Conclusion
Lower limb amputees account for approximately 86% of amputees worldwide. The need for biocompatible and affordable prostheses is great in developing countries, given the average cost of a high functioning lower limb prosthesis is approximately 18,000$. Biocompatibility, which is dictated by the percentage of compromised gait, is the most important aspect of design when constructing a prosthesis. The final iteration of design in this project resulted in only 5.3% compromised gait. This qualifies the prosthetic shank as a high functioning Level Four prosthesis. Conducting studies on elite runners to understand the forces involved with walking and running facilitated the design of a functional cost-effective 3D printable shank capable of sustaining running’s maximum force. 3D printability not only decreases the cost of production by 1700%, to less than 100 $; it enables the prosthesis’ characteristics to be readily scaled for any human and – further – for any production quantity. Models used for testing are proportional to the size of a human foot, and provided data related to the scaled weight applied, facilitating the ability to do complex prosthesis testing with limited resources. Applied physics and mathematics were used to understand the deformation of complex three-dimensional rigid bodies in response to the forces of movement. This led to the development of equations and an accurate method to compensate for the change in mechanical properties due to 3D printing. Understanding and accommodating for the change in mechanical properties increased the structural integrity of the design, such that it achieved a safety standard of 5.52ul, which is well within acceptable limits, and only .36% error from a perfect rating. This level of biocompatibility, affordability, function and safety in the finished shank could not have been accomplished without the use of applied physics and complex mathematics.
Future work
Future work will include contrasting ultimate strength of the Nylon 6 polymer with step cycles over time to determine functional life expectancy of the prosthesis as designed. Conducting research regarding DTI and its long-lasting effects on gait degradation will also be an important focus. To make the design more common among high-level activity athletes, future analysis of specialized prosthetics that provide extremely efficient strides, like cheetah blades (Olympic sprinter Oscar Pistorius’ prosthetic), will be conducted. This future research will not only globalize the design but also increase the availability and functionality for not only those in developing countries but those all around the world.