Researchers at The Johns Hopkins University, Baltimore, USA, have developed a software programme that works with currently-available procedures to assist a surgeon’s determination of which vertebra they are working on, thus improving accuracy and safety. Results from its first clinical evaluation show that the LevelCheck software achieves 100% accuracy in 26 seconds. Details of the study have been published in the April issue of the journal Spine.
“Wrong-level spine surgery is never meant to happen,” says Jeffrey Siewerdsen, a professor of biomedical engineering at Johns Hopkins and a member of the Armstrong Institute for Patient Safety and Quality. “But it happens nearly four times a week in the USA.”
Surgeons go to great lengths to get their procedures right and to avoid mistakes that are costly to patient health. They can result in pain, require follow-up surgeries, and create instability or degeneration of the spine, according to Jean-Paul Wolinsky, an associate professor of neurosurgery and oncology at Johns Hopkins and co-author of the study.
Before a standard spinal operation, patients receive a diagnostic computed tomography (CT) or magnetic resonance imaging (MRI) scan that the surgeon uses to plan the surgery. Once the patient is on the operating table, often days later, the surgeon typically counts down from the skull or up from the tailbone to determine which vertebra to operate on, often marking the patient’s anatomy with thin metal pins. These pins are visible in an X-ray image taken in the operating room to verify the target site. However, the doctor’s initial planning on the preoperative scan is not visible in the X-ray image leaving room for error, particularly when working on challenging cases exhibiting missing or extra vertebrae, a loss of anatomical landmarks from previous surgeries, or other anomalies.
LevelCheck uses a standard desktop computer outfitted with a graphics processing unit (of the type commonly used for computer games) to align a patient’s 3D preoperative CT image with the 2D X-ray image taken during surgery. The result is an X-ray image showing the pins that act as landmarks for the surgeon, overlaid with the planning information from the CT scan.
“LevelCheck does not replace the surgeon’s expertise. It offers helpful guidance and decision support, like your GPS,” says Siewerdsen.
To test its accuracy, the team analysed pre- and intraoperative images of 20 consecutive patients who had undergone spine surgery. By shifting the images, they simulated 10,000 surgeries and measured how long the software needed to correctly line up the images 100% of the time at 26 seconds.
“This study is the first to demonstrate that LevelCheck works with real patient images,” says Siewerdsen. “It shows that the software can deal with challenges like changes in patient anatomy and the presence of surgical tools in the X-ray image.”
Sheng-Fu Lo evaluated the results to find what factors can cause the software to fail. “The software does not always get it right if it is stopped early,” says Lo, “but given 26 seconds or more, LevelCheck found the right level every time.”
“We cannot eliminate the possibility of wrong-level surgeries,” says Wolinsky, “but this is an additional level of security—an independent check—that works quickly within our standard surgical workflow. Although LevelCheck in its current form requires a preoperative CT scan for most patients, the benefit is well worth it.”