Authors of section

Authors

Carlo Bellabarba, Marcelo Gruenberg, Cumhur Oner

Executive Editor

Luiz Vialle

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Anterior plating

1. Preliminary remarks

Anterior fixation is a useful technique for anterior decompression and reconstruction of the anterior column.

Direct decompression from disk or bone material can be performed directly without mobilization of the neurological structures.

Visualization of the dura allows direct confirmation of complete decompression.

Nerve roots are better identified from a posterior approach, but experienced surgeons can also perform an anterior foraminotomy.

anterior plating

Preoperative evaluation of potential anatomic variations in the course of the vertebral artery is mandatory. Unidentified anatomical variations may increase the risk of compromising the artery during decompression.

anterior plating

2. Approach and preparation

With the patient placed supine, one of the two following approaches may be used depending on the exposure needed:

anterior plating

3. Indications for anterior decompression

Indications for decompression during anterior reconstruction includes:

  • The presence of a traumatic disc herniation causing neurologic injury (discectomy alone)
  • The need to remove a portion or entire vertebral body followed by reconstruction for stability, or for relief of symptomatic neural compression
  • Kyphotic angulation with ventral compression.

Corpectomy is performed when the anterior column is severely compromised and/or to remove bone material from the spinal canal. In this procedure diskectomies above and below the fractured vertebra are performed first, allowing visualization of the upper and lower limits of the spinal canal.

Visualization

The procedure should be performed with adequate light and magnification; either loupes or a microscope.

4. Discectomy technique

Prior to performing the discectomy, the level is confirmed with intraoperative fluoroscopy.

The following landmarks are identified:

  • Midline
  • Unciform process

The midline will dictate the AP orientation of the discectomy.

The unciform processes dictate the lateral borders of the discectomy, establishing the safe area from the artery. This will leave a 3mm safe zone to the normal anatomy of the vertebral artery.

anterior plating

A small (nr 15) blade is used to open the annulus from uncinate to uncinate as close as possible to the endplates.

Pearls

To help stop a slipping blade, a Frasier tip suction is held in place in the direction the blade is cutting.

To prevent accidental durotomy and spinal cord transection, the annulotomy should not go deeper than 11 mm. The sharp edge of the nr 15 blade is 11 mm and can be used as a depth gauge.

anterior plating

The discectomy continues using a Pituitary rongeur forceps to remove the anulus and small curettes to scrape the endplates.

anterior plating

The use of a distractor or an intervertebral distractor will facilitate the removal of the posterior half of the disk and visualize the posterior longitudinal ligament.

The normal height of the area should be reconstructed. However, care should be taken not to over distract.

A complete discectomy will allow good visualization of the spinal canal and enhance fusion.

anterior plating

Meticulously remove all cartilage from the endplates. Pieces of cartilage may inhibit fusion if present either on the endplates or in the bony material used for the fusion.

anterior plating

A small probe is used to ensure that no fragments are left in the area behind the vertebra which is not directly visualized, or in the foramen.

Magnification and correct illumination is essential to make the final decompression.

anterior plating

5. Full corpectomy technique

Corpectomy technique

Prior to performing a full corpectomy, both the superior and inferior discs are removed to define the safe depth of bone resection.

Segmental vessels are identified and ligated in the mid vertebral body, away from the natural foramen. These vessels may already be disrupted due to the trauma.

anterior plating

Laterally the corpectomy is limited by the medial boarder of the unciform process.

The unciform processes dictate the lateral borders of the corpectomy, establishing the safe area from the artery. This will leave a 3mm safe zone to the normal anatomy of the vertebral artery.

anterior plating

At this point, the fractured portion of the vertebral body (but not the posterior third) is removed using a combination of Leksell rongeurs and osteotomes.

If a cage is used for the reconstruction, an instrument producing larger fragments of bone is preferred as it facilitates filling of the cage.

anterior plating

A burr is used to remove the posterior portion of the vertebral body as the spinal canal is approached.

anterior plating

The spinal canal is decompressed by the resection of the posterior wall of the vertebral body.

The posterior cortex should be thinned with the burr to an eggshell. Retropulsed bone fragments can be removed with curettes and thin footplate Kerrison punches.

This is optimally done with a high speed burr and curettes under loupe or microscopic magnification.

anterior plating

Pearl: protection of the dura

Care should be taken to protect the dura. Epidural venous bleeding can be troublesome at times, so meticulous hemostasis with bipolar cautery, cottonoid patties, and hemostatic adjuncts can be helpful.

anterior plating

6. Partial corpectomy technique

Partial corpectomy

In selected cases where there is enough uncompromised bone to hold the plate a partial corpectomy removing only one disk allows reconstruction of the spine, saving one mobile segment.

A partial corpectomy involves removal of the fractured superior or inferior vertebral body and adjacent disc.

anterior plating

Prior to performing a partial corpectomy, segmental vessels are identified and ligated in the mid vertebral body, away from the natural foramen. These vessels may already be disrupted due to the trauma.

anterior plating

The disc adjacent to the fractured endplate is removed as described above to define the safe depth of bone resection.

anterior plating

Laterally the partial corpectomy is limited by the medial boarder of the unciform process.

The unciform processes dictate the lateral borders of the corpectomy, establishing the safe area from the artery. This will leave a 3mm safe zone to the normal anatomy of the vertebral artery.

anterior plating

At this point, the fractured portion of the vertebral body (but not the posterior third) is removed using a combination of Leksell rongeurs an osteotomes.

If a cage is used for the reconstruction, an instrument producing larger fragments of bone is preferred as it facilitates filling of the cage.

anterior plating

A burr is used to remove the posterior portion of the vertebral body as the spinal canal is approached.

anterior plating

The spinal canal is decompressed by the resection of the posterior wall of the vertebral body.

The posterior cortex should be thinned with the burr to an eggshell. Retropulsed bone fragments can be removed with curettes and thin footplate Kerrison punches.

This is optimally done with a high speed burr and curettes under loupe or microscopic magnification.

anterior plating

Pearl: protection of the dura

Care should be taken to protect the dura. Epidural venous bleeding can be troublesome at times, so meticulous hemostasis with bipolar cautery, cottonoid patties, and hemostatic adjuncts can be helpful.

anterior plating

7. Reduction

B3 fractures are reduced by positioning the patient head with no extension. Placing additional padding behind the occiput will help correct the extension deformity. In these injuries traction should be avoided as it tends to accentuate the deformity.

anterior plating

8. Fusion after discectomy

Reconstruction using tricortical graft or allograft with plate

Tricortical graft is harvested from the iliac crest and inserted in to the empty disk space. Great care must be taken to trim the graft so that it shares axial load with the plate.

After the bone graft (or cage) is placed, the Caspar pins are removed.

anterior plating

When choosing the plate length, care must be taken to prevent it from damaging the mobile disks above and below. The necessary plate length (blue) is measured using a caliper.

anterior plating

Ideally the plate would extend as little as possible above and below the endplates of the injured level.

anterior plating

The plate is bent to accommodate the patients lordosis and fixed in place with two temporary pins placed in holes diagonal to each other.

The appropriate positioning of the plate is verified in AP and lateral views.

anterior plating

Malrotation of the plate is commonly seen on the AP view and can be adjusted by temporarily removing one pin while adjusting the rotation.

anterior plating

Based on a preoperative measurement of vertebral body depth, screw holes are prepared with the appropriate depth. This is performed under lateral fluoroscopic guidance.

anterior plating

Screws are then inserted but not fully tightened until all screws have been applied.

anterior plating

Final hardware positioning is verified in lateral and AP view.

anterior plating

9. Fusion after partial/full corpectomy

Fusion after partial and full corpectomy follows the same principles. To illustrate these we will here show the fusion after a full corpectomy.

The following two options are available for reconstruction after corpectomy:

  • Tricortical graft and plate
  • Mesh cage and plate

Care should be taken not to over distract the segment as this may compromise the postoperative stability.

anterior plating

Reconstruction using tricortical graft and plate

Tricortical graft is harvested from the iliac crest and inserted in to the defect. Great care must be taken to trim the graft so that it shares axial load with the plate.

Allograft may also be used.

After insertion of the graft, the Caspar pins are removed.

anterior plating

When choosing the plate length, care must be taken not to prevent it from damaging the mobile disks above and below.

anterior plating

The plate is finally bent to accommodate the patient's lordosis and fixed with two screws in each vertebra.

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Reconstruction using Mesh cage and plate

The corpectomy defect is measured using caliper.

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A mesh cage of the largest possible diameter is cut to a corresponding length.

anterior plating

The cage filled with tightly packed bone obtained from the corpectomy.

anterior plating

End plate rings should be added in patients with osteoporosis. They are optional in patients with normal bone. These often have variable angulation and can be used to accommodate non parallel endplates.

anterior plating

The cage is inserted and tapped into its final position under lateral fluoroscopic monitoring.

The Caspar pins are removed.

anterior plating

When choosing the plate length, care must be taken to prevent it from damaging the mobile disks above and below.

Note: Dynamic plates should be avoided in trauma as their principles often conflict with the goals of stabilization in the unstable spine.

Variable angle plates with locking screws are also an option if thought to be necessary.

anterior plating

Ideally the plate would extend as little as possible above and below the endplates of the injured level.

anterior plating

The plate is bent to accommodate the patients lordosis and fixed in place with two temporary pins placed in holes diagonal to each other.

The appropriate positioning of the plate is verified in AP and lateral views.

anterior plating

Malrotation of the plate is commonly seen on the AP view and can be adjusted by temporarily removing one pin while adjusting the rotation.

anterior plating

Based on a preoperative measurement of vertebral body depth, screw holes are prepared with the appropriate depth. This is performed under lateral fluoroscopic guidance. of appropriate length selected and

anterior plating

Screws are then applied but not fully tightened until all screws have been inserted.

anterior plating

Final hardware positioning is verified in lateral and AP view.

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10. Aftercare

Patients are made to sit up in the bed on the first day after surgery.

A collar is commonly used following surgical stabilization to moderate patient activity.

The purpose of a collar is to prevent ranges of motion outside of limits deemed unfavorable for fracture healing. Collar is optional.

Patients with intact neurological status are made to stand and walk on the second day after surgery. Patients can be discharged when medically stable or sent to a rehabilitation center if further care is necessary. This depends on the comfort levels and presence of other associated injuries.

Patients are generally followed with periodical x-rays at 6 weeks, 3 months, 6 months, and 1 year.

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