The Development of Novel 2-in-1 Patient-Specific, 3D-Printed Laminectomy Guides with Integrated Pedicle Screw Drill Guides.

OBJECTIVE: To determine if 2-in-1 patient-specific laminectomy and drill guides can be safely used to perform laminectomy and pedicle screw insertion. METHODS: This was a cadaveric study designed to test novel 2-in-1 patient-specific laminectomy guides, with modular removable pedicle screw drill guides. Three-dimensional (3D) printing has not been applied to laminectomy. This cadaveric study tests novel 2-in-1 patient-specific laminectomy guides, with modular removable pedicle screw drill guides. Computed tomography (CT) scans of 3 lumbar spines were imported into 3D Slicer. Spinal models and patient-specific guides were created and 3D printed. The bones were cleaned to visualize and record the under surface of the lamina during laminectomy. Pedicle screws and laminectomies were performed with the aid of patient-specific guides. CT scans were performed to compare planned and actual screw and laminectomy positions. RESULTS: Thirty screws were inserted in 15 lumbar vertebrae by using the integrated 2-in-1 patient-specific drill guides. There were no cortical breaches on direct examination, or on postoperative CT. Digital video analysis revealed the burr tip did not pass deep to the inner table margin of the lamina in any of the 30 laminectomy cuts. Average surgical time was 4 minutes and 46 seconds (standard deviation, 1 min 38 sec). CONCLUSIONS: This study has explored the development of novel 2-in-1 patient-specific, 3D-printed laminectomy guides with integrated pedicle screw drill guides, which are accurate and safe in the laboratory setting. These instruments have the potential to simplify complex surgical steps, and improve accuracy, time, and cost.

Geometric and volumetric relationship between human lumbar vertebrae and "Black-bone" MRI-based models.

BACKGROUND: This study will examine the differences between human lumbar vertebrae, three-dimensional (3D) scans of these bones, 3D models based on 'Black-bone' magnetic resonance imaging (MRI) scans, and 3D-printed models. MATERIALS AND METHODS: 3D mesh models were created from the "Black-bone" MRI data from two cadaveric human spines, and then 3D printed. Four models were analysed and compared: anatomic bones, 3D-scanned models, MRI models and 3D-printed models. RESULTS: There was no significant difference between when comparing the average of all measurements between all model types (p = 0.81). The mean dice coefficient was 0.91 (SD 0.016) and the mean Hausdorff distance was 0.37 mm (SD 0.04 mm) when comparing the MRI model to the 3D-scanned model. The mean volumes for the MRI model and the 3D scanned model were 10.42 and 10.04 ml (p = 0.085), respectively. CONCLUSIONS: The 'Black-bone' MRI could be a valid radiation-free alternative to computed tomography for the 3D printing of lumbar spinal biomodels.