Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty (PVP)

Our protocol utilizes 3D-printed guide template assisted percutaneous vertebroplasty to facilitate a comprehensive visualization of fractured vertebra and to develop individualized surgical plans for patients. This technique helps increase puncture accuracy, decreases puncture-related complications, minimizes the surgical time and radiation exposure, and shortens the PVP learning process for novice surgeons. Visual demonstration can provide a clear, step-by-step introduction that emphasizes the significant parts of the technique to facilitate a quick grasp of the method.

Before beginning the procedure, confirm the target area by x-ray fluoroscopy in a visual examination of the patient's back. Next, place three radiopaque markers along the midline of the patient's dorsal skin at the compressed vertebral level, and place a gradienter just inferior to the fixed markers. Then record the patient's body position before removing the gradienter, and acquire computed tomography images of the target vertebrae.

At the end of the acquisition, save the images in a DICOM format, and place a cotton pad on the patient's back to ensure that the markers remain in place until the operation. After acquiring the computed tomography images, import the images into an appropriate medical imaging processing software program, and select the target slices to reconstruct the compressed vertebra. Select Threshold Segmentation to adjust the threshold range for the target vertebra from 125-3071H, and create a mask.

Click Duplicate Mask to make two masks, mask A and mask B.Click Mask Edit to erase the target vertebra in mask A.Click Boolean Operations, and use mask B to minus mask A to form a new mask C.Then click Calculate 3D from Mask to reconstruct the target vertebra. To simulate the percutaneous vertebroplasty procedure via a bilateral transpedicular approach, define the MedCAD cylinder in the software as the puncture needle mode at the same length and radius as the puncture needle. Use the 3D views of the target vertebra to visualize the entry point, entry angle, and puncture needle depth for a real percutaneous vertebroplasty, using the move and rotate function to adjust the puncture needles to their ideal positions.

Then use these template guide data to print a three-dimensional polylactic acid guide template. For 3D-printed guide template assisted PVP, with patient lying prone in the same position as recorded by the gradienter for the computed tomography scan, measure the distance of the three radiopaque markers, and draw the outline of the three markers to match the template with the target location. Match a skin template with the skin outline, and insert two swabs through the needle trajectories of the template to mark the insertion points on the skin.

Mark the insertion points as point A and B.After draping the surgical area, place disinfectant tape over the skin, and place the tips of two puncture needles at the insertion points. Use the anteroposterior view of C-arm fluoroscopy to confirm whether the puncture points determined by the template are feasible. After administering local anesthesia, tap the two needles slightly into the target vertebra via the insertions through the guiding cylinders of the template, and use the C-arm fluoroscope to verify that the trajectories are good enough for insertion.

Make sure that the punctuation is within the pedicles before taping the needles to advance the tips until the end of the trajectory. When the needles are completely inserted into the guiding cylinders, verify with the C-arm fluoroscope that the needle tips have reached their optimal locations. Then inject two milliliters of bone cement through each needle into the vertebral body.

And use fluoroscopy to check the distribution of the cement within the vertebral body by the anteroposterior and lateral views. Pre-operation, posterioanterior, and lateral x-ray images show that the target vertebra of a representative patient before 3D guide template assisted PVP. Computed tomography images acquired from the coronal, transverse, and sagittal planes can be used to generate a 3D model of the target vertebra.

The length of guiding cylinders of the template can be determined, and the template can be fabricated for use in the PVP procedure. It is essential to match the template with the correction location of the patient's back for the success of the whole procedure.