Additive Manufacturing can show off its strengths
in medical applications like in no other field.
What is AM used for in medical?
Custom tailored hip replacements
A surgeon can test if the additively manufactured hip cup
made of Titanium will actually fit the patients bone structure.
For this purpose a model of the patients hip would be created
of Polyamide using LaserSintering technology. This is possible
all prior to surgery.
This has been done at Royal Hospital Perth already in 2006.
Read more about this here [link] .
What is required to apply AM in the medical field?
The key for AM in medical applications is the software.
Specialized software enables biomedical engineers to
create 3D models from CT,MRI and 3D Ultrasonic data.
The software enables to create virtual models where tissue,
bone structure and even blood vessels are represented in
separate files. This allows to build patient specific models,
instrumentation and implants using AM technologies.
There are several software solutions for these applications.
Mimics® from Materialise might the one be best known.
But there are others like the 3D Doctor from Abel Software.
True Life Anatomy is another program with the capability to
export DICOM data into STL.-format.
Data preparation and medical modelling
The software is one part but the input from the surgeons
is the next critical element. Based on this information
the biomedical engineers design the biomedical devices.
Often times a so called haptic-device is used for this work.
This digital input device allows to model virtual clay/wax
on virtual bone structure. The tool provides feedback when
clay/wax is modeled on the surface. This helps to create
the perfect matching implant, cutting jig or drill guide.
What are the applications?
Patient specific implants are mainly used for patients who cannot
be helped with a standard implant. This implants can be designed
to match the shape of missing bone structure. Mounting points
can be placed in locations for ideal force distribution. This implants
are likely to achieve higher lifetimes than standard implants or by
implants created with traditional techniques.
Especially in maxillofacial and craniofacial applications
Additive Manufacturing technologies offer great advantages
compared to traditional methods. Mainly used after accidents
bthe “missing puzzle part” of bone structure can be created.
Implants are usually build on powder bed fusion systems.
Most times Titanium alloys are used for these type of implants
but also PEEK became in recent years an option.
Patient specific instrumentation (PSI) is helping to increase
accuracy whilst making cuts, drilling holes and placing implants.
This devices can reduce stress for the surgeons and safe valuable
time in the theater.
This part is made using Selective Laser Sintering technology.
Devices like this are used during surgery to make cuts and
drill holes in a predefined position of the bone structure.
But is is not always about patient specific solutions
Implants with lattice structures
The Italian company Lima Corporate is using Electron Beam Melting
to produce acetabular revision kits. Sections of this implants are
made of a lattice structure in Titanium. Tissue can grow into the
scaffolds of the structure what improves the bonding.
Medical models for operation planning and education
Some Stereolithography resins allow to create parts in a clear material
with the option to add color locally. This is used to create see through
medical models where locally blood vessels or other features are highlighted.
Surgeons use this models to plan surgeries not just on a screen but with
a physical model in their hands. See an example here.
Multimaterial polyjet machines can also be used for this application.
Laser Sintering is oftentimes used to create models of bone structures.
This process is also used to create replicas of skeletons of rare or
extinguished animal species.
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