Orthopaedics: A1 Once Again, Thanks To 3D

11. October 2016

Three-dimensional printing techniques are revolutionising orthopaedics. All at once, entirely new pathways are opening up for colleagues in the treatment of complicated cases. Alongside artificial materials, biological materials are taking on a central role.

A look back at the history of medicine: since 1851, doctors have been dealing with fractures by using plaster. The method has barely changed over the decades. Patients perceive it as annoying and unhygienic. Several startups now offer stable “dressings” made of airy honeycomb structures.

Splinted in a lattice

A glance at the market: Zaid Musa Badwan, an engineering student, founded Mediprint in Mexico in order to produce orthotics. One competitor enterprise, Xkelet in Spain, recently even won a coveted Red Dot Design Award for 3D support devices. Both companies operate on the same basic principle. Doctors scan the broken limb. Based on the derived imaging, an app creates the suitable models and simultaneously manages all patient data. IT skills are not required for this.

This data goes to a 3D printer. Using heavy-duty, stable plastics as base material, within three hours a tailor-made model emerges. Patients are enthusiastic. They appreciate being less restricted in their mobility. They can work, take a shower or even go swimming. At the same time doctors have an easier time investigating the battered body parts. Turkish industrial designer Deniz Karasahin has even presented a version with an ultrasound source device in order to stimulate bone growth.

As is so often the case, there is a catch. 3D-lattice orthotics, depending on their complexity, hit the hip pocket to the tune of 2,000 to 5,000 US dollars per bill – no comparison with a mere few dollars needed for plaster casts. Nevertheless startups expect their inventions to soon make their way into daily clinical practice. In the US, they exist as a service option available to self-funders.

It does not work? Don’t say that!

This option is primarily suited for treating uncomplicated fractures. Three-dimensional printing technology can, however, do much more, as the following case shows. Little Joos had suffered a fracture of the left forearm bones while romping around. Doctors put a gypsum cast on him – the case seemed to be a routine one. Far from it: After removal of the bandage they realised with horror that the little patient could only move his forearm over a very limited range. X-rays showed that the bone had grown together wrong.

Dr. Frederik Verstreken, who works at Monica Hospital Antwerp, carried out an osteotomy. As part of this, 3D printed templates and titanium implants from Materialise were employed. Verstreken succeeded in re-establishing Joos’ limb functionalities.

This is no isolated case: little Helena had to be operated on because of a tumour in her knee. Dr. Gwen Sys, a surgeon at University Hospital Gent, managed to save the joint using surgical templates. Otherwise an amputation would not have been avertible.

Head over heals

Similar success was had by surgeons at the Prince of Wales Hospital in Sydney. Their patient also suffered from a bone tumour. Both the upper cervical vertebrae were affected, and instability was their fear. On the basis of imaging neurosurgeon Ralph Mobbs designed an implant and had it produced via 3D printing process. He removed the affected bone material in a twelve-hour OP and set up a perfect fit for his work: it was the world’s first application of innovative printing techniques used in the replacement of the cervical vertebrae. In other hospitals, sacral bones and parts of the pelvis have been able to be successfully replaced.

The implant lives

Now scientists are bounding on to the next stage. They are trying by way of 3D techniques to manufacture implants which grow into existing structures.

Warren L. Grayson from Baltimore experimented with polycaprolactones. He mixed these biodegradable polymers with a cell-free powder sourced from bovine bones. Grayson was able to show in animal experiments that stem cells are drawn in. After twelve weeks the sought-after bone growth occurred in mice.

A different approach was taken by EpiBone from New York. The start-up company took CT scans of the damaged bone as the basis for 3D models. Computers then control a 3D CNC milling machine so as to cut out tailored models from cow bones. The implant heads off together with stem cells into a bioreactor. Implants ultimately emerge, which form a unit together with the existing substance.

And the Centre of Excellence for Electro Materials Science, at Australia’s University of Wollongong, has brought us Biopen. Using Biopen, cartilage can be built up layer by layer. The gel, together with its stem cells, hardens immediately when exposed to UV light. Then the next layer follows. This manual 3D reconstruction helps doctors repair lesions in the bone with pinpoint precision. All laboratories are in agreement that their technologies will revolutionise orthopaedics.

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