The use of 3-D printers in medicine is no longer uncommon. The production of dentures, artificial joints and heart valves from the printer is busily researched.
Given the current skepticism about organ transplants, customized organs from the 3-D printer would be longed-for alternative, but this is still the case so far Science fiction. Models are already being researched that allow cartilage, bones, muscle tissue and other biomaterials to develop and “print” complex structures such as bionic ear (), but there is still long way to go before functional organ that functionally corresponds to its natural model (). However, there are already realistic applications for 3-D printers that use plastic, metals, synthetic resins and ceramics as building materials and do not rely on stem cells, proteins and growth factors.
Classic three-dimensional printing is process in which the desired workpieces are produced in layers from digital templates (). Depending on the process, different materials such as plastics, synthetic resins, ceramics and metals can be used, from which the three-dimensional shapes are additively built up using precisely controlled physical or chemical melting or hardening processes.
Initially, three-dimensional printing processes were primarily used to create prototypes and models, for example in mechanical engineering and in the aircraft and automotive industries (). As soon as the prototype met expectations, the respective component was manufactured using conventional methods. Due to technical advances and reduced (device and material) costs, 3-D printing processes are now also used to manufacture individually adapted objects, as adaptations can be made quickly depending on requirements or customer wishes. In the meantime, complex workpieces can also be manufactured in this way.
However, the road to get there was long: A printed volume model was first reported in 1981 (); The first functional 3-D printer was presented by Charles Hull, who also holds several patents relevant to the area of 3-D printing, in 1984 ().
The use of 3-D printers in medicine is no longer uncommon. The production of dentures, artificial joints and heart valves from the printer is busily researched.
Given the current skepticism about organ transplants, customized organs from the 3-D printer would be longed-for alternative, but this is still the case so far Science fiction. Models are already being researched that allow cartilage, bones, muscle tissue and other biomaterials to develop and “print” complex structures such as bionic ear (), but there is still long way to go before functional organ that functionally corresponds to its natural model (). However, there are already realistic applications for 3-D printers that use plastic, metals, synthetic resins and ceramics as building materials and do not rely on stem cells, proteins and growth factors.
Classic three-dimensional printing is process in which the desired workpieces are produced in layers from digital templates (). Depending on the process, different materials such as plastics, synthetic resins, ceramics and metals can be used, from which the three-dimensional shapes are additively built up using precisely controlled physical or chemical melting or hardening processes.
Initially, three-dimensional printing processes were primarily used to create prototypes and models, for example in mechanical engineering and in the aircraft and automotive industries (). As soon as the prototype met expectations, the respective component was manufactured using conventional methods. Due to technical advances and reduced (device and material) costs, 3-D printing processes are now also used to manufacture individually adapted objects, as adaptations can be made quickly depending on requirements or customer wishes. In the meantime, complex workpieces can also be manufactured in this way.
However, the road to get there was long: A printed volume model was first reported in 1981 (); The first functional 3-D printer was presented by Charles Hull, who also holds several patents relevant to the area of 3-D printing, in 1984 ().Only recently have the corresponding techniques reached level that makes them both affordable and practicable for wide range of applications.
Possible uses in medicine
There are several aspects that make the 3rd Make -D printing interesting for healthcare too. Above all, it is relatively inexpensive, readily available, fast process that leaves plenty of room for creativity, experimentation and innovation. Technology is developing rapidly, software and devices are becoming more and more convenient to use, and the range of printers and consumables is growing. Medical institutes willing to experiment can afford 3-D printers without great financial risk and implement their ideas in an uncomplicated manner.
3-D printing processes are being researched or are already being used in many areas of medicine (Figure 1, 2) . One example is the successful splinting of tracheobronchomalacia in 20-month-old toddler who received bioresorbable splint at the University of Michigan in February 2009. The product was developed on the basis of computed tomography (CT) images, which served as model basis for adjusting the splint on the computer, and was produced with 3-D printer (). The operation went smoothly, and after 21 days the child could be discharged without artificial respiration.
Prosthetic care after amputations is also an area of application that has recently come into focus: the University of Toronto in Canada, for example works together with the charity Christian Blind Mission Canada on simple methods for the creation of individualized prosthesis approaches for leg amputees in Uganda and thus enables broad health care that would not be possible without this technology for financial reasons alone.
Another example is called the supply of simple but easy to use and above all inexpensive 3-D printed hand prostheses with gripping function. There are different approaches, for example purely mechanical prostheses (www.robohand.net) , but also those with more sophisticated control mechanisms (www.openhandproject.org) . Sometimes the construction plans are even published here to enable simple replica of the prosthesis.
Possible uses in medicine
There are several aspects that make the 3rd Make -D printing interesting for healthcare too. Above all, it is relatively inexpensive, readily available, fast process that leaves plenty of room for creativity, experimentation and innovation. Technology is developing rapidly, software and devices are becoming more and more convenient to use, and the range of printers and consumables is growing. Medical institutes willing to experiment can afford 3-D printers without great financial risk and implement their ideas in an uncomplicated manner.
3-D printing processes are being researched or are already being used in many areas of medicine (Figure 1, 2) . One example is the successful splinting of tracheobronchomalacia in 20-month-old toddler who received bioresorbable splint at the University of Michigan in February 2009. The product was developed on the basis of computed tomography (CT) images, which served as model basis for adjusting the splint on the computer, and was produced with 3-D printer (). The operation went smoothly, and after 21 days the child could be discharged without artificial respiration.
Prosthetic care after amputations is also an area of application that has recently come into focus: the University of Toronto in Canada, for example works together with the charity Christian Blind Mission Canada on simple methods for the creation of individualized prosthesis approaches for leg amputees in Uganda and thus enables broad health care that would not be possible without this technology for financial reasons alone.
Another example is called the supply of simple but easy to use and above all inexpensive 3-D printed hand prostheses with gripping function. There are different approaches, for example purely mechanical prostheses (www.robohand.net) , but also those with more sophisticated control mechanisms (www.openhandproject.org) . Sometimes the construction plans are even published here to enable simple replica of the prosthesis.
Supported by imaging processes, 3-D printing can also be used profitably in other areas if it needs to be adapted to the specific anatomy of the respective patient. It starts with individually adapted implants (,) and extends to models on which an operation can be planned or trained in advance in the event of difficult findings (-). The use for printing surgical instruments has already been investigated (,).
Depending on the application, different variants of 3-D printing are available. Which method is ideally used depends, among other things, on the size of the planned product, the materials intended for use, the design of the product and its area of application, as well as the purchase costs of the printer. The range of 3-D printers is growing daily (). Websites like www.fabbaloo.com/3d-resources or www.3ders.org/pricecompare/3dprinters give an impression of the multitude of existing systems.
In the private sector, for example, enamel layering and stereolithography are widespread. The basic technical equipment for experimental enamel layering, as tested at the Hannover Medical School, is shown in Figure 3 . In the process, meltable plastic is made malleable with heatable nozzle and applied to work surface via movable head. When the material cools, it hardens again, whereupon the next layer is applied to the material that has already been printed. The 3-D object is created layer by layer. The market-leading plastics for this form of 3-D printing are acrylonitrile butadiene styrene (ABS) and polylactide (PLA). The main difference between these two plastics is the better heat resistance of ABS. PLA is very common because, among other things, it is somewhat easier to process.
In stereolithography, the desired object is created from special, liquid plastic. This is done by using suitable light source, such as laser, to “draw” the shape of the model into the liquid material layer by layer. The laser hardens the light-sensitive plastic and creates the model.
3-D powder printing, selective laser sintering
More expensive processes are more likely in the (semi-) professional sector, like 3-D powder printing (3DP) and laser sintering (SLS). While with the 3DP powder-like materials are applied together with binding agent, which after hardening with further layer of this mixture are used to build up the workpiece, with laser sintering the powder material is heated by laser and thus bonded neighboring particles. With this method, too, the model is built up in layers.Photo: Hannover Medical School
Supported by imaging processes, 3-D printing can also be used profitably in other areas if it needs to be adapted to the specific anatomy of the respective patient. It starts with individually adapted implants (,) and extends to models on which an operation can be planned or trained in advance in the event of difficult findings (-). The use for printing surgical instruments has already been investigated (,).
Depending on the application, different variants of 3-D printing are available. Which method is ideally used depends, among other things, on the size of the planned product, the materials intended for use, the design of the product and its area of application, as well as the purchase costs of the printer. The range of 3-D printers is growing daily (). Websites like www.fabbaloo.com/3d-resources or www.3ders.org/pricecompare/3dprinters give an impression of the multitude of existing systems.
In the private sector, for example, enamel layering and stereolithography are widespread. The basic technical equipment for experimental enamel layering, as tested at the Hannover Medical School, is shown in Figure 3 . In the process, meltable plastic is made malleable with heatable nozzle and applied to work surface via movable head. When the material cools, it hardens again, whereupon the next layer is applied to the material that has already been printed. The 3-D object is created layer by layer. The market-leading plastics for this form of 3-D printing are acrylonitrile butadiene styrene (ABS) and polylactide (PLA). The main difference between these two plastics is the better heat resistance of ABS. PLA is very common because, among other things, it is somewhat easier to process.
In stereolithography, the desired object is created from special, liquid plastic. This is done by using suitable light source, such as laser, to “draw” the shape of the model into the liquid material layer by layer. The laser hardens the light-sensitive plastic and creates the model.
3-D powder printing, selective laser sintering
More expensive processes are more likely in the (semi-) professional sector, like 3-D powder printing (3DP) and laser sintering (SLS). While with the 3DP powder-like materials are applied together with binding agent, which after hardening with further layer of this mixture are used to build up the workpiece, with laser sintering the powder material is heated by laser and thus bonded neighboring particles. With this method, too, the model is built up in layers.The connected particles ultimately form the desired object. Laser sintering processes are preferred in the industrial sector because they can process different materials such as metals, plastics or ceramics.
3-D models as printing templates
To produce small quantities or with little technical effort it is possible, instead of purchasing your own printer, to commission service providers to do the printing. Such service providers, see for example at www.shapeways.com , offer the printing of any 3-D model in selection of different colors and materials.
For use of 3-D printers, e.g. for the production of objects, in addition to the technical aspects of the printing process, the planning of the desired product and the creation of the print template are essential. Before it can be printed, the desired object must be available as digital model. Depending on the skill of the user, there are several options.
The user can model the desired 3-D models himself with professional CAD software (such as Solid Edge, AutoCAD). Classic modeling software for three-dimensional models is complex to operate and can only be used effectively after extensive training. In addition to paid solutions, there are also some free versions of such software such as Autodesk 123D (www.123dapp.com) or SketchUp (www.sketchup.com) , which are specially designed for beginners in the modeling also support simplified operating concepts. Web-based applications now offer the possibility of compiling simple 3-D models using drag and drop, see for example https://tinkercad.com or http://shapesmith.net .
For clearly defined application, special software can also take over the modeling of 3-D objects. In the clinical area, for example, existing image data, such as CT images, can be used to record the dimensions of patient and generate suitable 3-D object (,). If no image data is available, the physical characteristics of person can also be recorded with 3-D scanner in order to then create suitable 3-D model on this basis (Figure 4)
Platforms with completely constructed models
Since these two solutions are associated with lot of time and effort, more and more platforms are emerging on which completely constructed models, like from catalog, are available for selection.The connected particles ultimately form the desired object. Laser sintering processes are preferred in the industrial sector because they can process different materials such as metals, plastics or ceramics.
3-D models as printing templates
To produce small quantities or with little technical effort it is possible, instead of purchasing your own printer, to commission service providers to do the printing. Such service providers, see for example at www.shapeways.com , offer the printing of any 3-D model in selection of different colors and materials.
For use of 3-D printers, e.g. for the production of objects, in addition to the technical aspects of the printing process, the planning of the desired product and the creation of the print template are essential. Before it can be printed, the desired object must be available as digital model. Depending on the skill of the user, there are several options.
The user can model the desired 3-D models himself with professional CAD software (such as Solid Edge, AutoCAD). Classic modeling software for three-dimensional models is complex to operate and can only be used effectively after extensive training. In addition to paid solutions, there are also some free versions of such software such as Autodesk 123D (www.123dapp.com) or SketchUp (www.sketchup.com) , which are specially designed for beginners in the modeling also support simplified operating concepts. Web-based applications now offer the possibility of compiling simple 3-D models using drag and drop, see for example https://tinkercad.com or http://shapesmith.net .
For clearly defined application, special software can also take over the modeling of 3-D objects. In the clinical area, for example, existing image data, such as CT images, can be used to record the dimensions of patient and generate suitable 3-D object (,). If no image data is available, the physical characteristics of person can also be recorded with 3-D scanner in order to then create suitable 3-D model on this basis (Figure 4)
Platforms with completely constructed models
Since these two solutions are associated with lot of time and effort, more and more platforms are emerging on which completely constructed models, like from catalog, are available for selection.These models can then, depending on the license, be downloaded for free or for fee and printed out. One example of such catalogs is www.thingiverse.com , which it claims is the largest platform for sharing 3-D models. The aforementioned service provider www.shapeways.com also has database that contains various templates from jewelry to home accessories.
Such platforms promote the success of 3-D printing In the private sector this is decisive, since models that have been created in complex manner can easily be reused. Beginners can print models that they could hardly have modeled with their own skills, but also professional users save lot of time. Plans for health products such as rails or portable ramps for wheelchair users can already be found there.
We are at the beginning of new technical evolutionary step that will lead to the liberalization of product manufacturing: Now it is no longer just the big ones Companies that are able to manufacture industrial-type products in series. Rather, it is almost possible for anyone interested to be an idea generator, developer, producer, distributor and user in personal union. The provision of heavy and expensive machines is no longer requirement for production. This situation is already reality - also in the health sector.
The influence of technology can already be felt: Patients, organizations and institutions are becoming manufacturers of prostheses and other medical products. The responsibilities associated with production and the product are certainly not yet in everyone's awareness.
With 3-D printing in the health context, questions arise that are ethical as well as quality and safety aspects , legal and economic aspects that have to be seen and answered in the respective context of the manufacturer and country in order to use the new technology efficiently, fairly and safely.
Dr. med. Urs-Vito Albrecht, MPH, Stefan Franz, M. Sc., Peter L. Reichertz Institute for Medical Informatics at the TU Braunschweig and the Hannover Medical School
Dipl. Ing. Joerg Viering, Hannover Medical School, Central Research Workshops
Address for the authors: Dr. med. Urs-Vito Albrecht, MPH, PLRI MedAppLab, Peter L. Reichertz Institute for Medical Informatics at the TU Braunschweig and the Hannover Medical School, Hannover Medical School, 30625 Hannover, albrecht.urs-vito@mh-hannover.de
Such platforms promote the success of 3-D printing In the private sector this is decisive, since models that have been created in complex manner can easily be reused. Beginners can print models that they could hardly have modeled with their own skills, but also professional users save lot of time. Plans for health products such as rails or portable ramps for wheelchair users can already be found there.
We are at the beginning of new technical evolutionary step that will lead to the liberalization of product manufacturing: Now it is no longer just the big ones Companies that are able to manufacture industrial-type products in series. Rather, it is almost possible for anyone interested to be an idea generator, developer, producer, distributor and user in personal union. The provision of heavy and expensive machines is no longer requirement for production. This situation is already reality - also in the health sector.
The influence of technology can already be felt: Patients, organizations and institutions are becoming manufacturers of prostheses and other medical products. The responsibilities associated with production and the product are certainly not yet in everyone's awareness.
With 3-D printing in the health context, questions arise that are ethical as well as quality and safety aspects , legal and economic aspects that have to be seen and answered in the respective context of the manufacturer and country in order to use the new technology efficiently, fairly and safely.
Dr. med. Urs-Vito Albrecht, MPH, Stefan Franz, M. Sc., Peter L. Reichertz Institute for Medical Informatics at the TU Braunschweig and the Hannover Medical School
Dipl. Ing. Joerg Viering, Hannover Medical School, Central Research Workshops
Address for the authors: Dr. med. Urs-Vito Albrecht, MPH, PLRI MedAppLab, Peter L. Reichertz Institute for Medical Informatics at the TU Braunschweig and the Hannover Medical School, Hannover Medical School, 30625 Hannover, albrecht.urs-vito@mh-hannover.de
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