Planning tool allows surgeons to perform digital rehearsals

Jaw reconstruction – or orthognathic surgery – is a complicated medical procedure that involves replacing damaged or diseased bone tissue with an implant, usually a titanium plate or prosthesis.

The surgery involves treating a person’s jawbone for significant trauma, such as a car accident or gunshot wound, or diseases such as oral cancer, with a recovery time of as long as 12 weeks. Complications such as implant failure and infections are common, potentially requiring repeat procedures which can place a significant burden on the patient.

In recent years, biomedical engineers have developed a new generation of medical implants designed not only to replace bone, but to help regenerate tissue to its original state using scaffold fixation systems of 3D printed fabrics.

These devices enhance the innate healing potential of human tissue, using a scaffold as a temporary support structure for surrounding cells to attach and grow. Eventually, the scaffold should dissolve into the bloodstream, leaving new tissue in its place.

A digital twin

Ben Ferguson, a PhD student at the University of Sydney’s School of Aerospace, Mechanical and Mechatronic Engineering, is developing a surgical planning tool to help surgeons plan complex jaw reconstruction procedures using these devices new generation.

Using advanced computer technology and decision-making algorithms, the tool works by generating a “digital twin” of the patient using CT scan data. It then quickly simulates different designs of the implant before 3D printing the optimal final design, allowing surgeons to perform a digital “rehearsal” before the theater.

“These days, it would be unthinkable to construct a building without first carrying out an engineering simulation. This is the industry standard in civil engineering – the same expectation should be applied to surgery on a human,” said Ferguson, who is due to submit his doctorate in September.

“The jaw is a complex area – necessary for speaking, eating, chewing and performing tasks that require both finesse and strength. Because of its complexity, we want to give orthognathic surgeons the best tools to they are poised for success – hoping to reduce repeat surgeries and improve patient outcomes,” he said.

“A bone implant design may work in one patient, but fail in another. If this were you, you would probably want a team of surgeons and biomedical engineers to perform a simulation and evaluation of the medical device in your body before it was actually implanted.

Device design optimization

The surgical planning tool combines computer-aided design (CAD) tools with high-fidelity computer-aided engineering models and optimization algorithms that can accurately simulate the medical device under physiological load.

Ferguson’s supervisor, Professor Qing Li, said: “In addition to pre-surgical planning, this simulation data can also help the surgeon to optimize the design of the medical device, helping them solve problems that arise. inevitably when designing a device that must meet multiple medical designs and purposes.

“It’s a careful balancing act,” Ferguson said. “For example, an implant may need to mechanically stimulate surrounding tissue to improve healing, but mechanical stimulation may then increase the risk of implant failure. Our algorithms and data-driven approach help surgeons develop an optimal design without having to rely on intuition alone.

Professor Qing Li and Ben Ferguson.

Turning technology into clinical reality

The researchers recently teamed up with Professor Jonathan Clark, Chairman of Reconstructive Head and Neck Cancer Surgery at Chris O’Brien Lifehouse, to help translate the new technology into clinical reality.

Clark said: “Australia has been a leader in jaw reconstruction since Dr Ian Taylor’s groundbreaking mandibular reconstruction in 1974. Since then, jaw reconstruction has evolved significantly: digital tools have been integrated into preoperative planning, allowing surgeons to create more precise devices with better aesthetic and functional outcomes for patients.

“What’s really exciting about this tool and this data is that it offers the ability to scale technology beyond form, to also include biomechanical modeling, which can help predict tissue response. bone to physiological loads. This type of analysis – called CT-based finite element modeling – will be of great importance as we move away from using the patient’s bone for reconstruction and begin to incorporate custom scaffolds into the future.

Images courtesy of University of Sydney.