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Prosthetic Feet for Low-Income Countries

Craig, John CPO

JPO Journal of Prosthetics and Orthotics: October 2005 - Volume 17 - Issue 4 - p S47-S49
Does Foot Choice Influence Outcome?
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JOHN CRAIG, CPO, is affiliated with Abilene Artificial Limb, Abilene, Texas.

Correspondence: John Craig, CPO, Abilene Artificial Limb, 1202 Hickory Street, Abilene, TX 79601; e-mail:jgcraig@flash.net.

When recommending a prosthetic foot, prosthetists worldwide generally must consider the psychosocial impact of replacing the human foot with an artificial one of acceptable cost and function. In most low-income countries, there may be only one, or at best a few, options from which to choose. Often financial resources are quite limited and the functional demands on prosthetic feet are extreme. International aid groups (or indigenous companies) manufacturing feet under such circumstances generally do their best to marry function, durability, cosmetic appeal, and reasonable cost in their foot production.

In an effort to describe “appropriate” prosthetic foot function, many articles have made statements such as it is “only for walking”1 and to be worn in footwear, while restoring some of the “function and appearance” of the human foot2 including the provision of a “base of support.” Yet their use reportedly results in “asymmetry between the sound-side and the prosthetic-side”3 and an “increased metabolic energy expenditure.”4 Edelstein2 wrote that the important clinical distinction between prosthetic feet is “related to the internal design characteristics which enable the component to simulate some actions of the human foot,” (p. 1874) and that the “selection of a prosthetic foot should reflect consideration of the patient’s physical and psychological attributes and financial resources” (p. 1880).

These same considerations should not be forgotten in the provision of prosthetic feet in low-income countries. Furthermore, needs in such countries may differ based on functional demands, locally available materials, cost, and cultural issues. In a publication resulting from a 1995 International Society for Prosthetics and Orthotics (ISPO) consensus conference on appropriate technology in developing countries, Poonekar5 listed the ideal criteria for an appliance to be appropriate in India: 1) low cost; 2) locally available; 3) capable of manual fabrication; 4) considerate of local climate and working conditions (barefoot or sandal wear including rice farming in flooded fields); 5) durable; 6) simple to repair; 7) simple to process using local production capability; 8) reproducible by local personnel; 9) technically functional; 10) biomechanically appropriate; 11) as lightweight as possible; 12) adequately cosmetic; and 13) psychosocially acceptable.

Psychosocial acceptability might include such things as being able to squat for rest or use of a toilet and kneeling for religious prayers. Mtalo6 states that there are basic fac-tors which should be considered when selecting materials and lower limb prosthetic components: “function, durability, stability, cost, availability, cultural requirements, sustainability, climatic conditions, and ease of maintenance” (p. 241). Staats7 noted that financial and personnel resources are limited, while the demands are great to rehabilitate amputees in low-income countries. Thus the value of outcome assessments (including the provision of a very durable prosthesis) in real-life situations is often overlooked.

Following another ISPO consensus conference on appropriate orthopaedic technology for low-income countries, Poetsma8 noted, “the foot is still the weakest part of the prosthesis and must be improved in terms of durability without losing properties needed for good gait” (p. 185). Similarly, Heim9 commented that durability needs of the foot should be at least 3 years. Reportedly a humanitarian aid group was targeting a 3–5-year field life for prosthetic feet. It appears that 3 years is the minimal life-expectancy target for prosthetic feet in low-income countries.

Faced with limited funding, prosthetic service providers in low income countries have attempted to fabricate prosthetic feet ranging from basic “pegs” (POF,10 Wings of Calvary,11 etc.) to copies of developed-world feet (mainly of the solid ankle cushioned heel [SACH] or articulated foot variety). Unfortunately, some of these feet have not been culturally acceptable or have broken down quickly due to the use of inferior materials or poor manufacturing techniques. Feet imported at a very high cost to low-income countries do not hold up well when worn without shoes and exposed to the extremes of climate and labor conditions such as working in flooded rice fields. In some cases they don’t allow the functions necessary to squat or kneel, necessary for activities of daily living in those countries. International aid agencies such as the International Committee for the Red Cross (ICRC), Handicap International (HI), Veteran’s International (VI), and others have made many attempts to produce prosthetic feet that will meet the demands of low-income countries.

Some ingenious medical rehabilitation workers have also developed prosthetic feet to meet the demands of the people they serve. During 2001–2004, ISPO carried out a series of scientific studies, mostly prospective, with funding from USAID’s Patrick Leahy War Victims Fund. The purpose was to assess various lower limb prosthetic components both by mechanical testing methods and in prospective and retrospective studies. Among commonly used prosthetic feet were the (ICRC) CR-SACH foot, the HI Cambodia (SACH-type) foot, the VI multi-axial foot, the VI solid ankle (SACH-type) foot, and the Jaipur foot (a retrospective field study only). The HI and VI feet were vulcanized SACH-type rubber feet using a polypropylene keel with a hole in it to allow for foot bolt attachment to the shank of a prosthesis. The vulcanized rubber is mechanically bonded to the keel by means of holes or undercuts in the keel. The height and parallel proximal surface of both feet resembles feet from many developed countries. These feet are able to withstand submersion in water and rugged wearing conditions that might cause western feet to deteriorate quickly. They can be produced (sometimes locally using premade foot molds) at a relatively low cost in “mass production” settings. Still, there have been some problems with the rubber material “delaminating” or loosening from the keel. Poor natural rubber vulcanization can also create problems. The ICRC foot was designed to also use a polypropylene (regrind) keel similar to the above two feet, but with a polyurethane type of rubberized foot material for cosmetic and durability purposes. This foot is usually attached to the ICRC polypropylene alignable shank. Production of ICRC feet, which used to be done in numerous centers, has been centralized in Switzerland for quality-control purposes.

Mirithu12 describes the Jaipur foot, which was a part of the high-density polyethylene (HDPE) transtibial and transfemoral Jaipur Limb, which was the focus of the study in which this author was the chief field investigator. The Jaipur foot was designed by an orthopedic surgeon and his prosthetic technicians in the early 1970s because of problems they had encountered with imported feet not lasting in India where barefoot or sandal walking and working is the norm. The imported feet did not allow adequate foot motion or function to do squatting activities (such as using a squat toilet on the floor) or for common kneeling prayer activities. Although the Jaipur foot height is about 12–15 cm (5–6″), it functions as a highly flexible keel/multi-axial foot ankle system, which allows for ankle, mid-foot, and forefoot motion. It is somewhat similar to the stationary ankle flexible endoskeleton (SAFE) foot available in the United States.

The Jaipur foot is constructed of a wood supramalleolar block with or without a foot attachment bolt, to which a prosthetic shank may be secured (with the lower aluminum or polyethylene shank covering this portion of the foot. Microcellular rubber (similar to crepe rubber) calcaneal, mid-foot, and phalangeal “bones” are wrapped and secured with a black fiber type of adhesive cord or tape, with those parts then being completely encased in rubber vulcanized in premade foot molds.

Regarding whether a correlation exists between foot-ankle systems and prosthetic outcomes, in low-income countries, the major related issues seem to be durability, performance, and patient satisfaction.

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DURABILITY

Heim9 observed that in the low-income countries being studied, the shortest life span for a foot was about 3–9 months with some lasting 12–18 months. The exceptions were the Jaipur and the HI foot with lifespans between 2 and 5 years. Interestingly, ISPO also studied feet used in Honduras, India, and Uganda (where many feet were worn without footwear). Jensen13–15 noted that only the VI-feet and the Jaipur-rubber feet “stood the test” after 24 months. He reported that the survival rate amounted to 82% (73–89%) after 18 months and 53% (42–63%) after 36 months, which was considerably better than the results reported with the SACH foot modifications tested in small numbers in Vietnam.16 The Jaipur foot then had a very favorable durability record as compared to other feet in the studies cited—53% survived after 3 years. The Jaipur foot was recognized to have a life exceeding most low-income country feet.

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PERFORMANCE

One might ask what the acceptable patient compliance standard is for the use of low-income country prosthetic feet or limb systems. Gunawardena et al.17 presented the results of a study involving 461 transfemoral and transtibial amputee soldiers, where they found a mean wearing time of 11 (± 3.9) hours per day for transtibial amputees. Transfemoral amputees wore prostheses for a mean duration of 8.2 (± 4.2) hours per day. The authors also noted another study of amputees at the Nova Scotia Rehabilitation Center,18 which indicated 65% wore their prostheses for at least 9 hours per day. Older amputees of all causes, however, reportedly had comorbidities that affected their prosthetic use.15

Performance in prosthetic use by persons with lower limb amputations in low-income countries, seems to be adversely affected by the familial or societal “safety net” available: the less help and support, the better the functional use. Performance of the foot separately could not be determined clearly from the studies of the HDPE Jaipur Limb system. As a clinician interviewing the users of the HDPE Jaipur Limb, it was this author’s conclusion that persons who had suffered the loss of parts of both hands and both feet as a result of leprosy and who could farm two acres to survive, and/or who could use a bicycle to transport themselves for miles, had achieved an acceptable (successful) functional outcome.

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PATIENT SATISFACTION

Compliance in the use of prostheses in low-income countries has also been evaluated through field surveys. Jensen et al.14,15 noted that patient compliance and satisfaction are only relative measures of success. Prospective surveys16 in Vietnam of the Tanzania Training Center for Orthopedic Technology (TATCOT) system and the ICRC polypropylene system indicated that 83% of transfemoral users and 88% of transtibial users were satisfied with their HDPE Jaipur Limb prostheses. However, most of these amputees did not have any other experience to compare their prosthetic use against.

The use of HDPE Jaipur Limb systems was not recommended by ISPO based mainly on its provision by under-trained prosthetics clinicians or technicians. It should be noted that there was little follow-up care provided to amputees interviewed in our studies, and this factor could have affected the outcomes discovered in them.

Financial resources are probably the major deciding factor affecting the clinician’s decision as to what foot to supply to an amputee in a low-income country. But function, durability, and cosmesis cannot be dismissed in that process. Although the provision and use of prosthetic feet in low-income countries is a challenge, there are prosthetic feet being developed and provided at relatively low costs by indigenous or international aid groups that do meet rigorous functional and durability needs. High-functional-level feet such as the College Park Tru-Step and Flex-Feet or similar models are probably not appropriate for use in low-income countries because of the high cost, sophistication, availability, and maintenance necessary with these systems. Conversely, feet currently used in low-income countries would probably not be accepted in industrialized countries because of weight, cosmesis meeting different cultural needs, and liability factors.

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REFERENCES

1. Wing D, Hittenberger D. Energy storing prosthetic feet. Arch Phys Med Rehabil 1989;70:330–335.
2. Edelstein J. Prosthetic feet—state of the art. Phys Ther 1988;68:1874–1876.
3. Barth D, Schumacker L, Thomas S. Gait analysis and energy cost of below knee amputees wearing six different prosthetic feet. J Prosthet Orthot 1992;4:63–75.
4. Gitter A, Czerniecki J, DeGroot D. Biomechanical analyses of the influence of below knee amputee walking. Am J Phys Med Rehabil 1991;70:142–148.
5. Poonekar P. Prosthetics and Orthotics in India. Paper presented in the Report of a Research Planning Conference—Prosthetic and Orthotic Research for the Twenty-first Century, National Institute of Child Health and Human Development, Bethesda, MD, July 23–25, 1992.
6. Mtalo LB. Appropriate prosthetic prescription. Paper presented at the ISPO Consensus Conference on Appropriate Orthopaedic Technology for Low-Income Countries, Moshi, Tanzania, September 18–22, 2000.
7. Staats T. The rehabilitation of the amputee in the developing world: a review of the literature. Paper presented at the ISPO Consensus Conference on Appropriate Orthopaedic Technology for Developing Countries, Phnom Penh, Cambodia, June 5–10, 1995.
8. Poetsma P. ICRC polypropylene system. Paper presented at the ISPO Consensus Conference on Appropriate Orthopaedic Technology for Low-Income Countries, Moshi, Tanzania, September 18–22, 2000.
9. Heim S. Prosthetic foot design. Paper presented at the ISPO Consensus Conference on Appropriate Orthopaedic Technology for Low-Income Countries, Moshi, Tanzania, September 18–22, 2000.
10. Matthews D, Burgess E, Boone D. The all-terrain foot. J Prosthet Orthot 1993;5:29–31.
11. Snelson R. Wings of Calvary. Paper presented at the ISPO Consensus Conference on Appropriate Prosthetic Technology for Developing Countries, Phnom Penh, Cambodia, June 5–10, 1995.
12. Mirithu J. The Jaipur polyethylene system. Paper presented at the ISPO Consensus Conference on Appropriate Orthopaedic Technology for Low-Income Countries, Moshi, Tanzania, September 18–22, 2000.
13. Jensen JS. Outcome of clinical field testing of SACH-feet for low income countries. Paper presented at the ISPO 11th World Congress, Hong Kong, August 1–6, 2004.
14. Jensen JS, Craig J, Mtalo LB, Zelaya CM. Clinical follow-up of Jaipur HDPE TF prostheses. Prosthet Orthot Int 2004;28:152–166.
15. Jensen JS, Craig J, Mtalo LB, Zelaya CM. Clinical follow-up of Jaipur HDPE TT prostheses. Prosthet Orthot Int 2004;28:230–244.
16. Jensen JS, Heim S. Preliminary experiences with modified SACH feet manufactured and used in a tropical developing world setting. Prosthet Orthot Int 1999;23:245–248.
17. Gunawardena NS, Seneviratne RdA, Athauda T. Prosthetic outcome of unilateral lower limb amputee soldiers in two districts of Sri Lanka. J Prosthet Orthot 2004;16:123–130.
18. Sapp L, Little CE. Functional outcomes in a lower limb amputee population. Prosthet Orthot Int 1995;19:92–96.
© 2005 American Academy of Orthotists & Prosthetists