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Using a three-dimensional (3D) image-guided system helps to place screws in the spines of patients results in safe and accurate surgery

In the December 9, 2008 online edition of the Journal of Neurosurgery: Spine, Mayo physicians published the largest study yet using 3D image-guided technology to place screws in the spine for spinal fusion procedures. The screws are used to stabilize the spine in patients who suffer from collapsed discs or compressed nerves.

In the Mayo study, the research team analyzed that after implanting 1084 “pedicle” screws in 220 patients, surgeons reported a nerve injury rate of less than 1 percent. Additionally, less than 1 percent of the screws in this study were considered to be significantly misplaced. That compares 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, 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 one percent of all patients.

According to Mayo Clinic neurosurgeon Eric Nottmeier, M.D., the study’s lead investigator, “Using 3D image-guided technology to help us place these screws results in a much better outcome for our patients.” “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. 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.

“This technique allows us to have the best view possible of the vertebrae as we operate,” Dr. Nottmeier says, almost half of the patients in the Mayo study had a previous spine surgery.

Dr. Nottmeier says, In most other institutions, pedicle screws are placed using a freehand technique or by fluoroscopy, which uses X-rays to capture a one-dimensional 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. 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.

Based on the success of the technique, the image guidance system is now used in all spinal screw operations at Mayo Clinic’s campus in Florida.

Source: Mayo Clinic