Here are seven points about using biologics and stem cells during spine surgery from Richard Hynes, MD, President of The B.A.C.K. Center in Melbourne, Florida.
How we got here
Dr. Hynes was one of the many spine surgeons who participated in Medtronic's original trials for BMP-2 in the 1990's. While scientists have known about the ability of stem cells and BMP to generate bone for several years, Medtronic was the first company to develop a safe and effective molecule to stimulate cell growth. After completing the pre-market approval trials, the Food and Drug Administration granted approval for the BMP-2 product, Infuse, in 2002 for creating fusion in the Lumbar Spine placed through an anterior approach in a LT cage.
"In the original study, I experienced 100 percent of enrolled patients in my Practice achieving bone growth when combining BMP with the local cells that were already there," says Dr. Hynes. "Local 'stem cells' respond to BMP and become activated thereby creating bone. When I saw it worked in 100 percent of my enrolled patients, I was a true believer. I have used it in my practice since the study and FDA approval going back greater than 10 years."
What has changed is our ability to concentrate stem cells; Dr. Hynes harvests the stem cells from the iliac crest to combine with the BMP. It takes less than five minutes for his physician's assistant to harvest the cells, which are spun in a centrifuge while he begins the operation. After 10-15 minutes, the cells are ready and Dr. Hynes adds a small amount to the surgical field along with the BMP. The collagen sponge is placed within an interbody LT cage to keep the material from migrating.
"This has been an effective Bone Graft method and it has been an advantage for my patients who can avoid Iliac Bone Graft surgery and Donor Bone issues and cost," says Dr. Hynes. "It doesn't add to my usual procedure time. It does add a small cost, but I find it's worth the value proposition."
Since its inception and release, surgeons have been experimenting with its use in several different capacities, on- and off-label. However, articles published in The Spine Journal in July 2011 suggest complication rates may be higher than the original studies reported. Several physicians have reported positive and negative events based on individual practice date, and further research into its use will be necessary going forward. As with all products, on label and off label use is routine practice and common place. When used correctly, minimal side effects of swelling, seroma and osteolysis occur.
What the research says
There have been several clinical studies and basic science research projects published in professional journals discussing the efficacy of using BMP with local stem cells to enhance fusion. However, research on the impact of increasing the number of stem cells is still lacking. Dr. Hynes' current clinical work focuses on whether there is a better chance of achieving fusion with a higher concentration of stem cells.
He harvests stem cells from the iliac crest, percutaneously and painlessly, or vertebral body and extract about 60-80 ccs of blood. The desired stem cells are concentrated to a few ccs with centrifugation and has about a 50,000 cell count per "Spine Smith research data."
"We already know the mechanism by which BMP-2 activates stem cells. The stem cells are already very effective," says Dr. Hynes. "If we add to the population of stem cells that are already there that are available to regenerate new bone, it could make the procedure even better. Anecdotally, I have a high fusion rate for my spine patient population even before adding the extra concentration of stem cells. With the additional stem cells, I hope to achieve fusion at almost any level no matter how many levels are needed such as in degenerative scoliosis. In osteoporosis and aging spine patients, this has been extremely beneficial when compared to poor iliac crest from bone harvest.
Dr. Hynes' ethereal practice goal is to someday be able to "guarantee" that they will achieve fusion for every patient who undergoes surgery. This means stabilization. However, fusion does not guarantee "success" of the surgery but increases odds of the surgical success. At this point, he is close, with approximately a 95 percent fusion rate. "What I want to do before I retire is to be able to guarantee a fusion," he says. "I can't guarantee pain relief or other clinical outcomes, but I want to be able to confidently guarantee the fusion or stabilization component."
Options for harvesting stem cells
There are several bone graft options spine surgeons can choose from to achieve a fusion, and in the wake of recent controversies some surgeons are looking for an alternative to using BMP. Surgeons can go back to the traditional fusion method – the iliac crest – or using an allograft. Dr. Hynes says harvesting bone from the iliac crest can leave 30 percent of patients in more pain and add significant surgical time in the OR with increased blood loss. Allografts also have downsides, including graft consistency, quality, processing issues and less potential to achieve fusion than iliac crest or autogenous grafting methods.
"The bone for allografts may not be prepared correctly," says Dr. Hynes. "We don't always know the quality or consistency of the allograft compared to the patient's natural bone. If I'm putting a piece of bone in patients, it's better if it comes from their own bodies. That way, you can't tell the difference between the bone you grow and the natural bone. (What we are doing is creating a nice bone graft that balances the biomechanics of the fusion construct better than the allograft.)"
In some cases, the allograft bone could migrate or fracture or reabsorb after the procedure, which can cause significant pain and complications, often resulting in revision procedures. By using the combination of BMP and stem cells in an interbody device, Dr. Hynes is able to avoid most of those complications because the cells are attracted to the BMP, which is restrained in the cage.
Patients should have the final say – "Informed Consent"!
Like many surgeons, Dr. Hynes describes the different fusion options to his patients and allows them to choose which procedure they feel most comfortable with. He discusses the pros and cons of each technique, including the most recent concerns about BMP, as well as his personal outcomes. He says patients often choose BMP combined with stem cells because they like the idea of regenerating their own bone naturally, avoiding the extra surgery and potential pain of iliac crest bone grafts and decreased potential or effect of donor allograft bone.
"The psychology of healing is part of this," says Dr. Hynes. "Patients understand the procedure and like the idea of using their own cells as healing factors. People are very positive about that process because they feel like they are doing something natural instead of synthetic. Healing and surgery isn't just biomechanics and science; it's psychological as well. Successful outcomes of surgery depend on subjective relief as well as objective factors."
In his practice, Dr. Hynes says a significant number of his patients chose the BMP and stem cell combination with given the option. However, when the patients choose a different option, he performs the other procedures as well. "It's our duty to give patients their choice," he says. "I'm not always smart enough to know what the best choice is for any one individual, but I've practiced many years and learned that if you take time to educate patients to all the reasonable options, they will make good decisions and take responsibility for them."
Deciphering the complications
While Dr. Hynes hasn't experienced significant complications among his patients, it's clear that other surgeons have reported complications when they perform spinal fusions using BMPs. One reason for the discrepancy could be the dosage; well-documented evidence suggests that a higher dosage of BMP could cause swelling complications when used in the cervical spine. By using low doses of BMP and a pre and post-surgical protocol, swelling is completely avoidable in the cervical spine. Another factor is the surgical approach; Dr. Hynes says retrograde ejaculation ("RE") – one of the severe complications mentioned in the studies this past summer – is a complication risk of any anterior spine surgery and not related to use of BMP. "I have performed thousands of anterior procedures before and after approval of BMP for anterior lumbar surgery and I find no difference in RE noted in my patients."
"Every spine surgeon knows RE is a risk during anterior procedures and it usually will reverse on its own," says Dr. Hynes. "RE occurs in an extremely low frequency. RE occurs because of disruption 'surgically' of small nerves to a sphincterine the bladder. BMP does not cause this effect, but the use of the electrocautery tool, during surgery, likely does. Use a small dose of BMP and a cage as well."
In his practice, Dr. Hynes has never experienced a critical airway complication using cervical BMP. In early years, too high a dose would lead to swelling but not airway compromise which more commonly occurs with hematoma or blood clot, says Dr. Hynes. Papers published in The Spine Journal also mention cancer as an associated complication, which is something he hasn't necessarily noted either. "I haven't seen a rash of cancer in my patients, but I haven't been surveying for it either," he says.
He is currently going through his patient base to determine whether he can detect any cancer cases that could be associated with the procedure.
Whether to use BMPs
As surgeons report different findings based on their individual practice data, many of the studies and discrepancies have been reported in the media. However, full understanding of these complex issues is often lost in news reports. "I hate to see some of the surgeons and journals duking it out in the media," says Dr. Hynes. "That isn't the place to argue over the efficacy of stem cells and BMPs. We have to do it in the meetings where people understand the context. To lay this out in the newspapers exacerbates political agendas and confuses our patients. We need to speak honestly with each other about this at professional and scientific meetings, not in the press."
This controversy isn't the first time new spinal technology and procedures have been under attack. For a period of time, pedicle screws – which are a standard of care now – were under the microscope because complications were reported. In some instances, surgeons were sued and restricted from use at their hospitals for their alleged unfavorable outcomes. Now pedicle screws are the mainstay of spinal fusion procedures.
"At the time, there was only approval that pedicle screws could be used on single-level surgeries," says Dr. Hynes. "Now we use them at multi-levels. The pedicle screws ultimately won the day, but with public stimulation 'in the news' in the early 1990s, we almost lost the ability to use them. This was a public attack on the advent of a new fusion technology, and now we are seeing similar phenomenon's with BMP and other medical products."
Covering the cost of BMP
In some cases, surgeons may have a difficult time receiving reimbursement for BMP products because they were more expensive in the past. Dr. Hynes and his colleagues have worked with hospitals and surgery centers to cover the cost in both out-of-network and in-network contracts. In some cases, patients are willing to cover the cost of using stem cells with BMP. Due to the success and demand, the cost has now become competitive considering operative costs of iliac bone surgery or allograft. "The increased volume of use and effectiveness has caused a dramatic decrease in cost," says Dr. Hynes.
"I see patients from out of the Country and they are usually cash pay patients," says Dr. Hynes. "We have to line item every part of the procedure to show the actual cost and there is almost no increased cost for the use of low concentrated BMP compared to iliac bone grafts or allograft when taking OR time, surgeon's time and other OR costs into consideration."
Fortunately, the hospitals in Dr. Hynes' community allowed him to use BMP and conduct the clinical studies there. "We have more experience in our community with the benefits of this technology because we started so early," he says. "Our surgeries are very efficient and our operative time is less because of our long-term experience with the procedure using stem cells and BMP."
However, in some cases Dr. Hynes has made sacrifices to mitigate these costs. "I think about what I could live without and forego those expenses for stem cells and BMP," he says. "I might use less expensive blades or a new set of tools for the next year. I might continue to use my old led apron or do surgery without a super drape. I'm there to give patients a better outcome and I want to make sure they have the opportunity to have the stem cells."
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Stem Cells for Spine Surgery: 7 Points From Dr. Richard Hynes| May 23, 2012
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