Abstract
Brief Problem Robot-assisted (RA) techniques with pedicle implant placement have demonstrated improved accuracy and safety in thoracolumbar surgery, but their application in the cervical spine is less described. Although multiple robotic systems are currently approved for spinal fusion procedures, most studies focus on thoracolumbar instrumentation. As a result, cervical RA procedures remain underdiscussed regarding safety and efficacy.
Innovation A total of 8 patients (4 women [50%]) with a mean age of 63.1 years (range 49–75), in whom 50 cervical pedicle screws were placed, were identified. Preoperative diagnoses included degenerative (n = 2), tumor (n = 2), trauma (n = 2), and deformity (n = 2). The 50 pedicle screws were distributed at C1 (8 screws), C2 (8), C3 (6), C4 (6), C5 (6), C6 (8), and C7 (8). There was 1 inferior grade B breach on a C7 screw without clinical sequelae that was repositioned for a 98% total screw accuracy.
Clinical Relevance RA cervical pedicle screw placement appears to be a safe and effective adjunct in complex cervical spine surgery. The proposed stepwise workflow is reproducible and adaptable and includes several specific recommendations: the use of a Mayfield Halo, intraoperative computed tomography for registration, lower drill rates per minute, and additional cannulas. Further studies need to validate these findings in larger cohorts and evaluate long-term patient outcomes.
Level of Evidence 4.
Introduction
Spinal instability is commonly treated with surgical techniques that aim to provide biomechanical stabilization while avoiding damage to critical adjacent structures such as large vascular structures, spinal cord, and nerve roots. Accurate placement of hardware, particularly pedicle screws, is essential for mechanical stability, as screws are inserted into the pedicle of the vertebral body.1 Robotic guidance in minimally invasive surgery (MIS) of the spine has shown significant improvements in the accuracy of pedicle screw placement,2–4 particularly in regions where precision is critical. The cervical spine presents unique challenges due to the small size of cervical pedicles and the proximity of critical neurovascular structures, including the vertebral artery and spinal cord.5 This results in a narrow margin of error, making accurate and precise screw placement essential. However, the technical complexity of cervical pedicle screw (CPS) insertion, coupled with the high rates and catastrophic consequences of screw misplacement, has historically limited its widespread use.6,7
While the use of robot-assisted (RA) techniques has been well documented in the thoracolumbar spine with superior safety and surgical outcomes,1,4 their application in the cervical spine remains underexplored. Robotic systems offer the potential to enhance precision and reliability in creating accurate screw trajectories, minimizing the risk of severe complications. However, the current robust workflows with these platforms focus on thoracolumbar instrumentation and techniques, while their use in the cervical spine remains underreported.
At present, there is no detailed, stepwise workflow described in the literature for RA cervical spine surgery. Thus, this report aims to fill this gap by presenting a reproducible workflow for these procedures, focusing on technical nuances and the necessary modifications for optimal application.
Methods
This is a retrospective single-center series of consecutive patients who underwent RA CPS placement. All patients presented with cervical spine conditions deemed to require more robust posterior fixation in the cervical spine and the need for CPSs. Perioperative complications, radiographic results, and clinical outcomes were collected. Pedicle screw accuracy was graded based on the Gertzbein-Robbins (GR) classification.1,8 This research was approved by the medical center’s Institutional Review Board, and all patients consented to be involved in research prior to enrollment.
Surgical Technique
Positioning
Patients are placed in a Mayfield 3-pin head holder or halo ring and then positioned prone on a Jackson table with a rigid head positioning system (Levo Head Positioning System, Mizuho OSI, Union City, CA). A generous amount of tape is used to secondarily secure the head holder to the Jackson table at 2 different vectors on either side to remove any “wobble” and increase head and neck rigidity (Figure 1). The tape was both visible and tactile. Securing the ring to the bed with tape allowed for minimal to zero movement in the frame during RA CPS. The neck is then prepped and draped, and the posterior cervical spine is exposed in usual fashion.
Patient positioned prone in a lower profile halo ring secured to the bed with ample tape.
Robotics Setup
The robotic guidance platform is fixated to the patient using a spinous process clamp at the distal instrumented level (Medtronic Mazor X Stealth Edition, Minneapolis, MN). An intraoperative computed tomography (CT) scan is obtained (Medtronic O-arm, Minneapolis, MN), and this imaging is used for intraoperative planning of the CPSs on the software station (Figure 2).
Planning of cervical pedicle screw trajectories on the robotics software platform after completion of the intraoperative computed tomography.
Pedicle Screw Placement
The robotic arm is then moved into position along the planned trajectory, and pilot holes are placed at each level using a high-speed 3.0 diameter × 30 mm length decorticating drill to the appropriate depth (Figure 3a and b). All holes are made first, while the robotic system is most accurate immediately after registration, out of anticipation and concern that subsequent tap and screw placement through highly corticated cervical pedicle bone would still minimally shift the spine.
(A) Intraoperative image demonstrating robot-assisted drilling of the cervical pedicle screw trajectories through the robot arm guide. (B) On-screen view of the accurate high-speed drill down the planned pedicle screw trajectory.
Great care is taken not to exert excessive pressure in making these tracts so as not to push the spine out of registered alignment. Additionally, while the drill has a maximum speed of 75,000 RPM, the drill bit is used at a significantly lower rate of speed, 5,000–10,000 rpm, and advances slowly, to maintain some tactile feel and to mitigate concerns and sequelae of a possible breach. Once all drill tracts are made, the tracts are tapped undersized by 1 mm. This can now be performed either down the robotic arm with tubular inserts to guide the smaller tap shaft (MetRx tubes, Medtronic, Minneapolis, MN) or by a gentle freehand technique to follow the large 3.0 mm tract. A 3.5 or 4.0 mm diameter CPS with an appropriately selected length is then placed in a similar fashion.
Confirmation Imaging
An intraoperative CT scan is obtained to ensure appropriate positioning of all instrumentation. The surgical goals are then accomplished, and closure proceeds in the usual fashion.
Clinical Example
A 63-year-old man with a medical history of hepatocellular carcinoma presented to our institution’s emergency department for evaluation of neck pain with progressive paresis and numbness. A magnetic resonance image demonstrated a new large lytic lesion (4.0 × 3.8 × 2.2 cm) centered at the C7 spinous process with posterior extraosseous extension into the epidural space, resulting in severe spinal canal stenosis and spinal cord compression consistent with metastatic hepatocellular carcinoma. The patient was subsequently scheduled for a C4 to T2 posterior instrumented fusion and resection of the extradural mass at C7.
The patient was positioned as described in the technique above, and the spine was exposed in the usual fashion. The robotics platform was then docked, and the following pedicle screws were placed with robotic assistance: 3.5 × 24 at C4, 3.5 × 24 at C5, 3.5 × 24 at C6, 5.5 × 30 at T1, and 6.5 × 30 at T2. O-arm imaging was obtained to confirm the appropriate positioning of the screws. The tumor was then resected, rods placed, and closure proceeded in the usual fashion. Follow-up imaging confirmed stable instrumentation without interval complications (Figure 4).
Anterior-posterior and lateral postoperative x-rays of a patient with C4–C6 cervical pedicle screws.
Results
A total of 8 patients underwent RA CPS placement. Demographic analysis showed a mean age of 63.1 (range 49–75) with 50% women (4 patients). Diagnoses were degenerative (2 patients), tumor (2 patients), trauma (2 patients), and deformity (2 patients). A total of 50 pedicle screws were placed, distributed at C1 (8 screws), C2 (8 screws), C3 (6 screws), C4 (6 screws), C5 (6 screws), C6 (8 screws), and C7 (8 screws).
The GR classification is a scale from A to E, with A indicating that the pedicle is within the pedicle with no breach whatsoever, B indicating 0 to 2 mm cortical breach, C indicating >2 to 4 mm cortical breach, and D indicating 4 to 6 mm cortical breach, and E indicating >6 mm cortical breach or outside the pedicle. There was 1 inferior grade B breach based on the GR classification at a C7 screw without clinical sequelae that were repositioned for a total screw accuracy of 98% (Figure 5). There were no medial or lateral breaches seen on confirmatory intraoperative CT imaging and no neurological or vascular injuries. Over a mean follow-up of 7.5 months, there has been no implant loosening or complications noted.
Computed tomography scan demonstrating accurate placement of robot-assisted cervical pedicle screws.
Discussion
Surgical management of spinal instability aims to provide biomechanical stabilization while avoiding damage to critical adjacent structures.1 Historically, lateral mass screws have been the favored posterior cervical plating option given the larger surface area of the lateral mass with relatively decreased proximity to important neurovascular structures compared with pedicle screws.9 However, it has become widely understood that lateral mass screws are more prone to pull-out forces than CPS, and there is worse bony purchase.10 CPS fixation is considered the most rigid fixation method of the cervical spine and has many biomechanical advantages.11–13 Thus, for certain cervical pathologies that require strong fixation, such as trauma, oncological situations, and severe deformities, CPS fixation may be preferred.
Robotic guidance in MIS of the spine has shown significant improvements in the accuracy of pedicle screw placement and complication profile relative to conventional methods of cervical screw placement, including GR classification, operative duration, intraoperative blood loss, and radiation exposure,1–4 although their application in the cervical spine remains underexplored. The technical complexity of CPS insertion and the high risk of severe complications secondary to screw misplacement have historically limited its widespread use.6,7 Robotic systems offer the potential to enhance precision and reliability in creating accurate screw trajectory tracts, guiding taps and drivers, and minimizing the risk of such complications. A 2023 review by Beyer et al1 found that MIS RA screw placement in the cervical spine was associated with decreased operative time and blood loss compared with computer-assisted or fluoroscopic techniques. Furthermore, this same review reported only 1 (0.9%) postoperative complication associated with robotic assistance, which involved a surgical site infection.1 There were no breaches or revisions in the robotic group for the included studies, suggesting that RA screw placement demonstrated lower complication rates and revision rates compared with conventional fluoroscopy.1 A subsequent systematic review and meta-analysis published by Peng et al14 examined the safety and accuracy of RA CPS placement.14 A total of 6 studies were included with 148 patients in the RA CPS group, demonstrating statistically significantly higher perfect screw accuracy in the RA group compared with the freehand technique, as well as intraoperative blood loss, radiation dose, complication rates, and length of hospitalization.
The first case report of RA cervical screw placement was published by Tian in 2019.15 The author used the TiRobot system (TINAVI Medical Technologies Co., Ltd., Beijing, China) to place posterior unilateral C1 to C2 transarticular screw fixation as part of an occiput to C2 posterior instrumented fusion in a middle-aged man with atlantooccipital deformity and instability. This screw was placed safely with no intraoperative or postoperative complications. Fan et al16 published a randomized controlled trial in which patients requiring cervical surgery were randomized into screw fixation through either conventional fluoroscopy or RA surgery with the Tianji Robot (TINAVI Medical Technologies Co., Ltd., Beijing, China).16 Sixty-six patients were randomly assigned to the fluoroscopy group, and 61 patients were assigned to the RA group for a total of 390 cervical screws, with 94.9% of the screws overall deemed as acceptable placement (grades A and B on the GR scale). The RA group had statistically significantly better screw accuracy (0.83 mm planned screw deviation vs 1.79 mm) and GR scale (98.9% vs 91.2%), less blood loss, and shorter length of stay, but similar surgical time.
Kisinde et al published a retrospective cohort of 12 consecutive patients receiving cervical pedicular screw placement with robotic assistance using the Mazor XTM Stealth Edition robotic guidance platform (Medtronic Navigation Louisville, CO; Medtronic Spine, Memphis, TN; formerly Mazor Robotics, Caesarea, Israel).17 Eighty-eight consecutive pedicle screws were placed, with 100% of the screws being either grade A or B on the GR scale, with 15.9% being grade B and none causing any clinical consequences. Even more recently, Zhou et al18 demonstrated in a retrospective cohort study that when comparing 52 patients with traumatic cervical pathology requiring surgery, 26 in the RA and 26 in the conventional freehand group, 96.2% of the CPS were grade A or B on the GR scale compared with 87.4% of those in the freehand group.18 Furthermore, this study also demonstrated that the RA group had statistically significantly shorter postoperative hospital stay with similar minimal complication rates and clinical outcomes to the freehand group.
Our report presents a detailed reproducible workflow using current iterations of instruments and demonstrates high accuracy with robotic guidance. Our case series of 50 CPSs demonstrates a 98% overall CPS accuracy with only 1 screw having an inferior grade B breach that was redirected with no clinical sequelae. This accuracy level is in line with the upper level of reported RA CPS literature.
Over the course of our series, we developed a more refined workflow and made technical changes that led to intuitive improvements. A halo ring with a Mayfield adapter was utilized instead of the 3-pin Mayfield head holder to provide better positioning freedom on the Jackson table. This also allowed more room to then secure the ring to the bed with tape and reduce any kind of “wobble” in the frame. We found that the use of intraoperative CT instead of preoperative CT reduced registration difficulties due to bony shadows caused by the skull base or teeth. Given the higher risks involved with cervical spine surgery compared with the thoracolumbar region, it is imperative that the surgeon carefully reviews preoperative imaging, including the intraoperative CT, to take into account any anatomical variants or aberrant pathways of important neurovascular structures that the patient might have. We modulated the high-speed drill to reduce its RPM and reduced downward pressure to create a more tactile feel similar to a pedicle finder. Furthermore, the addition of cannulas to guide the cervical tools down the robotic arm also made it less likely to deviate from the preplanned trajectory, given the small margin for error seen in the cervical spine with pedicle screws. One of these cases was done percutaneously, while the others were all performed open. The current robotic systems are all prone to registration errors due to retractor-induced movement or aggressive soft tissue manipulation once the robot is registered. To mitigate retractor-based concerns and reduce the risk of registration errors, we found it helpful to make additional incisions outside of the primary incision or extend the incision to avoid excessive retraction or tension on the surrounding soft tissue. Overall, this series adds to the current literature of robotic-assisted CPS fixation to support its safety, feasibility, and overall accuracy.
Limitations
This technical case report is limited by a small sample and limited follow-up that may not fully capture long-term outcomes, complications, or instrumentation durability. Due to current limitations in instruments, the technique of RA CPS placement varies widely, and this technique can differ compared with other studies. Lastly, this report reflects the experience of a single surgeon at a single institution, which may not represent broader surgical practices or patient populations.
Future Directions
Despite our modest case series, we hope to conduct further studies as our patient sample and experience increase. There appears to be a strong need in the literature for a study that outlines a realistic learning curve for the spine surgeon interested in performing RA CPS placement. Furthermore, an important consideration to a novel surgical technique is the cost-effectiveness of its utilization. The cost-effectiveness of robotic spine technology has been reported with conflicting results.19,20 A recent pre-release article from earlier this year analyzed the economic viability of robotic systems in the operating room and reported a financial breakeven within the systems’ 7-year useful life and requiring 33.8 years to recover initial investment costs with optimal conditions.21 However, for those surgeons who already work at an institution that has access to a navigated spinal robot system, leveraging the robot for certain cervical cases as well might make the investment in the robot more cost-effective. Therefore, on top of its safety, efficacy, and potential learning curve, this technique’s cost-effectiveness will be important to encourage others to consider this new technique in their own practice.
Conclusion
RA CPS placement in cervical spine surgery offers the potential for improved accuracy and precision for these challenging implant trajectories and can lead to improved safety and patient outcomes. The proposed stepwise workflow for RA cervical spine fixation is precise, reproducible, and adaptable. There remains a need for more refined tools better adapted to robotic systems for improved workflows in the cervical spine.
Footnotes
Funding The authors received no financial support for the research, authorship, and/or publication of this article.
Declaration of Conflicting Interests The authors report no conflicts of interest in this work.
Disclosures Dr. Martin H. Pham reports personal fees from Medtronic, Globus, and Carlsmed outside the submitted work. Hayley Granberg, Kareem Khalifeh, Timothy Kim, and Mohamad Yman have nothing to disclose.
- This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2025 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.
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