Rapid Prototyping for Prosthetics

Did you know that according to a study by the World Health Organization from 2018, 30 million people are in dire need of prosthetics, but 75 percent of developing nations cannot cater to produce prosthetics?

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A prosthesis is a man-made limb for those individuals who have either faced an amputation due to an accident or were born with a natural deficiency. Amputations are also caused by several traumatic and medical conditions like diabetes, tumors or blood disease.

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According to WHO, about 0.5 percent of the global population requires prosthetics whereas only 1 in 10 people can afford them. The reason for the lack of reach of these devices is the cost which can range from a few hundred dollars to over a hundred thousand dollars. Not only is this massive capital cost involved but also there is a regular need for expensive maintenance and in the case of growing children, there is a need for replacement as well. To counteract with this dilemma, the use of additive manufacturing and rapid prototype manufacturing is trending. This article will discuss how these methods aid the prosthetics industry in greater detail as the article progresses.

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Counteracting the Dilemma

The core issue which lies in the prosthetics industry is the dire shortage of machining services and trained personnel. The main challenge in the prosthetics industry lies in the fact that there are no standard products that need to be repeatedly manufactured. Every case can vary in design and application. Therefore, manufacturing techniques that follow mass production principles are not viable. This is where rapid prototyping comes handy. It allows for review of design and amendments until a perfect prototype for the patient has been achieved.

Moreover, there is a major dilemma of massive capital costs involved. In this regard, it is worth quoting that according to a case study report by Day and Riley in 2018, they reported an average cost reduction of 56 percent when 3D printing and prototype manufacturing are incorporated to manufacture an assistive device for a person with finger amputation. Along with this, they also reported massive weight and environmental waste reductions. Let us now discuss major design considerations for prosthetics.

Vital Design Considerations for Prosthetics

In prosthetic devices, the prosthetic socket is the most critical part of the design process. It is the part that covers the remaining limb. There are some major considerations for this part including:

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The Workflow

Glenn Woodell, CC BY-SA 3.0, via Wikimedia Commons

Ensuring Conformity of the Prosthetics

Prosthetic devices are subjected to a diverse set of loading and environmental conditions. For instance, in the case of lower limb prostheses, two types of loads superpose i.e. static loads and cyclic loads. As a result, during natural walking, the prostheses bears up to 6 times the body weight. Similarly, upper limb prostheses must bear massive lifting moments.

Keeping these facts in consideration, a variety of ISO standards are followed to ensure conformity of prosthetics to international and medical standards. ISO 10328:2016(E) encompasses all the structural strength standards for lower limb prosthetic devices. It ensures conformity of a prosthetic device concerning the endurance of static and cyclic loads over its lifespan. It also dictates various testing methods which include static loading, torsional loading and cyclic loading tests for each part of the device. For instance, knee joints are particularly tested for torsional and cyclic loading under maximum flex condition. There are additional standards that cover the manufacturing and testing of prosthetic sockets.

Last but not the least, in today’s modern era, finite element analysis (FEA) is a handy tool when it comes to testing before manufacturing. It helps prototype manufacturer to save material and manufacturing costs. It also plays a major role in conditions where the components are so expensive to manufacture that destructive testing is out of the scope. Moreover, simulation results from FEA help to conduct risk assessment studies when providing a unique prosthesis.

We really hope that this article helped shed light on the rising use of prototype manufacturing in the prosthetics industry.

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