Use of Robotic Assistance in Complex Spine Cases

Abstract

To date, the role of robot-assisted spine surgery (RASS) has been that of a pedicle screw insertion device. In this application, it has proven effective and safe. An additional benefit is decreased radiation exposure to the operating room team. There are many exciting future applications of RASS with the advent of new end effectors and software; however, with the current platform it can have a significant impact in treating complex spine cases, specifically adult deformity. Deformity corrections in adults with osteotomies are associated with extremely high complication rates including implant failure, proximal junctional kyphosis, and persistent sagittal malalignment. RASS may play a significant role in decreasing these complications.1 In an attempt to decrease rates of pedicle screw pullout and rod breakage, four-rod constructs are commonly used in deformity surgery. Although this increases the stiffness of the construct, it relies on the same number of pedicle screw fixation points. Lateral cortical screws (LCS) are being used routinely as an alternate form of spinal fixation, typically in simple degenerative cases. It has been demonstrated that most vertebral bodies can accommodate a pedicle screw, as well as an LCS within each pedicle if planned preoperatively. This would allow a four-rod construct with more fixation points, which may decrease the rates of hardware failure. Although it is extremely difficult to pass a pedicle screw and LCS in the same pedicle free hand, robotic assistance makes this a simple task to execute.2 Persistent sagittal misalignment often occurs due to intraoperative work that does not match the preoperative plan. The use of RASS would make precise osteotomies possible, matching up the preoperative plan precisely, resulting in the desired correction. More commonly, spine surgeons are using minimally invasive techniques to avoid the morbidity of a large open case. This involves performing multiple lateral interbody fusions with or without anterior longitudinal ligament releases, and placing percutaneous pedicle screws. Linking the spine construct with pelvic fixation presents a challenge with long percutaneous constructs. Traditional iliac bolts require the use of offset connectors, and are therefore not feasible percutaneously. S2 alar iliac screws can be placed in line with pedicle screws, making rod passage possible; however, these screws can be challenging to place percutaneously. With the use of robotic assistance, these screws can be placed accurately and efficiently (Figure 1).3Figure 1: Preoperative planning screen for S2 alar iliac screw placement with robotic assistance © Mazor Robotics. Used with permission.