What Is Adjacent Segment Disease?The simplest definition of adjacent segment disease is when something abnormal occurs in the segment next to, or adjacent to, the spinal fusion. It is when there are changes to the vertebra or vertebral disc above or below the fusion. Most commonly these changes involve a bulging or herniated disc, stenosis, listhesis, spondylosis, or scoliosis. Yes, scoliosis or the continuation of the curve pattern or even a compensatory curve is a possibility above and below the fusion!
Adjacent Segment Disease diagnosisX-rays and MRIs allow for the diagnosis of adjacent segment disease. Sometimes we’re aware of these changes because they involve symptoms such as: discomfort or pain. And sometimes we’re not aware of these changes because they’re asymptomatic and don’t cause sensation. Research reports the occurrences of adjacent segment disease to be between 5.2% and 100%. Too often, too many of us with spinal fusions for scoliosis don’t understand adjacent segment disease or have never heard of it. Some people learn about adjacent segment disease when they are diagnosed with it. Combing through the research can feel frustrating, especially when it reports such a huge range of occurrence. Seriously, between 5.2% and 100%? Is that even considered proper research? The research also refers to “considerable controversies” of adjacent segment disease so it’s clear that even the experts aren’t in concurrence. I’m hopeful that people seeking more information will find the following helpful in their journey.
Adjacent Segment Disease CausesSome specialists believe that adjacent segment disease is a complication of spinal fusion surgery. The vertebrae and discs work together to distribute and absorb forces. When sections of the spine become fused, the fused vertebrae and discs no longer assist in distributing and absorbing forces. As a result, the vertebrae and discs above and below the fusion compensate for lost motion. They become hypermobile and experience additional wear and tear. Meanwhile, other specialists believe that adjacent segment disease results from the natural, spontaneous degenerative process of aging. Most likely adjacent segment disease isn’t an either/or situation. Many of us experienced scoliosis surgery at a young age so it makes sense that a lifetime of additional wear and tear on the adjacent segments might lead to accelerated deterioration. It also makes sense that the natural degenerative process of aging then compounds the risk of deterioration, especially for those of us prone to osteoporosis.
Adjacent Segment Disease Risk FactorsResearch shows that risk factors for adjacent segment disease include the following:
- Gender. The female to male ratio of adolescent idiopathic scoliosis for curves larger than 40 degrees is 7.2 to 1. Accordingly, the majority of people with scoliosis spinal fusion surgeries are female; though, there are some males as well. In addition, women are more prone to osteoporosis which can lead to degenerative changes.
- Osteoporosis. The National Osteoporosis Foundation reports that of the estimated 10 million Americans with osteoporosis, 80% of them are women.
- High BMI.
- More rigid, traditional approaches to fusion surgery. Most all of us with scoliosis spinal fusions received this traditional approach to surgery. Only in recent years are more minimally invasive approaches to scoliosis surgery being explored.
- Fusion length. Most, if not all, of us with scoliosis spinal fusions have multi-level fusions.
- Sagittal malalignment.
- Pre-existing deterioration in the adjacent segment. This risk factor applies to those that undergo spinal fusion surgery later in life. Oftentimes, doctors take the health of adjacent segments into when advising on fusion length.
- Tobacco use.
Adjacent Segment Disease Treatment OptionsThe most common treatment options for adjacent segment disease include physical therapy to improve mechanics, medications and injections to ease inflammation and pain, as well as additional surgery. Additional surgery in the realm of scoliosis spinal fusions is referred to as revision surgery. Oftentimes the fusion length increases with this option to include those adjacent segments that are deteriorating. Even the surgeons agree that improving prevention is a goal because surgical management remains challenging. Naturally, what I find most interesting is the inclusion of physical therapy to improve mechanics. I am a huge proponent of physical therapy, especially with a physical therapist that specializes in scoliosis and spinal fusions. Generally, I suggest people research the seven major schools of Physiotherapy Scoliosis-Specific Exercises (PSSE) of which Schroth Physical Therapy is most widely available in the US. We can also use movement (Pilates, yoga, and strength training) as a way to understand and improve mechanics so that we become more aware of whether parts of our unfused spine are compensating for lost motion, and thus, experiencing additional wear and tear. Decreasing the load of the spine involves understanding the whole body and may include the following questions:
- How can hip hinging and squatting reduce the forces on my spine and build strength through the lower extremities?
- What does neutral spine mean for me? Neutral spine involves understanding sagittal alignment. Poor sagittal alignment is one of the risk factors listed above for adjacent segment disease.
- How can understanding and finding balance between the concavities and convexities help me find ease in my body and everyday movement?
- How can axial elongation and global expansion benefit me?