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The process of creating reliable prosthetic devices to amputees has remained a stagnant challenge to researchers and physicians that hope to make the lives of amputees easier without causing them any additional pain or discomfort.
While prosthetic devices have continued to advance throughout history, 3D printing technology has emerged as a revolutionary way to enhance this medical device by avoiding the traditional negative impacts that are often associated with modern prosthetics through the most sensitive and ultimate customization possible.
Some of the earliest recorded uses of prosthetic limbs is found in Ancient Egyptian history, however, it was not until 1536 when French Army barber and surgeon Ambroise Paré invented the first prostheses for both upper- and lower-extremity amputees1.
Modern Uses of Prosthetic Technologies and their Materials
While these original prostheses were typically made of heavy iron and wood, modern prostheses are now much lighter, as they are often comprised of plastic, aluminum and other composite materials.
In addition to offering amputees a greater functionality with modern prostheses as compared to any other time in history, current prosthetic devices equipped with silicone covers also offer a more attractive appearance that more closely resembles a natural limb as compared to its predecessors.
The structure of a modern prosthetic device will typically consist of a socket that is designed to custom fit the amputee, a pylon, which describes the internal structure of the device, cuffs and belts that attach the prosthesis to the body, as well as cushions between the device and the area in which it directly contacts.
While the socket of the prosthesis is most often comprised of polypropylene, the pylon can be made of titanium or aluminum, however, some of the newest developments of prosthetic limbs have found that carbon fiber can add an even greater lightweight nature to the limb as compared to these metals.
What Mechanical Techniques are Used to Produce Prosthetic Limbs?
There are various mechanical techniques that can be utilized to produce the various parts of a prosthetic limb. Molds are designed according to a plaster cast that is created from the patient’s stump in order to create an exact duplicate for prosthetic attachment.
The plastic parts of the prosthesis, of which include the liners or padding found on the device, can be formed by using traditional plastic forming methods such as injecting molding, which forces melted plastic into a mold that is then cooled and extruded, or through vacuum forming methods.
Similarly, the pylon of the prosthesis is formed by forcing the liquid metal, whether that be titanium or aluminum, into a steel die that is of the desired shape2. Prosthetist technicians then assemble the full limb, which is then fitted specifically to each individual patient’s needs.
What are the Challenges Associated with the Use of Prosthetics?
While modern prosthetic devices provide amputees with a greater quality of life as they improve their ability to live productive lives, there are significant challenges that are associated with the use of prosthetics.
Of these negative impacts can include osteoporosis, back pain, inflammation, dermal necrosis that is due to ongoing skin breakdown at the side of the connection, phantom limb pain, a sensation that the amputated limb is still present and several other side effects3.
During the fitting stages of a prosthetic, prosthetists take careful measurements of the relevant body parts to ensure that the amputee’s prosthetic limb(s) will be as comfortable and useful to the individual as a natural one. Despite this, it remains a difficult endeavor to immediately assess how a patient will react to and adapt to their prosthetic limb following its continued use.
How 3D Printing has Revolutionized Prosthetics Development
In an effort to address some of these deleterious effects that can be associated with the use of prosthetic limbs, three-dimensional (3D) printing technologies have offered a revolutionary way to personalize prostheses without compromising the health of the patient.
3D printing, a type of additive manufacturing, has already found its successful application in a wide variety of industries including architecture, food, mechanics, aeronautics, drone technology, robotics, automotive, electronics, medicine, and many more4.
Within the medical field, 3D printing has not only allowed for custom-made devices, such as implants, fixtures and surgical tools, to revolutionize the way patients are cared for during and recover following surgical procedures, but is also a far less expensive option that can be made at a much faster and reliable rate as compared to traditional manufacturing methods.
Current medical uses of 3D printing have been incorporated to produce bones, ears, jaws, eyeglasses, cell cultures, stem cells, blood vessels, tissues, organs, drug delivery devices, vascular networks, plants, and even prosthetic devices5.
The first successful implantation of a 3D printed prosthesis was performed by a team of researchers at the BIOMED Research Institute of Belgium who manufactured a titanium mandibular prosthesis for an 83-year-old patient suffering from a chronic bone infection6.
Xilloc Medical, an engineering company that thrives itself on creating personalized medicine, created the jaw by using a series of lasers to successively melt thin layers of titanium powders to provide an exact replication of the measurements taken from the CT scans of the patient’s jaw.
Xilloc Medical continues to pioneer the world of 3D printed prosthetics, particularly those used to reconstruct the facial and skull anatomy, with their CT-Bone technology. Once a CT-scan of the patient is taken, Xilloc’s team of biomedical engineers design a calcium phosphate implant that is specific to the patient’s anatomy, thereby fitting perfectly into the patient during the surgical procedure.
As compared to other 3D printed prostheses that are often made of ceramics, the CT-Bone does not require a thermal process during its manufacturing, which allows for a better fusion and fit to occur between the implant and the bone7.
3D printing manufacturing companies from around the world are following the trend of manipulating certain materials and technologies in order to produce some of the most comfortable, aesthetically pleasing and highly functional prosthetic devices.
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For example, Bioniks Pakistan, a subsidiary of Viscous.co, has devoted its work to developing advanced 3D printed bionic arms that incorporate motorized joints that provide a custom fit to meet specific patient requirements8.
E-Nable is a unique 3D printing company that offers 3D printable designs for hands and arms to individuals around the world, particularly those living in areas of political, religious and cultural turmoil, at a significantly reduced cost. E-Nable’s global movement has changed the lives of thousands of people around the world in a way that offers them such an advanced technology that drastically improves their quality of life9.
Improving the Comfort of Prosthetic Limbs Through 3D Printing
While 3D technologies have focused their work on enhancing the flexibility and mobility of prosthetic joints, little research has been committed to improving the comfort of the socket of the prosthesis.
As stated, one of the most common problems that prosthetic users face with their devices is associated with the discomfort caused to the patient by the socket of the device. Inspired by the frustrations that they felt with traditional prosthetic socket solutions, two clinicians founded LIM Innovations that is committed to providing amputees a custom-molded socket, known as the Infinite Socket.
By taking specific measurements from a digital image of the amputee’s limb, carbon fiber is printed to create a precise representative mold for the individual10. This dynamic device is equipped with an adjustability component that allows amputees to adjust the socket according to their daily movements and activities.
As the prosthetics industry, as well as a plethora of other aspects of medicine, continue to benefit from 3D printing technologies, 3D printed prosthetic devices provide patients with a highly customized device that is a significant improvement as compared to traditional options. By not only reducing the costs associated with these devices, but 3D prosthetics also offer amputees a substantial improvement in their comfort and physical needs.
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References and Further Reading
- “A Brief History of Prosthetics” – Amputee Coalition
- “Artificial Limb” – How Products are Made
- “Prosthetic Problems” – the London Prosthetic Centre
- “3D Printing Applications per Industry” - Sculpteo
- “Medical Applications for 3D printing: Current and Projected Uses” – P&T Community
- “Transplant jaw made by 3D printer claimed as first” – BBC News
- “CT-Bone®: real bone from the 3D printer” – Xilloc Medical
- “BIONIKS” – Bioniks.org
- “About Us” – Enabling the Future
- “About LIM” – LIM Innovations