Percutaneous Pedicle Screw Placement




Indications





  • Lumbar fusion for symptomatic isthmic, degenerative, or traumatic spondylolisthesis; intractable discogenic back pain; or correction of symptomatic degenerative scoliosis



  • As an adjunct to direct lateral, transforaminal, posterior or anterior interbody fusion



  • To supplement a posterolateral arthrodesis



  • As a posterior adjunct to an anterior decompression or stabilization procedure for any of the following conditions:




    • Trauma (e.g., burst fracture, Chance fracture)



    • Neoplasms (resulting in instability)



    • Infection (e.g., vertebral osteomyelitis, diskitis, spinal tuberculosis)



    • Degenerative conditions (anterior lumbar interbody fusion [controversial])






Contraindications





  • Severe osteoporosis



  • Inability to obtain adequate images even after modification of the contrast mode on fluoroscopy machine, as a result of severe osteopenia or morbid obesity



  • Disease process (e.g., tumor, infection, fracture) involving or extending into pedicle of interest





Planning and positioning





  • The following equipment is needed:




    • Fluoroscopy (needs to be draped in such a fashion as to allow anteroposterior and lateral imaging without risk of operative field contamination)



    • Radiolucent table and frame



    • Table that allows for free passage of the fluoroscopic C-arm gantry from anteroposterior to lateral position (i.e., Jackson table)



    • Kirschner wire, Kirschner wire driver, and Jamshidi needle



    • Cannulated instruments for pedicle screw placement (various systems from different manufacturers can be used)




      Figure 84-1:


      The patient is positioned prone on a radiolucent table and frame with adequate padding of all pressure points with the extremities placed outside the field of radiation.






Procedure





  • The spine is viewed on the fluoroscopic monitor in the same orientation as the patient is positioned on the table; this helps to prevent mental calculations when moving the pedicle targeting needle.




    Figure 84-2:


    The level is identified using a lateral fluoroscopic view and an 18-gauge spinal needle ( arrow ).



    Figure 84-3:


    A, The anteroposterior view can be used to identify the lateral aspect of the pedicle ( arrow ). B, The midline can be marked by palpation of the spinous processes or anteroposterior fluoroscopy using an overlying Kirschner wire.



    • The fluoroscopic C-arm is positioned in the anteroposterior view to target the pedicles of the desired vertebral body. To enhance the image of the targeted vertebral level, one order of magnification is used, and the image is adjusted to achieve the maximum bone visualization using the collimator mode.



    • The targeted vertebral body is placed in the center of the fluoroscopic monitor to prevent parallax distortion.




  • The end plate of the targeted vertebral body is viewed as a single line composed of the posterior and anterior margins of the vertebral end plate. To achieve this, the fluoroscopic C-arm gantry is moved in the proper Ferguson view plane.




    • The spinous process of the targeted vertebra is placed between the pedicles by moving the C-arm gantry in the lateral coronal projections.




Lateral-Medial Targeting of Pedicle



Jun 15, 2019 | Posted by in NEUROSURGERY | Comments Off on Percutaneous Pedicle Screw Placement

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