On the cutting edge of degenerative scoliosis
Date: April 30, 2012
Many people in the United States are familiar with adolescent idiopathic scoliosis because of the mandatory screening that they, or their children, underwent during middle school. However, they’re often less familiar with degenerative scoliosis, which occurs at the opposite end of life.
“Some people are outliving their bones,” says neurosurgeon Tim Witham. “In a significant number of cases, the spine doesn’t last as long as the rest of the body.”
During aging, Witham explains, vertebral discs and facet joints sometimes degenerate, leading to the characteristic S-shaped curvature in the spine. Though slight curvatures are often invisible to the untrained eye and typically need no treatment, Witham says, severe curvatures can cause a host of complications, including pain and weakness, limited range of motion and even respiratory issues in extreme cases.
Traditionally, orthopedists have treated most patients with degenerative scoliosis. Today, Witham says, neurosurgeons like himself share the load, often handling special cases in which preserving a patients’ nerve function can be a difficult and complicated task.
When patients are referred to Witham and his colleagues, they undergo specialized imaging done only for scoliosis patients to visualize the spine from top to bottom to assess its global alignment. They also receive an extensive workup to make sure surgery is a viable option; besides the typical risks inherent to all spine operations, including lingering pain and loss of function, the risks involved in surgery for degenerative scoliosis are magnified, Witham explains.
These operations tend to be lengthy, often six to eight hours. The risk of infection is increased because incisions are usually large. Additionally, blood loss is frequently extensive, he says, because bone bleeds tremendously during surgery. Even if patients are healthy enough for these rigors, poor bone quality from osteoporosis may still disqualify them from surgery.
Once prospective patients pass every test, the surgery itself involves straightening the spine by removing bone and fusing joints with hardware, usually at multiple levels of the spine. During the process, surgeons decompress the spinal cord and nerve roots to lessen pain and improve neural function. It’s a procedure Witham says that he and his colleagues at Johns Hopkins, both in neurosurgery and orthopedics, are well equipped to do.
Because Hopkins tends to get more complicated cases, he says, the hospital has a routine practice of dealing with patients with an assortment of presentations—a factor shown again and again to produce better outcomes. Witham adds that he and his colleagues are always gathering outcomes data to determine whether small tweaks in technique can produce better results. Further research in the lab using animal models may one day develop improved ways to grow bone to help spinal fusions be even more successful.
“We’re pushing the envelope and trying things that even 15 years ago wouldn’t have been a possibility,” Witham says.
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