Advanced imaging technology bests fluoro as spinal surgery aid

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Using a 3D image-guided system to help place screws in the spines for spinal fusion procedures results in safe and accurate surgery with a decrease in the number of misplaced screws and subsequent injuries, seen in more traditional operations, according to a study in the Dec. 9 online edition of the Journal of Neurosurgery: Spine.

Physicians at the Mayo Clinic in Jacksonville, Fla., and colleagues reported that after implanting 1084 pedicle screws in 220 patients, surgeons found a nerve injury rate of less than 1 percent.

Additionally, less than 1 percent of the screws in the study were considered to be significantly misplaced, compared to a reported nerve injury rate of up to 8 percent and a misplacement rate of up to 55 percent using standard technology. As well, they reported a re-operation for removal of a misplaced screw has been reported in other surgical literature to be as high as 6.5 percent but occurred in less than half of 1 percent of all patients, according to the researchers.

“Using 3D image-guided technology to help us place these screws results in a much better outcome for our patients,” said Mayo Clinic neurosurgeon Eric Nottmeier, MD, the study's lead investigator. “In addition to the decreased incidence of nerve root injury, this technology allows us to place larger screws into the spine, which can also increase the success rate of the operation.”

The technology uses a special camera on a computer that uses infrared light to track a surgical instrument in 3D space, according to the researchers. The surgeon places the instrument on the patient's spine and navigates the spine using the computer. The surgical instrument is used to determine the best entry point and trajectory for each screw. An image-guided screwdriver is used to place a screw.

In most other institutions, pedicle screws are placed using a freehand technique or by fluoroscopy, which uses x-rays to capture a 1D image on a television screen of the process of screw placement. Not only is the image less detailed, but both patients and the operating room staff can be exposed to radiation and must use lead clothing for protection, Nottmeier said.

He noted that almost all patients in this study were given a CT scan following surgery, so that a radiologist could independently determine how well the screws were placed.

“This technique allows us to have the best view possible of the vertebrae as we operate,” Nottmeier said.