The Surgical Approach to Subaxial Cervical Spine Injuries

Subaxial Cervical Spine Injuries • Dvorak et al
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ommendation is that a circumferential fusion be performed.
Unilateral or Bilateral Facet Fracture Dislocations (No
Vertebral Body Fracture). This injury category contains
a variety of injuries from the bilateral facet dislocation
(bilateral locked facets), through a unilateral facet dislocation,
to a variety of facet, lateral mass, and posterior
element fractures all with rotational or translational instability.
There is no consensus in the literature on the
role and timing of closed reduction as opposed to obtaining
MRI, or even proceeding to immediate surgical decompression
in these injuries and this topic is beyond the
scope of the present article. However, when this controversy
is resolved, the surgeon is still faced with the question
of which approach to choose for surgical stabilization,
since all of these injuries are treated surgically.
If by means of a prereduction MRI or after neurologic
deterioration during closed reduction, the surgeon becomes
aware of a fragment of disc material displaced
into the spinal canal, then an anterior discectomy, open
reduction, fusion, and plating becomes necessary. 2,7,9 In
approximately half of the cases, a closed reduction will
be successful in reducing the dislocation before surgery.
50 In the majority of the others, an intraoperative
reduction performed after the discectomy and decompression
will achieve anatomic reduction. 9,51 For those
patients in whom an anterior discectomy and decompression
have not been successful in reducing the dislocation,
then a supplemental posterior open reduction
should be performed. 52
As is the case in the vast majority of these unilateral or
bilateral facet fracture dislocations, if there is no evidence
of a loose fragment of disc in the spinal canal, then
the surgeon may choose either anterior or posterior fixation.
The decision between anterior and posterior approach
when both are viable treatment options is based
on a number of factors in addition to those factors discussed
above in the distraction section of this article.
There are several reports that compare anterior and
posterior surgery for subaxial cervical trauma, 13,14,53
only 1 of which has been formally published. Excellent
results have been reported with both approaches; however,
each approach has its own unique advantages. The
posterior approach is biomechanically more robust, particularly
when used to stabilize primarily posterior injuries.
15,16 The posterior approach is familiar to surgeons,
has a high radiographic success rate, and enables direct
open reduction of dislocated posterior elements and thus
is favored by many. 3–6,10,25,26 There have been concerns,
however, regarding the rate of wound infection and the
ability of posterior alone stabilization to neutralize the
development of segmental kyphosis as the injured disc
collapses and settles. 13,21,53
The anterior approach is favored by some because the
traumatized patient does not have to be positioned
prone, disc herniations can be directly removed, thus
decompressing the canal, and the high fusion rate and
maintenance of segmental lordosis are attractive.
2,7,9,13,21 The criticism of the anterior approach for
cervical subaxial trauma originates from its biomechanical
inferiority when compared with posterior fixation,
although it is still stiffer than an intact spine segment.
15,16 Other concerns are the complications of dysphagia,
hoarse voice, and early radiographic failure
when used in the presence of end-plate compression fractures
and very comminuted or large facet fracture fragments.
13,20 Although the guidelines described by Spector
et al relate to the prediction of failure of nonsurgical
treatment, likely a similar measurement of the size of the
facet fracture fragment would also predict the success of
stand-alone anterior discectomy and fusion for facet
fracture dislocations. 54
The Influence of the Discoligamentous Complex
There are several morphologic categories for which the
pattern and extent of DLC disruption is the critical factor
in determining the surgical approach within this algorithm.
The hyperextension or posterior ligament injuries
are often best treated by an approach from the direction
of maximal soft tissue disruption. The extent of disc disruption
and potential displacement can also define the
primary surgical approach in the case of facet dislocations
as has been discussed above. The reliability and
validity of diagnosing injuries to the DLC are currently
undergoing prospective study.
The Influence of Neurology
In the majority of cases where there is a spinal cord injury,
complete or incomplete, surgery will likely be performed.
In many of these cases, effective decompression
of the spinal canal is a primary goal of treatment, if not to
obtain distal recovery, then to achieve local root or segmental
recovery. The neurology guides the approach in
the case of the incomplete spinal cord injury without
instability. Neurology also influences the surgical approach
when there is cord compression from a vertebral
body fracture, anterior traumatic disc protrusion, or a
facet fragment causing foraminal root compression.
Discussion
Spinal injuries occur in an estimated 150,000 people per
year in North America, 11,000 of which have concomitant
spinal cord injuries (1 out of every 25,000 people
annually). 19,55 The exponential increase in the technology
available for surgical fixation in the subaxial spine
has not been paralleled by the evolution of guidelines or
evidence-based recommendations on when to use this
technology. One of the obstructions to the development
of evidence-based consensus guidelines has been the
largely descriptive and nonstandardized classification of
injuries to the subaxial cervical spine.
The SLIC severity scale, based on 3 components of
injury (morphology, neurology, and DLC disruption),
which, by consensus, represent major and largely independent
determinants of prognosis and management, is
an attempt to characterize injuries based on injury mor-