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Hometown U: Computers and 3-D modeling help reconstruct a face

Kathleen McCoy
This post-operative CT scan shows the repair implants surgeons used to reconstruct the face of a Southcentral man after an accident shattered the bones in his face. (Photo provided by James Kallman)
The shattered face of a Southcentral man injured in April when a nylon strap snapped under pressure, slamming a metal fixture into the middle of his face. The blow shattered his jaw, forehead, cheekbones and eye sockets, and pushed his nose back into his face. The internal bone that makes a floor for the brain was shattered, and his brain had herniated down into his nose. This was the repair job surgeon James Kallman faced. (Photo provided by James Kallman)

Repairing a severely damaged human face is never easy, but an Anchorage surgeon and a mechanical engineering professor from UAA shaved hours off the challenge with computer software and 3-D modeling.

The surgeon, James Kallman, was recently highlighted in a new book, "Beyond the Bear," for repairs to fisherman Dan Bigley after a brown bear knocked him down at the Russian River and severely chewed his face and forehead. That surgery a decade ago took Kallman and his colleagues 14 hours.

The repair to a Southcentral man's face this spring -- shattered after a nylon strap snapped, slamming a metal fixture into his mid-face -- was accomplished in about eight hours, Kallman said. Evolving technology made the difference, and the use of a 3-D printer in UAA's Rapid Prototype Lab under the direction of professor Jeff Hoffman was part of the solution.

Kallman was on call for Providence Alaska Medical Center's Emergency Room one week in late April. The patient, Terrence Hinz, had taken a blow so severe that it shattered his jaw, forehead, cheekbones and eye sockets. It pushed his nose back into his face. The internal bone that makes a floor for the brain was shattered, and his brain had herniated down into his nose.

After stabilizing Hinz and closing his surface wounds, the surgeon had to allow about a week for swelling to go down before he could begin repairs. While he waited, Kallman began brainstorming better ways to deal with the puzzle he would soon have to put back together. If he could only figure out a way to turn the patient's two-dimensional CT scan into a physical 3-D model, he could use it as a template for designing implants well ahead of surgery, saving valuable time in the operating room.

"I blindly called UAA," he remembered. "I said, 'I've got this guy's face to repair and it's essentially shattered. It would really, really be helpful if I could get a 3-D model.' "

On the other end, Jeff Hoffman took the call. He was right in the middle of finalizing spring semester, with stacks of homework assignments students needed back.

"I'll try," Hoffman told Kallman. He dropped everything and began figuring out how he could turn a CT scan into a format that could be rendered on a 3-D printer.

The first thing Hoffman had to do was find a way to isolate bone, including fragments, from all the other tissue. Amazingly, he found open source software, called Slicer, to do it. He took the refined file created by Slicer and sent it through UAA's 3-D printer. The large model took 26 hours to print, creating the polymer version of the skull that documented Hinz's crushed face.

Hoffman had a volunteer student, Sean Jensen, monitoring the printer's progress as it lay down layer after layer of cream-colored polymer. "When I got back," Hoffman said, "there were half a dozen students waiting for me with questions like, 'You're printing a skull?' "

Hoffman provided the model to Kallman Saturday morning, giving him time to design facial reconstruction plates before surgery Monday morning.

Working on a parallel path, Kallman had contacted local representatives from the biomedical company Stryker to assist with selecting proper implants.

"He'd completely lost the framework of the face that we typically use for repairs," the surgeon explained. Kallman had to rebuild it. He needed to re-secure Hinz's forehead and brain support, bring the nose forward and restore vertical supports in the middle of the face between the forehead and the jaw.

Stryker representatives put Kallman in touch with a company called Medical Modeling out of Colorado to create the "hoped for" finished face, a second 3-D model. With both models in hand that Saturday, Kallman was able to try out different materials, pre-forming the implants he would use in the operating room.

When Kallman began surgery Monday morning, he took both models into the operating room for reference. He was joined by his practice partner of many years, Dr. Dwight Ellerbee.

Later, Ellerbee said the software and 3-D models had allowed Kallman to get most of the trial-and-error work done ahead of time, without the pressure of a patient lying on the table exposed to potential infection.

"He did all the thinking outside the operating room," Ellerbee said. "All we had to do was execute the plan."

With Alaska 3,500 miles away from the next closest medical center, and Alaskans exposed to potentially serious injuries from logging, mining and fishing jobs, not to mention their propensity to live and play hard, both Kallman and Hoffman are excited by the prospects of their collaboration. Use of software and 3-D modeling to help in reconstructive surgery could be invaluable.

Hinz, 22, is home mending well, has sight in both eyes, and is cognitively at 100 percent. Kallman and Hoffman plan to document their process and share the results with the biomedical community.

 

Kathleen McCoy is an electronic media specialist at UAA, where she highlights campus life through social and online media.

 

 


Kathleen McCoy
Hometown U