Adjacent Segment Disease

When the Biomechanics After Fusion Surgery Put too Much Pressure On Your spine

Xray image of arthritic spine.
Arthritis is one cause of cervical radiculopathy. CNRI/Science Photo Library/Getty Images

Adjacent segment disease is a form of adjacent segment degeneration (ASD) that causes new symptoms following a spinal fusion or other back surgery. Adjacent segment disease is an advanced form of ASD. (ASD refers to degenerative changes in your intervertebral joints above and below the area of a spinal fusion or other back surgery.)

The amount of time you’ve had symptoms, as well as the type of symptoms, are key when differentiating between adjacent segment degeneration (ASD) and adjacent segment disease.

Adjacent segment disease is a diagnosis in which you experience symptoms you have not had before.

These include pain and neurological symptoms.

Diagnosing Adjacent Segment Disease

To diagnose adjacent segment disease, your doctor will likely evaluate any radiculopathy (pain/symptoms down an arm or leg) and/or myelopathy (pain/symptoms that occur when the spinal cord is affected). If your doctor can trace those types of pain back to the motion segments above and/or below your surgery site, you may have adjacent segment disease.

According to Dr. Frank Cammisa, orthopedic surgeon and Chief of the Spinal Surgical Service at Hospital for Special Surgery in New York, in the lower back, symptoms of adjacent segment disease may or may not include radiating leg pain (sciatica).

Should You Get Treatment for Your Adjacent Segment Degeneration?

A 2007 review of studies published in the Bulletin of the NYU Hospital for Joint Diseases looked at (among other things) the need to treat adjacent segment disease.

The reviewers concluded that there was a lack of correlation between symptoms and “clinical relevance.” In other words, you probably won't need further spine treatment for your adjacent segment disease, as the report found that many patients do well without it.

But if you do need treatment, it may consist of conservative care, NSAID medications, physical therapy or pain management modalities, steroid injections, and possibly revision surgery.

Treatment for Adjacent Segment Disease - How Well Does It Work?

“Generally, outcomes for each type of treatment are similar to what they would be for the original problem,” Cammisa says.

But according to Dr. John Toerge, Medical Director of the Musculoskeletal Institute at the National Rehabilitation Hospital in Washington, D.C., and professor of medicine at Georgetown University, none of the treatments for ASD are particularly effective in resolving symptoms. “As with most interventions, there are risks and benefits for each option,” he says.“Conservative treatment is probably the best course of action for the patient.”

Surgery for Adjacent Segment Disease

Cammisa says that some surgeons “top off” a spinal fusion surgery by placing dynamic stabilization hardware at sites where degeneration may possibly occur in the future. For example, the doctor may give you a rigid fusion at the lesion site, and pedicle screws (in this case used as a motion-sparing technique) at those levels above and below that show degeneration on films.

Does that help? A 2014 protocol (a study that is planned but not yet executed) says that while new “topping off” hybrid systems may decrease the number of complications related to spinal fusion surgery, so far there's no evidence to confirm their usefulness in the clinic. Plus a topping off system costs more, they say.

But Commisa disagrees. “Personally, I have not been impressed with the long-term results of this type of procedure,” he comments.

Sometimes a second surgery is the treatment of choice for ASD. A 1999 study done by Hilibrand, published in the Journal of Bone and Joint Surgery followed 374 anterior cervical fusion patients for 10 years. The researchers found that 25% developed adjacent segment disease, and 2/3 of those people (about 16% of the total study population) needed another surgery because of it.

Toerge warns that you should allow enough time after your initial procedure before considering a second surgery. This is so you can heal from the trauma associated with the surgery itself, and get your spine moving again, he says.

The Future, Perhaps

Spinal fusion has been a standard back surgery for a long time, and its use is on the rise. Just the same, there are many unanswered questions about adjacent segment disease and ASD as a consequence of spinal fusion.

Data from long-term studies are still needed, but as of February 2016, a relatively new type of surgery (in the U.S.) – artificial disc replacement – may show promise in terms of better spinal biomechanics, post procedure. Proponents of disc replacement say the improved biomechanics will likely reduce the degree of degeneration in the nearby spinal levels over the long term.  

But others are not so sure.  Saavedra-Pozo, et, al, in their review entitled, "Adjacent Segment Disease Perspective and Review of the Literature, published in the spring issue of the. Ochsner Journal says there's insufficient evidence at this point to support the idea that total disc arthroplasty (i.e., disc replacement) is better than the standard surgery done in the neck (anterior cervical discectomy with fusion) for minimizing adjacent segment disease.  The authors go on to say medical studies clearly suggest that adjacent segment disease, as well as adjacent segment degeneration, is not caused by fusion alone, but rather (most likely) by fusion and abnormal alignment at the ends of the fused bones (which is generally kyphosis.)

The authors conclude by saying their research casts even further doubt on the rationales that exist in favor of total disc arthroplasty - at least in terms of how such a procedure might impact adjacent segment disease.

Here is a list for further reading on total disc replacement:

Sources:

Cammisa, F., M.D., F.A.C.S. Chief, Spinal Surgical Service at Hospital for Special Surgery. Email Interview. Jan 2012.

Etebar S, Cahill DW. Risk Factors for adjacent-segment failure following lumbar fixation with rigid instrumentation for degenerative instability.J Neurosurg. 1999;90(2 Suppl):163-9.

Kyoung-Suok Cho, M.D., et. al. Rik Factors and Surgical Treatment for Symptomatic Adjacent Segment Degeneration after Lumbar Spine Fusion. J Korean Neurosurg Soc. 2009 November; 46(5): 425–430.

Hilibrand, A., MD.Et. al. Radiculopathy and Myelopathy at Segments Adjacent to the Site of a Previous Anterior Cervical Arthrodesis.Journal of Bone and Joint Surgery. 1999.

Lee, C.K. Accelerated degeneration of the segment adjacent to a lumbar fusion.Spine (Phila Pa 1976). 1988 Mar;13(3):375-7.

Levin, et. al. Adjacent Segment Degeneration Following Spinal Fusion for Degenerative Disc Disease. Bulletin of the NYU Hospital for Joint Diseases 2007;65(1):29-36

Saavedra-Pozo, F., et. al. Adjacent Segment Disease Perspective and Review of the Literature. Ochsner J. Spring 2014. Accessed: Feb 2016. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3963057/

Schlegel JD, et. al. Lumbar motion segment pathology adjacent to thoracolumbar, lumbar, and lumbosacral fusions. Spine (Phila Pa 1976). 1996 Apr 15;21(8):970-81.

Siewe, J., et. al. Evaluation of efficacy of a new hybrid fusion device: a randomized, two-centre controlled trial. BMC Musculoskelet Disord. 2014. Accessed: Fbe 2016. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4161882/

Toerge, J. DO, Medical Director Musculoskeletal Institute National Rehabilitation Hospital, Washington, DC. Email Interview. Jan 2012.

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