To robot or not? 15 key thoughts from spine surgeons


Robotic technology for spine surgery has evolved significantly over the past two decades in an attempt to improve accuracy, reduce radiation exposure and create better outcomes. But systems still come at a significant expense. Are they worth it now?

Srinivas Prasad, MD, department of neurological and orthopedic surgery at Thomas Jefferson University in Philadelphia, and Eric W. Nottmeier, MD, St. Vincent's Spine and Brain Institute, were on a panel discussing robotic technology and computer-assisted guidance at the North American Spine Society Annual Meeting last month.


Here are 15 key thoughts from the presentation.


1. Measuring pedicle accuracy focuses on anatomical accuracy; where is the pedicle screw with respect to the pedicle when everything is done? Is there a breach or not? How much of a breach is there? There has been some exploration in the literature to find these answers, but more work is necessary.


"Correlating [breaches] with neurological consequences is I think still not something that has been done," said Dr. Prasad. "[Additionally], accuracy may impact fusion rate and it may impact adjacent level disease. There are a lot of other collateral consequences of inaccurate screw placement that haven't been that well characterized."


2. A large meta-analysis from 2007 shows 130 studies with 37,337 pedicle screws placed. There was 91.3 percent screw placement accuracy overall; 90.3 percent accuracy without navigation and 95.2 percent accuracy with navigation. There were 35 different assessment methods "showing how heterogeneous this is," said Dr. Prasad. Most studies didn't talk about that angle of the breach, and the study authors didn't recommend one method over another.


3. As the level of technology increased, the level of accuracy tightened and increased with time. "With better technology in the thoracic spine or accuracy, maybe there is some value in a subset of cases," said Dr. Prasad. There is another system approved and available in Europe today that shows promising advancement on other current technologies for surgical guidance.


4. The three-dimensional guidance technology available in the United States today shows benefit in the literature over two-dimensional navigation and conventional surgery. The study was published in The Journal of Neurosurgery: Spine in 2014 and showed with the three-dimensional navigation, cervical, thoracic and lumbar spine surgeries all reported 90 percent or higher accuracy; the two-dimensional fluoroscopy navigation and conventional accuracy were all significantly lower. The overall accuracy for each area was:


• Conventional accuracy: 68.1 percent overall
• Two-dimensional fluoroscopy navigation accuracy: 84.3 percent overall
• Three-dimensional navigation: 95.5 percent overall


5. The literature consists primarily of meta-analyses, which have several challenges:


• They don't have the same definition for "accuracy" so it's hard to go back and compare.
• There are variable accuracy assessment methods, including CT and O-arm
• There are varied definitions for what constitutes a "breach."
• Studies have limited revision and neurological deficit data.
• There are heterogeneous patient populations and conditions.
• Study authors have disparate inclusion criteria for navigation


However, the work is still valuable. "Meta-analyses, though structurally flawed, suggest that pedicle screw accuracy is better with navigation than freehand or conventional techniques," said Dr. Prasad.


6. Dr. Prasad found with the studies that there may be some value to the cervical pedicle screw placement with navigation, but the most value potential is in the thoracic spine. "There appears to be a value in all regions, but perhaps the most in the thoracic spine," he said.


7. There is a learning curve to incorporating surgical navigation. A prospective cohort reported in the Chinese Medical Journal followed two surgeons for two years. The perforation rate was initially a little higher, but declines with time. "Within a year, the surgeon had enjoyed improvement," said Dr. Prasad. "It raises the possibility that it makes the surgeon more consistent."


8. There is a time cost associated with implementing the robotic technology. It takes surgeons longer in the beginning. The same study from the Chinese Medical Journal compared time for navigated and non-navigated spine surgeries. When surgical navigation was introduced, the time was significantly higher for both surgeons but dropped with experience to a quicker time than even the non-navigated procedures. "You get faster using it and you get more accurate," said Dr. Prasad.


9. Saving time in the operating room leads to cutting costs significantly. Dr. Nottmeier reported on operating room cost and time. Simple cases cost around $29 per minute in the OR and complex cases cost around $80 per minute, for an average cost of $65 per minute. Shaving time from the total OR time makes a difference; reducing 30 minutes of time could save around $2,000.


10. Current systems appear to reduce radiation, according to recent studies. However, the radiation exposure to surgeons is one factor and radiation exposure to patients is another. The robotic guidance systems can reduce radiation exposure to the surgeon, but it's important to keep the patient in mind as well.


11. Robotic systems are expensive, but can they be cost-effective? The technology runs anywhere from $500,000 to more than $1 million. "This is a significant capital expense to the hospital," said Dr. Nottmeier. "It's not surprising there has been a lot of scrutiny lately, especially with image guidance and its cost." Hospitals are under more financial constraint and payers are scrutinizing costs more. There are some payers denying image guidance for select procedures.


However, despite the significant capital expense and payment pressures, Dr. Nottmeier found significant cost savings could exceed original cost of the technology within the first two years of implementation.


12. There was significant marketing success with the Da Vinci Robot, but are hospitals having the same success with robotic technology and image guidance for spinal procedures? "I may have a handful of patients each year that come to my practice that want their surgery done with image guidance, but they are definitely not lining up outside the door wanting image guided spinal surgery and don't have near the response that we saw with the Da Vinci Robot," said Dr. Nottmeier. "I wouldn't say the use of image guidance or marketing image guidance will significantly increase the patient volume at your hospital."


13. Hospital costs can be lowered for revision surgeries due to misplaced screws if the surgeon is more accurate. A study published in 2010 in Open Orthopaedics Journal showed no revisions with the navigation system in 100 fusions versus 3 percent of 100 patients who underwent non-navigated spinal fusion. The average cost for revision surgery for patients with misplaced screws was $23,800 per case. In the study, the hospital spent $71,400 on revision surgery for the non-navigated group.


14. Average cost of cannulated pedicle screws is about $250 more than non-cannulated screws. Dr. Nottmeier published a study on using tree-dimensional image guidance to percutaneously place pedicle screws without bioplanar fluoroscopy or Kirschner wires. By performing the technique without cannulated pedicle screws, the hospital can save:


• Single level procedures: $1,000
• Two-level procedures: $1,500
• Three-level procedures: $2,000


Theoretically, if a surgeon uses mage guidance to perform 200 single-level minimally invasive lumbar fusions per year and is able to decrease OR time by 15 minutes and use non-cannulated screws, the surgeon could produce around $400,000 in total savings per year.


15. At Mayo Clinic, Dr. Nottmeier examined reimbursement for stereotactic computer-assisted volumetric (navigational) procedures, intracranial, extracranial or spinal. There were 167 cases reported and the hospital billed for $282,875; they collected $119,089 and produced a cost savings of $500,000 per year with image guidance.


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