Going Solo: Developing a Medical Device Without Institutional Backing

Some people take up fishing or golfing in retirement. Donald Corenman is developing a biological disc replacement.

Peer Reviewed

When most people retire, they relax. They kick back for a few, maybe travel a little. Donald Corenman, MD, DC, did…for the first month, anyway.

These days, though, the Colorado spinal surgeon and SpineUniverse Editorial Board member is back at work, though in a different way. He’s developing a new means of artificial disc replacement (ADR) that, if successful, could lead to an easier recovery and improved outcome for patients with degenerative disc disease.

Disc that needs to be replacementCan a pubic symphysis graft replace an intervertebral disc?

First, however, there’s an essential process for research and testing, as well as submitting innovations to the appropriate regulatory organizations. Taking these critical steps is often challenging, drawn-out and exorbitantly expensive. And Dr. Corenman is right smack in the middle of it.

An Invention Origin Story

The seeds of Dr. Corenman’s idea were planted over a decade ago. A renowned spine specialist, he was more than familiar with lumbar ADR. And he knew it had its place as an alternative to spinal fusion, helping to relieve pain and maintain motion. Still, he found the metal and plastic devices used in the procedure to be problematic.

“They are implanted anteriorly which makes revision surgery somewhat dangerous. They are also not designed to absorb shock,” he ticks off. “And they fail—not uncommonly—when the endplate fractures or erodes. The disc can be implanted in too large a size or off-center, which I’ve seen,” he says. Revising a failed ADR can be dangerous and even life-threatening. He wondered if there was an alternative.

Then, when in the University, some patients came to him with spontaneous spine infections. “I put them on antibiotics and cured their infections., Their discs melted away into a fibrous union,” he says. Remarkably, many patients with these fibrous unions retained some motion and didn’t seem to have pain. “And I said, ‘I wonder if there’s some way I can recreate that situation.’”

Enter the Transplant

Instead of using a manufactured device, Dr. Corenman’s idea was to replace a damaged spinal disc with a bone graft. He chose the pubic symphysis, a durable, cartilaginous joint located towards the bottom of the pelvis.

“I thought, since you have a joint with two bony surfaces, you could take it out of a cadaver specimen and transplant it into the spine,” he says. “It’s the right size in depth and in height, it could be transplanted anteriorly, laterally or even posteriorly.

The implant is intended for lumbar discs—particularly L5-S1—and its potential perks are both numerous and intriguing.

“One is that it heals in biologically, so it’s not like the artificial disc where you have ingrowth of metal into bone,” he says. There is no mismatch of material stresses. “Number two, it absorbs shock. And number three, it can be revised from the back of the spine to perform a TLIF-like fusion without putting the patient in peril of having a catastrophic problem.”

By avoiding an anterior approach, he explains, you sidestep potentially devastating injuries to delicate veins. “That’s an oh-my-god moment in surgery. That’s a surgical moment you never want to have,” he says.

Dr. Corenman began considering the pubic symphysis implant seriously around 2015 and applied for a patent about three years later, by his own estimation. “I put in the patent and it turns out nobody else had thought of this,” he says. He was approved.

What Comes Next

Now, with patent in hand, Dr. Corenman is looking towards next steps. Currently, he’s gathering statistics and information about spinal discs, so he can eventually compare the performance of his implant. “There should be data for normal loads for the lumbar spine, normal amounts of rotation, compression—and I’m just starting to do the research to find that data,” he says.

After that comes bench testing, during which he’ll evaluate how much stress, torsion and compression the implant can tolerate. Since the stress normally placed on a pubis symphysis is different than that typically placed on a spinal disc, he says, “I have to find out how many cycles it can go through before it falls apart.”

He also plans on testing whether the implant can be inserted from the side or the back, rather than the front—"if they both work, if one works better, or if it doesn’t work at all.”

Going It Alone

To help research and try out his invention, Dr. Corenman is seeking support—namely, institutional backing. Developing an implant without it can have significant drawbacks. Among them, he lists “the amount of energy it takes to talk to people, educate them, to have them understand what the device is, why it works the way it works, what its advantages and potential disadvantages are, and whether it’s worth investing money for a percentage of the potential profit.”

The profit question is key. “How does a company make money selling a biological transplant? Because obviously that’s the bottom line, for business investment,” he says.

Advice for Inventors

The implant isn’t Dr. Corenman’s only patent. He also has an O-arm and back table surgical drape that is currently licensed with a company. With these experiences under his belt, he has suggestions for innovators, largely about taking steps to protect their ideas.

“The first thing you need when you talk to companies is a non-disclosure agreement (NDA),” he says. A legally binding contract, the NDA prevents others from sharing any confidential information—vital in the fast-moving world of medicine.

Second, if you decide to go for a patent, understand that it can be a pricey, prolonged process. Dr. Corenman estimates his pubic symphysis patent cost in the neighborhood of $150,000 and took two-and-a-half years to procure. And that was before the COVID-19 pandemic; there may be additional delays now.

Looking Ahead

Ultimately, Dr. Corenman hopes to make serious headway with his implant development soon. His timeline? Twelve months. “A year is what I look for, for progress,” he says. Needless to say, it’s an ambitious retirement.

Updated on: 07/07/21
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Cervical Artificial Disc Replacement Outcomes at 5 to 10 Years
Donald S. Corenman, MD, DC

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