Long-Term Study Shows No Major Adjacent Degeneration in Most Patients After Fusion for Scoliosis

Young patients who undergo spinal fusion for scoliosis are likely to be doing well 10 years after surgery, according to study results published online in Spine.

The findings contrast beliefs that the surgery would cause damage to the spine just below the fused discs due to increased stress at uninstrumented caudal intervertebral discs and accelerated degeneration, according to a press release from Hospital for Special Surgery (HSS).

“Fusion for adolescent idiopathic scoliosis using the newer generation spine implants appears to spare junctional disc degeneration and allows patients 10 years out to have a relatively normal, pain-free lifestyle,” Daniel Green, MD, lead author and pediatric orthopedic surgeon at HSS, stated in the release.

The investigators performed a retrospective chart and imaging review of patients aged 21 years and younger with idiopathic scoliosis who underwent posterior fusion and segmental instrumentation between 1991 and 1997. Surgery had to approach the spine from the back rather than the front or side, and patients had to have fusion of the spine in the lower back, between vertebra T12 and L3.

The investigators studied 90 discs below the fused level in 20 patients with an average follow-up of 11.8 years. The study noted a distal level of fixation at L1 on average, with the major curve averaging 55·±11· preoperatively and 25·±10· at follow-up.

According to the study findings, follow-up MRI revealed new disc pathology in 85% of patients. One patient displayed significant degenerative disc disease at the junctional level — most pathology was seen at the L5-S1 disc. Average Pfirmman grade at uninstrumented levels deteriorated from 1.1 preoperatively to 1.8 at follow-up, with average degenerative scores increasing in the L5-S1 disc space from 1.2 preoperatively to 2.3 postoperatively.

Three of the patients with severe disc disease were taking NSAIDs for pain, but the study pointed out that none were taking narcotics.

“We wanted to see how the patients were doing 10 years down the road, specifically focusing on the part of the spine that did not have surgery,” Green stated in the release. “The standard belief was that the area of the spine just below the surgery would wear out, because of the increased stress that the surgery or the fusion would put on that part of the spine.”

“That is not what we found,” he added. “We found that the area of the spine adjacent to the fusion was pretty healthy and did not show any major degeneration 10 years later. While mild degenerative changes were noted in almost every patient, the severe changes that we were concerned we might find were not there at all.”

Though the findings pointed to an accelerated rate of L5-S1 disc degeneration, the authors found good functional scores and maintenance of correction during the 10-year follow-up 10 years.

“There is a lot of research and investment being done looking for new technologies that do not use fusion,” Green stated. “This study would suggest that there is a challenge for those trying to do that because the patients doing fusion are doing well.”

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