Sandia's bone of invention may ease pain

By Sue Vorenberg
Tribune Reporter

Bone graft surgery is a nasty, painful business.

To replace an injured bone section from a traumatic head injury or spinal fracture, doctors have to cut a graft out of the patient's pelvis, carve it into a specific shape and place it into the damaged area. The surgery causes lingering pain and forces the patient to recover from two injuries rather than just one.

Scientists at Sandia National Laboratories in Albuquerque think they've found a better way.

They've made a robotic machine that can build a bonelike substitute graft, almost as strong as bone, that lets the patient's natural bone grow through it - like flowers through a garden trellis - to replace the damaged area without need of carving up another part of the patient's bone structure.

Surgeons in Illinois were able to test the substitute graft earlier this month, but they couldn't leave it in the patient's body because they don't yet have Food and Drug Administration approval to test it on humans.

"I was able to watch the surgery when we tested an implant," said Joe Cesarano, a Sandia Labs scientist. "It worked great, but then the doctors had to go back and do the standard procedure.

"I think what got to me more than watching the surgery was the noise - the power tools grinding and the clunk, clunk as they chiseled the bone from the patient's hip."

The purpose of the test was to see if the Sandia Labs machining process would work when doctors provided the specifications of what they needed. The implant was built without the Sandia Labs scientists having ever seen the patient.

"When this project started I'd never met the doctor or the patient," Cesarano said. "I'd only talked to a professor at the University of Illinois. In hindsight it's amazing how many people came together on this and how well it worked. We were able to build a part that fit perfectly into this patient's jaw. The doctors actually used it as a template to carve the bone part they put in afterwards."

Ultimately, Cesarano says, he envisions a central company with robotics machinery that can build bone grafts and ship them to doctors all over the country. The grafts could be used to repair bone damage from traumatic head injuries, dental deterioration and spinal injuries, he said.

Russ Jamison, a doctor and biochemist at the University of Illinois in Urbana, has been trying for the past few years to develop an alternative to natural bone out of a material called hydroxy apatite - essentially the chemical that bone is made out of.

Jamison met Cesarano through students who were working at the university and interning at Sandia Labs in the summers. They told him Cesarano's technology - which makes very specific-sized lattices out of a variety of materials - could be the perfect way to shape hydroxy apatite into usable bone replacements.

"What you need is a material that is strong enough to bear a load, like bone, but porous enough to let natural bone cells and body fluids move around in it," Jamison said. "Joe was able to create a perfect lattice out of that material using Sandia's technology, called robocasting."

Sandia Labs' robocasting technology uses a machine to lay out layers of paste in a specific array that, when baked, form solid but porous materials with a variety of properties. To make an implant, the machine creates a tiny Lincoln Log-like lattice block that is then carved down by another machine into a specific bone graft shape.

Robocasting's main purpose at Sandia Labs is to create replacement weapon parts almost instantly on the battlefield so that repair crews don't have to carry around a wide variety of gun or tank parts.

When Jamison asked Cesarano if it could also be used to make parts for the human body, the result was the implant.

"When we tried the implant out it saved more than an hour of time in surgery," Jamison said. "Usually the surgery takes two teams of surgeons, one to cut the bone from the hip and another to work on the area that needs to be repaired. They have to carve the bone to a specific shape in the operating room.

"With this, we were able to save the surgeons' time, which will cut down on surgery costs, and if we had been able to implant it we would also have saved the patient a lot of pain."

The body can only naturally heal bone defects up to a certain size - about that of a pencil eraser. Any bigger, and a damaged bone won't grow back into the gap. In traumatic injuries, such as those that might leave a hole in a patient's head, natural bone must be grafted from another part of the body in order to repair the damage, because it is the only thing that can effectively bridge the gap, Jamison said.

"You can't make a bone graft out of a solid material," Jamison said. "It turns out if you do that the body will treat it like an intrusion, put scar tissue around it and wall it off. That's no good. What you need is a porous material that is big enough for bone cells and body fluids to move around in."

The Albuquerque lab has applied for a patent to use the robocasting technology for medical purposes, and University of Illinois scientists have started testing manufactured bone grafts in animals, but it will likely be five to seven years before the FDA approves it for testing in humans, Jamison said.

"The FDA requires a lot of data before they let anybody do that," he said. "They require all our lab results; they require animal results before they even let any testing begin in a very small number of patients."

Jamison and Cesarano said they'd both like to work with a private company to help transfer the technology out to the mainstream.

In the meantime, the two will continue to develop and streamline the process, Cesarano said.

"I never thought I'd do a medical technology," Cesarano said. "This has been really exciting for me. It's fascinating work."