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  • Placement of Thoracic Transvertebral Pedicle Screws Using Three-Dimensional Image Guidance

    Final Number:
    1501

    Authors:
    Eric W. Nottmeier MD; Stephen M. Pirris MD

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2012 Annual Meeting

    Introduction: Originally described by Abdu(1), transvertebral pedicle screws have been used successfully in the treatment of high-grade L5-S1 spondylolisthesis.(2,3) An advantage of transvertebral pedicle screws is the purchase of multiple cortical layers across two vertebrae thereby increasing the stability of the construct.(4) The use of transvertebral pedicle screws at spinal levels other than L5-S1 has not been reported. The authors report on the placement of transvertebral pedicle screw placement in the thoracic spine using three-dimensional (3D) image guidance.

    Methods: Eight patients undergoing thoracic fusion had 31 thoracic transvertebral pedicle screws placed using 3D image guidance in conjunction with the O-ARM (Medtronic Inc., Littleton, Massachusetts)(Fig. 1) All screws were graded for pedicle breach using either intraoperative cone beam computed tomography (cbCT) scans or postoperative CT scans.

    Results: No complications occurred in this study as a result of transvertebral pedicle screw placement or image guidance. Review of the imaging studies revealed all screws to be across the superior disc space with the tips in the superior vertebral body (Fig. 2). Six pedicle screws were placed using the in-out-in technique in patients with narrow pedicles and were excluded from breach analysis. Of the remaining 25 screws, one was found to have a grade 1 (<2mm) medial breach with no clinical consequence. A noticeable increase in insertional torque of the transvertebral pedicle screws were observed by the authors as compared to standard pedicle screws that were placed contralaterally or at other levels in the same patient.

    Conclusions: Thoracic transvertebral pedicle screws can be inserted safely and accurately with 3D image guidance. Insertion of these screws allows for purchase of multiple cortical layers of bone with a noticeable increase in insertional torque. Additionally, this technique can allow for placement of 4 screws into the most superior vertebral body of the construct increasing fixation across the most superior segment, which is a segment vulnerable to pseudoarthrosis. (Fig. 3)

    Patient Care: By describing a new technique of pedicle screw placement that may yield an increase in the biomechanical stability of long-level constructs with a possible subsequent increase in fusion rates.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1. Describe the technique for placement of thoracic transvertebral pedicle screws. 2. Recognize the possible advantages of transthoracic pedicle screws. 3. Describe how image guidance can help aid screw placement in difficult cases.

    References: 1. Abdu WA, Wilber RG, Emery SE. Pedicular transvertebral screw fixation of the lumbosacral spine in spondylolisthesis. A new technique for stabilization. Spine (Phila Pa 1976) 1994;19:710-5. 2. Beringer WF, Mobasser JP, Karahalios D, et al. Anterior transvertebral interbody cage with posterior transdiscal pedicle screw instrumentation for high-grade spondylolisthesis. Technical note. Neurosurg Focus 2006;20:E7. 3. Rodriguez-Olaverri JC, Zimick NC, Merola A, et al. Comparing the clinical and radiological outcomes of pedicular transvertebral screw fixation of the lumbosacral spine in spondylolisthesis versus unilateral transforaminal lumbar interbody fusion (TLIF) with posterior fixation using anterior cages. Spine (Phila Pa 1976) 2008;33:1977-81. 4. Minamide A, Akamaru T, Yoon ST, et al. Transdiscal L5-S1 screws for the fixation of isthmic spondylolisthesis: a biomechanical evaluation. J Spinal Disord Tech 2003;16:144-9.

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