Accuracy of Patient-Specific 3D-Printed Guides for Pedicle Screw Insertion in Spine Revision Surgery: Results of a Retrospective Study

Purpose: This retrospective study was performed to evaluate the safety and efficacy of patient-specific 3D-printed guides (MySpine (R) Medacta, Switzerland) for pedicle screw placement in spine revision surgery. Overview of the Literature: Placement of pedicle screws in spine revision surgery can be challenging due to the loss of anatomical landmarks and the presence of a fusion mass. Nevertheless, only a few papers have dealt with this topic. Several strategies, ranging from the freehand technique to navigation and robotics, have been developed. However, they all have drawbacks, including the amount of radiation given to the patient, the complexity of the equipment with a consequent increase in surgical time or costs, and the need of extended surgical training. Therefore, no consensus has yet been found regarding the best choice for dealing with revisions. Recently, patient-specific 3D-printed guides for screw placement have been introduced. Prospective studies have demonstrated their superiority over the freehand technique in primary deformity cases, but there are no studies on their results in revisions. Methods: Patients who underwent revision surgery for adult spinal deformities with 3D-printed guides were included. Radiographical parameters and complications were collected. The accuracy of each screw was measured on postoperative CT scan and graded according to the Gertzbein-Robbins and Zdichavsky classifications. Results: Nine patients (mean age 34.6 years, mean follow-up 34.4 months) were included for a total of 203 screws. The relative accuracy (Gertzbein-Robbins A+B) was 94.7%. Of the 11 misplaced screws, 8 (72.7%) were lateral, 3 (27.3%) were anterior and 0 were medial. No perioperative complications were recorded, and no screw needed revision. Conclusions: The present technology appears to be effective and safe for pedicle screw placement in spine revision surgery and does not require the costs, training and radiation exposure associated with navigation and robotics.