The European Robotic Spinal Instrumentation (EUROSPIN) Study

Introduction A decade ago, minimally invasive surgery (MIS) was considered a promising development in spine surgery, yet the value of the pioneering technologies was questionable. With the growing number of experienced MIS surgeons, the influx of evidence in favour of MIS is rapidly increasing. This makes a compelling argument towards MIS offering distinct clinical benefits over open approaches in terms of blood loss, length of stay, rehabilitation, cost-effectiveness and perioperative patient comfort. Due to the limited or inexistent line-of-sight in MIS procedures, surgeons need to rely on imaging, navigation, and guidance technologies to operate in a safe and efficient manner. Therefore, a plethora of new and ever improving navigational systems have been developed. These systems allow a consistent level of safety and accuracy, on par with results achieved by very experienced free hand surgeons, with a reasonably short learning curve. Computer-based navigation systems were first introduced to spine surgery in 1995 and while they have been long established as standards in certain cranial procedures, they have not been similarly adopted in spine surgery.

Designed to overcome some of the limitations of navigation-based technologies, robot-guided surgery has become commercially available to surgeons worldwide, like SpineAssist® (Mazor Robotics Ltd. Caesarea, Israel) and the recently launched ROSA™ Spine (Zimmer-Biomet, Warsaw, Indiana, USA). These systems are rapidly challenging the gold standards. SpineAssist®, and its upgraded version, the Renaissance®, provides a stable drilling platform and restricts the surgeon's natural full range of motion to 2 degrees of freedom (up/down motion and yaw in the cannula). The system's guidance unit moves into the trajectory based on exact preoperative planning of pedicle screws, while accounting for changes in intervertebral relationships such as due to distraction, cage insertion or changes between the supine patient position in the preoperative CT and the prone patient on the operating table. Published evidence on robot-guided screw placement has demonstrated high levels of accuracy with most reports ranging around 98% of screws placed within the pedicle or with a cortical encroachment of less than 2 mm.4 Although the reliability and accuracy of robot-guided spine surgery have been established, the actual benefits for the patient in terms of clinical outcomes and revision surgeries remain unknown. We have recently conducted cohort studies that showed some evidence that robotic guidance lowers the rate of intraoperative screw revisions and implant related reoperations compared to free hand procedures, while achieving comparable clinical outcomes. We now want to assess these factors, among others, on a higher level of evidence. We aim to conduct a prospective, multicenter, multinational controlled trial comparing clinical and patient reported outcomes of robotic guided (RG) pedicle screw placement vs. navigated (NV) vs. free hand (FH) pedicle screw placement using pooled data from three centers.

Study Design The European Robotic Spinal Instrumentation (EUROSPIN) study is a prospective, international, multicentre, pragmatic, open-label, non-randomized controlled trial comparing the effectiveness of three techniques for pedicle screw instrumentation, namely RG, NV (CT-, O-Arm, or 3DFL-based), and FH. Following the baseline evaluation, patients will receive one of the three treatments, and will subsequently be followed up for 24 months (Figure 1). The primary analysis will be conducted using the 12-month data.

Sample Size Calculation It was determined that, to detect an intergroup difference of 5% in the primary endpoint, 205 patients are required per group to achieve a power of 1 - beta = 0.8 at alpha = 0.05. The incidence rates were based on the published literature, with an approximated incidence rate of the primary endpoint of 0% for the intervention and 5% for the control group. Because the study protocol is in line with the normal clinical follow-up of most centers, a low dropout rate is expected. This led to a minimum total sample size of 615 patients.

Monitoring An epidemiologist from the sponsor institution will organize an initiation monitor visit at every participating center before starting recruitment. This monitor visit will check whether all study staff are properly trained and the delegation of tasks are well documented (complete Investigator Site File, training and delegation logs). An additional audit will be carried out at 6 months after initiation of recruitment to check whether source documentation and eCRF documentation is similar. Throughout the entire study additional queries by the monitor are send to the investigator in the data capturing system to ensure proper data capturing.

• Transpedicular Instrumentation (Procedure): Transpedicular screw placement and instrumentation

Primary outcomes

• Revision Surgery for a Malpositioned Pedicle Screw [12 months]: We defined the primary endpoint as required revision surgery for a malpositioned or loosened pedicle screw within the first postoperative year.

Secondary outcomes

• Intraoperative Screw Revision [Intraoperative]: Revision or redirection of a placed screw during the same general anesthesia session
• Duration of Surgery [Intraoperative]: Duration of Surgery in minutes
• Length of Hospital Stay [Through hospital stay (From admission to discharge of the hospital stay in which the primary surgery was carried out)]: Length of Hospital Stay in days (Defined as from admission to discharge, during the hospital stay in which the primary surgery was carried out)
• Radiation Dose (DAP) [Intraoperative]: Radiation Dose as DAP (Dose Area Product, cGy cm2)
• Estimated Blood Loss [Intraoperative]: Estimated Blood Loss (ml)
• Need for Blood Transfusion [Through hospital stay (From admission to discharge of the hospital stay in which the primary surgery was carried out)]: Need for blood transfusion during the hospital stay (Defined as from admission to discharge, during the hospital stay in which the primary surgery was carried out)
• Intraoperative Complications [0 weeks]: Intraoperative Complications
• Postoperative Complications [6 weeks]: Postoperative Complications
• EQ-5D-3L [2 years]: EQ-5D-3L (Health-related quality of life) EuroQOL-five dimensions 3-level version measures health-related quality of life. The scale is subdivided into an index, ranging from 0 to 1 and normalized to population-specific values, and a "thermometer" or visual analogue scale, ranging from 0 to 100. The two subscores are not combined towards a single score. Higher values represent a better health-related quality of life in both subscores.
• NRS Back Pain Severity [2 years]: Numeric Rating Scale (NRS) of back pain severity The scale ranges from 0 to 10. Only integers are available to choose from. Higher values represent a higher amount of pain. There are no subscales.
• NRS Leg Pain Severity [2 years]: Numeric Rating Scale (NRS) of leg pain severity The scale ranges from 0 to 10. Only integers are available to choose from. Higher values represent a higher amount of pain. There are no subscales.
• Oswestry Disability Index [2 years]: Oswestry Disability Index (ODI) for functional impairment

Other outcomes

• Frequency of Use of Analgetics [2 years]: Frequency of use of analgetics (daily/weekly/not regularly)
• Satisfaction With Symptoms [2 years]: Satisfaction with symptoms (satisfied/neutral/dissatisfied)
• Smoking Status [2 years]: Smoking status (active/ceased/never)
• Working Status [2 years]: Working status (able to work/unable to work)
• Return to Work [2 years]: Return to work (number of weeks/not yet)
• Overall Rate of Reoperations [2 weeks]: Overall rate of reoperations

Sex: All, ages: 18 Years to any

Inclusion Criteria

* Informed consent
* Thoracolumbar pedicle screw placement
* Indication for surgery: Degenerative pathologies (stenosis, spondylolisthesis, degenerative disc disease, recurrent disc herniation), infections, tumors, fractures, trauma
* Age ≥ 18

Exclusion Criteria

* Deformity surgery
* >5 index levels

Participant flow

Outcome results

• Revision Surgery for a Malpositioned Pedicle Screw (Primary), Number, Patients: Robot Guided 4; Navigated 7; Freehand 4
• Intraoperative Screw Revision (Secondary)
• Duration of Surgery (Secondary)
• Length of Hospital Stay (Secondary)
• Radiation Dose (DAP) (Secondary)
• Estimated Blood Loss (Secondary)
• Need for Blood Transfusion (Secondary)
• Intraoperative Complications (Secondary)
• Postoperative Complications (Secondary)
• EQ-5D-3L (Secondary)
• NRS Back Pain Severity (Secondary)
• NRS Leg Pain Severity (Secondary)
• Oswestry Disability Index (Secondary)
• Frequency of Use of Analgetics (Other pre specified)
• Satisfaction With Symptoms (Other pre specified)
• Smoking Status (Other pre specified)
• Working Status (Other pre specified)
• Return to Work (Other pre specified)
• Overall Rate of Reoperations (Other pre specified)

Adverse events

Time frame: 1 year

Serious adverse events by term

Other adverse events by term

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• Results publication: Staartjes VE, Molliqaj G, van Kampen PM, Eversdijk HAJ, Amelot A, Bettag C, Wolfs JFC, Urbanski S, Hedayat F, Schneekloth CG, Abu Saris M, Lefranc M, Peltier J, Boscherini D, Fiss I, Schatlo B, Rohde V, Ryang YM, Krieg SM, Meyer B, Kogl N, Girod PP, Thome C, Twisk JWR, Tessitore E, Schroder ML. The European Robotic Spinal Instrumentation (EUROSPIN) study: protocol for a multicentre prospective observational study of pedicle screw revision surgery after robot-guided, navigated and freehand thoracolumbar spinal fusion. BMJ Open. 2019 Sep 8;9(9):e030389. doi: 10.1136/bmjopen-2019-030389. PMID 31501123

• Study Protocol and Statistical Analysis Plan (PDF, 2019-09-08)

• Victor E Staartjes, MD, PhD, Study director, Department of Neurosurgery, University Hospital Zurich
• Granit Molliqaj, MD, Principal investigator, Department of Neurosurgery, Hôpitaux Universitaires de Genève
• Enrico Tessitore, MD, Study chair, Department of Neurosurgery, Hôpitaux Universitaires de Genève