March 29, 2010

More Options Emerge for Scoliosis Patients
By Carolyn Gutierrez
For The Record
Vol. 22 No. 6 P. 24

New tests and experimental procedures could lead to breakthroughs in how the condition is treated.

People diagnosed with scoliosis have traditionally been treated for their spine curvature with years of bracing or open surgery requiring months of recovery time. With innovative minimally invasive surgical techniques promising to stabilize the spine within weeks and advances in surgical instrumentation streamlining traditional spinal fusion procedures, back surgery has now become a more viable and less daunting option for those with severe scoliosis.

Background        
Scoliosis, a condition in which the spine curves into an “S” or “C” shape, can have many causes. According to Michael G. Vitale, MD, chief of pediatric spine and scoliosis surgery at NewYork-Presbyterian Morgan Stanley Children’s Hospital, “It can have different etiologies. It can be something kids are born with because they have an extra piece of vertebra or an abnormal connection between the vertebrae. It could be something that results from a neurological problem like cerebral palsy or something that’s related to another syndrome like muscular dystrophy. It’s also associated with other diseases like cardiac disease or kidney disease. But in the majority of patients, we don’t really know the cause and we call it idiopathic scoliosis. And idiopathic scoliosis can span the whole spectrum from infantile to juvenile to adult scoliosis. But the most common type of scoliosis is what we call adolescent idiopathic scoliosis [AIS].”

AIS can present in children aged 10 to 18 but occurs most frequently in preteens and more commonly in girls. Patients present with an asymmetry in their spine, a bump in their back, or a difference in their shoulder height, and it’s thought to be related to a growth spurt common for children in this age group. Most patients are otherwise healthy with no prior medical history. If the curve of the spine is less than 25 degrees, treatment may not be necessary. The general recommendation is that the child be observed by his or her clinician every four to six months to determine whether the curve has worsened. If the child’s spinal curve is between 25 to 45 degrees, bracing may be the next step. Although the brace cannot correct a curve, it is effective for preventing it from progressing.  

Bracing for Scoliosis                                                         
According to Frank La Marca, MD, director of the section of spine surgery in the University of Michigan’s department of neurosurgery, “The utility of a brace is controversial in some cases, but if a child is skeletally immature (that is, still growing) and the curve does not present characteristics of which you feel it would progress rapidly, we would opt for a brace. The problem with a brace, and the reason it’s controversial, is that many children don’t wear them. They get them fitted but then compliance is the main issue.”

The goal of a brace is twofold, La Marca says. It can serve to decrease progression of the curve until the child reaches an age where surgery can be performed or it can help them achieve skeletal maturity with a curve that has not progressed, thereby avoiding surgery altogether. “The bracing is always a problem because young, active children just don’t like them, and you can’t blame them,” he notes. “They have better braces now—braces that also address the location of the curve and so forth—but regardless of how the brace is made or applied, it’s still a compliance problem.”

“It’s much easier to brace a kid with one or two years of growth remaining than it is to brace a kid with 12 years of growth remaining—their entire childhood. So we less commonly use bracing in younger children,” adds Vitale.

It is believed that AIS may be genetic—about 30% of patients have a family history of the condition. To assess the likelihood of curve progression in patients diagnosed with AIS, the ScoliScore AIS Prognostic Test was recently developed. The multimarker genetic test analyzes DNA extracted from saliva samples and, after comparing them with genetic markers from clinical studies, assigns a numerical score to a patient predicting a low, medium, or high chance of curve progression.                 

“It’s a very new test,” notes Vitale. “We’re still trying to figure out how accurate and sensitive it is, but I think it has the potential to really change the climate because it’s clear that not every patient will progress yet we end up now recommending a brace if a kid’s in that range. On the flipside, it’s fairly clear that some of these kids will progress even with the brace. The brace is not 100% effective, so I think the ScoliScore will allow us to better target appropriate treatment—maybe not to brace some kids, to be more vigilant about bracing other kids, and maybe even to intervene surgically with a kid if we feel that [he or she is] at a very high risk of progression.”   

Conventional Surgery
When the spinal curve is greater than 50 degrees or an increase of 10% each year is noticed in adolescents, surgery is recommended. This is relatively rare, with about three to five of every 1,000 children with scoliosis needing surgery. The surgical mainstay for treating scoliosis is spinal fusion in which the curve of the spine is straightened using stainless steel or titanium rods, hooks, wires, or screws. Small bone fragments are then placed over the spine, helping to fuse the spine into its proper position as it grows.
           
Instrumentation without fusion is a surgical procedure in which rods are attached to the spinal cord to stabilize it without fusing together the vertebrae. The parts of the spine that are fused are no longer able to grow, making instrumentation without fusion preferable for children. For the best results following this procedure, the child must wear a brace full time.

“We’ve understood in recent years how important it is not to do spine fusions in very young kids because of the harm that spine fusion can result in, in terms of the development of the lungs,” Vitale says. “As it turns out, if you have a spine fusion at a very early age, you end up not developing the sort of lungs that you need to support adult life, and it can be a real problem with the quality of life with lung function. Even early death has been described in people who had an early fusion.”

Nevertheless, instrumentation without fusion is “a pretty big operation,” says La Marca. “It is really like an internal brace, almost and that changes normal biomechanical properties of anybody’s spine, so it obviously affects flexibility and the way they walk and the way they breathe. But kids are very adaptable and can go on to lead a normal life and participate in sports and so forth after the surgery.”

Surgical History                                                           
From the 1960s to the 1980s, the Harrington rod was the gold standard in repairing spine curvature. Anchored to each end of the spine, it effectively “pulled” out and straightened all the curves. The Harrington rod was beneficial for the most part, but as La Marca notes, “It also created other problems because it eliminated the normal curves that the spine has. The spine typically has curves that in the thoracic and lumbar areas help balance out the spine and when you straighten it out entirely, you push the patient forward, so you would see problems of straight back. Also the fixation wasn’t the greatest, so as the child grew further, we’d have what they called the crank shaft phenomenon where the spine would continue to rotate even though it was straight. This caused deformities in the rib cage. But [the Harrington rod] was what we had at the time and it did its job.”

This rod is no longer used in scoliatic surgery in North America. Now physicians are able to correct AIS with more precise control using pedicle screws that permit surgeons to manipulate each vertebral segment independently. Using pedicle screws, “in their application in a thoracic and lumbar spine, [surgeons] can actually control each vertabra and rotate them and move them with much more strength than what we used in the old days,” La Marca notes. The pedicle screws provide such a refined correction and stabilization for scoliosis that surgeons are now using them to correct deformities in adults, including those in their 70s—patients who back specialists would never have considered operating on in the past.          

There are two main approaches to the spine when performing scoliosis surgery. There is the posterior approach, in which a surgeon makes a midline incision along the back of the spine, and the anterior approach, in which the surgeon makes an incision through the front rib cage and abdominal cavity. Both approaches have their distinct advantages and disadvantages, but generally for AIS patients, the posterior approach is more commonly used, as it can be applied to a wider range of curve types. The anterior approach is slightly more limited and is used when only a single thoracic or lumbar curve needs to be straightened.          

Minimally Invasive Surgery
For both children and adults with scoliosis, there is the burgeoning option of minimally invasive surgery. Although still in the experimental phase for scoliosis patients, this type of surgery has shown great promise, minimizing the blood loss and muscle damage often associated with traditional open surgical procedures. Surgeons performing minimally invasive surgery on patients with degenerative disc disease have achieved fusion and stabilization between the vertebral segments with good outcomes and quicker recovery rates. Conventional surgery for scoliosis often includes stripping the muscles off the spine to allow for the positioning of the rods and screws. This can weaken the back and lead to chronic pain. With minimally invasive surgery, the incisions are small and no stripping of the muscles is needed; surgeons are able to navigate their instruments between the layers of muscle fiber. Scarring is minimal and patients are often able to go back to their day-to-day lives within two to six weeks.

La Marca, one of the pioneering surgeons who performs minimally invasive surgery on scoliosis patients at the University of Michigan Health System, says that “translating this technology to a deformity is obviously a lot more challenging. There are several centers that have been working on this and we’re working also in cooperation with companies that produce spinal instrumentation because it’s all about the tools most of the time not just the idea, and we’ve had some pretty good results. It has a long way to go yet, but we’re hopeful that it will continue to improve, [that] this may become the standard of care just like it has for gallbladder surgery.”

The best candidates for minimally invasive surgery are those with the smallest curves (approximately 60 degrees) with the least amount of degeneration and the most flexibility. Because it is important for surgeons to be able to view the nerves during surgery, the procedure is not ideal in patients who have chronic leg pain due to compression. Interestingly, some surgeons have been performing a “hybrid” surgery in which they perform minimally invasive surgery on curves in the lumbar region combined with an open procedure in the thoracic region. Currently, the safest location for minimally invasive back surgery is the lumbar region, but this may change as the technology advances.                    

A minimally invasive procedure called extreme lateral interbody fusion has been successfully used in patients who have scoliosis or other debilitating lower back conditions. The procedure is particularly effective in helping adult patients with severe back pain. Navigating through 2-inch incisions made to the lateral flank region, surgeons remove damaged or deformed disk material and place a spacer known as the cage between the vertebrae, causing the bone to “line up.” For scoliosis patients, a rod is sometimes placed as well, inserted by “punching” through the skin. Patients are often able to walk a few hours after the procedure and are typically discharged the next day—unheard of in conventional back surgery.

“Again,” notes La Marca, “these [procedures] are experimental. It takes a surgeon who has experience both in deformity, as well as minimally invasive, and there’s not a lot of them—most either go one way or the other. At the university [of Michigan], we’ve got the advantage of having experts in both fields, so working together we’ve been able to do that. I don’t want to send the message out that minimally invasive is the right thing to do because then people, through all the hype, get the impression that doing an open is wrong. Minimally invasive is promising, but we’re being very selective and it could take years before we can say what’s right or what’s wrong.”

— Carolyn Gutierrez is a freelance writer based in New York City.