In-vivo clinical validation of perpendicular to superior articular process as thoracic pedicle trajectory: A retrospective case series of 60 pediatric scoliosis

Abstract

Study Design: This is a retrospective case series study. Objective: Thoracic pedicle screw insertion can be technically challenging because of narrow pedicles. Placement of thoracic pedicle screws in pediatric scoliosis and adult deformity surgeries, due to three-dimensional rotation of vertebrae, is even more challenging because the usual landmarks are less evident, and the sagittal trajectory is more difficult to correctly orientate due to the vertebral rotation. We describe a variation of freehand technique to guide sagittal trajectory of thoracic pedicle screw. Materials and Methods: The inferior articular process of cranially adjacent vertebrae is osteotomized using a Capener Gouge to expose the superior articular process (SAP) of the thoracic vertebrae to be instrumented. An O’Connell dissector is then placed flush on the SAP. The main shaft of the dissector is at right angle to the base plate; pedicle finder is placed parallel to the shaft and follows the same sagittal trajectory as the shaft. Results: A total of 390 pedicle screws were identified in a consecutive series of 60 scoliosis patients inserted using this technique. Only one screw was revised for lateral breach. There was no intra-operative complication or neurological sequelae in any of our patients. Conclusion: Freehand pedicle screw placement remains a very common technique, used particularly by pediatric scoliosis surgeons. One of the drawbacks of previous reports of the freehand technique is that the sagittal trajectory is not clearly defined. Our technique fills this gap, and this series demonstrates that the technique produces a reliable and consistent result.