“I’ve read a lot about artificial disc replacement as a first surgical treatment option to restore and help maintain neck movement. However, my cervical spine surgery was a fusion procedure, and now, years after what was a successful surgery, I’m in pain. I’m an avid basketball player, in relatively good health. Am I a candidate for artificial disc replacement?” — Larry, Verona, CA
Not every patient is seeking spinal surgery. A substantial minority of patients I see have had previous cervical (neck) fusion surgery or artificial disc replacement. These patients may be experiencing progressive disease affecting other vertebral levels, a non-healed fusion or nonunion, or other degenerative process that requires surgical treatment.
From speaking with these patients, many of whom have visited other spinal surgeons, there seems to be a prevailing notion that once someone undergoes cervical spinal fusion surgery, that is the end of the line. The belief seems to be that there is no going back to an artificial disc. In some cases, it seems the message to patients is, essentially, either you undergo fusion surgery again or you must somehow learn to live with your pain and other symptoms. However, in certain properly selected patients, artificial disc replacement may be used to revise a previous cervical fusion. The term revise means a previous surgery requires reoperation.
Success with artificial disc replacement as revision
My specialty is motion preservation spinal surgery; a type of surgery that is an alternative to spinal fusion. Like many spine surgeons, I’m keenly interested in patient outcomes, both short- and long-term, and track case data to be reported in research publications. In a review of my motion preservation spine cases, so far, I have noted three relative indications for artificial disc replacement as an alternative to spinal fusion in revision cases:
At this point in time, I would not advocate for revising a fusion in a patient who has no symptoms, or a patient who does not need an additional spinal surgery just to restore spinal motion. However, I may consider offering artificial disc replacement as a potential revision procedure if the patient meets one of the three clinical scenarios mentioned above.
Normal facet joints appear to be the key to success
If I consider artificial disc replacement as a revision for either a prior fusion or a previous artificial disc, I use CT imaging rather than MRI. Why? CT imaging enables me to closely examine the facet joints. If the patient’s prior fusion was performed using an anterior approach (from the front of the body), often I find the relevant facet joints are perfectly normal. If the facet joints are normal, past experience tells me that an artificial disc may work at that level even if the anterior portions of the affected vertebra are partially or fully fused. If I see encouraging results on the spinal CT scan, I clearly explain to the patient that I may be able to perform artificial disc replacement if conditions are right during surgery. The default choice or fallback position, if you will, is to proceed with a revised fusion surgery.
The final decision comes during the surgery. Once I am able to access the affected disc—drilling out the sections where the fusion has failed as needed—I can place distractors to evaluate motion in the intervertebral space. In other words, I am testing whether an artificial disc would be successful at that level. In my experience, normal facet joints examined by CT imaging usually predict what I will see during the surgical procedure. Often, proceeding with artificial disc replacement as planned is possible.
Understand this procedure is “off-label”—what that means
It is important for doctors and patients to be aware that using artificial discs in the way I have described is currently “off-label”. In other words, the US Food and Drug Administration (FDA) have not evaluated studies that examine the use of artificial discs in this specific manner. On the other hand, the FDA does not regulate how a physician chooses to use an FDA-approved device. Artificial discs are FDA-approved. If the doctor decides the device can be safely used to help the patient, the doctor is free to proceed if the patient is fully informed of the potential risks and benefits of the procedure and provides consent.