Yeongchi Wu

Lower-limb prostheses and wheelchairs in low-income countries [An Overview]

This review covers a range of topics related to lower-extremity prostheses (LEP) and wheelchair technology and service provision. A description on how recent advances in LEP technology for low-income countries have come about through research and field studies is presented and a discussion on the required technical advances and associated research that would increase LEP production capacity is given. The paper also discusses several approaches used for designing, manufacturing, and providing WCs to and in low-income countries; there is also a discussion on past research and highlight current efforts to build research capacity in the field. Last, the paper includes an in-depth description of the social, societal, economic, and physical constraints in India to demonstrate the difficulties in successfully applying this technology.

Comparison of á priori alignment techniques for transtibial prostheses in the developing world – pilot study

Purpose. The purpose of this study was to evaluate three alignment systems based on two alignment theories that can be utilized in the fabrication of monolimb prostheses that have acceptable alignment. A second goal was to assess the feasibility of technology transfer for providing prosthetic services to remote areas of landmine-affected countries. Method. Five prosthetists and five healthy transtibial amputees participated in the study. Each prosthetist was trained and then used each of the three systems to capture alignment measurements for one subject. Three monolimbs identified as X, Y and Z were fabricated for each subject and assessed during clinical static and dynamic gait conditions. Training materials and methods were also evaluated. Results. All three systems captured acceptable alignments fairly well, although the two systems that incorporated weight-bearing into the alignment process had slightly better outcomes. Each system has its own advantages in terms of ease of use, required equipment, and ease of technology transfer. Conclusion. All three systems have the potential for application in outreach prosthetic services and warrant continued evaluation. Minor changes need to be incorporated into the alignment systems and procedures to make them easier to use and more effective.

CIR sand casting system for trans-tibial socket.

The authors have developed a transtibial socket fabrication system based on the “dilatancy” principle, a process that has been commonly used in forming wheelchair Seating. The CIR Sand Casting System replaces plaster of Paris with sand for forming both a negative sand mould and a positive sand model, which can be modified for either thermoplastic socket formation or resin lamination. Initial clinical trials suggest that fabrication times are approximately 90 minutes from patient evaluation and casting to dynamic alignment. Compatibility with all existing prosthetic components is retained. It is believed the CIR socket fabrication system may be a competitive alternative for prosthetic service providers in developing countries.

CIR Casting System for Making Transtibial Sockets

This paper describes a new casting system for transtibial socket fabrication. Like the earlier CIR Sand Casting System, the CIR Casting System is based on the ‘dilatancy’ principle that is similar to the packaging process for coffee beans by which loose beans become a solid mass when a vacuum is applied. The main difference from the CIR Sand Casting System is that the CIR Casting System uses light-weight, polystyrene beads in place of silica sand as the primary material for casting the negative mold. The formed negative mold can be converted into a positive sand model for modification and socket formation. With the new plaster-less casting system, the prosthetist can fabricate a transtibial prosthesis in about one hour. It reduces the set-up cost, overall weight and size of the casting system, and increases portability for service in remote areas. The System also creates minimal waste and is energy-conserving and environmentally-friendly.

Á priori alignment of transtibial prostheses: a comparison and evaluation of three methods

Purpose: The objectives of this study were to compare three á priori alignment methods and evaluate them based on initial gait quality and further alignment changes required to optimize gait. Á priori alignment is requisite for monolimbs, transtibial prostheses in which the socket and pylon are made from one piece of plastic, because monolimbs have no alignment adjustability. Method: The three methods investigated were traditional bench alignment (TRAD), vertical alignment axis (VAA) and anatomical based alignment (ABA). Endoskeletal components were utilized for the study, rather than monolimbs, so that alignment could be experimentally manipulated. Three endoskeletal prostheses were aligned, one according to each á priori method, for each of seven subjects. Gait and alignment data were captured, dynamic alignment was performed to optimize gait, and data were captured again. Results: VAA and TRAD methods required less change compared to ABA in socket flexion angle. Looking at subjects individually, VAA produced a better alignment and better gait for the greatest number of subjects. Conclusions: A new refined method of á priori alignment is proposed based on the results of this study, and is applicable for á priori alignment of monolimbs or any type of transtibial prosthesis. Implications for Rehabilitation This study shows that there is a wide range of acceptable alignments for a transtibial prosthesis. Using the best possible alignment for a monolimb could produce a high-quality transtibial prosthesis at a great cost savings.

Plastic soda bottles: a reusable material for making transradial sockets.

This paper describes a new fabrication process for making low-cost transradial sockets using recyclable plastic soda bottles. Easy, fast, and inexpensive to fabricate, the resulting socket can be used as a temporary device for stump care. Multiple sockets can be made and individually incorporated with various terminal devices for light-duty self-care or functional activities, such as feeding, showering, typing, swimming, or gardening. The formed socket is lightweight and also suitable for use with a cosmetic passive hand prosthesis. This process has been developed as a potential cost-effective assistive technology appropriate for individuals with transradial amputation in resource-limited countries.

Evaluation and comparison of á priori alignment techniques for transtibial prostheses in the developing world - field trial in Nicaragua.

Purpose. The purpose of this study was to transfer three simplified alignment techniques to prosthetic technicians in a developing country through training materials and a hands-on training workshop, and to subsequently evaluate the efficacy of the alignment systems in producing acceptably aligned monolimb prostheses. Method. Prosthetists utilized the anatomically-based-alignment (ABA)-standing, ABA-supine and vertical alignment axis (VAA) alignment systems to produce three monolimbs for each of 30 healthy and active transtibial amputees. Prosthetists assessed all three monolimbs for each subject in both static and gait conditions to determine which monolimb had the best alignment and produced the best functional gait. Subjects also selected the monolimb which they believed had the best alignment; subjects utilized each monolimb for a 1-month home assessment. Results. Twenty-eight subjects completed the study. Eighty-four monolimbs were evaluated by the prosthetists and the subjects. A few monolimbs had minor socket fitting and alignment issues, but none prevented evaluation in the laboratory or during the 1-month home assessment. Only three monolimbs had poor alignment and could not be worn by the subjects. Conclusions. All three systems captured acceptable alignments, although the two systems that incorporate weight bearing, the ABA-standing and VAA alignment systems, produced slightly better outcomes. The alignment ratings between these two systems were statistically insignificant.

Dilatancy-based impression and fabrication technique for custom foot orthoses

Background and aim: Current methods used to take impressions for custom foot orthoses include plaster bandage, foam box, fiberglass, and laser-optical scanner. Impressions are converted to positive plaster or foam models. These methods create waste and may not be feasible in resource-limited areas. This technical note presents an alternative, greener impression and fabrication technique for foot orthoses that utilizes the dilatancy principle. Technique: Steps of the dilatancy (vacuum-based) procedure include taking an impression of the foot, converting the negative mold to a positive sand model, modifying the positive sand model, and thermoforming the foot orthosis. Discussion: This plaster-less system is inexpensive to set up and maintain, is reusable thereby minimizing cost and waste, and is clean to use. It enables a practitioner to quickly take an impression for fabricating a foot orthosis in a short period of time during a single clinic visit by the patient. Clinical relevance The dilatancy casting system could potentially be a cheaper, faster, and greener alternative procedure for fabricating custom foot orthoses in both developing and developed countries.