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ORIGINAL RESEARCH ARTICLES

Implementation of the Transtibial Johnson Prosthetic Leg in Tegucigalpa, Honduras

Mabry, Michael R. DO; Johnson, Phillip CPO; Erazo, Xiomara MD; Palmieri, James PhD; Sutphin, Dean PhD

Author Information
Journal of Prosthetics and Orthotics: January 2020 - Volume 32 - Issue 1 - p 24-31
doi: 10.1097/JPO.0000000000000247
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Abstract

PREVALENCE OF AMPUTATION

Amputations are a growing issue worldwide with numerous causative factors.1 It can be a challenge to accurately estimate the incidence and prevalence of amputations because of factors that include the lack of standardized reporting and limited medical access. A document published in 2015 by the World Health Organization (WHO) estimated that 110 to 190 million people, including 93 million children, are currently living with disabilities, which significantly limits their functionality.2 This same study found that 80% of these individuals reside in developing nations and have decreased access to medical support. The WHO, in conjunction with the International Society for Prosthetics and Orthotics, estimated by 2010 more than 25.5 million people in the world needed a prosthesis or orthotic device to best function in society.3

CAUSES OF AMPUTATION

Causes of amputation can vary by geographic region. This is evidenced by a 2002 retrospective study that looked at causes of amputations performed in the United States compared with India. They noticed that 82% of amputations performed in hospitals in the United States were related to vascular disease often secondary to diabetes.4 This is in comparison to a 2005 study, in Mumbai, India, that found 63% of amputations were related to trauma and only 22% due to vascular complications.5 Although the major causes for amputation can vary from one country to the next, two common causes worldwide are due to chronic illness and traumatic injuries.

Chronic diabetes mellitus can lead to amputation.6 Estimates vary, but as of 2011, the American Diabetes Association (ADA) estimated by the year 2025 an excess of 300 million patients would be diagnosed with diabetes mellitus worldwide.7 In this same period, however, the International Diabetic Federation (IDF) estimated closer to 552 million and stated developing nations may see the largest increase in incidents of diabetes.8 The IDF estimates that up to 70% of all lower-limb amputations could be related to diabetes.8

Common traumatic injuries that lead to amputations include landmines and motor vehicle accidents. Landmines are a major issue in parts of Africa, the Middle East, and Southeast Asia.9 As of 1994, it was estimated that 100 to 400 million landmines had been placed in the earth during times of conflict and may remain for decades after the conflicts have concluded.10 A majority of these mines are in combat zones, but many are placed in areas of civilian and commercial activity.11 Presently, data suggest that amputation risk persists related to landmines and other explosive ordinances in current day conflicts in nations such as Pakistan and Syria.12,13 Some nations have thousands of persons with amputation because of landmine explosions who are in need of prosthetic devices.

ECONOMIC AND SOCIAL CONSEQUENCES OF AMPUTATIONS

Research suggests those living with a low socioeconomic status have a higher incidence of lower-limb amputation when compared with those in living in areas with higher economic status.14 Sinha et al.5 found that unemployment was one of most influential factors determining a person's quality of life after an amputation. It was found that 52% of patients with amputation in the study were unemployed and 82% of the patients lost their employment as a direct result of amputation.5 Physical labor is often an important part of the workforce in developing nations, and persons with amputation may be limited in performing these types of jobs. An example of these types of jobs include agriculture, mining, sugar, coffee, wood products, and tourism services.15

Socially, persons with amputation may feel like they do not fit into society.16,17 Some of the reasons stated by these patients include difficulties with social relationships, physical functioning, emotional well-being, and general health status. As far back as 1892, research indicated that psychological issues were prevalent in individuals with amputation evidenced by nearly two thirds of the 72 patients in a study who had psychiatric symptoms in the form of depression, anxiety, crying spells, insomnia, loss of appetite, and suicidal ideation.18 To this day, persons with amputation continue to demonstrate higher levels of depression and anxiety when compared with the general population.19

OBSTACLES FOR DEVELOPING NATIONS

For the purposes of this study, a developing nation is defined as a nation with a gross national income per capita of less than US $4,125.20 The two primary barriers to patients receiving prosthetic devices are prosthetic technician shortages and the high cost of prosthetic materials. The WHO found that over 75% of developing nations had no prosthetic or orthotic training program with an estimated worldwide deficit of 40,000 prosthetic technicians.3 Modern prosthetic legs have advanced technologically in recent decades, but are often made from costly materials and some require computer components to function.21 The US Department of Defense and the US Department of Veterans Affairs undertook a study in 2010 to determine the costs of helping soldiers returning from war (Vietnam and Iraq) with limb-loss injuries. The cost of a transtibial prosthetic leg ranged from $6,409 to exceeding $45,563, depending on the type of device required.21 This same study showed the additional costs over time for adjustments, repairs, and replacements equaled a lifetime cost of approximately $1.4 to $1.8 million per veteran, making it difficult for those in developing nations to purchase such devices. This is evidenced by a 2004 study conducted in Haiti, which found that only 40 (24%) of 167 patients with amputation had the ability to purchase a prosthetic leg.22

This research took place in Tegucigalpa, Honduras, as there were existing relationships between members of the research team and the JMA medical clinic located in Tegucigalpa. According to the United Nations Development Program,23 Honduras is classified as a developing nation and is located in Central America. The official language is Spanish, and it has a population of 8,746,673 with the average life expectancy of 71 years. It is second only to Haiti as the poorest country in Central America with 2.7 million people living below the international poverty line of $3.10 per day. The Central Intelligence Agency World Fact Book states that in 2016, 63% of the population of Honduras lived in poverty and 6 of 10 families in rural areas lived in extreme poverty, making less than $2.50 per day. The workforce demographics are 39.3% agriculture, 20.9% industry, and 39.8% services. In addition, Honduras is greatly underserved in terms of health care with an average of only 57 physicians per 100,000 people.23

TRANSTIBIAL PROSTHETIC LEG DESCRIPTION

A transtibial prosthetic leg includes three basic components: a socket, a pylon, and a foot with variations of each component available. A photo of a commercial prosthetic leg can be seen in Figure 1. The socket is the portion that will allow the prosthetic leg to attach to the patient's residual limb and is unique for every patient. The pylon replaces the length of the leg that was amputated and connects the foot to the socket. Often commercially available prosthetic feet have some ability to flex to assist the patient with walking.

F1
Figure 1:
Commercial transtibial prosthetic leg with the standard components labeled.

AN IDEAL PROSTHETIC DEVICE FOR DEVELOPING NATIONS

When designing an ideal prosthetic leg for use in developing countries, Cummings et al.24 suggested a list of 13 important factors for developing prosthetic devices. Although their study took place in India, these factors may be applicable to other geographic areas as well. Some of these factors include low production cost, simple to repair, manual fabrication, reproducible by local personnel, biomechanically acceptable, componentry readily available, lightweight, and psychosocially acceptable.

HYPOTHESIS

The researcher's hypothesis was that a newly designed low-cost prosthetic leg, the Johnson prosthetic leg (JPL), could enhance the ability of a person with amputation to gain employment. This would be determined by at least 50% of the participants previously unable to work being able to obtain a paying job after using the JPL designed and produced in this study.

MATERIALS AND METHODS

STUDY DESIGN AND PARTICIPANT RECRUITMENT

This study was approved by the institutional review board (IRB) at Edward Via College of Osteopathic Medicine (VCOM) located in Blacksburg, VA (IRB# 2014–033).

When a participant was found to be a candidate for a JPL, a consent form in Spanish was read to and signed by each participant. The reading was performed by a native Spanish speaker, and the certified IRB-approved copy was given to each participant. Informed consent included that the prosthetic leg was a prototype that had not yet been tested. The risks and advantages of the study were explained to each participant, including that the prosthesis would be provided at no financial cost. Participants were then scheduled to go through the process of being fit for their prosthetic leg.

The organizations involved in this study include VCOM, Hope To Walk (HTW), and Baxter Institute (BI). VCOM is an osteopathic medical institution whose mission is to serve the medically underserved. BI is a Christian higher learning university in Tegucigalpa, Honduras, and is where the JMA clinic is located. HTW is a 501(c)(3) humanitarian organization whose mission is to develop low-cost prosthetic legs for individuals with amputation in developing nations. VCOM and HTW partner to medically assist patients at the JMA clinic. Any dollar amounts discussed in this article will be given in US dollars.

This study was designed as a cohort study to take place in Tegucigalpa, Honduras, and to be performed within the time frame of 2014 to 2017. The participant population included men and women 18 years of age and older who live in Tegucigalpa, Honduras, and the surrounding areas within a 50 km radius. Participants were recruited by word of mouth and by speaking in local churches. Participants would call or come to the clinic to begin the intake process. All patients with amputation regardless of the type of amputation were assessed at the clinic by a medical doctor and a certified prosthetist. The reason transfemoral amputation patients were also assessed was to perform demographics for the local area and to have a database in place if the research team begins to build transfemoral prosthetic legs. They were not participants in this research project and are only included here so as to better assess the number of individuals with amputation in the surrounding areas.

MEDICAL ASSESSMENT

An IRB-approved assessment form was used to assess the participant's ability to safely use the transtibial prosthetic leg, which is under investigation. Each participant was assessed by a certified medical doctor and given an identification number. All recorded participants' information was stored in a locked filing cabinet at BI. Patient medical history was obtained, and physical examination was performed. After the medical assessment, participants were immediately notified if they were not found to be a candidate for receiving a JPL. Reasons for exclusion included having an active infection, having a poor quality of surgery that limited prosthetic options, or having other medical conditions that limited their mobility.

PROSTHETIC LEG FITTING

After the medical assessment, participants were scheduled to be seen by the research team. They received a compression shrinker before their appointment, which was used to help decrease swelling in the residual limb so as to improve the fit of the prosthetic leg. After they wore the shrinker for 2 to 3 weeks, they were cast for their prosthetic leg. The fiberglass was used to form a cast unique to each participant and was then reinforced with additional layers of fiberglass to construct the socket. The pylon was then cut to length and the foot ground to the appropriate size. Typically, the same day the participants were cast, they left with the new leg.

PARTICIPANT FOLLOW-UP

Each participant was scheduled for a follow-up evaluation to be performed by a medical doctor at the BI clinic. Participants were also instructed to call or to return to the clinic if they had any questions or concerns with their prosthetic device. A team of US and Honduran physicians, a PhD researcher, and a prosthetic technician established an IRB-approved survey instrument form, which was used during the follow-up interview. Figure 2 shows the form that was used by the native Spanish speaker when interviewing the participants. There were nine questions related to prosthetic usage and comfort, four questions regarding self-esteem and the improved ability to perform work or hobbies, and three questions that allowed participants to give feedback regarding the prosthetic leg.

F2
Figure 2:
Participant assessment form that was used weeks to months after the participants received their prosthetic leg.

RESULTS

Images of the low-cost prosthetic components used in this research are shown in Figure 3. Its components include the socket, coupler, pylon, and Johnson foot (JF). A coupler was designed to connect the socket to the pylon. It was made of three materials: a small polypropylene disc, polyvinyl chloride (PVC), and a prosthetic foaming agent. The pylon was constructed by chemically bonding a 1-inch wooden dowel rod inside of a 1-inch PVC pipe. The JF was constructed by adhering a crepe material to a hardwood base, which served as the ankle and connection to the pylon. All feet were made to a US size 10 and could be ground to each participant's specific measurement.

F3
Figure 3:
Components used to manufacture the JPL.

Of 306 patients with amputation interviewed, 149 (48.7%) had transtibial amputations, 144 (47.1%) had transfemoral amputations, and 13 (4.2%) patients had other amputations (Table 1). Infection secondary to diabetes was the most common cause of amputation in 118 patients (38%), followed by traumatic injuries in 95 (31%), which were caused by motor vehicle accidents, electrical accidents, and agriculture-related accidents (Table 2). The remaining amputations resulted from infection not related to diabetes (27%), birth defects, and cancer (4%).

T1
Table 1:
A chart representing the number of persons with amputation originally surveyed organized by type of amputation
T2
Table 2:
A graphical representation of the causes of amputation experienced by this patient population: causes of amputations (306 total patients)

In this study, 66 participants received a JPL and were followed up by the research team. The length of time the prosthetic legs were in use ranged from 6 to 27 months. Before the study, it was noted that 38 participants (57.6%) had some ability to receive income or had a paying job, whereas the other 28 (42.4%) reported no ability to perform a paying job. After the study completion, 59 (89%) had the ability to perform a paying job. This indicated that 21 (75%) of the 28 participants who previously reported the inability to work were able to obtain a paying job after receiving the JPL device.

Sixty-four participants (96.9%) used their leg 6 to 7 days each week, whereas 2 participants (2.9%) used their legs 4 to 5 days per week. Of those 66 participants, 35 (53%) wore their leg between 4 and 7 hours each day, whereas 31 (47%) wore their legs between 8 and 12 hours each day. Participants were assessed on their satisfaction of the socket's comfort. On a scale of 1 to 10 with a score of 10 being the most comfortable, the following was reported: 26 reported a score of 10 (39%), 16 reported a score of 9 (24%), 22 reported a score of 8 (33%), 1 reported a score of 7 (1.5%), 1 reported a score of 5 (1.5%), and 1 reported a score of 4 (1.5%).

Based on the above results that 50% of participants obtaining the ability to work who previously could not, it was concluded that the JPL device could assist participants in improving their quality of life (defined by having the ability to obtain work and assisting them to better perform activities of daily living).

DISCUSSION

CAUSES OF AMPUTATIONS

Roughly half of participants interviewed at the clinic were individuals with transtibial amputation. Of our patient population, 69% of the amputations were the result of either diabetes or traumas. It was common that some of our diabetic patients reported they were unaware they had diabetes before receiving their amputation. They would have a nonhealing wound, which would cause them to seek out a doctor, and they would receive their diagnosis. Trauma from car wrecks, motorcycle accidents, and agricultural injuries were common in our study participants.

PARTICIPANT PERSPECTIVE

Since the initiation of this study, over 350 persons with amputation patients sought help from the research team. It was common for participants to have previously sought help at other clinics and being sent away due to the inability to pay for a commercial prosthesis. This is a challenging situation, as a large percentage of Hondurans live in poverty and after an amputation often lose their ability for gainful employment. The research team discovered elderly persons with amputation may be homebound, and some persons with amputation resort to begging. This project offered the possibility for an inexpensive option that could potentially affect their ability to earn an income, improve their quality of life, and offer improved social integration.

Great efforts were taken to ensure quality care for all participants. All participants were counseled on the use of the JPL prosthesis and the potential beneficial and adverse events that could be encountered. Many were able to participate in society by performing simple tasks such as walking with their family in the park, cooking, cleaning, and even more advanced skills such as playing soccer. Of note, it was found that the Honduran participants were highly motivated to succeed now that they had the opportunity to walk, which may contribute to their success. One such example of a motivated participant can be seen in Figure 4.

F4
Figure 4:
One of the participants in the study who received his leg and immediately was able to walk, as shown as he holds up the crutches that he once depended on to stand.

Only one individual chose not to use her leg after it failed to meet her expectations of cosmesis as she expected metal and polypropylene plastics. As a result of this unexpected occurrence, all future participants were shown the JPL before beginning the fitting.

PROSTHETIC DEVICE

Since the first JPL prototype in 2014, three structural and one aesthetic modification were developed. The initial JF was discovered to wear out in one location after extensive use. This was corrected by grinding the heel block differently and placing a Kevlar material between the layers of crepe to add to the JF strength. The crepe as part of the foot was essential for five key reasons: low cost, durability, water and heat resistance, ability to flex while weight bearing, and its ability to be adjusted using an electric sand belt grinder.

The socket occasionally caused abrasions or ulcers on the participant's residual limb, which can be a common complication of other types of prosthetic sockets. This was addressed by using padding and using a casting balloon to ensure a smooth inner layer of the socket as can be seen in Figure 5. The initial design of the coupler attachment to the socket was found to loosen after extensive use so an alteration was made so that it was attached in a different fashion. The coupler is now bonded to the inside of the socket with a prosthetic foaming agent and wrapped in fiberglass for additional support. Figure 6 shows the completed socket with the coupler residing within the bottom portion.

F5
Figure 5:
The socket used with the JPL with a distal end padding, which functions as a cushion to improve participant comfort.
F6
Figure 6:
The completed socket with the coupler residing within the bottom portion of the socket. This design change improved the functionality of the socket by no longer becoming loose.

Care was taken to ensure all materials used to manufacture these prosthetic legs were available in developing nations. Thus far, it has been noted that the JPL device can be used up to 27 months before requiring replacement. Using the self-esteem questionnaire, of the participants who received and utilized the JPL, 65/66 (98.48%) reported their self-esteem had improved since using their leg and that they would recommend the JPL prosthesis to other individuals with amputation.

STUDY LIMITATIONS

There were several limitations during this study. The first limitation related to the minimal financial funding that was available for staff for constructing legs, traveling, fitting legs, or performing follow-up research. This was challenging as each member of the research team had full-time jobs outside the study obligations while attempting to travel to Honduras to assist patients with amputation patients. In the future, it is recommended that financial funding be allotted so that more time may be spent in the host country to conduct research. The second was limitations with language barriers and communication. Many of the participants did not speak English or own cell phones and would either have to come to the clinic to speak with staff or use cell phones belonging to friends or neighbors. This problem is not unique to Honduras and is common in other developing nations. This communication limitation was helped by partnering with BI so the participants always had a physical location where they knew the team could be reached.

FUTURE RESEARCH

This JPL device has the potential to address all 13 of the factors suggested to be of importance for the development of prosthetic legs in developing nations as cited by Cummings et al.24 This included low cost, cosmetic, functional, and biomechanically appropriate.

Future research will be needed to focus on refining the transtibial prosthesis as well as developing low-cost transfemoral and pediatric prosthetic legs. Functional improvements will be made, as well as cosmetic alterations, which take into consideration the participant's desires. For example, Figure 7 shows the JPL device with the newly designed cosmetic cover installed. The color can be adjusted to match the skin tone of the participant, and this substantially improved the aesthetic appearance of the leg and adds a minimal cost of $11.

F7
Figure 7:
This image represents the JPL with a recently developed cosmetic cover. The cover has yet to be widely implemented but is planned for future use. The cosmetic cover does not add to the functionality of the prosthetic leg but is believed to improve patients' perception of their leg, especially in the social setting.

A long-term vision is to develop a JPL training program so that individuals in developing nations can be trained to manufacture, install, and repair with JPL components. This is an attempt to develop a sustainable initiative that could spread to other nations and potentially impact tens of thousands of persons with amputation living in poverty around the world. To date, organizations and individuals from over 25 nations have requested technical training from this research team so they may utilize this prosthetic device to assist patients.

CONCLUSIONS

The research hypothesis was accepted based on a priori criteria of greater than 50% of participants having increased their ability to obtain a paying job. This prosthetic leg has the potential to increase the ability of a person with amputation to obtain a paying job as well as increase his or her morale—thus improving the quality of life of the prosthesis user. The JPL costs approximately $100 to manufacture, in comparison with a commercial transtibial prosthesis that costs in excess of $3,000 to S4,000. By removing the barrier of high costs, this device may be able to help individuals with amputation around the world. This successful cohort study of an alternative method of developing low-cost prosthetic legs in Honduras provides justification for continuation and monitoring for any additional refinement. Additional survey indicators such as the participants' recommendation for other persons with amputation to use the JPL provide the basis for study in other countries, settings, and cultures to determine efficacy to assist additional individuals with amputation.

The research and development of a low-cost prosthesis alternative is important because studies suggest the incidence of diabetes, one of the leading causes of amputation, is expected to continue to rise.7–9 This research team believes there are two important areas of focus that are important to consider to help millions of individuals with amputation around the world. The first is to develop measures to prevent amputations including, but not limited to, education for diabetes and vehicle safety, improving wound care, and assisting war-torn areas to remove landmines. The second is to increase the access of affordable prosthetic devices that are made of quality materials and are accessible to the poorest people in the world.

ACKNOWLEDGMENT

The authors thank Jim Palmieri, PhD, who daily gives his time to invest in medical students to see them excel. His encouragement and consistency has helped give life to this research.

The authors also thank the volunteers of Hope To Walk, Inc, for their unending selflessness and support of others in need; Dr. Steve Teel and the medical faculty at the Baxter Institute in Tegucigalpa, Honduras, for their exceptional kindness and dedication to loving and serving the people of Honduras; and Jan Willcox, DO, Liang Shan, PhD, Brian Dickens, DO, and the staff of Edward Via College of Osteopathic Medicine for their continued partnership and dedication to training physicians to serve the underserved both locally in the United States and in Central America.

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Keywords:

amputation; transtibial; developing nation; Honduras; Johnson prosthetic leg; low cost; poverty; prosthetic device; prosthetic leg; quality of life

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