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Adjacent Segment Disease (ASD) Puts Spinal Fusion Patients At-Risk for Additional Surgeries

May 18, 2018

Spinal fusions can be successful. However, they are associated with high rates of adjacent segment disease (ASD). Meaning, if you have spinal fusion surgery, according to the evidence, there is a 40 percent chance you’ll experience similar back problems either above or below your original fusion within 5 years due to adjacent segment disease (sometimes called adjacent segment degeneration).

During fusion surgery, the vertebral motion segment within the affected area of your spine is removed and replaced with bone graft, rods and spacers. Once fused, the material locks above and below the vertebrae creating a solid bone mass. The procedure has the potential to relieve back pain, but not without consequence.


 There is a 40 percent chance you’ll experience similar back problems either above or below your original fusion within 5 years due to adjacent segment disease.

As the area around your fusion solidifies, the spine segments above and below the fusion are required to carry the excess load where two separate areas existed. While the goal is to reduce or remove pain caused by instability in the spine, fusion causes the facet joints and discs above and/or below to work harder. As they weaken, adjacent segment disease results.

Addressing the concerns of adjacent segment disease with ADR

For fusion patients with additional disc degeneration concerns, artificial disc replacement is an option that reduces or prevents adjacent segment degeneration from developing. Artificial disc replacement (ADR) is a surgical procedure by which a degenerated intervertebral disc is replaced with an artificial disc. Unlike spinal fusion, ADR preserves movement of the spine.

In a comparative study to the effectiveness of artificial disc replacement to spinal fusion in patient outcomes and future development of adjacent disc disease, the findings revealed, “Lumbar ADR is 79% superior to lumbar spinal fusion.” The study went on to explain that complications after lumbar ADR fell “between 0% and 13% per device implanted.” Patients in one case series within the study showed a 2% adjacent disc generation rate over an 11-year follow-up period.

What does this data mean?

Showing pain area within the spineIt points to artificial disc replacement as an alternative option for patients with disc degeneration or those patients with fusions who are concerned about degeneration risk. Even in patients who underwent spinal fusion and required re-operation, choosing artificial disc replacement instead of a second fusion yielded better results. A 2017 study chronicling 32 patients who underwent artificial disc replacement for the treatment of adjacent segment disease after a previous spinal fusion showed that ADR was an effective treatment for post-fusion ASD. The conclusion: the best way to protect degenerative areas of the spine is to avoid fusion. Patients who chose artificial disc replacement over fusion were four times less likely to need additional surgery due to adjacent segment degeneration.

Recent findings in a study by Drs. Jack Zigler, Scott Blumenthal, Richard Guyer, Donna Ohnmeiss and Leena Patel support the data. The analysis revealed, “An extremely low incidence rate of radiographic adjacent level deterioration at five years (only 9.7% of patients) compared to previous reports of deterioration at levels superior to fusion (28% of patients) and an even lower rate of clinically-significant ASD that resulted in additional surgery (in just 2.29% of patients).”

This means that artificial disc replacement proved more effective at slowing the adjacent segment degenerative degeneration than fusion.

“Our analysis found that no patients who exhibited asymptomatic radiographic ASD changes at the time of preoperative assessment required any additional surgery at those levels at five years. In other words, even five years later, the implantation of a LTDR (lumbar total disc replacement) did not accelerate radiographic, non-pain-generating ASD to the point of requiring surgical treatment,” says Zigler.

What it means for patients and providers

Doctor and patient discussing ASDThis analysis alone could help make artificial disc replacement a cost-saving and worthwhile treatment option for health insurance carriers to offer their clients. Last year, major health care insurance carriers Humana, Blue Cross Blue Shield of Louisiana and Highmark Blue Cross Blue Shield provided positive coverage for lumbar artificial disc replacement. The data presents a case about the importance of educating health plan decision makers regarding the medical necessity of artificial disc replacement.

It’s estimated that over the course of the next eighteen months, the remaining health insurance carriers will adopt coverage of lumbar total disc replacement. It only makes sense for carriers to cover the procedure given the adjacent segment disease rate caused by fusion.

“It is evidence like this that will hopefully move the needle with health plans in favor of a procedure that is less costly in the short- and long-term,” says Scott Blumenthal, MD (Center for Disc Replacement at Texas Back Institute, Plano, TX), who co-authored the study with Zigler and who performed the first lumbar disc replacement in the US 18 years ago. “It is time we acknowledge the strength of the current evidence base for this life-improving procedure.”

Last change: May 18, 2018
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