Preoperative Robotics Planning Facilitates Complex Construct Design in Robot-assisted Minimally Invasive Adult Spinal Deformity Surgery

Introduction: The correction of adult spinal deformity often requires long complex constructs with multiple fixation rods that often traverse several important biomechanical levels. Preoperative robotics planning of these constructs in minimally invasive spinal deformity surgery has not yet been extensively described in the literature.

Methods: Data was collected retrospectively from a series of patients undergoing minimally invasive deformity correction with ≥8 fusion levels into the lower thoracic spine with preoperative robotics construct planning and robot-assisted fixation by a single surgeon between July 2020 to October 2022.

Results: There were 9 patients (8 female, mean age 70.1 years) with a diagnosis of either degenerative scoliosis (6 patients) or sagittal imbalance (3 patients). All underwent preoperative robotics planning to assist in minimally invasive robot-assisted percutaneous or transfascial placement of pedicle and iliac screws with multiple-rod constructs. Mean operative values per patient were 10.0 levels posteriorly instrumented (range 8-11), 18.6 screws (range 13-24), 3.2 rods (range 2-4), 4.1 interbody cages (range 3-6), and estimated blood loss 244 cc (range 150-300). Mean improvement in sagittal parameters was 5.6 cm sagittal vertical axis (range -0.9 to 21), 11.2° pelvic tilt (range 1-23), and 21.4° pelvic incidence – lumbar lordosis mismatch (range -5 to 47). Six patients with scoliosis showed improved Cobb angles of 27.5° (range 22-43). Mean length of stay was 6.0 days (range 4-11) with no ICU admissions. Eight patients ambulated on postoperative day 1 or 2. Of 167 screws placed minimally invasively with robotic assistance, there were 4 breaches (3 lateral, 1 medial) for a screw accuracy of 97.6%.

Conclusion : Spinal robotics allows for the preoperative design and intraoperative execution of complex constructs for minimally invasive correction of adult spinal deformity. Future prospective studies are needed to validate these initial findings and their advantages over fluoroscopic or navigated techniques.