3D printing for medical applications is growing, more and more medical physicians are realising the benefits to medicine that 3D printing can bring Applications to name but a few, prosthetics, bone fracture replication, dental, Bionics. Slice3D is one of the few 3D printing bureau companies in the uk that can produce these types of models.
An good example of 3D printing for medical applications in the world of medical science, is damage that occurs all too frequently to the skull, this is referred to as an orbital blow-out, without going in to much detail, when the head experiences a significant trauma or impact usually the result of a car crash, a fall or even a blow from a fight. The resulting trauma often has the effect of breaking the orbital floor in the skull due to either an impact to the upper cheek bone or sudden increase in pressure to the eye socket/eye ball; Clever mother nature intended this bone to break so as not to burst the precious eye ball. The orbital floor bone, is a very fine fragile, contorted plate type bone, at its thinnest point can be 0.37mm thick. It basically holds the eye in position, something we all take for granted I’m sure, but when this injury occurs it can have significant impact to the sight of the patient. As a result of an orbital fracture very often a hole can be present referred to as a trapdoor (highlighted in the image), over time the eye and its control muscle will progress downwards through the hole into the maxillary sinus cavity pulling the eye with it.
3D Printing Medical Uses
In the case of orbital floor correction, first a C.A.T scan is produced, this is a series of pictures taken layer by layer of the damaged area all of the layers are electronically stitched together, one on top of the other to form a 3D image of the skull this is then converted into an .STL file (Standard Tessellation Language) this is a standard file format for 3D printers.
The file is then printed and an exact solid copy of the patient’s skull is produced; including all of the damaged area. The model at this stage has proved invaluable in purveying information to the patient during consultation with their surgeon, as all of the damage can clearly be seen on a model, when looking at a C.A.T scan image the damage is not always clear to the untrained eye. After consultation the model is then sent to the prosthetic lab. Soft wax is used to fill in the holes in the orbital floor and re-craft the original surface of the floor prior to the damage, using the opposite socket as a guide to the symmetry for the new surface. A plaster cast is made of the inside of the eye socket. This producing the reverse shape of the re-crafted orbital floor, a releasing agent is then applied to the cast usually a spray wax. Another cast is produced of the first. There are now two halves, one with a reverse and one with an emboss of the new orbital shape.
A thin 0.5 mm metal titanium sheet is roughly cut to size and placed in between the two moulded shapes, a large pressure is applied to the mould and the metal takes on the exact shape of the orbital floor.
A final check is made using the 3D model as a reference to ensure the correct fit; it is very important that the front of the prosthetic plate lips over the check bone at the front of the eye socket and that it fits like a glove. If all is correct Holes are drilled through the bottom of the plate to allow fluid migration and increase adhesion of new tissue growth. Two further holes are then drilled at the front of the plate for fixing to the cheek bone of the patient with micro screws.
The metal is then trimmed to its final shape, the edges de-burred, the surface bead blasted and colour anodized in straw yellow. Why straw yellow? Straw yellow in fact, gives the best colour match in combination with the covering skin, It is difficult to distinguish the prosthetic through the skin when the prosthetic is in situ and coloured straw yellow. Utilizing 3D printing in this way enables an extremely accurate custom fit plate to be made prior to any operation, this instilling complete confidence in both patient and surgeon. Using 3D printing in this way is known to drastically reduce follow up operations and save up to 50% of the surgeons/theatre time. A great step forward! Slice3D is one of the few 3D printing services UK to offer this type of modelling.
A regular use of 3D printing in the medical field is to use a replication of a human bone part that displays a defect. The 3D print is made using images taken from a C.A.T scan of the patient, this information is stitched together to form a digital image of the whole part, this image is then converted to form an editable, printable file, known as a .STL file suitable for 3D prints.
This file can then be altered by removing parts of the model that do not need printing e.g. The skull; this saves money and time on the cost of the 3D print. If we take the case of a bone fracture in the jaw of a patient due to bone erosion from cancer. To halt the progress of the cancer, very often more of the bone has to be removed as it can be infected; this can be deduced from a 3D print of the bone. The prosthetic team use the 3D print of the Jaw to bend and fit a perforated titanium plate to the model this increases the strength of the jaw, the model is an exact replica of the patient enabling a precise fit when the bar is fitted.
If after reading this you feel inspired by a thought or an application that you think may benefit the medical industry, please get in touch, we would love to hear from you and investigate it further with you. Our details can be found on our contacts page.