Artificial disc replacement has made great strides since it was first approved to treat low back pain in 2005 and neck pain in 2007. Todd H. Lanman, MD, a spinal neurosurgeon and leader in total disc replacement, shares his thoughts on the current state of this surgical alternative to spinal fusion.
Dr. Lanman: I was a sub-investigator on a clinical trial examining the Charité artificial disc in the lumbar spine. This was such a novelty in the treatment of spinal disorders at the time, and I was intrigued by the possibility of preserving motion at the disc through replacement rather than fusion.
Q: What have you observed about the evolution of artificial disc devices over the years?
Dr. Lanman: I believe that the ProDisc-L, which is a semi-constrained lumbar artificial disc had some improvements over its predecessor. This device, having a two-piece component, after implantation provided a single center of rotation that provided excellent results. That has been FDA approved and in use since 2005. Cervical artificial disc replacements were approved in 2007, beginning first with the Prestige-ST artificial disc. Today, we have a relative abundance of options for treatment of both the cervical and lumbar spines. The original Prestige-ST has now evolved into the Prestige-LP or low-profile artificial disc. Surgeons are better able to select devices based on the specific needs of the patient.
Q: Will you explain to our readers why artificial disc replacement may be a good choice?
Dr. Lanman: Artificial disc replacement in the cervical spine is an excellent choice for many patients with degenerative disc disease affecting the neck. We now have clinical trial data at seven-year follow-up for one- and two-level disc replacement showing that disc replacement is better than fusion in every outcome measure: improved neck pain, arm pain, neurologic outcome, and fewer revision surgeries.
In my opinion, disc replacement is really the best choice in patients who still have healthy and intact facet joints at the treatment level. Remember, motion is preserved through those joints (facet joints) after disc replacement, so those facet joints need to be healthy enough to handle the workload. I would say the same is true for the lumbar spine, too. Replacement is superior to fusion for people who have degenerative lumbar disc disease with healthy facet joints.
Q: How many different cervical and lumbar artificial discs are available in the United States, and how do you choose the best one for your patient?
Dr. Lanman: Currently, there are 10 FDA-approved artificial discs. Three artificial discs have been approved for the lumbar spine: ProDisc-L, Charité, and the ActiveL lumbar artificial discs. Seven devices have been approved for use in the cervical spine: the Prestige-ST, Prestige-LP, Mobi-C, Bryan, Secure-C, ProDisc-C, and PCM artificial discs.
There are more similarities among the discs than there are differences. All the devices preserve mobility and motion. There are differences in the way each disc is designed and manufactured, but these are subtle. I consider patient factors when I’m choosing among artificial discs. For example, what is the dynamic motion of the patient’s cervical spine on flexion and extension x-rays? That may make me lean toward one disc over the others.
Dr. Lanman: Artificial disc replacement should not be used in cases where the facet joints have degenerative arthritic changes. If a surgeon places an artificial disc at a level surrounded by diseased facet joints, the patient may still have pain from those facet joints after the surgery. In cases where there is significant disease in the facet joints, fusion is probably preferable to replacement.
I will say, though, that over the many years I’ve been implanting cervical artificial discs, I have become more liberal in using artificial discs in patients with mild facet joint pathology. The stresses and loads placed on the cervical spine are much less than they are in the lumbar spine. Patients can still have good outcomes with minimal facet joint pathology.
On the other hand, if someone has facet joint problems in a diseased lumbar area, I usually elect to fuse the lumbar spine level. The sheer forces placed on the disc at those levels are just too great, and there is a higher incidence of failure.
Q: Is surgery involving implantation of an artificial disc performed minimally invasively or open?
Dr. Lanman: The technical aspects of artificial disc replacement surgery are more challenging than they are for fusion. For example, the artificial disc must be precisely placed. The center portion of the disc needs to be well within a small margin of error, such that the vertebrae will move normally. This type of surgery is done with a mini open incision approximately an inch to two inches long. For lumbar disc replacement, we commonly make a vertical incision, or sometimes use an incision around the belly button. That way, there is no visible scar on the abdomen.
One- or two-level cervical disc replacement can be done in an outpatient setting. Each disc that is replaced takes approximately one hour, and patients leave the surgery center approximately eight hours after surgery. When treating three levels or more, my preference is to admit the patient to the hospital for one night of observation. For comparison, I tend to keep patients one or two days in the hospital for a single-level replacement in the lumbar spine.
Q: Is the patient’s recovery faster or better with an artificial disc compared to spinal fusion?
Dr. Lanman: The patient’s recovery is faster with disc replacement than fusion. By six to eight weeks after surgery, the artificial disc is fused well into the spine. Conversely, it traditionally takes about three months for a fusion to become firmly fixed. That can be a substantial and meaningful difference for patients.
Q: What advice do you give patients about choosing artificial disc replacement?
Dr. Lanman: If a patient requires surgical treatment and meets all the appropriate criteria (eg, reasonably healthy facet joints in the context of degenerative disc disease), I routinely recommend cervical and lumbar artificial disc replacement or arthroplasty over spinal fusion.