For decades, spinal fusion was the go-to answer when a worn-out or herniated disc caused chronic neck or back pain. Take the disc out, fuse the adjacent vertebrae, and eliminate motion at that segment for good. But a growing number of spine surgeons say that calculus has changed. For Ramin Raiszadeh, MD, of San Diego Spine and Brain Institute, disc replacement for active patients isn’t just an alternative anymore. It’s become the default.
“Anybody who comes in, even if they’re 50, 60 … this replacement, I love it. I think it’s absolutely my default operation for sure,” Dr. Raiszadeh said.
Why the shift happened
Dr. Raiszadeh traces the change in his own practice to roughly the last five to seven years. He points to two reasons driving the shift industrywide.
Replacement better preserves patient movement. Unlike fusion, which locks a spinal segment in place permanently, disc replacement inserts a device designed to maintain flexibility at the treated level. For an active patient, that difference is the whole appeal — it’s the reason he calls disc replacement his default operation for anyone who’s young, healthy, and wants to stay functional.
It also can mean fewer reoperations and less adjacent-segment disease. When a spinal segment is fused, the levels above and below it absorb more mechanical stress over time. Dr. Raiszadeh put the risk of developing problems at those adjacent levels at roughly 2% to 3% per year following a fusion — which compounds to a 20% to 30% chance of needing another operation within a decade. Disc replacement, he said, has been shown to be non-inferior to fusion on core outcomes while lowering that adjacent-segment risk and reducing how often patients need another surgery.
The procedures are similar in pursuit — but different in what they demand
Dr. Raiszadeh described disc replacement and fusion as nearly identical operations up to a point. Both require removing the damaged disc and preparing the space between vertebrae — what he called “carpentry” — clearing cartilage from the end plates before placing an implant.
Anesthesia, access and recovery protocol immediately after surgery are the same regardless of which device goes in.
The difference is what each operation depends on to succeed. A fusion depends on biology — the bone has to heal solid around the implant, a process that can take three to four months. A disc replacement depends almost entirely on surgical precision.
“It’s a very technique-dependent operation as compared to a biology-dependent operation for a fusion,” he said. Because there’s no bone-healing process to wait on, patients can typically start physical therapy around six weeks after a disc replacement, versus three to four months after a fusion.
Who’s eligible
Given those advantages, Dr. Raiszadeh said the main reason he wouldn’t choose disc replacement for an eligible patient comes down to the patient’s own biology and lifestyle, not the technology itself.
His ideal candidate is young, active and healthy, with neck or back pain that has failed six or more weeks of non-operative treatment. For that patient, disc replacement is close to automatic.
The calculation changes for patients with an inherently unstable spine — conditions like spondylolisthesis (vertebral slippage), large fractures, infection, malignancy or osteoporosis. In those cases, a device built to preserve motion can migrate or fail outright.
Why not everyone has made the leap
If the case for disc replacement is this strong, why do many surgeons still default to fusion? Dr. Raiszadeh pointed to two main factors.
One factor is a surgeon’s comfort level. Surgeons getting reliable results from fusion, he said, don’t always see a reason to change technique, even as newer data accumulates. “The most dangerous surgeon,” he said, “is that surgeon who feels he or she could do whatever without understanding the ramifications of what they do” — but he was careful to frame sticking with fusion as a reasonable, even responsible, choice for some of his peers, not a lapse.
The other factor — and the one he called the more significant obstacle — is insurance authorization. He described repeated denials and multiple rounds of appeals for operations he considers clearly indicated, adding that reviewers deciding whether to authorize the surgery are sometimes not spine surgeons at all. The administrative burden, he said, is a recurring drain on practice resources and one of the more demoralizing parts of the job. That tension between clinical evidence and insurance approval is a thread he suggested is showing up broadly across the field, not just in his own practice.
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