The benefits of 3D printing within the medical industry include better clinical outcomes for patients as well as improved economics.
Additive manufacturing applications within the medical industry are diverse. The technology enables quick, cost-effective development of new devices, and customised end-use products that improve the delivery and results of patient care. This article examines medical applications using Stratasys FDM and PolyJet technology.
Rapid prototyping and product development
The ability to quickly create new products and speed the development cycle is a hallmark of 3D printing, achieved by replacing, where appropriate, time-consuming and costly traditional manufacturing methods. It gives designers and engineers tools to quickly create and iterate designs and reduce time to market. Functional prototypes using high-performance materials allow designers to test designs in verification and validation protocols earlier in the design process. Gaining feedback early helps designers identify areas for improvement, resulting in devices that can better contribute to positive outcomes.
Biorep, a manufacturer of devices aimed at finding a cure for diabetes, had traditionally used machine shops or service bureaus to quickly prototype small parts. However, an increase in manufacturing volume created the need to bring this capability in-house. Part accuracy and surface finish were key design parameters, leading Biorep to choose a mid-sized PolyJet model, which enabled in-house prototyping in an easy-to-use 3D printer with a small footprint. Quickly creating low-cost prototypes helped Biorep engineers gain management support for a novel pinch valve design, and to thoroughly test it, avoiding costly delays.
Rapid prototyping also lets designers quickly gather physician feedback on part design. Within hours, the designer can digitally iterate the design based on physician input and print the revised part for evaluation. The fast feedback loop accelerates development.
Anatomical models
Historically, clinical training, education and device testing have relied on animal models, human cadavers or mannequins for hands-on experience in a clinical simulation – all options with various deficiencies. When it comes to individual patient care, pre-surgical analysis and planning using computed tomography (CT) and magnetic resonance imaging (MRI) scans remain limited to 2D screen images.
The advent of 3D printing — especially in multiple materials, colours and textures — offers new possibilities in training, device testing and execution of surgical procedures. 3D-printed models made with different materials representing bone, organs and soft tissue are produced in a single print procedure. They can be designed based on actual patient anatomy to capture the complexity and realism of treating the human body.
The ability to model a patient’s anatomy and pathology for analysis and practice prior to an operation also offers clinical benefits, like anticipation of complications and reduced surgery time, enhancing the likelihood of favourable results and faster patient recovery. Models can be stored digitally to allow production as needed, and can be used in an office without special environmental controls.
Kobe University Graduate School of Medicine in Japan uses PolyJet multi-material technology to produce anatomical models for surgical preparation and medical training. While CT and MRI offer some visualisation of a patient’s status, they may not reveal conditions that could cause complications. The university’s large, colour 3D printer lets doctors create full-size models of a patient’s organs.
According to Dr Maki Sugimoto, associated professor at Kobe, multi-colour, multi-material bio-models help surgeons uncover tissues and blood vessels that may be blocked by larger organs in the 2D scans. Surgeons can examine models from different perspectives and mark them as needed to plan procedures, slashing operating time. The models provide clearer perspectives and better visualisation, allowing more accurate treatment.
A desire to use bio-models for training led the University of Malaya’s Centre for Biomedical and Technology Integration (CBMTI) to use 3D printing. CBMTI chose PolyJet for its speed, ease of use, and its ability to print in multiple materials. This allows technicians to make more and better models, scaling them down to save material when full size isn’t necessary.
CBMTI printed a human skull section that replicated bone and tissues encountered during a brain tumour operation, which entails cutting the skin, opening the bone, cutting the brain lining and removing the tumour. This technology lets CBMTI provide researchers and medical instructors training models with accuracy, realism and tactile feedback consistent with human physiology.
Realistic texture and form also make 3D printed anatomical models effective tools for testing medical devices. Researchers used a model to validate the Covidien Solitaire Flow Restoration stent retriever, comparing its performance with conventional catheters, and ultimately demonstrating its higher success rate of neurovascular recanalisation. The model’s realism also let researchers note the specific anatomical location of blood clot loss during the tests.
Patient-specific surgical guides
When it comes to the precision needed during joint replacement or to repair bone deformities, scanning technology has limitations. Doctors must still rely on scan images and experience, as well as generic surgical guides, to accurately place hardware for bone repair.
The use of 3D printed surgical guides refines the traditional means of orthopaedic care by allowing doctors to shape them to the patient’s unique anatomy, accurately locating drills or other instruments used during surgery. This makes placement of restorative treatments more precise, improving post-operative results.
The Prince of Wales Hospital in Hong Kong uses FDM to make surgical guides and tools along with bone models. The printed models are used to plan and test locations for stabilising screws or plates that conform to the patient’s bone surface. The outcome is reduced risk of post-surgical complications like bleeding and infection.
According to Professor Kwok-sui Leung of the Chinese University of Hong Kong, 3D printing allows in-depth assessment and pre-surgical rehearsal, resulting in implants fitted more accurately to the curvature of the bone. On average, operation time was reduced by an hour when incorporating 3D printed parts in the pre-surgical process.
FDM also benefits this application with materials such as PC-ISO, a biocompatible thermoplastic in its raw state that can be sterilised using ethylene oxide (EtO) or gamma radiation. Surgical guides, derived from patient scans to precisely match their anatomy and made from PC-ISO, are compatible with human tissue for short-term contact. This allows them to be placed against the patient’s anatomy for a more precise cut or drill hole.
End-use parts for clinical trials
Reducing the time to bring a medical device concept to the clinical trial stage has positive ramifications throughout the medical supply chain. Producers reduce cost and get products to market faster, and patients benefit from new devices sooner. One obstacle is the time and cost to manufacture the product and revise it sufficiently to reach the right design. Lead times to create tooling, whether in-house or outsourced, can be lengthy and expensive.
Additive manufacturing can drastically shorten development. Concepts can be produced overnight, validated or quickly revised as needed, and be ready for clinical use without the need to implement the full design and manufacturing process. Manufacturers can use additively manufactured parts to support clinical trials or early commercialisation while the final design is still in flux.
Ivivi Health Sciences in San Francisco, US, develops non-invasive, electrotherapy devices to accelerate patient recovery, and needed consistent production of devices in small quantities for clinical trials. However, the necessary planning and product development typically took months. Ivivi also outsourced manufacturing, and design adjustments were common prior to finalising the design.
To streamline the development cycle, Ivivi turned to 3D printing, choosing a PolyJet system to satisfy the need for parts with a very smooth surface finish and sufficient durability. Using this technology, Ivivi could quickly create devices and deliver them to trial participants. The adoption of 3D printing provided Ivivi with a return on investment in less than one year, and enhanced its capacity to develop new prototypes and quickly modify devices.
Personalised prosthetics, bionics and orthotics
Additive manufacturing is well suited for individualised healthcare, enabling creation of prosthetic and orthotic devices tailored to a patient’s specific anatomy and needs. In addition, the economics of 3D printing are ideal for low-volume and custom production, meaning cost often drops even while effectiveness increases.
Albert Manero is a PhD student in mechanical engineering at the University of Central Florida and Executive Director of Limbitless Solutions, an organisation with the goal of developing bionic replacement limbs for a lower cost. One beneficiary of its efforts was six-year-old Alex Pring, a boy born without a lower right arm. Limbitless Solutions designed and produced a low-cost bionic lower arm and hand for Alex. It uses electromyography sensors and a microcontroller in combination with Alex’s bicep to operate the hand. His new arm was made via FDM, using ABSplus material to keep it strong but lightweight. The total cost was $350, compared with $40,000 for conventional medical solutions. As Alex grows, new arms can be made without the normal financial burden for this type of ongoing care.
FDM also helped Emma Lavelle, who was born with arthrogryposis multiplex congenital (AMC), a joint condition that limits her ability to move her arms. Experts at the Nemours/Alfred I DuPont Hospital for Children developed the Wilmington Robotic Exoskeleton (WREX), a device made from metal and resistance bands, that lets people with AMC move and control their limbs. WREX devices attached to a wheelchair had been made for children as young as six, but Emma was only two and able to walk. The Nemours team developed a scaled-down, lighter WREX, using an FDM printer to make parts customised for Emma’s size – too small and detailed to be produced on a CNC machine. Emma’s customised WREX lets her do things she couldn’t before, and a new WREX can easily be made as she grows.
Laboratory and manufacturing tools
A more conventional application of 3D printing involves the creation of tooling, fixtures and other equipment that lets labs and medical device manufacturers work faster and reduce costs. Tools specific to a lab or process can be created quickly and revised as needed for little cost, simply by changing the tool’s CAD file and reprinting it. They can also be stored digitally, eliminating the need for physical storage.
Hospitals and clinics benefit by making custom surgical trays for specific needs, and with FDM materials such as ULTEM 1010 resin, these can be sterilised using a steam autoclave process. A 3D printer is indispensable for the DeRisi Lab of the University of California San Francisco, which makes custom pipet racks, gel combs and other small parts. The lab even benefits from printing parts already available from medical suppliers. For example, the lab printed its own small centrifuge at a total cost of $25, less than 10% of the supplier’s price of $350.
Conclusion
Additive manufacturing offers new possibilities for both medical device developers and health care providers by circumventing traditional manufacturing methods, replacing them with faster, less costly technology, suitable for customisation. Stratasys FDM and PolyJet technologies from Objective3D give medical device developers the tools to reduce product development costs and time to market. They give physicians the capability to model a patient’s anatomy using realistic materials for better planning that shortens surgical procedures. This is not technology to come; it has already been adopted in the medical industry as an essential means of improving the economics and outcomes of healthcare.