Adult Deformity

The current treatment for scoliosis for surgical candidates is spinal fusion. This halts curve progression and prevents the potential medical ill effects of severe curves. Modern techniques also may straighten the spine and enhance cosmesis and spinal balance. In adults, fusion may also decrease pain but the procedure is typically more extensive due to the need to include all the segments of the deformity. However, a fused spine cannot bend and in scoliosis fusions, a functional decrease typically occurs due to the many levels typically needed for fusing the entire scoliotic curve. The detrimental effect of fusion upon function is particularly notable when fusions include the lumbar spine where there is normally more motion than in the thoracic spine.

Due to the loss of mobility in the lumbar spine, and hence its detrimental effect on function of activities of daily living, spine surgeons when performing fusion for pediatric idiopathic scoliosis, will often perform a selective fusion. That is, the thoracic but not the lumbar spine will be fused and a moderate residual lumbar curve, if present, will be tolerated as a better option than fusing the entire spine. Unfortunately, during the middle age years, these lumbar curves often progress and become symptomatic. Long-term follow-up studies of the results of fusion surgery for adolescent scoliosis are few and were typically qualitative. Mid-term studies of pediatric scoliosis patients are just now becoming available and at >5years, the Principle Investigator and others have found a small decline (worsening) of outcomes (Buttermann 2008-a, Upasani 2008).

One of the most complex and challenging conditions encountered by the spinal surgeon is that of the patient who has a preexisting scoliosis and with aging has progression of their lumbar compensatory scoliosis. These patients will often have a stable thoracic scoliosis or have had a prior selective thoracic spinal fusion and have mild to moderate residual compensatory lumbar scoliosis throughout their young adult years. With aging and disc degeneration, many of these patients will have progression of their lumbar curvature. They may get a lateral listhesis near the apex of the lumbar curvature typically at L3-4 which is a sign of instability due to degenerative disc disease (Buttermann 2008-b, Schwab 2006).

Progressive low back pain may occur and some patients will also develop stenosis with secondary leg pain. Depending on the rigidity and number of degenerative discs involved, these patients may require extensive spinal fusion surgery down to L5 or S1 possibly with a decompression and possibly using anterior and posterior combined approaches. These types of surgeries, however, have more risk compared to that for patients who have degenerative disc disease of the lumbar spine without deformity. The outcomes of adult scoliosis surgery, as shown in multiple studies, leads to improved pain and a small improvement in function, but the function is never considered to be”normal” (Buttermann 2001, Smith 2009). A study by the PI found a 4 point improvement (0 to10 scale) in pain, and approximately a 15 point improvement in Oswestry Disability Index (function). This degree of improvement has been found in other studies of adult scoliosis (Bridwell 2009, Smith 2009).

We have also shown that over the last fifteen years, improved techniques in adult scoliosis surgery have led to lower pseudarthrosis rates, lower revision surgery rates and lower complication rates, however, when using the identical outcomes instruments of the above study, the current pain and functional outcomes improvement are similar to what they were 15 years ago (Buttermann 2008-a, Buttermann 2001).

One may conclude that fusion surgery for adolescent and adult scoliosis results in improved pain outcomes, but in the long-term there appears to be a slow gradual decline. Adult scoliosis surgery does not result in a functional spine even in the short term due to decreased spinal mobility.