Introduction of Robotics in Spinal Surgery

The correct placement of pedicle screws is a critical aspect of thoracolumbar posterior instrumentation. Incorrect placement can result in severe complications, such as neurological deficits or vascular injuries.

The risks associated with incorrect pedicle screw placement are due to the proximity of critical structures such as the spinal cord, nerve roots, and associated blood vessels. In the past, manually-guided pedicle screw placement has had a high rate of inaccuracy.

While accuracy has improved with the use of fluoroscopy, the risk of nerve and vascular injury still exists. The use of intraoperative fluoroscopy also carries the risk of increased radiation exposure for both the surgeon and the surgical staff, especially during minimally invasive spinal procedures.

As a result of the increased risk of inaccurate pedicle screw placement and the potential harm from radiation exposure, there has been a need for innovation in spinal surgery. This has led to the development of robotics in the field.

The significant increase in published literature on the use of robots in spinal surgery in recent years indicates a growing interest in the potential benefits of using robots, including improved consistency, reduced complications, and shorter hospital stays.

Robotic Systems

Multiple choices are available when it comes to robotic systems utilized in spinal surgery.

• Renaissance® Surgical Guidance Robot by Mazor Robotics: The process depends on the fusion of the pre-operative CT scan with the intraoperative fluoroscopy. By doing so, the robot can direct surgeons according to the preoperative CT scan and 3D planning.
• Mazor X by Mazor Robotics: It operates similarly to the Renaissance Robot.
• ROSA® by Medtech: Robot-assisted instrumentation with 3D planning can be achieved using intraoperative fluoroscopy or CT scan, without the need for a preoperative CT scan. Real-time tracking of instruments is made possible by utilizing an image-guided reference and a navigation camera.

The robotic arms of both systems have the ability to move in multiple planes.

Radiation Exposure Time

Literature has shown that there is no significant difference in the duration of intraoperative radiation exposure between the freehand and robotics procedures.

Operative Time

Previous studies have demonstrated that freehand procedures tend to take slightly longer, although the extent of the difference varies across different studies.

Accuracy

When comparing freehand fluoroscopy-guided surgery to robot-assisted percutaneous operations, the robot-assisted procedures achieve 100% accuracy, whereas the freehand procedures have an accuracy rate of 98.6%. The accuracy rate of screw placement is 97.3% with ROSA assistance, which is higher than the 92% accuracy rate achieved with freehand placement.

The accuracy of the robot may be affected, for example, by dislocation relative to the patient, which can result from the surgeon’s decision to use a “bed mount” for the robot, as well as cannular skidding that can occur due to degenerative facet joint hypertrophy.

Pedicle screw placements can be more challenging in pediatric patients because their pedicles are shorter. Nevertheless, robotic assistance in surgery demonstrated accuracy rates between 92.8% and 97.6%, and the use of prone positioning for imaging was associated with improved accuracy.

Length of Stay

Literature has stated that for freehand procedures, the average time required to return to ambulation is 39.7 hours, while for Renaissance-assisted surgery, it is 36.2 hours. Minimally invasive approaches that result in less muscle dissection and trauma to soft tissues can contribute to a shorter hospital stay and quicker recovery, regardless of the use of a robot.

Complications

According to literature, post-operative infections have been reported in 2.7% of robot-guided procedures, which is significantly lower than the reported 10.7% in open non-robotic surgeries.

Robot-guided procedure complications can be related to technical problems with the robot, such as hardware or software failure and fluoroscopy-to-CT registration failure, or cannula skidding, which resulted in misplaced screws.

Clinical complications associated with the robot included hemothorax, cerebrospinal fluid (CSF) leakage, and pulmonary embolism. When compared to robot-assisted procedures, freehand procedures have a higher incidence of dural tears.

The inaccuracy of pedicle screw placement using conventional freehand methods and the subsequent clinical complications have been a driving force for technological innovation.

There is a growing interest in the use of robot-assisted instrumentation in spine surgery, and its integration into routine clinical practice. At present, the FDA has only approved Mazor, ROSA, and the recently added Excelsius as robotic systems for providing guidance on pedicle screw trajectory.

Reducing radiation exposure to the surgical team is becoming increasingly important, and the use of robot-assisted instrumentation may provide a potential advantage in this regard.

Robotics is still in its early stages of development in spine surgery, both in terms of industrial advancements and surgeon experience. To ensure patient safety and widespread use, it is crucial to continuously innovate and improve the robotics technology in spine surgery.

This includes reducing sensitivity to soft tissue pressure, enhancing work volume, improving registration, and developing surgeon-friendly software. Accuracy and complication rates of robotic screw placement are currently considered acceptable.

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