Old Spines, Need New Ideas: Spine Hardware Update

“Don’t be afraid to give up the good to go for the great.” – John D. Rockefeller

Before you’ve blown out the candles on your 50th birthday cake, your bones have probably started to lose density. That fun fact comes courtesy of the Bone Health and Osteoporosis Foundation. And, you have company—44 million Americans have low bone density—and another 10 million carry an osteoporosis diagnosis.

More than 50 million Americans, many of whom also have back pain, are at increased risk of fracture.^[i]

When these folks, most of whom are active well into their later years, do have severe back pain, and the best recommendation their doctor can offer is spine surgery, then the problem of relying on osteopenic or osteoporotic bone to secure metal rods and screws rears its ugly head.

Lumbar spine fusion is a well-established standard of care for treating degenerative spondylolisthesis, stenosis and other spine pathologies. While spine fusion success rates are high, between 65-95%, they are not without potential complications.^[ii]

In strong, non-osteoporotic bone, pedicle screw loosening rates are about 1-15%. In osteoporotic bone those rates soar to more than 60%. Old spines need new ideas.^{[iii] [iv]}

What would spine fusion look like, particularly in patients with low bone density if implant fixation and the resulting spinal stabilization was non-metal?

For starters, probably easier post-op visualization. But, more to the point of this article, as recent studies have demonstrated, less risk of implant loosening in patients with compromised bone quality.

Spine surgeons want to do the right thing, which can also mean doing the familiar thing. But, when the patient is older or diabetic or under a course of care that affects bone quality, then is a big spine fusion surgery where a mass of metal is deployed to treat spinal stenosis, degenerative spondylolisthesis and perhaps instability, still “the right thing?”

“Probably not,” says Pierce D. Nunley, M.D., founder and director of the Spine Institute of Louisiana. “When it comes time to discuss surgery with my over-65 patients who have spondylolisthesis, low bone mass, and stenosis, I show them a model with the two options: on one side a bulky pedicle screw model, and the other side a metal-free, small zip tie-looking strap made of PEEK.”

“Once they see that, no one wants the metal.”

Fixation and Stability for Older Spines – It’s Karma!

“We have no shortage of patients contending with complications associated with the aging spine,” states Dr. Nunley. “These cases can be particularly complex, so we need evolved solutions such as Karma. This device gives surgeons a sense of confidence that they have a spinal device that addresses the challenges in treating the aging spine patient.

The “this is what you’ve been waiting for” procedural solution—known as the Karma Posterior Fixation System—was designed by the engineers at Spinal Elements to perform in either an open or MIS [minimally invasive surgery] approach.

It’s a low-profile device that successfully stabilizes the spine during the fusion and throughout the healing process. It’s Karma!!

Fusion plus hardware works like a charm—until it doesn’t. The key, we know, is patient selection. Not all patients need metal. Fact is, estimates of lumbar fusion failure rates remain stubbornly in the 30% to 46% range.[v]  Should it really be called “the gold standard?”

Old Spines Need New Ideas

In 2020, according to the World Health Organization, 619 million people had low back pain, globally.

By 2050, because of aging and population growth, that number could very well rise to as much as 843 million cases.[vi]

Face it, old spines are a growth industry. Every spine surgeon needs (and patients deserve) rigorously tested and viable options for any patient who presents with life altering back pain yet contends with low bone density.

Anchoring for Stability – It’s Good Karma!

Karma is the first-ever spine fixation device to take advantage of the cortico-pedicular corridor—the densest portion of the spine.

“You get exceptional purchase with Karma because you are drilling through four areas of cortical bone—the part of the spine with the most closely compacted bone,” says Dr. Nunley. “The density of cortical bone is far less effected by age-related degeneration, so surgeons can obtain excellent fixation via good quality, stable bone.”

And with a recent study indicating that cortico-pedicular fixation is safe and reproducible,^[vii] Karma is well-positioned to address the ongoing issues of pedicle screw fixation.

Pedicle fixation plus poor bone quality…What could possibly go wrong?

“Pedicle fixation is imperfect and coupled with bone quality issues, can lead to loosening and implant failure,” adds Dr. Nunley. Indeed, says the research, screw loosening occurs in about 10% of patients, a number that increases to above 60% for osteoporosis patients.^[viii]

Versatile Karma!

According to Terrence Crowder, M.D., an orthopedic spine surgeon with Sonoran Spine in Arizona, there are many indications for a non-metal, low bone density solution.

“First of all, there are legions of people with degenerative spondylolisthesis who don’t know they have it, in part because it can take 15-20 years to develop. This is accompanied by a slow onset of lumbar stenosis and neurogenic claudication, and, since it’s slow it is easy to miss because as people age, they think—or are told—that it’s arthritis. Unfortunately, primary care physicians, physician assistants and nurse practitioners are often misdiagnosing these patients. There is a clear educational gap here.”

“Second, looking at the range of treatments, i.e., from injections to interspinous devices to laminectomy then fusions with posterior screws, I think laminectomy plus Karma provides an ideal solution as it adds a great deal of stabilization, leverages cortical bone, spares tissues, and allows for proper decompression. Karma bridges the gulf between those who do fine with a laminectomy and those who need a fusion that is a less burdensome operative experience.”

“Third, most patients recoil from the thought of a big surgery where they are left with cumbersome screws and rods for the rest of their lives. When patients know there is an alternative, they ask for Karma.”

The Data and Patient Outcomes

“In my experience,” states Dr. Nunley, “Karma is perfect for patients who have up to a grade 2 spondylolisthesis and are not terribly unstable—so a decompression plus Karma is typically in order. Equally, individuals without spondylolisthesis, but with severe stenosis also benefit from this implant.”

“Surgeons are torn between doing a decompression and hoping they won’t have to do a fusion versus jumping straight to fusion…Karma takes that issue off the table.”

Dr. Crowder has had success treating a range of patients using Karma. “Those with severe leg pain (neurogenic claudication or radiculopathy) and degenerative spondylolisthesis are ideal for this device. It’s fantastic that you can do this surgery on an outpatient basis, meaning less blood loss, a smaller incision, and patients can leave the same day. Because this is a less disruptive procedure overall, even some patients with challenging pathologies can have a laminectomy with Karma. In our efforts to ‘do no harm,’ we should consider not putting an older person through a larger-than-necessary surgery.”

Karma’s proprietary curved drill provides circumferential cortical fixation through the lamina, pedicle, and facets. In a recent study, researchers found that among 35 curved holes done with Spinal Elements’ drill, there were no breaches of the anterior cortex. In the finite element analysis study, the Karma provided comparable clinical stability and reduced anterior stress shielding compared to the conventional screw-rod construct.^[ix]

Dr. Nunley: “Karma’s sophistication is based on a ‘perfect storm’ of attributes: it has a small footprint, the incision is small, it uses cortical bone, requires one tray, is radiolucent and involves a patented curvilinear drill that takes a deep dive into the pedicle.”

And this perfect storm of attributes is needed for the perfect storm of aging spines.

Each year in the U.S., osteoporosis leads to roughly 2 million fractures, including 550,000 vertebral fractures.^[x] Grade 1 spondylolisthesis accounts for 75% of all cases.^[xi] As for lumbar spinal stenosis, it is the most significant cause of spinal surgery in patients over 65 years of age.^[xii]

“Karma is not just another iteration of a procedure or device,” concludes Dr. Nunley. “This is innovation in the true sense of the word—it is disruptive and improves the lives of our patients.”

Old spines need new ideas…fortunately, the sages at Spinal Elements have generated good Karma.

References:

[i] https://www.bonehealthandosteoporosis.org/wp-content/uploads/Osteoporosis-Fast-Facts-2.pdf
[ii] https://pubmed.ncbi.nlm.nih.gov/31894472/
[iii] https://pubmed.ncbi.nlm.nih.gov/25616349/
[iv] https://pubmed.ncbi.nlm.nih.gov/26815440/
[v] https://www.ncbi.nlm.nih.gov/books/NBK539777/
[vi] https://pubmed.ncbi.nlm.nih.gov/37273833/
[vii] https://www.sciencedirect.com/science/article/pii/S1878875023002693
[viii] https://link.springer.com/article/10.1007/s00586-022-07187-x
[ix] https://www.sciencedirect.com/science/article/pii/S1878875023002693
[x] https://www.uptodate.com/contents/bone-density-testing-beyond-the-basics/print
[xi] https://www.ncbi.nlm.nih.gov/books/NBK430767/
[xii] https://www.ncbi.nlm.nih.gov/books/NBK531493/