despite the activities of many orthotic and prosthetic provision organizations in resource-limited environments, there is still a great need and there are several areas for improvement, as identified in Part One of this series.

OBJECTIVES

Our goal was to examine outcomes and conclusions of research studies to produce an evidence base for determining factors that may lead to successful provision of orthoses and prostheses in resource-limited environments.

STUDY DESIGN

Literature review.

METHODS

We conducted a scoping literature review of all information related to orthotic and prosthetic provision in resource-limited environments published from 2000 to 2010. We extracted measured outcomes reported in all types of articles and analyzed conclusions from research studies.

RESULTS

Reported outcomes included durability, cost, satisfaction, use/nonuse of device, amount of utilization, walking speed, discomfort, pain, fit, misalignment, capacity for service provision, number of devices produced or delivered, and number of graduates from training programs.

CONCLUSIONS

There are many gaps in the evidence base, notably in measuring inclusion, participation, and quality of life for orthosis and prosthesis users in resource-limited environments. There is a paucity of reported outcomes for orthotics. Valid, reliable, and standard methods of data collection and reporting are needed to advance the field and enhance the evidence base.

Assistive technology in developing countries: a review from the perspective of the Convention on the Rights of Persons with Disabilities

BACKGROUND

The 'Convention on the Rights of Persons with Disabilities' (CRPD) requires governments to meet the assistive technology needs of citizens. However, the access to assistive technology in developing countries is severely limited, which is aggravated by a lack of related services.

OBJECTIVES

To summarize current knowledge on assistive technology for low- and lower-middle-income countries published in 1995 or later, and to provide recommendations that facilitate implementation of the CRPD.

STUDY DESIGN

Literature review.

METHODS

Literature was searched in web-based databases and reference lists. Studies carried out in low- and lower-middle-income countries, or addressing assistive technology for such countries, were included.

RESULTS

The 52 included articles are dominated by product oriented research on leg prostheses and manual wheelchairs. Less has been published on hearing aids and virtually nothing on the broad range of other types of assistive technology.

CONCLUSIONS

To support effective implementation of the CRPD in these countries, there is a need for actions and research related particularly to policies, service delivery, outcomes and international cooperation, but also to product development and production.

CLINICAL RELEVANCE

The article has a potential to contribute to CRPD compliant developments in the provision of assistive technology in developing countries by providing practitioners with an overview of published knowledge and researchers with identified research needs.

Lower-limb prosthetic technologies in the developing world: A review of literature from 1994-2010

In the mid-1990s, a number of key publications and meetings of experts identified major technical issues associated with prosthetic technologies intended for developing countries. These included inadequate durability of prosthetic feet, poor socket quality and prosthetic fit, improper alignment of prostheses, and inferior function of components. To examine the progress that has been made since then in addressing these issues, a comprehensive review of literature was performed. In total, 106 articles were selected and included in the review. The review examined prosthetic technologies categorized into feet and ankles, knees, sockets and suspension, and materials, structures, and alignment methods. Moreover, publications were categorized as technical development, clinical (lab-based) testing, or clinical field testing studies. The results reveal important work that has been carried out to develop and implement standardized outcome measures during field testing, allowing various existing prosthetic technologies to be evaluated in terms of their use, function, durability, and other factors. Progress has also been made toward addressing the aforementioned limitations of prosthetic technologies, however, more research and development is required. This includes improving the durability of the external cosmetic features of prosthetic feet, developing more functional prosthetic knee joints, and simplifying fabrication techniques to further improve outcomes associated with socket fit and prosthetic alignment. Research and development collaborations between developed and developing countries, and the dissemination of ongoing research, development, and evaluation activities are essential to the advancement of prosthetic technologies in these regions.

Preliminary experiences with the CIR casting system for transtibial prosthetic sockets

A sand-casting technique for transtibial sockets was applied to 28 amputees in 2005. Although this meant an improvement in the quality of fitting as compared to historical reports with plaster of Paris casting, a total contact required three (two to five) stump socks. Continuing research leads the inventor, Dr Y. Wu, to replace the sand with micro polystyrene beads and simplify the equipment by eliminating the need for fluidization of silica sand by an air compressor during casting of the amputation stump. In a pilot series of 10 transtibial amputees, socket casting was performed with the new CIR casting technique and compared with the former sand-casting technique conducted by the same Category-I prosthetist. It was possible to obtain a good fit in eight out of 10 cases, which is an improvement from 19 out of 28 in the old series. Furthermore, there was a highly significant reduction in circumference measurements on the positive model with the new technique as compared to sand-casting.

Quality of polypropylene sockets for trans-tibial prostheses in low-income countries

Based on six series of patients (n = 198) participating in clinical field testing of prosthetic feet and all provided with trans-tibial prostheses in accordance with the polypropylene component and assembly system developed by the International Committee of the Red Cross (ICRC) follow-up studies by teams consisting of an orthopaedic surgeon and a Category-I prosthetist-orthotist were conducted. A series of quality measures were tested against previously published quality benchmarks. The polypropylene system gives a consistent product and allows for increased demands on quality benchmarks. The acceptance of discomfort and pain could be reduced to 5 +/- 5%. The technical performance demands were reduced for misalignment to 10 +/- 5%. In general for all quality measures the range could be reduced to +/- 5%. These new demands reflect what an orthopaedic workshop outside of a teaching system should be able to attain.

Sand-casting technique for trans-tibial prostheses

A sand-casting technique for trans-tibial sockets was applied to 28 amputees, and the prosthetic fit observed through transparent check sockets. The results were better than historical reports of fittings with plaster of Paris casting by qualified prosthetists. The fit was consistently and evenly larger than the stump, but total contact could be achieved by applying three (two to five) stump socks. This would normally be considered on the high side of a good fit.