Oral bone reconstruction – or orthognathic surgery – is a complicated medical procedure in which damaged or diseased bone tissue is replaced with an implant, usually a titanium plate or prosthesis.
The surgery involves treating a person’s jaw for significant trauma, such as from a car accident or gunshot wound, or diseases such as oral cancer, with recovery up to 12 weeks. Complications such as implant failure and infections are common, potentially requiring repeated procedures, which can be a significant burden on a patient.
In recent years, biomedical engineers have developed a new generation of medical implants designed not only to replace bone, but also to help restore tissue to its original state using 3D-printed tissue scaffold fixation systems.
These devices enhance the innate healing potential of human tissue, using scaffolding as a temporary support structure for surrounding cells to adhere and grow. Eventually, the scaffold is expected to dissolve in the bloodstream, keeping new tissue in 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 jawbone reconstruction procedures using this new generation of devices.
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 final, optimal design, allowing surgeons to perform a digital ‘rehearsal’ before the theater.
“Today, it would be unthinkable to build a building without running a technical simulation on it beforehand. This is the industry standard in civil engineering — the same expectation should be applied to surgery on a human,” said Ferguson, who will submit his doctorate in September.
“The jaw is a complex area – required to talk, eat, chew and perform tasks that require both finesse and strength. Because of its complexity, we want to give orthognathic surgeons the best tools so they are ready for success – hopefully the number of reduce repetitive surgeries and improve patient outcomes,” he said.
“A bone implant design may work in one patient, but fail in another. If it were you, you’d probably want a team of surgeons and biomedical engineers to simulate and assess the medical device in your body before actually implanting it.”
Optimize device design
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 while under physiological load.
Ferguson’s supervisor, Professor Qing Li, said: “In addition to pre-operative planning, this simulation data can also help the surgeon optimize the design of the medical device, helping them solve problems that inevitably arise when designing a device that must meet multiple design and medical purposes.”
“It’s a careful balancing act,” Ferguson said. “For example, an implant may need to mechanically stimulate the surrounding tissue to promote healing, but mechanical stimulation may then increase the risk of implant failure. Our algorithms and data-driven approach help surgeons develop optimal design without relying solely on intuition.”
Turning technology into clinical reality
The researchers recently collaborated with Professor Jonathan Clark, Chair of Head and Neck Cancer Reconstructive 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 in 1974. Since then, jaw reconstruction has evolved significantly, incorporating digital tools into preoperative planning, enabling surgeons to create more precise devices with better aesthetic and functional outcomes for patients.
“What’s really exciting about this tool and data is that they provide the opportunity to advance the technology beyond shape, to also include biomechanical modeling, which can help predict the response of the bone tissue to physiological loads. This kind of thing.” analysis – called CT-based finite element modeling – will be of great importance as we move away from using the patient’s own bone for reconstruction and start incorporating custom scaffolds in the future.”
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