Low-cost patient-specific stereotactic skin surface templates for minimally invasive transforaminal lumbar interbody fusion surgery.

Abstract

Computer modelling, intraoperative CT, and robotics were introduced to improve screw placement accuracy and simplify surgical technique. However, these technologies do not eliminate radiation exposure or screw malpositioning. Further, these technologies are costly, introduce additional intraoperative processes, and generate additional waste. In this study, we report the performance of a novel low-cost skin surface pedicle screw template for MIS TLIF surgery.

The surgeon collaborated with engineers using 1:1 scale 3D-printed lumbar spine biomodels, patient CT data, and computer modelling software to plan pedicle screw entry points, trajectories, and sizes. These specifications were used to 3D-print a patient-specific stereotactic skin surface template for Kirschner-wire insertion. Template fiducials were aligned with the patient’s spine and K-wire placement was guided with stereotactically oriented portholes and entry point fiducials, using minimal fluoroscopy. The template was removed once the K-wires were inserted.

Our data describes the performance of a single surgeon at a single centre, for 100 patients (65 female) who underwent MIS TLIF using this template. Surgical performance was assessed by average operating time (150±46 minutes), radiation exposure (1900±456 cGycm2), complications (n=3), revisions (n=4), surgical trays (n=14), waste volume (75±25 L), length of stay (5±3 days), and CT verified pedicle screw accuracy (97.7% Grade A or B, Gertzbein and Robbins).

Our data indicates that patient-specific templates are comparable to alternative surgical tools for achieving acceptable pedicle screw insertion. Future research comparing this process with existing techniques using standardised measures will enable an assessment of healthcare resource utilisation for MIS TLIF surgery.