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3D Design, Visualization and Prototyping. Part 5: Prosthetic Arms

By Mitch,

March 15th 2024

A black metal prosthetic arm
Sleek design. Prosthetic arms are now complex and funtional

We've reached Part 5 of our series looking at 3D Design, Visualization and Prototyping and this time we're covering the medical world. We'll show you how 3D printing is revolutionizing the field of prosthetic arms by streamlining the manufacturing process and saving the industry money in the process.

The term "prosthetic" can cover a vast array of items but when we're talking about 3D Design, Visualization and Prototyping, we mean the physical objects that are in everyday use. Added to that are prosthetics and artificial parts used in surgeries and transplants. The subject field is vast so we won't be going into every aspect in minute detail but we will give you an overview of what 3D printing is bringing to the field.

Unlike the previous articles in this series, we're not really looking at style when it comes to design etc. but more at the functionality of the item. However, prosthetic arms, for example, are sometimes visible so we will be looking at some interesting customized versions later in the article!

Let's then look at some of the things that 3D Design, Visualization and Prototyping are bringing to the world of prosthetic arms.

Leaving the Past Behind

A man being attacked by another man with a prosthetic arm
Always the bad guy. The perception of prosthetic arm users in movies has changed

In our previous articles, "3D Printing: Not Just for Small Toya and Models" and "3D Printing: How it Can Solve Your Problems", we took a look at prosthetics and how 3D printing is making these items much more accessible and cheaper. However, what about customization and "one off" designs tailored to the individual patient?

If we look, for example, at prosthetic limbs and specifically at the lower arm and hand, there was a time when all that was available was a hook for a hand. These are now more associated with something from a pirate story or with the bad guy in a movie.

Following on from the hooks were then prosthetic "hands" either still shaped like a hook or with a simple grab function. Neither of these was much more help to the user but I suppose it did at least have a function. When dealing with prosthetics though, the focus has to be on the user.

The next incarnation was a cosmetic prosthetic but these served no other purpose than to cover up the fact that the user had a missing limb and protect the sensibilities of onlookers who may have stared at an amputee. Thankfully, those days are behind us in most civilized societies and prosthetic arms are now being made to be as functional as the real thing or indeed more so in some cases.

A woman in white with a black, high tech prosthetic arm
The future is here. Design and functionality have greatly advanced

3D Design

In the field of prosthetics, 3D design really comes into its own as the designer can work closely with the user to get things perfect for the individual. For prosthetic arms to be compatible with the individual for instance, there really isn't any room for using a "stock" or "off the peg" arm as this is unlikely to be suitable.

The arm ideally needs to be perfectly tailored to the user in order for them to feel comfortable using it and for its functionality to be optimal. Obviously, there is a basic anatomical template for a human arm but size and orientation (left or right) do come into play at this stage.

In the case of a prosthetic arm, the user may have been born with the condition so the prosthesis will need to change as the user grows. 3D design would therefore be an ongoing partnership between the designer and the user to ensure correct progression. You could almost say that the design needs to evolve with the growth of the user. Using 3D design software is therefore streamlining this process where previously the prosthetic arm may have just been physically adapted.

Then of course there are the aesthetics of the design and as mentioned earlier, these can be subtle and understated or striking and even outlandish! There are a lot of very innovative and talented artists who either design and custom paint prosthetics for others of have customized their own prosthetics to show off their talents. This can also be an expression of the personality or even a fashion statement where the prosthetic is almost used as and accessory for an outfit.

Another field where prosthetic users can "own" their disability and use the prosthetic to their advantage is Cosplay. For anyone not familiar with this pastime, fans of particular fictional characters (usually from video games, comic books or fantasy movies) dress up and take on the persona of the character. They will then show off their work at conventions and specific Cosplay meetings.

A woman dressed in Cosplay outfit with a robotic prosthic arm
Making a bold statement. Cosplayers are using their disabilities to their advantage

With a prosthetic arm for instance, this can work to the Cosplayer's advantage if the character they are portraying has a robotic arm anyway. You will often find that comic book heroes and villains alike will have some form of disability that they have either overcome or used to their advantage in their story. This then opens up a whole area in which a prosthetic user can make the most of their disability and show it off to their peers.

3D Visualization

As we've discussed before in this series, 3D visualization and 3D design overlap somewhat as they both involve the beginnings of the design prior to the prototyping stage. However, with something as important and functional as a prosthetic arm, these aspects need to be perfected before moving on.

Visualizing a prosthetic arm should be fairly straightforward as we would all hopefully know what one should look like. In the case of prosthetics though, we're working with the basic human "design" and retro-engineering in a way. Obviously, we're not looking at the complex microbiology involved in a living, flesh and blood arm, but we are looking to replicate its function as closely as possible.

Therefore, we're not really starting from scratch but we are almost trying to reinvent the wheel as the saying goes. The design and visualization will then be based around these keys factors:

  • Functionality - Does it do what the user needs

  • Design Aesthetics - Is it pleasing to the user and those seeing the prosthetic

  • Comfort and ease of use - This is hopefully self explanatory

  • Practicality - Is the weight, size and functionality appropriate for the user

  • Adaptability - Can the design be modified as the user grows or their needs change

All of these are the things that will need to be considered and discussed between the designer and the user to make sure that everything they need is covered.

3D Prototyping

A man standing and holding onto balcony railings with his prosthetic arm
Design, quality and functionality. Prosthetic limbs can be as good or even better than the real thing

The final stage before actual production of the prosthetic arm is the prototyping stage.

The design itself has been finalized and both designer and user have visualized the final model using CAD software and 3D rendering. Now is the time to convert the design into a 3D printable model of the actual arm.

This process could be done either with the entire prosthetic arm being printed as one or with each component part being individually printed and assembled. The method used here would depend on the actual design and how complicated the mechanisms or control parts are.

If you're just looking to prototype the size and look of the arm then it can be printed as one in the first instance to get the general idea. Moving on from that would be a more functional prototype and then a final model which includes all the functionality and design of the final prosthetic.

In 3D printing terms, the prototype could be made using either FDM, SLA or SLS methods or indeed a combination of these. Have a look at our previous article "3D Printing: Comparing, FDM, SLA and SLS* for more insight into each of these methods.

The end goal when prototyping is to produce a fully functional version of the prosthetic arm that can be tried by the user and will perform as well as the final item. The finished product could of course then also be 3D printed but certain components may need to be machine made or indeed already be widely available. The literal nuts and bolts as it were!

So there you have our latest article in this series. All the methods mentioned in terms of 3D design, visualization and prototyping can be carried out by our talented technicians here at Politech so please get in contact and we'll be more than happy to assist.

In the meantime, thank you for reading and look out for the next part in this series!



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