oandp.com

In a 2009 publication, the World Health Organization estimated that 650 million people worldwide have disabilities, the vast majority of whom live in low-income countries.¹ The 2004 World Health Survey further defined the extent to which the burden of disability is disproportionately borne in lower-income countries: The prevalence rate of disability in the adult population is 18 percent compared to only 12 percent in high-income countries.² Thus, while low-income countries account for 84 percent of the global population, they bear 90 percent of the total disease burden.¹ The small percentage of people with disabilities in low-income countries who have access to rehabilitation services, 3 percent according to estimates, further aggravates this disparity.² Specific to prosthetic rehabilitation, recent estimates suggest that there are roughly 30 million people in low-income countries who need prostheses.¹

There are a number of issues associated with addressing this global challenge. This article introduces some of the current and projected demographics in low- and lower-middle-income countries along with a popular polypropylene transtibial prosthetic system designed by the International Committee of the Red Cross (ICRC) to meet the needs of the amputee community in resource-limited countries.

DEMOGRAPHICS

In a recent literature review of this topic, Harkins et al. summarize some of the unique demographics that have been identified with low-income countries. These include urban versus rural living conditions, the influence of lower life expectancies, amputation etiologies, and the changing prevalence of diabetes in low- and lower-middle-income countries.²

In contrast to the preponderance of urban environments that characterize many high-income countries, low-income countries have largely rural populations.² For example, according to the World Bank, the United States has a rural population of 59 million, constituting 19 percent of its total population. Ethiopia, though, has a rural population of 78 million, or 81 percent of its total population. Given the challenges of obtaining transportation to remote treatment facilities in resource-limited settings, this consideration often constitutes a substantial barrier to obtaining treatment. A sampling of low- and lower-middle-income countries and their rural population statistics is shown in Table 1.

Given the longer life expectancies encountered in high-income countries, the population of individuals with amputations is largely older and have amputation etiologies of peripheral vascular disease, diabetes, and other lifestyle-related diseases. However, in low-income countries with reduced life expectancies, the population of individuals with amputations is younger, with a higher prevalence of pediatric patients. In contrast to the lifestyle diseases of high-income countries, diseases such as polio and malaria that have long been eradicated in other parts of the world may be common in low-income settings. Further, traumatic amputations due to lower occupational safety standards, civil unrest, and poor road safety are more common.²

As an example, Harkins et al. describe a study of P&O services in India that characterized these trends. The study found that male patients outnumbered female patients four to one and that all patients were under age 30. Male patients were generally between the ages of 11 and 30, and female patients were generally below the age of ten. This is consistent with many low-income societies in which women remain at home and men perform manual labor in environments with poor health and safety standards.²

While the casualty rates from landmines and other explosive remnants of war continue to decline, their consequences have been disproportionately experienced in low-income countries. According to the Landmine and Cluster Munition Monitor (www.themonitor.org), more than 43,000 nonfatal injuries have occurred between 1999 and 2013 due to these explosive devices. Of the 11 countries with more than 1,000 casualties since 1999, seven of them are classified by the World Bank as low income (Chad, South Sudan, the Democratic Republic of Congo, Ethiopia, Somalia, Cambodia, and Afghanistan), and one of them, Sudan, is classified as lower-middle-income. The collateral impact associated with past and current conflicts continues to increase the number of people who undergo amputations in less-resourced settings.

In addition to the demographics described thus far that have long characterized the populations of people with amputations in resource-limited settings and provided challenges to the provision of their care, low-income countries are increasingly encountering a rise in the incidence of type 2 diabetes. As global urbanization trends address some of the challenges associated with large rural populations, that same trend has been cited by the International Diabetes Foundation as a driver for increasing many of the risk factors for type 2 diabetes in developing countries.³ For example, the prevalence rate of diabetes in the United States in 2013 was reported at 9.2 percent, with 24 million affected adults. The projected prevalence rate for 2035 is no different, with roughly 30 million adults likely to be affected simply due to population growth.³ By contrast, in Ethiopia the prevalence rate of diabetes in 2013 was only 4.9 percent but is projected to increase to 5.5 percent with the number of affected adults growing from just under two million to almost 4.5 million, a 138.5 percent increase.³

The highest regional prevalence for diabetes in 2013 was North America (including Canada, Mexico, and the United States), at 11 percent. While Africa had the lowest prevalence of adult diabetes (5.7 percent) in 2013, it is also projected to have the highest proportional increase in adult diabetes by 2035, with a regional increase of 109 percent. The International Diabetes Foundation summarized its projections in the assertion that the expected proportional increase in the number of adults with diabetes will be greatest in low-income countries (108 percent) followed by lower-middle-income countries (60 percent), upper-middle-income countries (51 percent) and high-income countries (28 percent).³ Healthcare infrastructures in limited-resource settings are generally restricted in their ability to screen and manage the increasing number of individuals with type 2 diabetes. The current and projected prevalence of diabetes in a sample of low- and lower-middle-income settings is reported in Table 2.

Collectively, these observations underscore the challenge of providing prosthetic care in low- and lower-middle-income countries. Transportation limitations among largely rural populations constitute a barrier to obtaining treatment for younger, mostly male populations with traumatic amputation etiologies. Meanwhile, the prevalence of diabetes appears to be increasing in these impoverished areas, threatening further demands on often inadequate treatment resources.

SERVICE MODELS

Figure 1: Polypropylene transtibial prosthesis modeled on the design concepts of the International Committee of the Red Cross.

Several design concepts have been put forward to address the need for appropriate prosthetic technology in developing economies. As part of their recently published literature review of considerations for success in the provision of P&O services in resource-limited environments, Ikeda et al. summarize the qualities of successful lower-limb prosthetic design strategies.⁴ Ideal designs should be affordable, durable, lightweight, cosmetically acceptable, and consider the physical environment.⁴ While several prosthetic components and systems have been designed with these considerations in mind, this article describes one of the more commonly used prosthetic solutions, the ICRC’s transtibial polypropylene component system (Figure 1).⁵

The ICRC’s Physical Rehabilitation Program began in 1979 with the objective of creating prosthetic technologies suitable for war-torn, low-income, and developing countries.⁵ The stated objectives of these efforts include systems that are:

• Durable, comfortable, and easy for patients to use and maintain
• Easy for technicians to learn, use, and repair
• Standardized but compatible with the climate in different world regions
• Low cost but modern and consistent with international accepted standards
• Easily available

The ICRC’s original prosthetic systems that were fabricated using locally available materials such as wood, leather, and metal were later replaced by a standardized polypropylene system that can trace its origins to efforts in Cambodia and Colombia in the late 1980s and early 1990s. The current system includes a standard transtibial kit that can be readily fabricated and a custom polypropylene socket with an inner foam liner. More than 20,000 ICRC polypropylene prostheses are provided globally each year.⁵ The fabrication technique for this system has been made openly accessible.⁶ Using local techniques, the prosthetist obtains an acceptable positive transtibial socket shape. The equivalent of a Pelite liner is fabricated over this plaster model. Then the model is positioned in alignment over a polypropylene “cylindrical TT [transtibial] cup,” a short plastic cup with a distal hole that will serve as the proximal attachment point for the ICRC components. After fixing a nail to the end of the model, it is brought in contact with the cup, and a slurry of plaster is used to temporarily attach the cup to the foam liner in a proper alignment.

Figure 2: Posterior view of the distal aspect of a transtibial polypropylene socket where it connects through a polypropylene convex disk into the concave proximal surface of a polypropylene cylinder. The pairing of the convex and concave surfaces permits proximal alignment adjustability.

After the plaster is hardened and its transition smoothed, a small foam disk is then nailed into the hardened plaster over the hole in the center of the cup to act as a fabrication dummy. The model is then moved to a horizontal vacuum jig where a sheet of polypropylene is drape-molded with a posteriorly positioned seam to create the outer socket (Figure 2).

Once the plastic is cooled, removed from the model, trimmed, and polished, the distal aspect of the socket and the foam disk are ground away, revealing the hole in the cylindrical TT cup. A bolt is dropped through the socket, the cup, and a retaining washer where it exits the socket and runs through a polypropylene “convex disk” and into a T-nut recessed in the proximal aspect of one of two “concave cylinders.” The pairing of the convex disk against the proximal concave surface of the cylinder provides proximal alignment adjustability. Socket flexion, extension, abduction, adduction, and rotation can all be manipulated by adjusting the contact area between the two surfaces and tightening the proximal bolt to secure the alignment (Figure 2). In addition, the position of the disk beneath the socket can be shifted up to 1cm in any desired direction.

Figure 3: Medial view of the connection between the prosthetic foot and the distal polypropylene components. The pairing of the convex ankle surface and the distal concave surface of the cylinder permit alignment adjustability at the ankle joint.

Figure 4: Posterior view of a polypropylene transtibial prosthesis showing the alignable connections at the ankle and distal aspect of the socket along with the welded seam of the two polypropylene cylinders in the midshaft of the prosthesis.

At the distal aspect of the prosthesis, a bolt is driven superiorly through the chosen regionally preferred, available prosthetic foot and through a polypropylene “convex ankle” where it bolts into a T-nut recessed in the distal concave surface of a second polypropylene cylinder (Figure 3). As with the proximal socket connection, the pairing of the convex ankle surface with the distal concave surface of the cylinder allows plantarflexion, dorsiflexion, inversion, eversion, and rotational adjustments at the ankle along with desired shifts.

With the socket and ankle connections established, the prosthetist determines the ideal prosthetic height. Equivalent lengths are removed from the proximal aspect of the distal cylinder and the distal aspect of the proximal cylinder with a cut that is precisely perpendicular to the long axes of the cylinders. The cut edges of the two cylinders are then placed on a hot surface (mirror welder) until a roll of melted polypropylene forms on the cut ends. These ends are welded together with firm pressure to establish the completed height of the prosthesis (Figure 4). Once dynamic alignment has been satisfactorily obtained, a polypropylene rod is used to weld the connection between the concave and convex surfaces at both the distal socket attachment and the ankle.

This prosthetic system continues to meet the needs of thousands of people with transtibial amputations in less-resourced settings, providing prostheses that meet the requirements for an ideal design. In a representative study, van Brakel et al. report on a cohort of 818 subjects from Ho Chi Min City, Vietnam, who reflected many of the demographics identified earlier.⁷ Namely, the study cohort was over 80 percent male with less than 14 percent of the subjects reporting an urban living environment. Landmine injuries, gunshot wounds, and traumas accounted for over 90 percent of the amputation etiologies. Fitted with ICRC polypropylene prosthetic systems, subjects wore their prostheses, on average, 9.6 hours per day with a user satisfaction rating over 90 percent.⁷

CONCLUSION

The ICRC polypropylene component system represents one of several design strategies that have been developed to address the unique challenges of prosthetic care in low- and lower-middle-income countries. Current estimates suggest that there are 30 million individuals with amputations in these settings in need of ongoing prosthetic care. This figure, combined with the looming impact of increasing rates of diabetes in adults, indicates that the needs in these communities will continue to be substantial.

Phil Stevens, MEd, CPO, FAAOP, is in clinical practice with Hanger Clinic, Salt Lake City. He can be reached at .

References

1. Eide, A. H. and T. Oderud. 2009. Assistive technology in low-income countries. In Disability & International Development: Towards Inclusive Global Health, ed. M. Maclachilan and L. Swarts, 149-160. New York: Springer.
2. Harkins, C. S., A. McGarry, and A. Buis. 2013. Provision of prosthetics and orthotic services in low-income countries: A review of the literature. Prosthetics and Orthotics International 37 (5):353-61.
3. Guariguata, L., D. R. Whiting, I. Hambleton, J. Beagley, U. Linnenkamp, and J. E. Shaw. 2014. Global estimates of diabetes prevalence for 2013 and projections for 2035. Diabetes Research and Clinical Practice 103 (2):137-49.
4. Ikeda, A. J., A. M. Grabowski, A. Lindsley, E. Sadeghi-Demneh, and K. D. Reisinger. 2014. A scoping literature review of the provision of orthoses and prostheses in resource-limited environments 2000-2010. Part one: Considerations for success. Prosthetics and Orthotics International 38 (4):269-86.
5. Garachon, A. 2004. The Brian Blatchford Prize acceptance speech. Prosthetics and Orthotics International 28 (3):216-8.
6. International Committee of the Red Cross. 2006. Manufacturing guidelines trans-tibial prosthesis, Physical Rehabiliation Programme. www.icrc.org/eng/assets/files/other/eng-transtibial.pdf.
7. van Brakel, W. H., P. A. Poetsma, P. T. Tam, and T. Verhoeff. 2010. User satisfaction and use of prostheses in ICRC’s special fund for the disabled in Vietnam. Asia Pacific Disability Rehabilitation Journal 21 (2). www.dinf.ne.jp/doc/english/asia/resource/apdrj/vol21_2_2010/7prosthesisvietnam.html.