3D printing puts bold new face on science

3D PRINTING, or additive manufacturing, is considered among the most disruptive technologies of our time.

It offers immense possibilities for future development and is deemed to be at the forefront of the Fourth Industrial Revolution (4IR).

3D printing will effectively change the way we manufacture almost everything, whether it consists of metal, polymer, concrete or even human tissue.

The medical sector is one of the early adopters of 3D printing and has over the years become one of the most vibrant areas for additive manufacturing.

The rapid adoption rate can mainly be ascribed to the customisation and personalisation capabilities of 3D printing, as well as the continuous improvement of processes and materials to meet the high medical grade standards.

Surgical uses of 3D printing started in the mid-1990s with anatomical modelling for bony reconstructive surgery. From this developed the personalised or patient-matched 3D-printed orthopaedic metal implants.

What makes these implants unique is that they are printed with porous surface structures to facilitate osseointegration (the connection between living bone and the artificial implant).

In March 2014, surgeons in Swansea used 3D- printed parts to rebuild the face of a motorcyclist who had been seriously injured in a road accident. Today, 3D printing technology is used to routinely manufacture stock items, such as hip and knee implants, personalised for specific patients.

Earlier this year, in a world first, South African surgeons used 3D printing to restore the hearing of a 35-yearold man whose ear was severely damaged in a car crash.

The surgeons reconstructed the broken bones of his middle ear by using 3D printed bones. According to Professor Mashudu Tshifularo, the head of the department of otorhinolaryngology at the University of Pretoria, they only 3D printed the ossicles that were not functioning properly from titanium and replaced themendoscopically.

He believes that this breakthrough could provide a long-term solution in curing patients and even babies of hearing loss caused by damage, disease or infections to the inner ear. Hearing is restored immediately after the lessthan-two-hour operation.

The surgeons initiated the process by comprehensively scanning both the functioning and damaged ears of the patient before developing a personalised 3D model with the help of Computer Aided Drawing (CAD) software, whereafter some of the smallest bones in the human body were accurately printed on a 3D printer.

In China’s Shanghai Changzheng hospital, surgeons used a 3D printer to create titanium alloy bone implants for a cancer patient. The patient was suffering from a rare and particularly difficult-to-treat type of bone tumour that affected six separate bones in her spine.

The six bones had to be removed to prevent the cancer from returning. The 13-hour operation was extremely challenging and risky, since it could leave the patient paralysed or dead if anything went wrong.

Over a period of three weeks, every element of the personalised bone implants were crafted with the highest degree of precision through the use of a 3D model of the affected vertebrae. The model was eventually printed using a sophisticated metal 3D printer, to ensure the implants’ dimensions were captured with perfect accuracy.

The implants were designed with a microporous structure so that they would integrate with the patient’s natural bone material. The operation was a huge success and the patient recovered fully.

3D printing is also used in the step-by-step virtual planning of surgery and for 3D printed personalised instruments in many areas of surgery, including total joint replacement and craniomaxillofacial (mouth, jaws, face and skull) reconstruction.

One example of this is the bioresorbable (naturally dissolving) trachial splint developed at the University of Michigan to treat newborns with tracheobronchomalacia (flaccidity of the tracheal support cartilage leading to tracheal collapse).

In April this year a team of Israeli researchers from Tel Aviv University revealed the world’s first 3D printed heart from biological material and the patient’s own cells. What makes this small heart unique is that it was complete with cells, blood vessels, atria and ventricles.

Cardiovascular disease is still the leading cause of death in South Africa after HIV/Aids. Every hour in South Africa five people have heart attacks. Heart transplantation is often the only treatment available to patients with end-stage heart failure. But the waiting list for heart transplants is long and many patients die while waiting.

The personalised Israeli 3D printed heart is made from human cells and patient-specific biological materials and may revolutionise organ replacement in the future.

Bioengineers at Rice University published, in Science of May 3, a new technique which uses stereolithographical bioprinting to create entangled vascular networks that correspond with the human body’s natural passageways for vital fluids such as blood and air.

The researchers developed a hydrogel “lung” air-sac in which airways deliver oxygen to blood vessels. The team also managed to implant bioprinted constructs containing liver cells into mice with chronic liver injury.

3D bioprinting and regenerative medicine (the restoring of damaged tissues and organs) should be watched closely since they could be the real game-changer for the medical world.

It may seem like science fiction, but bioprinting may provide a fast and sustainable way of producing complex human tissues and organs for transplanting in a world where the waiting times for organs are long.

Professor Louis Fourie is the deputy vice-chancellor: knowledge & information technology at Cape Peninsula University of Technology.