Development and Testing of a Novel, Patient and String-of-Pearls Plate Specific, 3D Printed Drilling Guides as a Proof of Concept for Lumbar Spinal Fracture Reduction and Stabilization

Introduction: The purpose of this study is to describe a de novo, patient-specific, String-of-Pearls (SOP) plate-specific, 3D printed, drilling guides for spinal stabilization, and to determine screw placement accuracy.

Materials and Methods: The study utilized three normal 3D printed spinal models, three normal cadavers, and three models of historical vertebral body fractures. For each, a CT was used to straighten the spine and/or reduce the fracture. Patient-specific drill guides for an SOP plate were then created and 3D printed. Eighteen mock surgeries were performed using the drilling guides to stabilize the spine with an SOP plate. CT was used to assess the accuracy of screw placement by virtual measurements and modified Zdichavsky classification.

Results: A total of 140 screw trajectories were evaluated and compared with the presurgical plans. All 140 were graded as one (optimally placed) in the modified Zdichavsky classification. The transverse angles and the craniocaudal angles were similar between all comparisons. All but two entry and exit measurements were statistically different with a p < 0.05, however, the average difference was <1 mm in all cases, limiting clinical significance.

Discussion/Conclusion: The de novo, patient-specific, SOP plate-specific, drilling guides allowed safe and accurate placement of screws in the T12-L5 vertebra of medium-sized dogs. With presurgical planning and predrilling the holes, spinal straightening and fixation were subjectively fast and easy in six cadaver surgeries and may facilitate the reduction and fixation of vertebral fractures. Further actual clinical case studies are warranted.

Acknowledgment

The authors wish to thank MedDimensions for the development and 3D printing of the drilling guides and models used in this study. The cost of development for the drilling guides was donated and the models and drilling guides were sold at cost. They also wish to thank Orthomed for the use of their SOP plate virtual models.

 

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Publication History

Article published online:
15 July 2025