For much of modern spine surgery, fusion has been the dependable answer to a long list of structural problems: decompress the neural elements, stabilize the spine and accept the loss of motion as the price of a durable repair.
Wilson Z. Ray, MD, chief of spine surgery and vice chair of neurosurgery at Washington University School of Medicine in St. Louis, thinks that bargain is becoming more selective.
Cervical disc replacement has matured. Minimally invasive decompression and endoscopy offer alternatives for some patients. Laminoplasty is regaining attention. Together, those options are expanding the circumstances in which surgeons can consider preserving motion rather than eliminating it.
That expansion is running ahead of a separate question: whether insurers will pay for it. Coverage policy, not just clinical evidence, is increasingly shaping how far surgeons can act on this shift, a tension that surfaces repeatedly in how Dr. Ray describes the decision.
But Dr. Ray does not see the field moving toward a simple fusion-versus-non-fusion divide. The more important shift is happening earlier in the decision: Does this patient need stabilization at all?
“I think that threshold for fusion is definitely becoming more selective,” Dr. Ray told Becker’s. “Increasingly, we’re trying to avoid a fusion or the need to treat the pathology via a fusion.”
That does not make fusion obsolete. Instability, deformity, destructive disease and severe degeneration will continue to require it. Instead, spine surgery may be moving toward a more selective approach: preserving motion when it can be done without compromising treatment of the underlying pathology.
Motion preservation is the goal, until it compromises the operation
The appeal of preserving a motion segment is easy to understand. If a surgeon can decompress a nerve, relieve symptoms and leave a functional spinal segment intact, preserving that motion can offer an advantage over fusion.
But Dr. Ray puts an important condition on that principle.
“Preserving motion is the goal, but not at the expense of not solving the underlying problem,” he said.
That distinction shapes the patients he considers most suitable for a motion-preserving strategy. The pathology should be relatively focal. Alignment and stability should be preserved. And the motion segment should otherwise be worth saving.
Once those conditions disappear, the calculation changes. True instability, substantial deformity, advanced degeneration, infection, trauma or other destructive pathology can make stabilization essential.
In those cases, fusion remains an important biomechanical solution. Increasingly, the issue is not whether surgeons can perform a fusion safely and effectively. It is whether the pathology requires one.
The smaller operation may require the harder decision
Laminoplasty offers Dr. Ray one example of that shift. The procedure decompresses the cervical spinal cord while preserving motion rather than converting the treated levels into a fusion construct. It is not new, but Dr. Ray sees renewed interest in it as surgeons reconsider when fusion is necessary.
“Laminoplasty has certainly come back into vogue,” he said.
Its resurgence fits a broader movement toward considering less disruptive operations when the patient’s pathology allows it. That could mean a focal decompression rather than a fusion, a disc replacement rather than eliminating a motion segment, or a laminoplasty rather than a multilevel posterior fusion.
The operation can be smaller without the decision being simpler. The surgeon still has to determine whether the anatomy will remain stable and whether the operation can provide a durable result without fusion.
That makes patient selection, rather than the device or technique itself, one of the central challenges.
Cervical disc replacement has crossed an evidence threshold
Not every motion-preserving strategy is at the same stage of maturity. Dr. Ray sees cervical disc arthroplasty as the clearest example of one that has developed a substantial evidence base. He pointed specifically to long-term outcomes for two-level cervical disc replacement.
“That really is exceptional data and supports the evidence,” he said of the cervical arthroplasty literature.
The lumbar spine is harder. Even with his experience, Dr. Ray said he does not believe he can consistently identify the “perfect” lumbar disc replacement patient. He sees a cohort that does extraordinarily well. The problem is knowing with enough confidence before surgery who belongs in it.
“I don’t know that I have that figured out,” he said.
That leaves an important unresolved issue in motion preservation: Surgeons increasingly have the technical ability to preserve movement, but identifying the patients most likely to benefit remains imperfect.
When the pendulum swings too far
That uncertainty creates another concern as motion-preserving techniques expand. Surgeons can become better at a new procedure and begin expanding its indications. Innovation depends partly on understanding where a new technique can safely be used.
But Dr. Ray also expects a familiar pattern: The pendulum can swing too far before the field establishes a procedure’s limits.
“I think we’re at some risk of that with all new technology,” he said.
Early adopters push the boundaries. More conservative surgeons resist. Over time, Dr. Ray said, evidence and experience can move the field toward clearer indications.
His point is not that motion preservation should replace fusion as a default. The procedure still has to match the pathology. What matters, he said, is finding the appropriate biomechanical solution for the individual patient.
The evidence is expanding faster than the coverage
There is another force shaping that decision that has little to do with biomechanics: insurance.
Dr. Ray pointed to hybrid procedures as one example of the disconnect. A patient may have two adjacent levels with distinctly different pathology. One could be well suited to disc replacement, while the other has enough degeneration or instability that fusion makes more sense. The individualized solution may be a hybrid: preserve motion at one level and fuse the other.
Yet coverage can be difficult because insurers may categorize hybrid constructs as experimental. “That has continued to be a point of frustration,” Dr. Ray said.
Lumbar disc arthroplasty can present similar barriers even when a surgeon considers a patient clinically appropriate. The result is a tension between increasingly individualized surgical strategies and coverage policies that may not recognize them.
The next breakthrough may be better selection
Asked what spine surgery might look like a decade from now, Dr. Ray did not predict the disappearance of fusion.
“I don’t think fusions are going away,” he said.
What he expects instead is greater precision around when to use them. AI could become part of that shift. As the field accumulates imaging, outcomes and clinical data, AI could eventually help surgeons identify which patients are more appropriate for fusion versus motion preservation.
Dr. Ray cautioned that medicine is still exceptionally early in understanding what AI will become. He compared the current moment to the age of AOL and dial-up internet, transformative in hindsight, but primitive relative to what followed.
The real shift is from “Can I?” to “Do I need to?”
For decades, innovation in spine surgery has expanded what surgeons can accomplish. Dr. Ray believes the next stage may be defined by greater selectivity.
For some patients, that may mean disc replacement, decompression or no surgery at all. For others, fusion will remain necessary.
The goal, he said, is to choose “the least destructive operation to address the pathology” while still providing a durable result.
Fusion is not disappearing. Its role is becoming more specific.
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