Surgeons now able to print out life-sized models of patients' bodies
Orthopaedic surgeon and anatomy lecturer Dr Rudolph Venter said 3D printing technology had been used in medicine for a long time already, but at such an exorbitant cost that it could only be used in the realm of funded research.
Now, instead of paying thousands of rand for an engineering firm to produce a 3D model, doctors from Stellenbosch University and Tygerberg Hospital’s Division of Orthopaedic Surgery are able to print their own - for just a couple hundred rand.
“Something that was out of reach for most patients is now done for people walking off the street into Tygerberg Hospital - 3D printers are now very affordable and the software is so easy to use. The orthopaedic surgeons are learning how to do it,” Venter said.
The 3D printers have been used for 10 big cases so far, seven of which were public health-care patients. In one case, Venter needed to cut a tumour out of surrounding bone, together with lead surgeon Professor Nando Ferreira. The patient had CT scans done and the imaging data was sent to the printer to be mapped into a 3D object. A life-size model of the anatomy was then printed out, with the bone printed in hard plastic and the tumour tissue in softer, rubbery plastic.
Just by feeling the model in his hand, Venter was able to familiarise himself with exactly which parts were tumour and needed to be excised.
The purpose of the model goes beyond lab preparation, though. “We sterilise the model and take it to theatre with us,” Venter said.
During the operation, he could have one hand on the actual bone and tumour, and one hand on the 3D printed model to guide him.
“It’s like having this amazing, tactile road map of the patient’s anatomy inside their body.”
Beyond getting familiar with a particular patient’s anatomy, the 3D printing models also allow surgeons to rehearse procedures. One such patient needed a hip implant, but he had achondroplasia - a bone growth disorder which causes dwarfism - so his bones were not the standard size.
“We weren’t sure whether the hip replacement implants were going to fit, so we printed out his hip bone and practised it,” Venter said.
Together with surgeons Dr Koos Jordaan and Dr Gerard Pienaar, they cut the printed femur and put the implant in.
“We went to theatre feeling like we’d done this operation before. You know what to expect; your fingers have felt this before.”
A kilogram of the PLA plastic used to load up the printer costs about R400, and Venter said he could print about 20 femurs with that much plastic.
In another case last year, surgeons needed to correct a child’s spine deformity by removing a partially formed vertebra without damaging the complex structures surrounding it. Venter printed out a 3D model of the child’s spine for spinal surgeon DrSanesh Miseer.
“He was so excited about this model, he took it home and dissembled it to deeply understand exactly what the patient’s anatomy is going to look like,” Venter said.
“He said it was like taking a CT scan out of the screen and holding it in your hand.”
Venter hopes the printers will benefit many different medical disciplines.
“It’s going to open a lot of doors,” he said. “We’re very excited for the implications of training medical students, and it’s awesome to have our patients benefit at grass roots level.”
In the future, the printers will be used to produce instruments that are tailor-made for patients.
Surgeons will also be able to design implants specific to each patient and send those designs off to be manufactured by engineering firms with the capability to 3D print metal objects using titanium powder.