Many spinal surgeries require the use of implants called pedicle screws to stabilize the spine, and precise positioning is critical for a successful surgery. “Compared to conventional free-hand techniques, both robotic-assisted navigation and the use of augmented reality have demonstrated superior accuracy,” said Darren R. Lebl, MD, MBA, a spine surgeon and director of research at HSS, and principal investigator of the study. “Our study is the first to directly compare RAN to AR with respect to screw placement precision.”

Over the last decade, numerous robotic-assisted navigation and augmented reality systems designed for spine surgery have emerged. “In addition to enhanced accuracy, the potential advantages of both technologies include reduced radiation exposure and provide for improved safety in spine surgery,” Dr. Lebl notes. “A growing number of major medical centers nationwide are using at least one of these technologies.”  

RAN involves robotic guidance of surgeon-operated instruments. A robotic arm, along with 3D images of the patient’s anatomy and navigation technology similar to GPS, enables the surgeon to perform a minimally invasive procedure that is planned ahead of time on advanced software. AR-assisted spine surgery superimposes 3D images of a patient’s anatomy onto the surgeon’s visual field during surgery via an augmented reality headset. A preoperative CT scan of the patient’s spine is used to plan and perform the surgery.

The HSS study included 212 adult spine surgery patients who had a total of 1,211 pedicle screws placed using either robotics (108 individuals received 827 screws) or augmented reality (104 patients received 384 screws) between June 2020 and October 2023. They underwent surgery in the lumbar and/or sacral spine for degenerative spinal conditions. One experienced surgeon performed all of the robotic cases, while two other experienced spine surgeons used the AR system.

The position of each pedicle screw was assessed after surgery based on either CT scan or 3D fluoroscopy using the Gertzbein-Robbins classification system, which assigns a grade of A, B, C or D to evaluate accuracy. The HSS researchers considered Grades A and B to be acceptable. The A rating is assigned to screw placement completely within the pedicle, a bony structure on the vertebra that protects the spinal cord. Grade B, still acceptable, is assigned to a screw that is 2mm (1/16 inch) outside of the desired location. In the study, any screw with a Grade C or D would be deemed unacceptable.

After surgery, two independent spine surgeons assigned a grade to all the pedicle screws. No significant difference was found between RAN and AR screw placement in terms of accuracy, with 99.6% of RAN screws rated as Grade A or B, and 98.7% of AR screws classified as A or B. Overall, 92.6% of the screws achieved the top Grade A rating.

“Our results confirmed excellent accuracy for both techniques, making both robotics and AR safe tools for accurate positioning of lumbosacral pedicle screws,” Dr. Lebl said. “However, a higher rate of Grade A screws was seen in the RAN group, potentially highlighting superior precision for robotics.”

Dr. Lebl believes the study represents the future of spine surgery. “Our team at HSS is working to advance spine surgery to make it safer, less invasive and more precise, with less radiation exposure,” he explains. “Our team has already implemented spine surgery with real-time confirmation of implant accuracy in the operating room so that everything is optimally positioned before the patient goes to the recovery room. In the future, more focus will be on decisions regarding the timing and type of surgery, and the actual execution of the surgery will become much more automated.”

What follows are some highlights from the meeting:

Intravenous versus Oral Administration of Acetaminophen Perioperative to Instrumented Lumbar Fusion: A Single-Center, Randomized Controlled Trial

In patients undergoing certain orthopedic surgeries, giving intravenous (IV) acetaminophen for pain relief has been shown to have fewer side effects and potentially lower risk than opioids but is associated with higher costs than oral acetaminophen. In this single-center, randomized controlled trial, investigators led by Darren R. Lebl, MD, MBA, and Celeste Abjornson, PhD, prospectively evaluated clinical outcomes of IV versus oral acetaminophen after circumferential lumbar fusion. One hundred patients between the ages of 18-85 were randomly assigned to one of the two groups (50 in each) and were included in the study. There was a specific dosing regimen that started within the three hours prior to surgery and continued for the next 48 hours. Patients were able to access supplemental opioid analgesics as needed. The researchers found that morphine consumption was significantly lower for the IV acetaminophen group compared with the oral acetaminophen group within the first 48 hours post-operatively. The average daily morphine usage after 48 hours for those who received the IV acetaminophen regimen was also significantly lower. The research suggests that IV acetaminophen is a safe and effective supplement to opioid-based pain management after surgery, and that it provides a promising option for pain control.

Authors: Gregory Paschal; Fedan Avrumova; Philip Paschal; Ellen M. Soffin, MD, PhD; Joseph Nguyen; Federico P. Girardi, MD; Andrew A. Sama, MD; Frank P. Cammisa Jr., MD; Darren R. Lebl, MD, MBA; Celeste Abjornson, PhD, (HSS)

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Racial Disparities in Outpatient Anterior Cervical Discectomy and Fusion and Cervical Disc Replacement

Recent reports have suggested disparities within cervical spine surgery, including lower utilization rates and worse perioperative outcomes for Black patients. In this retrospective cohort study, a team led by HSS resident Troy B. Amen sought to assess whether these disparities also exist for outpatient cervical spine surgery. Using data collected by the American College of Surgeons National Surgical Quality Improvement Program between 2010 and 2019, the team looked at patients who underwent primary anterior cervical discectomy and fusion (ACDF) or cervical disc replacement (CDR) and stratified them by race and ethnicity. They categorized procedures as inpatient or outpatient based on length of stay. They found that, overall, Black patients were significantly less likely to undergo ACDF (5.9%, vs. 10.6% of white patients) as well as CDR (19.9%, vs. 26.1% of white patients) as outpatients. Between 2010 and 2019, these disparities increased, even when adjusting for other factors. The findings highlight the need for renewed intervention by orthopedic surgeons and policymakers to address inequalities in outpatient care.

Authors: Troy B. Amen; Patawut Bovonratwet, (HSS); Samuel S. Rudisill (Rush Medical College); Lauren Barber; Yusef Jordan, (HSS); Abhinaba Chatterjee (Weill Cornell Medicine); Jung Kee Mok (UNC Chapel Hill); Nathan Varady; Sheeraz Qureshi, MD, MBA (HSS)

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Improving Racial and Ethnic Disparities in Ambulatory Surgical Center Utilization for Anterior Cervical Discectomy and Fusion

Although racial and ethnic disparities within the field of spine surgery have been documented, the link between the recent emergence of ambulatory surgical centers and access to these procedures in the outpatient setting isn’t known. A study led by HSS resident Troy B. Amen sought to assess disparities in the use of these outpatient surgical centers among white, Black, and Hispanic patients having spine surgery. The investigators also looked at how racial differences have changed between 2015 and 2018. Using data from the Healthcare Cost and Utilization Project New York State Ambulatory Database, the researchers looked at differences in same-day discharges in patients having anterior cervical discectomy and fusion (ACDF). They found that during this time, Black and Hispanic patients were significantly less likely to undergo ACDF surgery at an ambulatory center compared with white patients, but that these disparities lessened over time. They note that these improvements are encouraging and may help counteract previously documented disparities in spine surgery in the inpatient setting, although additional research is needed to confirm that.

Authors: Troy B. Amen, (HSS); Abhinaba Chatterjee (Weill Cornell Medicine); Sheeraz Qureshi, MD, MBA (HSS)

Predictors of Non-improvement After Minimally Invasive Lumbar Spine Surgery

Minimally invasive surgery of the lumbar spine is associated with good clinical outcomes, but a small number of patients may not improve, or may even worsen, after this surgery. A study led by HSS research fellow Junho Song sought to identify predictors of patients who are not likely to improve. The study included 448 patients who underwent minimally invasive transforaminal interbody fusion, laminectomy, or microdiscectomy at HSS between 2017 and 2021. At follow-up of at least six months after surgery, the patients were categorized as better, the same, or worse. A total of 66 patients reported no significant improvement; among these, 35 patients reported worsening after surgery, and the rest reported no change. Patients who did not fare as well were more likely to be older or obese. The researchers found that smoking was also a factor for those who didn’t do as well, likely due to changes in metabolic systems and local vasculature caused by tobacco use. The investigators say these findings provide valuable evidence that may be useful for improving the selection of patients to undergo minimally invasive spine surgery. They may also help to establish clearer patient expectations for those undergoing this procedure.

Authors: Junho Song; Pratyush Shahi; Kasra Araghi; Robert Kamil; Dimitra Melissaridou; Sidhant Singh Dalal (University of Arkansas for Medical Sciences); Daniel Shinn; Sheeraz Qureshi, MD, MBA; Sravisht Iyer, MD (HSS)

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Robotics Reduces Radiation Exposure in Minimally Invasive Lumbar Fusion Compared to Navigation

For minimally invasive spine surgery, navigation and robotics technologies have helped reduce surgeons’ exposure to ionizing radiation. Studies have compared radiation exposure during surgery using robotics or navigation to procedures using traditional fluoroscopy, but none have compared robotics and navigation to each other. This study compared the two techniques in terms of fluoroscopy time and radiation dose for minimally invasive transforaminal lumbar interbody fusion (MI-TLIF). The study included 111 patients in the robotics cohort and 133 patients in the navigation cohort. The investigators, led by HSS research fellow Pratyush Shahi, found that for both one- and two-level TLIFs, the fluoroscopy time for surgical procedure, total fluoroscopy time, and total radiation dose were significantly less with robotics compared to navigation. For one-level TLIFs, the overall time of radiation exposure was also lower.  Overall, time in the operating room was similar, with robotic procedures lasting longer but requiring less time for setup and image capture. Based on these findings, the investigators say robotic surgery leads to a significant reduction in radiation exposure both for the surgeon and the patient compared to navigation, but multicenter prospective trials are needed to confirm these findings.

Authors: Pratyush Shahi, Sidhant Singh Dalal (University of Arkansas for Medical Sciences); Junho Song; Daniel Shinn; Robert Kamil; Kasra Araghi; Sheeraz Qureshi, MD, MBA (HSS)

Many spinal surgeries require the use of implants called pedicle screws to stabilize the spine. Precise positioning of these screws is critical for a successful outcome. “Two-dimensional biplanar radiographs [BPR] have been the gold standard to confirm pedicle screw placement in spine fusion surgery for many years. However, when utilizing BPR, there is the potential that a two-dimensional image alone will not properly demonstrate the successful placement of a screw,” said Darren Lebl, MD, a spine surgeon at HSS and principal investigator of the study. “As an alternative, three-dimensional intraoperative imaging systems are now available, offering improved visualization.”

Dr. Lebl and colleagues set out to compare the accuracy of BPR versus 3D imaging when assessing intraoperative pedicle screw placement. “Our study is the first to compare the differences in intraoperative biplanar radiography and 3D imaging for pedicle screw accuracy in thoracic and lumbar cases using robotic technology,” Dr. Lebl noted.

Investigators analyzed data from 103 patients who underwent spinal fusion by a single surgeon from 2019 to 2022. Pedicle screw placement was assessed with both intraoperative BPR and 3D imaging in each case.

“CT scans taken after surgery were compared to the findings of intraoperative BPR and 3D imaging to detect either false-positive or false-negative readings,” explained Fedan Avrumova, BS, an HSS clinical research coordinator who presented the study at the AAOS meeting. “False positive findings are instances when BPR imaging suggests the screw was not in an acceptable position, while in fact a more advanced 3D image (intraoperative 3D scan or postoperative CT scan) showed the screw to be in an acceptable position. Conversely, a false negative instance was when a BPR image led one to believe or looked as though the screw was in an acceptable position, when in fact a more advanced 3D image or post-operative CT scan showed that it was in fact not acceptable.”

Postoperative CT imaging revealed a clinically significant number of patients who had false-negative and false-positive screw placement readings on BPR. However, screw position shown on intraoperative 3D imaging was found to be much more accurate, Avrumova added.  

“Based on our study, BPR imaging may lead one to think a screw is acceptable when in fact it is not, and also may miss many screws that are not in fact acceptable. In our study, it was approximately one percent of cases where this occurred. However, for surgeons and centers that implant hundreds and thousands of screws per year, this is going to result in a significant clinical impact for many people,” Dr. Lebl noted. “Even one misplaced screw can have a significant impact for a patient, a surgeon, and a hospital system. Therefore, based on these findings, we suggest that for intraoperative confirmation of screw position 3D imaging may soon represent a new standard of care.”

Authors: Fedan Avrumova, BS; George Gorgy, MD; Philip K. Paschal, MS; John A. Carrino, MD, MPH; Darren R. Lebl, MD (HSS)

Cervical disc disease, or degenerative disc disease, is the progressive deterioration of spinal discs and arthritic changes in the facet joints. During this procedure, surgeons will test the safety and efficacy of removing discs at two levels and implanting an artificial disc device at each level of the cervical spine between the vertebrae where the disc was removed. The artificial disc will serve to stabilize the spine while preserving greater motion than a conventional fusion surgery.

Previous patients who underwent artificial disc replacement reported greater improvements in their pain relief, mobility, and activities of daily living than those who underwent spinal fusion surgery, the standard treatment. It is less invasive but as effective as spinal fusion surgery, however the procedure using this particular device has not been validated through a clinical trial to date.

“The concern with doing a fusion type operation is that over the long term the other discs have to accommodate for the motion lost at the fused level,” said Darren Lebl, MD, a minimally invasive spine surgeon who is leading the research at HSS. Over time, the increased mechanical demand on the surrounding vertebrae can make the discs in the region more vulnerable to additional degeneration.

“We do know very clearly that fusion is limiting motion,” Dr. Lebl added. “The concept of the two-level disc replacement is to preserve motion with two moving mechanical devices.”

To be eligible for participation, patients must be between the ages of 18 and 69 years and have received a diagnosis of radiculopathy (impingement of the nerves in the spinal column) or myelopathy with radiculopathy, a more severe form of damage to the spinal cord involving vertebrae in the neck, defined at cervical discs C3 through C7. Patients must also be experiencing symptoms associated with disc problems, such as neck or arm pain, decreased muscle strength and abnormal reflexes that has not responded well to conservative treatments such as rest, heat, physical therapy and pain relievers.

The trial will include at least 390 patients once enrollment is complete. Patients will receive regular evaluations for two years after surgery and may be examined in periodical follow-up visits for a total of seven years.

For more information about the trial at HSS, contact Philip Paschal at paschalp@hss.edu or 917-260-4285.

The use of robotics and computer navigation in spinal surgery is rapidly expanding. Increasing numbers of hospitals and spine surgeons are adopting the technology, which aims to enhance precision, accuracy and predictability, according to Darren R. Lebl, MD, MBA, a spine surgeon at Hospital for Special Surgery (HSS).

He believes the technologies have reached a tipping point. “I think they’re good enough to greatly improve what we do in terms of minimally invasive surgery,” said Dr. Lebl. “In my own practice, I’ve seen the benefits for patients in terms of a shorter hospital stay, quicker mobility and decreased healing times.”

The main barriers to implementing the new technologies include additional time in the operating room (OR) and concerns regarding the accurate placement of pedicle screws. Many spinal surgeries require the use of hardware such as pedicle screws to stabilize the spine, and precise positioning is critical.

Dr. Lebl and colleagues at HSS launched a study to evaluate the accuracy of robotic- and navigation-assisted technology in screw placement. They also set out to determine the extra time needed in the OR, noting that there is a learning curve for a surgical team when implementing a new system.

The study, “K-wireless Robotic and Navigation Assisted Pedicle Screw Placement in Adult Degenerative Spinal Surgery,” was presented today at the American Academy of Orthopaedic Surgeons (AAOS) 2021 annual meeting. The results were also published in The Journal of Spine Surgery in June 2021.

“Our main finding was that the screw positioning was very accurate, and the additional time needed to adopt these technologies into practice was small,” Dr. Lebl noted. “In our study, the speed of robotic screw placement showed improvement within the first several cases.”

The research included 65 adult patients (mean age of 59) with lumbar degenerative pathology who underwent a robotic-navigated posterior spinal fusion from June 2019 to July 2020. A total of 364 instrumented pedicle screw implants were planned robotically. A single orthopedic surgeon performed the surgeries using the Medtronic Mazor X Stealth Edition system.

The robotic/navigation time in the OR, screw placement times and positioning times were recorded. Following screw placement, all patients had intraoperative 3D fluoroscopy, and screw trajectory was compared to a preoperative CT image. Reasons for conversion from robotic navigation to k-wire or freehand technique were recorded.

“The spine surgeon in the study had more than 10 years of experience and had placed thousands of screws with previous techniques, such that he had alternatives if it was determined that robotic-assisted placement of a screw would not be possible,” said Fedan Avrumova, BS, a research assistant in the HSS Spine Service. “It is important to note that the robot can be a valuable ‘assistant’ but does not replace surgical experience and good judgment.”

The mean time per screw placement was 3.6 minutes robotically versus 3.7 minutes freehand, with a significant decrease in time between the first 10 and last 10 cases: 5.5 minutes versus 2.3 minutes. Setting up the robotic navigation system in the OR showed a decrease in time between the first 10 and last 10 cases: 9 minutes versus 6 minutes.

“Many spine surgeons recognize the value of the technology, but the concern has been the additional time needed in the OR,” Dr. Lebl said. “As we got further along in our study, we found that it actually saved time in the OR. The benefits of the technology easily outweigh the additional time needed in the early implementation of the system because the accuracy is unmatched.”

“When we evaluated outcomes, we found zero complications and no revision surgeries were needed,” Ms. Avrumova noted. “The surgical team learned how to use the robot successfully and became more efficient with robotic implantation when compared to conventional minimally invasive and conventional open techniques. In addition, the accuracy was as good as, if not better than, open or conventional minimally invasive techniques, which we confirmed with a 3D imaging study in every patient during surgery.”

“Just a few years ago, there were two FDA-approved robots to assist in spine surgery. Now there are five or six,” said Dr. Lebl. “The technology is revolutionizing the way we do things, and it’s a very exciting time to be a spine surgeon.”

Study Title: “K-Wireless Robotic and Navigation Assisted Pedicle Screw Placement in Adult Degenerative Spine Surgery”

Authors: Fedan Avrumova, Kyle Morse, Madison Rae Heath, Roger F. Widmann, Darren Richard Lebl. All at HSS.

Disclosures: Dr. Lebl has received research support from Medtronic.

By the time she saw a doctor after the lockdown lifted, she could barely walk for 10 minutes without having to stop. Sometimes, the pain shot down her leg. “I couldn’t do much physical activity,” she recalls. “Simple tasks like standing and doing dishes became painful. At times it felt like someone was pulling both ends of the nerve in my left leg really tight.”

After seeing several doctors, Amanda, who lives in Bay Shore, Long Island, was referred to Darren R. Lebl, MD, MBA, a spine surgeon at Hospital for Special Surgery (HSS) who practices in both Manhattan and at HSS Long Island in Uniondale. Around the time she saw Dr. Lebl, he had just completed his 100^th minimally invasive, robotic-assisted spine surgery.

The robotic system would be used in Amanda’s surgery to correct a spinal condition called spondylolisthesis, which causes one of the lower vertebrae of the spine to slip forward onto the bone directly beneath it. This was putting pressure on a nerve.

The first step for Amanda was a virtual visit with Dr. Lebl. After she felt comfortable talking to him remotely, she went to his office for an examination and for an explanation of her condition and what surgery would entail. He explained that he performed the procedure with assistance from robotic technology in the O.R., which allowed for an ultraprecise surgery.

“Over the past few years, advances in surgical technique and technology have enhanced the accuracy and predictability of spinal surgeries, and patients like Amanda benefit,” said Dr. Lebl. “Advances such as computer navigation, 3D imaging and robotic-assisted surgery have been tremendous in terms of allowing us to do less invasive, yet more precise surgeries.”

The use of very small incisions preserves muscles and other structures surrounding the spine, so patients generally experience less pain after surgery, a shorter hospital stay and a quicker return to activities compared to traditional open surgery, he explains.

Amanda had a spinal fusion in December 2020. “A vertabra in her lower spine had shifted or ‘slipped’ forward, causing impingement on a nerve root,” Dr. Lebl explained. “Through a minimally invasive technique, we were able to realign her spine and take the pressure off the nerve to relieve her pain.”

Dr. Lebl uses the robotic system to treat conditions such as Amanda’s, as well as a herniated disc, spinal stenosis or scoliosis. Prior to surgery, detailed images of the patient’s anatomy are obtained to plan and customize the procedure for each individual patient. Preoperative CT and MRI scans create a three-dimensional map of the patient’s spine that is used during surgery. Dr. Lebl performs the procedure with small incisions and robotic guidance, always maintaining full control. Visualization of the surgical field is provided by a computer console that displays the high-definition 3D image of the patient’s anatomy in real time.

Many spine surgeries, including Amanda’s, require the use of hardware such as titanium screws to stabilize the spine, and their accurate placement is critical to the success of the surgery. “The robotic arm, along with 3D imaging and navigation technology similar to GPS, allow for pinpoint accuracy in the placement of hardware, and this is a major advantage of the system,” Dr. Lebl says.

Amanda said the thought of having spine surgery was a frightening prospect, especially during the pandemic. It would be the first surgery she ever had, and she was worried about pain. But it was never an issue. “I was very surprised at how little pain I had after surgery,” she says. “The whole time in the hospital, I never had real pain, it was more like discomfort. The nurses would come in and ask, ‘What is your pain level on a scale of 1 to 10?,’ and for me it was ‘1 to 3.’ Everyone around me was very impressed with how quickly I recovered and how well I’m doing.”

Amanda had her surgery on a Friday and went home on Monday. Now, about six weeks after the procedure, pain-free, she goes to physical therapy and is back to her online classes as a full-time grad student. She is enrolled in a four-year program to receive a Doctor of Audiology degree and looks forward to the day in-person classes and her volunteer work in an audiology clinic can resume.

Dr. Lebl notes that the use of robotics in minimally invasive spine surgery requires special training and advises patients to choose a physician with ample experience in the technique. He also recommends that patients choose a surgeon with whom they feel comfortable and who takes the time to answer all their questions. When considering where to have surgery, hospitals that perform a high-volume of such procedures have been shown to have the best outcomes.