Additive manufacturing is shaping up to be an increasingly versatile manufacturing technology, which can be adapted to the most varied fields and sectors. Recent innovation and research into materials is evolving to support the design and development of manufacturing processes for orthopaedic medical devices.
When talking about introducing 3D technologies into the manufacture of orthopaedic devices, the factor that draws the most attention is the sustainability of the process in terms of time and phases of production.
In contrast to the currently used CAD-CAM technologies, which involve the use of numerically controlled machinery for milling a block of material, which means subtracting said material to obtain the desired geometry of whatever model you are trying to make, the additive manufacturing process, as the name suggests, is based on the deposition and addition of material layer by layer. The amount of material used is that which is only necessary to complete the required geometry. This allows for a clean environment, free from the presence of scraps and residues of material, as well as heavy machinery.
Furthermore, the complete digitalization of the design of orthopaedic aids ensures that the three-dimensional scan of the contours of the patient’s body is always precise.
Each phase of the process that has been digitalized due to the use of 3D technologies, streamlines the traditional workflow considerably and would otherwise require the use of a greater number of manual instruments and take longer to properly acquire a precise model of the anatomical region being focused on.
Among the health professionals who can benefit from the development of 3D technology, the podiatrist has a particular advantage, because they can directly manage the patient’s treatment, and accurately model the corrective plantar aid according to the pathology in question.
The space needed for one of these machines is not particularly large. A modest size professional desktop 3D printer, such as the Raise3D E2 equipped with IDEX (Independent Dual Extruders) technology, can completely fulfil most print quality requirements. When it comes to foot orthotics especially, IDEX technology is perfect for optimizing the manufacture of a pair of insoles, which can be produced simultaneously.
Together with podiatry specialist, Dott. Mirko Valenti we started a process of introducing 3D technology into his daily workflow, complementing the medical examination with the internal design and production of tailor-made aids, based on the care prescribed by the physician.
Dr. Valenti has identified the most suitable material capable of conferring support and flexibility for the various corrective elements of the insole. Polypropylene is proving to be a widely versatile material in the orthopaedic sector, thanks to its properties of low density, elasticity and strength, that make it lightweight and capable of absorbing the body’s physiological loads.
During the slicing and preparation phase of the model for printing, it is also possible to modify the mechanical properties by varying the parameters of the infill: in particular, a honeycomb-pattern infill confers stiffness to the entire structure, while varying the percentage of the infill allows the user to obtain different results in terms of the orthotics' deformability and lightness.
Dr. Valenti has chosen to treat a clinical case of posterior tibial tenosynovitis with conservative orthotic therapy, favouring biomechanical compensation and the “unloading” of the tendon via the use of an EVA-coated polypropylene insole.
The orthotic was modelled in such a way as to ensure support of the foot’s arch, guarantee the stability of the heel and control pronation by compensating the affected areas by CAD-modelling directly on the scan of the sole. Subsequently, during the preparation of the print file via the slicing process, the required mechanical properties were given to the main load and support areas previously identified for therapy.
Finally, after the printing phase, we moved on to the final phase sheathing the sole in EVA or other specific material that is suitable for skin contact.
This pair of orthotic soles was made in less than 24 hours, which is remarkable considering the scanning, design, and manufacturing phases all took place completely in-house.
The patient was examined 4 months after using the orthotic to verify her degree of satisfaction and the effectiveness of the personalized orthopaedic treatment.
The specialist was able to evaluate both the material’s resistance and the patient’s improvement in relation to the pain and discomfort she previously suffered due to the pathology.
The use of 3D technologies has proved successful for the specialist in identifying a personalized orthopaedic treatment, significantly reducing manufacturing times that are usually encountered when entrusting the production to third parties.
We thank Dr. Mirko Valenti, who carried out the case study on a podiatry therapy based on plantar orthotics by means of additive manufacturing processes, providing us with information of the clinical case treated.