- Poor Decision Making/Indications for Index Procedure
- Trying to treat axial neck pain without identifiable cause
- Difficult to treat because defining the exact pain generator with MRI is highly challenging.
- Cervical discography is unreliable for this purpose due to high false-positive and false-negative rates, alongside poor sensitivity and specificity.
- Operating on axial neck pain in the absence of myelopathy, radiculopathy, trauma, or tumor risks fusing a relatively normal joint, which can cause abnormal motion and increased pain at adjacent levels.
Reasons for revision cervical surgeries
Pseudarthrosis
- Rates depend on
- Number of levels fused
- Graft type (autograft versus allograft)
- Adjunctive instrumentation
- Smoking
- Prior surgeries
- Symptomatic pseudarthrosis is a straightforward indication for revision cervical reconstruction.
- Clinical feature:
- Persistent or recurrent symptoms after 6 months of follow-up
- Investigation
- Flexion/extension radiographs
- CT scans to evaluate for fusion.
Adjacent Segment Degeneration
- Adjacent segment degeneration occurs at an estimated rate of 2.9% per year.
- The degeneration rate is lower for multi-level fusions than for single-level fusions, which suggests that adjacent segment disease may be related to the patient's underlying disease rather than the fusion itself.
- Both anterior cervical discectomy and fusion (ACDF) and disc replacement are considered for this indication, though disc replacement is not FDA-approved specifically for adjacent segment disease.
Implant/Technical Failure With Anterior Cervical Surgery
- Graft complications includes
- Graft collapse
- Subsidence
- Adjacent vertebrae fractures
- Graft extrusion
- More common with prior laminectomy and kyphosis.
- Carries a risk of significant dysphagia and neurological injury.
- To prevent graft extrusion,
- Use segmental kyphosis correction
- Careful endplate preparation
- Posterior graft seating on C7–T1
- Avoid spanning plates for corpectomies exceeding two levels.
- Improper plate placement can
- threaten the vertebral artery (if too lateral),
- cause adjacent segment ossification
- If too high
- place the plate into the caudal disc space (if too low).
Iatrogenic Instability/Deformity
- Postoperative kyphosis is typically caused by
- prior destabilizing procedures such as laminectomy or, less commonly, laminoplasty.
- Postlaminectomy kyphosis involves a triad of
- Deformity
- Incomplete soft tissue restraints
- Neurological compromise, which can lead to the spinal cord draping over the anterior vertebral bodies.
- Surgical correction strategies focus on
- lengthening the anterior column
- shortening the posterior column
- Employing anterior-posterior approaches to improve construct stability and reduce graft failure
PREOPERATIVE PLANNING
- Initial evaluation of a failed cervical spine reconstruction requires assessing whether
- There was a prior pain-free interval
- A prior pain-free interval indicates that the initial (index) surgery was well-indicated and successfully executed
- If a patient experienced an excellent early result but later developed recurrent pain (often similar to their original pre-surgery pain), this specific history strongly points to a late-developing issue, such as pseudarthrosis (failed fusion)
- The index surgery was well-indicated
- There is a failure of fusion versus fixation
- CT
- Flexion and extension radiographs
- Sagittal balance is appropriate.
- Full standing xray of the whole spine.
- A C1 plumb line distance of greater than 10 mm from C7 is associated with worse neck disability index outcomes, highlighting the need to carefully analyze and correct preoperative positive sagittal balance.
- Advanced imaging
- Flexion/extension radiographs and CT scans are ideal for identifying pseudarthrosis, while MRI or CT myelography can identify areas of neurological compression.
Surgical options
- Transitioning a revision into a primary-like surgery (such as using a left-sided approach if the prior was right-sided)
- Employing posterior-anterior-posterior approaches
- Osteotomies (Smith-Petersen or pedicle subtraction osteotomies) to correct positive sagittal balance.
COMPLICATIONS
- The risk of complications increases dramatically with revision surgery compared to primary surgery.
- Complication rates:
- 27% incidence in a study of 30 revision patients (Gok 2008)
- 68% rate (13 of 19 patients) in an unpublished series. (Unpublished)
- Risk of anterior revisions surgeries
- Oesophageal injury
- Vocal cord paralysis
- Dysphagia (10% in Gok 2008)
- Neurological injury
- Durotomy
- Risk of posterior revisions
- Wound complications
- Durotomy
- Neurological injury