A relatively new perspective on preventing or treating adjacent segment disease that occurs after a back surgery comes from proponents of motion preservation. These forward thinking surgeons and medical device manufacturers say that altered biomechanics after a spinal fusion surgery tends to put a lot of pressure on the adjacent intervertebral levels. For this reason, they are in favor of using of technology to develop prosthetics and surgical tools that keep the spine’s movement capacities intact, rather than doing away with them, as what occurs with most fusions.
I spoke with Dr. Rick Delamarter, co-director of the Spine Center and vice chairman for Spine Services in the Department of Surgery at Cedars-Sinai in Los Angeles. Dr. Delamarter is a foremost researcher in the field of motion preservation surgery, particularly disc replacements.
Dr. Delamarter informed me that terms “motion sparing,” “motion preservation,” and “dynamic stabilization” are used to refer to this type of back surgery.
According to Dr. Delamarter, motion preservation surgeries are designed to allow the intervertebral joints of the spine to continue to move after the procedure is complete. Spinal fusion does not fit into this category of surgeries, he says. “Spinal fusion creates stiffness, which increases the pressure on nearby joints. This raises your risk for adjacent segment disease above and below the level where the surgery is done,” Dr. Delamarter says.
Examples of motion sparing surgery include (but are not limited to) the total disc replacement, interspinous spacers such as the X-stop for stenosis, and plastic rods.
Artificial Disc Replacement – Promising Motion Preservation Technology?
In the U.S., the artificial disc replacement is the “new kid on the block” as far as motion sparing spine surgeries go.
“People who have a disc replacement rather than a fusion are less likely to need a second operation because of adjacent segment disease," Dr. Delamarter says.
So far, research does suggest that people who undergo an artificial disc replacement surgery have less chance of needing a reoperation (called revision surgery) in the future.
For example, in a comparison analysis of three studies involving unpublished data (the studies were done by disc manufacturers as part of the application to the FDA for approval for the devices) researchers found that for disc disease with radiculopathy at one level in the neck, both fusion and disc replacement yielded good outcomes for patients after two years. The disc replacement was associated with a higher degree of success in relieving nerve symptoms, and resulted in fewer revision surgeries. The analysts concluded that a disc replacement in the neck may also be associated with a lower rate of adjacent segment disease after 2 years, but they caution that more studies are needed before this can be confirmed.
While the data on disc replacement looks good (as of January 2012), the studies published in the U.S. have so far only followed up with patients in the short-term. Longer-term data is coming soon, Dr. Delamarter promises.
Sources:
Rick B. Delamarter, MD. Co-Medical Director, The Spine Center and Vice Chairman for Spine Services, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles. Telephone Interview. Jan 2012.
Upadhyaya, et al. Combined Results of the 3 US IDE Randomized Cervical Arthroplasty Trials With 2-Years of Follow-up: 923. Neurosurgery: August 2010 - Volume 67 - Issue 2. doi: 10.1227/01.NEU.0000386995.74131.4B
