Interesting 3D printing solution for grafting a long bone segmental defect
Break a Bone Badly? You Could Be a Candidate for This Innovative 3-D Printed Medical Device (J&J DePuy – Scott Larsen)
Watch the Video explanation on the OTA site here
The Trumatch® Graft Cage – Long Bone is a cutting-edge device that could revolutionize trauma care—and help improve outcomes for patients who have the kind of catastrophic bone injuries that can happen in car accidents.
A long, painful recovery. Amputation. Those are words no patient ever wants to hear. But for people who’ve experienced an extremely serious bone injury—say, a fall from a great height, a bone tumor or a vehicular accident—these can be very real scenarios.
But a groundbreaking innovation from DePuy Synthes, part of the Johnson & Johnson Medical Devices Companies, is poised to help people suffering from such traumatic injuries.
It’s called the Trumatch® Graft Cage – Long Bone—a first-to-market implant that’s able to be absorbed into the body and 3-D printed in just 10 days, making it highly customizable to a patient’s anatomy. It works by supporting bone grafts, which act as fillers or scaffolds to aid new bone growth.
A lot of other implants for such injuries are shaped like a container, forming walls around the area where there’s bone loss,” explains the device’s inventor Scott Larsen, Principal R&D Engineer, DePuy Synthes Trauma. “But our cage looks more like one of those dome jungle gyms you played in as a kid—there are lots of bars that act as shelves, which real bone can grow onto, and eventually encase the entire implant.”
The result: a more precise fit inside the body, and a supporting structure that reducesthe chances that a patient might need follow-up surgeries. And because it’s 3-D printed, the device can be made more quickly for a patient in need—for example, the digital design of the graft cagecan be produced in a few hours.
To see exactly how this cutting-edge technology could help change lives, we’re taking you on a virtual journey of the process—from day 1 through to the day a patient is sent home to begin recovery.
The Patient Arrives at the E.R.
The patient has a large open wound, and has lost a large section of bone. The trauma surgeon’s first step is to debride the wound, which means cleaning it out, removing not just germs but also dead bone.
“The patient is now left with an open space between the two ends of the bone, which is sometimes temporarily filled with polymethyl methacrylate (PMMA), an artificial substance usedto prepare the bone void for grafting,” explains Glen Pierson, R&D Director, DePuy Synthes Trauma.
The wound is then sewn back up by the surgeon, and the patient goes home for a few weeks to recover.
A CT Scan Informs the Digital Design
A CT scan of the patient’s injured limb is sent to DePuy Synthes.
“We’ve created custom software that auto-generates the graft cage from information from the CT scan,” explains Pierson. “We’re able to tell exactly what the patient’s bone void looks like, which allows us to design a cage that’s specifically fit for the individual patient withina few hours.”
When the designer is finished, they email a 3-D picture to the surgeon, who reviews it and sends any feedback to the designer via email or video conference.
“There are about three or four things we’re able to tweak,” Pierson says. “For example, the opening slot in the graft cage can be moved to a different position to accommodate the surgeon’s incision.”
Once the design is complete, the surgeon gives their electronic seal of approval and the 3-D file is sent to the printer.
Week 3 – Week 4
The 3-D Printer Goes to Work
“The graft cage printer, also called a Selective Laser Sintering machine, is roughly the size of a large refrigerator—and actually looks like one,” explains Pierson.
It has a hopper on top, where a blend of polymer, polycaprolactone (PCL) and hydroxyapatite used to make the graft cage is fed in. PCL is designed to resorb over a relatively long period of time, and it’s biocompatible, meaning it can be placed inside the body.
Depending on the size of the implant, several can be made at the same time. The manufacturing process takes about 10 days, and once the graft cage is printed, the coating process commences.
“It’s kind of like growing sugar crystals—we essentially drop the cage into a solution of water, with the components for forming calcium phosphate dissolved in it, which then grows into a bone-like coating,” explains Kris Kita, Ph.D., Principal Scientist, DePuy Synthes Trauma.
The coating is so fine that you can’t see it with the naked eye, but it has a crucial function.
“In order for bone to remodelin the area, new cells need to grow, and calcium phosphate is very conductive to this growth,” Pierson explains.
The TruMatch Graft Cage – Long Bone (a digital rendering is shown at right), now fully complete, is inspected at the facility to make sure it’s in tip-top shape before being sterilized, packaged and shipped to the patient’s hospital.
Meanwhile, as the patient has been waiting for the cage to arrive, “soft tissues have been growing around the PMMA implant, creating a membrane that will ultimately be wrapped around the graft cage and provide the biological components needed for bone reconstruction,” Pierson explains.
The Patient Has Surgery to Implant the TruMatch Graft Cage – Long Bone
The surgery, which is usually done under anesthesia, takes about a few hours. The length of hospital stay depends on the patient’s health.
They’ll then be scheduled for a follow up visit with their surgeon four to six weeks later to make sure the bone is remodeling well around the graft cage.
“In all of our work and research, it really hit home that, if other procedures like this aren’t an option, then amputation could be these patients’ reality because they have lost too much bone to be a candidate for other surgical options,” Larsen says. “We’re trying to help save them from that outcome.”
Indeed, “complex cases such as these are the ones that keep surgeons up at night,” says I.V. Hall, Worldwide President of Trauma, Extremities, Craniomaxillofacial and Animal Health for DePuy Synthes. “We’re excited to combine our expertise in trauma with the 3-D printing technology to bring this solution to patients who require this kind of care.”