Feet for life

Leprosy is among 20 poverty-related, neglected tropical diseases prioritized by the World Health Organization (WHO). The disease affects the skin and nerves. Damage to the nerves leads to lifelong and irreversible loss of sensation and muscle imbalance. The WHO Weekly Epidemiological Report September 2023 highlights that over the past decade (2013 – 2022) 1,925,114 people have been diagnosed with leprosy worldwide, and 114,391 individuals (5.9%) have developed severe disabilities due to nerve damage. More than half the world's leprosy-affected population live in India.

The ability to feel pressure and pain is what protects us from injury during our activities of daily living. Excessive pressure from prolonged walking or standing on feet which have lost their sensation of pain and muscle balance often leads to pressure injury and ulcers with further deformity and disability. Apart from necessitating expensive hospitalization, the ulcers and deformity are a stigmatizing hallmark of leprosy leading to social exclusion. Plantar (sole) ulcers can only heal with complete rest. Repeated hospitalization and periods of complete rest from daily activities adversely affect the livelihoods of people who earn around $6-7 a day doing agricultural or manual labor. We estimate this is a loss of nearly two-thirds of their income annually! As the ulcers will recur on resuming daily activity, without effective protective footwear a person would inevitably walk their way to amputation, continuing the vicious cycle of disability and poverty. 

This situation is similar for people living in poverty with other diseases, like diabetes, that cause neuropathy (nerve damage) in the feet. The WHO estimates 77 million diabetics in India with more than 50% of people unaware of their diabetic status until very late, leading to neuropathic feet and increasing their risk of foot ulcers, infection, and the eventual need for limb amputation.

Artificial biofeedback system: In 2019, we had an innovative idea of an insole that could alert the wearer through a signal when plantar pressures peaked to dangerously high levels. The prototype was developed and tested during 2019-2022. An artificial biofeedback system used force sensing resistors (FSRs) embedded in manually made insoles to measure plantar pressures at critical points on the sole of the foot when walking and standing during activities of daily living. Threshold limits were identified based on the walking patterns of people wearing the insoles. Patients who wore and tested the prototype received gait education on how to walk to maintain plantar pressures within threshold limits and reduce the forces exerted on their neuropathic feet. Despite this, and because of the sensory loss, there would be times when peak plantar pressures would increase. This is when the biofeedback mechanism came into play. The FSRs transfer plantar pressure data to a transmitter via a data acquisition system, which then provides biofeedback to the wearer via Bluetooth technology, triggering an audible alarm. This alarm, fitted to the footwear, alerts the wearer when pressures cross the threshold limits of the calibrated insole sensors. On receiving this feedback, the wearer could immediately alter their gait or take their weight off the neuropathic foot, while also subconsciously ‘learning’ how to walk and stand to not set off the alarm.

CAD CAM technology: In 2021, we acquired a CAD CAM machine and three-dimensional foot scanners to fabricate custom insoles based on the anatomical contours of the foot. The technology involves scanning the foot using a computerized 3-D scanner, designing an insole through a computer program, and milling the insole using a computerized milling machine. The custom insoles are fitted into prefabricated extra-depth footwear which can be either purchased or manufactured. The fabrication system uses either the standard triangle language (.stl) format for additive technology like 3-D printing, or the standard for the exchange of the product data (.stp), also known as ISO 10303, which is ideal for 3-D milling technology with complete computer-aided designing data. The .stp file format is in some instances converted to .stl format (which contains the model’s surface level detail) for 3-D printing. The scanning and designing can be done remotely by trained personnel at any place where patients are seen, and the custom design of the insole is sent via email or cloud storage to our Central Fabrication Unit. After producing the designs with the CAD CAM system, the new insoles are mailed back to the original site. 

In 2023, we had the innovative idea of utilizing peak plantar pressure data acquired through the FSR insoles to fabricate the ideal computer-based custom insoles, superior to those made using anatomical contours of the foot alone. Our solution, therefore, is about interfacing these and other technologies for software development to fabricate pressure data-based, custom protective insoles for people with neuropathic feet from many disease conditions.

The foot is a complex structure of 28 bones, 214 ligaments and 34 muscles, bearing our body weight as we walk every day. Custom orthotics (insoles) are essential for people whose foot biomechanics are altered due to neuropathy and the consequential pressure stresses and injuries the foot will be subject to while walking. For people in lower socioeconomic strata who have no option but to carry on working barefoot or with unsuitable footwear, this will eventually lead to tissue damage and bone loss, ulceration, and possible amputation. Loss of ambulation and productivity, and the resultant dependency, are devastating for people living in poverty or on the edge of poverty.

Our solution has the potential to impact the lives of millions of people with neuropathic feet from leprosy, diabetes, and similar conditions that cause nerve damage. 

Specialized foot care is limited to few hospitals in India, so people typically access care closer to home first, through non-formal medical practitioners. When ulcers do not improve, they then seek out hospitals that will treat them. Frequent visits to healthcare facilities for ulcer treatment require patients to take time off work and lose wages, all while accruing out-of-pocket expenses. On average, individuals with leprosy neuropathic feet and recurrent plantar ulcers require five to six hospital admissions per year, with each hospital stay lasting approximately three weeks. Additionally, they typically need at least two follow-up visits to the hospital after discharge. The annual financial burden on patients, including loss of wages and travel expenses, could range anywhere from USD 1,000 -1,500. This expense is heavily influenced by the distance between their homes and specialized leprosy hospitals and can equate to nearly a year's wages. 

At the Schieffelin Institute of Health – Research & Leprosy Center (SIHRLC), where leprosy care is provided free of charge, the annual expenditure for treatment of a patient with neuropathic feet falls between USD 4,500 and 5,000. This can include multiple hospital admissions, ulcer surgeries or amputations, provision of prostheses, and other assistive devices. 

By using indigenous technology to provide patients with a truly custom insole with higher protection that can be easily fitted into any footwear, we can introduce a simple yet powerful solution that addresses a permanent need in a highly cost-effective and practical manner. We estimate the cost of the prototype pressure data-based insole, once we have the software, will be not much higher than the current $80 cost for the CAD CAM or FSR insoles, which last for one year under normal wear and tear (as they become the person's only footwear).

While the economic benefits for the patient and health care systems are significant, the impact exceeds financial considerations. In addition to preventing lost wages and worsening disability, our solution allows patients to remain ambulant and continue providing for themselves and their families, to be included as productive members of their community. The social and emotional benefits of promoting self-sufficiency in patients with neuropathic feet are immeasurable. 

American Leprosy Missions (ALM) is a long-time partner of the Schieffelin Institute of Health – Research & Leprosy Center (SIHRLC), in Karigiri, India, one of the world’s leading leprosy research and training centers. Both organizations have been involved in leprosy-related healthcare since their establishment in 1906 and 1955, respectively. ALM has been supporting SIHRLC’s pioneering research and innovation, professional training, and patient care for the management of neuropathic feet and other disabilities. In 2008, the Institute was recognized as a “Center of Excellence for Foot Care'' by the World Diabetes Foundation. 

SIHRLC sees around 1,300 to 1,800 people with leprosy neuropathy every year and has more than 2,000 consultations annually for the treatment of leprosy plantar ulcers. More than 250 patients are admitted every year for nearly a month-long stay to manage severe ulcers, undergoing major debridement surgery and amputations. Around 2,000 special footwear, assistive devices, and artificial limbs are manufactured and dispensed at the hospital every year for patients with leprosy neuropathic feet. This has built expertise and empathy and has fostered innovations to improve the quality of life of people suffering from the double burden of poverty and disease. Inclusion and human dignity form a critical part of the Institute’s values.

Staff at SIHRLC, many themselves affected by leprosy, are well acquainted with the multifaceted problems of leprosy and seek to address these needs in an integrated and holistic fashion. ALM has worked closely with SIHRLC on many projects and endeavors, with co-design, technical support, staff support, and financial support. Apart from outpatient and inpatient care, the Institute’s outreach programs for leprosy care incorporate patient education and counseling as integral parts of disease management. SIHRLC constantly improves patient care and management based on learning from research, innovations, and patient feedback.

While operating at the highest level of technology, the preliminary prototype FSR insole design utilized inclusive practices and was conceptualized in consultation with people affected by leprosy experiencing disability. The good rapport and trust between SIHRLC and its patients ensured test users who faithfully wore and tested the preliminary low-cost, crude prototype for an entire year. The team’s regular interaction with the users of the FSR insoles and the CAD CAM insoles elicited their perspectives on ease of use and comfort, as well as potential design improvements. These inputs were taken into consideration in subsequent footwear designs. 

The Institute's scope of services has evolved with the changing needs of the community, including people with disabling diseases other than leprosy such as those with the sequelae of diabetes and other neuropathic diseases, locomotor diseases, and those marginalized because of social and societal problems. Our commitment to these needs is reflected in the recent USAID ASHA grant award to ALM to build a Prosthetics and Orthotics Center at SIHRLC to enable further innovation, research, and development of new prostheses and orthoses, as well as improved management of people with lower limb disabilities.

We have selected ‘prototype’ as our solution’s stage of development as we are creating an interface between a prototype (FSR insoles and an artificial biofeedback system) and an established solution (CAD CAM technology) to fabricate custom insoles based on plantar pressure data.

The prototype FSR insoles and an artificial biofeedback system were developed and tested during 2019-2022. The artificial biofeedback system used force sensing resistors (FSRs) embedded in manually made insoles corresponding to critical points on the sole of the foot. Peak pressure threshold limits were set based on repeated walking patterns of persons wearing the insoles. The FSRs transferred plantar pressure data to a transmitter via a data acquisition system, which then provided biofeedback to the wearer via Bluetooth technology, triggering an audible alarm fitted on the footwear when pressures exceeded the set threshold limits of the calibrated insole sensors. 

None of the 50 persons with leprosy neuropathic feet who wore the initial prototype for a year developed ulcers, whereas we would anticipate that 70% of patients (or an estimated 35 people in the study) would have developed ulcers based on clinical observations. Currently, SIHRLC has 160 patients using these insoles, and the team is collecting the pressure data from 70 who follow up regularly.

The established solution is 3-D foot scanners and CAD CAM technology. It is the key solution for people with neuropathic feet as it delivers high-fidelity, custom, cost-competitive footwear using 3D scanning, designing, and printing technology (custom insoles produced via computer-aided scanning, computer-aided designing and computer-aided fabrication). More than 600 patients have been using these CAD CAM insoles manufactured at SIHRLC, about 70% with leprosy neuropathic feet and 30% with diabetic neuropathic feet. Around 600 patients regularly follow up to report efficacy of the footwear (ulcer development); satisfaction with the footwear (usage, returning for a 2nd or 3rd pair); and quality of footwear (durability compared to standard issue microcellular rubber footwear).

Effective interface technologies will allow us to develop software that could fabricate and modify insoles with the raw peak plantar pressure data acquired through the FSRs. We would identify a user's peak plantar pressure thresholds through the sensory feedback system while walking and standing on representative even and uneven terrains for reasonable lengths of time. With this data, we would then design and produce their pressure data-based insoles using this new software.

This prototype software would allow health staff with minimal technical qualifications, in remote geographical locations, to design custom insoles that could be fabricated using a (to be developed) portable printing unit. Eventually, we are looking at a cost effective system that would help design and fabricate custom insoles for people with neuropathic feet within a few hours, and at their location.

There are limited technologies that transfer peak plantar pressure data as .stp files for three-dimensional printing or milling. These are also expensive. For our context, it is critical to develop a cost-effective indigenous technology that will easily process the pressure data acquired from the various pressure areas of the foot in order to fabricate a truly custom insole based on pressure data and anatomical contours. The technology should also facilitate modifying the G-code used in the manufacture of the insole either through printing or milling technologies. MIT Solve’s technical expertise and innovator network would be invaluable in creating the interfaces required, as described below. 

The project initially would identify unique software that would be compatible with interfacing the raw dynamic peak plantar pressure data acquired from the tactile sensors. Then the project would also develop the software program that would be compatible with acquiring and interfacing the raw peak pressure data in the identified platform. Simultaneously, the team would be involved in developing/acquiring unique images for developing a virtual 3-D model where the pressure data would be collected or modified. Following this, the simulation and transfer of raw peak pressure data to the 3-D model developed through CAD (AutoCAD) software would be tested in a virtual medium. In the final phase, real-time data (peak pressure) acquisition would be carried out on patients to test the efficacy of the developed simulation models. The ideal model/system identified and developed virtually along with the peak pressure data, would be interfaced and tested in real-time.

Financially, the MIT Solve Global Health Equity Challenge would help us in developing the prototype: its iterations and modifications. The prize money would also be used to develop and fabricate the new insoles. Additionally, the Prize will fund the monitoring of user outcomes and impact and dissemination of the results.

Legally, we would need support in procuring intellectual property rights and patents if the product is to be marketed in countries other than India, either as a separate product (insole) or designed with footwear.

Footwear specifically designed for persons with neuropathic feet with insoles that reflect the wearer's unique peak plantar pressure data is the ultimate customization to correct the user's foot biomechanics and prevent pressure build-up and tissue breakdown. The technology would take into consideration all the biomechanical factors that are required for safe walking on neuropathic feet.

This is a solution that uses science, technology, and innovation for custom insoles that could be fabricated to fit standard footwear styles. 

Our solution is simple, practical, and cost-effective; when used daily, it can prevent a first ulcer from ever occurring, retaining the person’s ability to walk and work. It can keep people out of the hospital and save the costs incurred in long-term ulcer management. Our analysis using SIHRLC’s data shows that an $80 pair of footwear with the current insoles can save up to $7,000 in combined out-of-pocket and health system expenditures per patient annually. Additionally, our solution has the potential to prevent disability-related dependency and poverty with its attendant psychological and social impacts. 

In terms of being catalytic, our solution has immense potential to impact people with sensory loss in their feet due to leprosy, diabetes, and other neurological disease conditions in India and across the world. Our linkages with leprosy hospitals in India and India's National Leprosy Programme can extend our solution to an estimated 8,000 new cases of leprosy plantar anesthesia in India alone. If we include diabetic feet, around 39 million people could benefit. Projecting this globally, our solution has the potential to impact millions more through a truly custom insole that can be inserted in most footwear. We expect that the market will create new footwear designs that can accommodate such an insole.

If we can interface indigenous technologies that incorporate peak plantar pressures and anatomical contours of the neuropathic foot to fabricate uniquely custom insoles, then we can offer people and health systems around the world a cost-effective solution to the damaging effects of neuropathy keeping people ambulant, productive, injury- and ulcer-free, and significantly minimize the need for hospitalization.

Design & fabrication

Users

Growth

Activities

Design and develop a user interface to fabricate insoles with peak plantar pressure data.

Health staff trained in the modification and fabrication of insoles with the peak plantar pressure data.

Research studies and other documentation; social media posts, and updates initiated.

Outputs

Insoles designed,  customized and fabricated for users with peak plantar pressure data.

User feedback informs usage and compliance to health staff in remote field settings.

Dissemination of the solution and research findings through publications, conferences, social media posts, press releases, etc. to potential customer base of health/ foot care providers, orthopedic footwear manufacturers, and others.

Short Term Outcomes

Improved designs of insoles fabricated as indicated by user feedback and pressure data analysis.

Solutions become available for patients and health staff in remote locations. 

Interest expressed to partner, fund, invest, buy.

Long Term Outcomes

Affordable, accessible, reliable insoles that would dissipate peak plantar pressures and prevent neuropathic damage.

People with neuropathic feet remain active, ulcer-free, and productive despite permanent loss of sensation. Health system expenditure decreases.

Increased customers /commercial partners. Profits reinvested into developing improved/ new solutions for foot care in leprosy and leprosy service provision.

In Year 1, we would identify suitable software to initiate the development of front-end and back-end software for the process of developing an appropriate software and hardware solution.  

In Year 2, apart from being involved in developing the front-end and back-end software, we would use advanced software like ANSYS to simulate and test foot models to develop low-cost computer-aided designing and manufacturing technologies (CAD-CAM). These could help ease the insole design and fabrication time. The system would also be developed such that it could be used by clients irrespective of their remote geographical locations. 

In Year 3, the front-end and back-end software would be developed. The prototype would be tested and modified with user inputs and feedback. 

In Year 4, an ideal portable fabrication unit prototype (computer-aided designing (CAD) and manufacturing technologies (CAM)) would be developed to design and print the insoles with peak plantar pressure data acquired through the tactile sensors. 

Year 5 will be small-scale production where our designing and fabrication system could be used by health staff in remote locations, providing an equitable, affordable, and accessible solution to prevent the detrimental complications of neuropathic feet for patients who would otherwise be unable to access such insoles.

Excessive force on the neuropathic foot leads to tissue breakdown, ulcers, and deformity. The sensory feedback system through the force-sensing resistors (FSRs) provides feedback on plantar pressure variations. Integrated circuits and electronic devices are used for transferring the data from the sensors to the microcontroller which triggers the alerting device. The threshold pressure value for triggering the alert is controlled by the open-source Arduino Integrated Development Environment (IDE) software. A micro cellular rubber (MCR) insole is trimmed for accurate fit. The plantar pressure-prone areas are identified by a Harris mat; a simple foot imprinter and semi-quantitative pressure mat used in clinical settings. The high pressure areas identified by the Harris mat  (inked more darkly), are marked on the insole for the placement of the FSRs. The FSRs are then connected to Arduino UNO which acts as a data acquisition board. Arduino UNO used in the data acquisition system is an open-source microcontroller with the feature of compatible programmability. The Bluetooth module (HC-05) integrates and shares the data to the computer as well as to actuate the coin vibration motor. The Bluetooth module works with the input of 3.3-6V and 30mA current.

The FSR heads are placed in the identified plantar pressure regions to obtain accurate pressure values. Respective force values exerted on the FSR heads placed at the plantar pressure area of the foot are obtained through the serial monitor. A 10 Volt battery is used to power this circuit. All force-sensitive resistors and the circuit board are adequately soldered to minimize the error caused by the misplacement of circuits. After integration of the circuit, the FSR heads are placed at the plantar pressure-prone areas of the foot identified on the insole. The insole with the sensors is fixed into the patient’s footwear to obtain the values of forces acting on the plantar region of the foot while walking. The data acquired are evaluated to recognize the peak pressure on the plantar area of the foot which helps in determining the threshold limit for integrating an alerting circuit.

Ideal software for developing the interface would be identified after carrying out a detailed background review, analysis, and literature search. Appropriate coding of either C, C++, or JAVA programming platforms would be used to develop front-end and back-end software for developing unique user designs for fabricating insole interface software. The simulation studies would be done through virtual models developed through programs like SOLIDWORKS. Programs like ANSYS would be used to simulate the developed working models that are designed. 

The solutions would be through Internet of Things (IoT) based solutions and designs would be through cloud-based systems. 

Our core solution team has nine full-time staff of SIHRLC and two full-time staff of ALM: 

• 1 Biomedical engineer, Technical lead,  involved in ideation and technology development.

• 1 Electrical engineer, to design and develop the data acquisition system.

• 2 Physiotherapists, to assess patients for the insoles.

• 2 Prosthetics technicians, to design and modify the insoles.

• 2 Footwear technicians, to fit the insoles into footwear.

• 2 Technical Advisors, the Director of SIHRLC, and the ALM Regional Director, Asia, to provide strategic inputs for the solution.

• 1 Team Lead, Vice President of Programs, ALM

We have been working on our solution for nearly 4.5 years, since November 2019. Ideas have led to innovative technologies, insole and footwear design, and innovative uses of existing technologies. Along the way, it has become very clear to us that we must develop indigenous technologies and hardware to be sustainable and cost-relevant to our specific client base.

At the forefront of our approach to serving marginalized people affected by leprosy and other disability-related diseases, living in poverty and resource-scarce locations, is inclusion and dignity of the individual. 

ALM’s staff is diverse and is dispersed across the US with field and research staff located in Ghana, Libera, India and the U.K. Many have immigrant stories to share and celebrate dual citizenship. While we are required by the IRS to have a “headquarters” we are truly a dispersed organization that accommodates “work from home” and strives to include everyone regardless of their location and work situation. Our global program empowers women in traditional societies, and persons with disabilities and stigmatizing diseases, to live productive, healthy lives and to advocate for essential services like healthcare, clean water, and sanitation for themselves and their communities. ALM’s programs are implemented through local partners like SIHRLC which have deep local knowledge and the professional expertise required to provide excellent care and innovative solutions in their communities and contexts. ALM is proud to work with partners that are locally led. 

SIHRLC is committed to diversity, equity, and inclusion in the service of people affected by leprosy, people with physical disabilities, and those marginalized because of social and societal problems, working to improve their participation in community and family life. SIHRLC has people affected by leprosy and people with disabilities on staff. SIHRLC has excellent gender representation on staff with 48% of its 219 staff being women. 40% of SIHRLC’s 53 students enrolled in professional health-related training courses are women. SIHRLC’s “beneficiaries” are included in the design of tools and technology, as demonstrated by this project as well as other adaptive technologies we are working on. It partners with the Society for the Help and Rehabilitation of People Affected by Leprosy and Other Disabilities to form self-help groups of marginalized people who set up various enterprises to support themselves economically.

Feet for life  Social Business Model Canvas  .docx

For sustainability, we plan to work on a social enterprise model where free-of-cost leprosy services will be subsidized through revenue generated by clinical services to paying clients and selling our product to paying clientele. Our linkages and partnerships within the leprosy and health sector in India and other leprosy-endemic countries will help us expand the enterprise’s customer base. The business would facilitate the creation of a funding mechanism that would expand the mission of the organization. We will continue to seek funding to support the core leprosy foot care services and continued research and development of this product and other products useful in managing neuropathic feet. 

If we are successful in obtaining a patent for our solution, we can expect sustained funding if the solution is accepted by the Indian and global markets.