• Percutaneous pedicle screws for traumatic burst fracture

    Case Presentation

    • 21-year-old female in MVC, back pain
    • Trauma transfer --> L3 burst fracture
    • Bilateral lower extremity (BLE) numbness
    • Bowel/bladder incontinence
    • Motor strength full in BLEs

    Alternatives

    Brace or Surgery

    • Neurologically intact patient
      • Less than 40% height loss
      • Less than 10 degrees of kyphosis on upright imaging
      • Compliant
        • Education
        • Mental
        • Age
        • Other factors - body habitus
        • Circumstances of accident

    Non-operative management

    • Mumford et al
      • 41 patients with thoracolumbar burst fxs w/o neurologic deficit were treated conservatively.
      • At injury, canal compromise averaged 37% at 2-year follow-up, 2/3 resolution of fragments occluding canal.
      • Outcome evaluation: 49% patients reported excellent outcome relative to pain and function.
      • Progression of body collapse on imaging averaged 8%.
      • 1 patient developed neurologic deterioration prompting surgery. All other patients remained intact.
    • Cantor et al.
      • 18 Neurologically intact patients without PLC disruption were treated with early ambulation and bracing.
      • Kyphosis was 19 degrees at time of injury and 20 degrees at follow-up.
      • VB height loss was 36% on presentation, maximum change of 5% on follow-up.
      • At follow-up, 15 patients rated their pain as little or none, and 17 patients had little or no restriction of activity.
      • CT scan 1 year after injury in 8 patients showed > 50% resorption of retropulsed bone.
      • No patient had deterioration of neurologic function.

    Surgical Results in Thoracolumbar Burst Fractures

    • Studies comparing anterior and posterior surgery have equivalent neurological outcomes.
      • There is a tendency for less kyphosis and better pain and function outcomes with anterior surgery.
      • Reduced degenerative changes resulting from saving motion segments with anterior procedures has not been proved.

    Approach

    • L1-L5 posterior percutaneous instrumentation with pedicle screws and rods
      • To serve as internal bracing
    • L3 laminectomy
      • Decompression of nerve roots
      • Ventral decompression of fracture fragments

    Positioning

    • Prone
    • Jackson OSI table
    • Arms up, all joints < 90 degrees
    • Chest pad on sternum, above nipples
    • Pads on iliac crests and thighs
    • Wrists, knees, and feet padded
    • C-arm

    Incision

    • Use lateral fluoroscopy to plan incision
    • 3 levels: paramedian incisions lateral to the pedicles
    • 3 levels: midline incision
    • Suprafascial, i.e., dissect down to level of fascia
    • Other option:
      • Stab incisions

    Operation

    • Place Jamshidi needles into the bilateral pedicles (L1, L2, L4, L5).

    • Start with fluoro in AP, to ensure that Jamshidi needles start at the lateral aspect of the pedicle and traverse towards the medial aspect.

    • Then use lateral fluoro to tamp the Jamshidi needles into the vertebral bodies.

    • Other options:

      • Two C-arms
      • Navigation
      • Wiltse
    • Sequentially place pedicle screws.
      • Place a K-wire down the Jamshidi needle.
      • Remove the Jamshidi needle.
      • Tap a screw tract over the K-wire with the use of lateral fluoroscopy just into the vertebral body.
      • Remove the tap.
      • Place an appropriately sized pedicle screw over the K-wire.
      • Use lateral fluoroscopy to ensure that the screws are parallel with the superior endplate of the given vertebral body.
      • Ensure all screws have good purchase.
    • Select appropriately sized rods, and contour into lordotic shape.
    • Use rod introducer to place rod through extension tabs on screws.
    • Tunnel subfascially, and visualize the rod enter the screw head. Special attention should be paid to ensure that there is enough rod above the most rostral screw and below the most caudal screw and that the rod is maintained in the lordotic position.
    • Place set screws to fasten the rod to the screw and final tighten.
    • Remove the rod introducer, and break off the extension tabs.

    Open L3 laminectomy

    • Expose the L3 spinous process and lamina.
    • Transect the interspinous ligaments above and below the spinous process.
    • Remove the spinous process with Leksell rongeurs.
    • Use a high-speed drill to perform a laminectomy down to the level of the ligamentum flavum.
    • Visualize the rostral attachment of the ligamentum flavum to the lamina and epidural fat.
    • Remove any remaining lamina and ligament with Kerrison rongeurs with care taken to protect the underlying dura and not incur a durotomy.
    • Perform a wide enough laminectomy to visualize the lateral aspect of the thecal sac such that it appears nicely decompressed.
    • Retract the thecal sac medially, and use down-pushing curettes ventral to the thecal sac on the fracture elements to mobilize bony fragments away from the thecal sac.
    • Palpate ventrally with a Woodson elevator to ensure there is no compression.

    Outcome

    • At 1-month post-op,
      • Back pain is gone
      • BLE numbness is better
      • Bowel/bladder incontinence persists.

    Pearls and Pitfalls

    Technique Pearls for Posterior Instrumentation

    • More instability or deformity or poor bone quality = more failure with short segment posterior instrumentation.
      • More points of fixation
      • May require anterior column support

    Inappropriate Screw Placement

    • Durotomy
      • Nerve damage
      • Vascular or visceral complications
      • Late onset discomfort or pain
        • Secondary to pseudoarthrosis, hardware failure

    Entry Point Lumbar Pedicle Screws

    • Start out by marking the entry points with K-wires or short pins using the fluoroscopy in the AP direction.
    • The correct positioning and orientation can be verified by adjusting the fluoroscopy to where the K-wire is a "point," which lies clearly within the pedicle.
    • The integrity of five walls is essential to insert the screw.
      • Most important are medial and inferior due to presence of spinal cord and nerve root, respectively.
    • Avoid the medial half of the superior facet and its caudal projection.
    • Scrutinize intraoperative x-rays --> true A/P at each level.
    • Utilize intraoperative CT scan.

    References

    • Youmans Neurological Surgery. 6th Edition. Ch. 318-319. Pages 3216-3249.
    • Management of Thoracolumbar Spine Trauma and Stabilization Techniques - D. Kojo Hamilton, M.D. Seatle Science Foundation.
    • Cantor, J, et al. Non-operative management of stable thoracolumbar burst fractures with early ambulation and bracing. Spine 1993; 8:971-976.
    • Mumford, J et al. Thoracolumbar burst fractures: The clinical efficacy and outcome of nonoperative management. Spine 1993; 8: 955-970.

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