In one-year follow-up study, Mayfield Clinic neurosurgeons find minimally invasive fusion technique safe and effective

CINCINNATI – Patients who underwent a new type of minimally invasive fusion of the lower spine experienced outcomes that were similar to those of other fusion techniques, neurosurgeons at the Mayfield Clinic have found. The study was published in the June issue of the SAS Journal, the official journal of the International Society for the Advancement of Spine Surgery.

The researchers studied the clinical outcomes, one year after surgery, of the first 50 patients who underwent the minimally invasive fusion procedure of the lower spine at the Mayfield Clinic, beginning in June 2005. The procedure, known as presacral axial lumbar interbody fusion (presacral ALIF), utilizes a novel surgical route to stabilize the spine in patients who suffer from degenerative disc disease, spondylolisthesis, and spinal stenosis.

Patients in the study showed a 50 percent improvement in clinical outcome scores after one year, while 88 percent demonstrated fusion. Only one significant complication relating to the surgical approach was reported.

The findings are important because the presacral ALIF procedure involves a smaller incision and less tissue disruption when compared to conventional open fusion techniques. The procedure is still considered experimental and is not covered by all insurance companies.

Not all patients with spinal problems are suitable candidates for the procedure. The authors emphasize that selecting the most appropriate treatment for each individual patient is the most important factor in successful spinal surgery outcomes.

Presacral ALIF is a minimally invasive approach to the lumbosacral spine, which includes two vertebrae (L4 and L5) of the lower (lumbar) spinal column and the first vertebra (S1) of the sacrum (tailbone). The procedure requires an incision of less than one inch near the top of the buttock and utilizes long, narrow instruments to fixate the spine.

William Tobler, MD, a neurosurgeon with the Mayfield Clinic and Associate Professor of Neurosurgery at the University of Cincinnati College of Medicine, was the principal investigator. Co-investigators were Robert Bohinski, MD, PhD, a Mayfield neurosurgeon and Assistant Professor of Neurosurgery at UC, and Viral Jain, MD, Assistant Professor of Orthopedic Surgery at UC and Cincinnati Children’s Hospital Medical Center.

"Our fusion results were outstanding, and the procedure’s safety was excellent," said Dr. Tobler, who is also Director of Neurosurgery at The Christ Hospital. "It is an important procedure and especially applicable for some patients with spondylolisthesis, a debilitating condition in which one or more vertebrae slip forward."

"Our study of presacral ALIF affirms the effectiveness of this procedure," said Dr. Bohinski. "This type of fusion adds to the armamentarium at our disposal for the treatment of spine problems. It is a viable option for patients whose medical history and physiology make them good candidates for this particular fusion approach."

Presacral ALIF, marketed as AxiaLIF® and developed by TranS1, Inc., a medical device firm based in Wilmington, N.C., utilizes the axial corridor to the spine. The surgeon approaches through the space in front of the sacrum, which has no muscles or neural elements. Surgery is performed through a 10-millimeter tube.

"This is a paradigm-changing procedure," Dr. Tobler says. "With the AxiaLIF® procedure, there is less tissue disruption compared to conventional open procedures. This can result in reduced recovery time and discomfort for the patient. We have found that up to 10 percent of patients are able to undergo the procedure on an outpatient basis."

Of the 50 patients who underwent presacral ALIF in the study, only one patient developed a major complication, a perforation of the rectum and pre-sacral abscess. The patient recovered completely. But as a result of the complication, which occurred early in the study, patients with a history of local surgery, inflammation, radiation treatment, trauma or infection were subsequently excluded.

The percentage of significant complications, at 2 percent, was less than or comparable to those associated with other fusion techniques reported in the medical literature.

Meanwhile, the rate of fusion success with presacral ALIF was comparable to fusion of other techniques. Exact comparisons could not be made because over the years fusion assessments have been made in different ways. In Dr. Tobler’s study, an independent neuroradiologist determined fusion by studying both plain x-rays and high-resolution CT scans.

Dr. Tobler and colleagues say they will continue following patients treated with the presacral ALIF technique. "Long-term followup will help us further define the effectiveness, fusion rates and complications of this minimally invasive type of fusion," he said.

Each of the four other fusion techniques follows a different route to the spinal column. They are:

-anterior lumbar interbody fusion (ALIF), in which the surgeon approaches through the front (the abdomen);

-posterior lumbar interbody fusion (PLIF), in which the surgeon approaches from the back of the lower spine;

-transforaminal lumbar interbody fusion (TLIF), in which the surgeon approaches from the back of the lower spine;

-and extreme lateral lumbar interbody fusion (XLIF), in which the approach is from the patient’s side.

The authors also have many years of experience with conventional spinal-fusion surgery and minimally invasive modifications of these approaches. Dr. Bohinski stressed that, "Not all patients with spinal problems affecting the lower lumbar segments are candidates for the AxiaLIF® procedure or other minimally invasive spine procedures. Further comparative trials are necessary to determine which procedures are best to treat specific spinal problems. In some cases, combinations of these procedures may be the best answer."

In addition to Drs. Tobler and Bohinski, the following Mayfield Clinic neurosurgeons also perform various spinal fusion procedures: Arthur Arand, MD, Steven Bailey, MD, Paul Cohen, MD, Bradford Curt, MD, Charles Kuntz, IV, MD, Tann Nichols, MD, Thomas Saul, MD, Bradbury Skidmore, MD, and Hwa-shain Yeh, MD.

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Disclosure: Dr. Tobler is a consultant and recipient of research grants from TranS1, Inc., and Zimmer Spine and is a stockholder in TranS1. Drs. Bohinski and Jain have no financial disclosures.

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The Mayfield Clinic is recognized as one of the nation's leading physician organizations for clinical care, education, and research of the spine and brain. Supported by 20 neurosurgeons, five neurointensivists, an interventional radiologist, and a pain specialist, the Clinic treats 25,000 patients from 35 states and 13 countries in a typical year. Mayfield's physicians have pioneered surgical procedures and instrumentation that have revolutionized the medical art of neurosurgery for brain tumors and neurovascular diseases and disorders.

The procedure requires an incision of less than one inch near the top of the buttock and utilizes long, narrow instruments to fixate the spine.