Long Term Outcome of Treatment of Subaxial Cervical Spine Fractures

              Long Term Outcome of Treatment of Subaxial Cervical Spine Fractures

                                                          Dr KS Dhillon

Classification of subaxial cervical spine fractures

The widely used classification for lower cervical spine injuries is the one by the AO group. It divides lower cervical spine injuries into 3 types i.e type A, B, C based on the trauma mechanism.

A: compression
B: distraction
C: rotation

Type A compression injuries are further subdivided into type:
 A.1  =  impaction
 A.2  =  split
 A.3  =  burst.

Type B distraction injuries are further subdivided into:
 B.1  =  posterior distraction with vertebral body intact
 B.2  =  posterior distraction + fracture of the vertebral body
 B.3  =  anterior distraction + hyperextension.

Type C rotation injuries are subdivided into:
C.1  =  unilateral facet fracture-dislocation
C.2  =  unilateral facet dislocation
C.3  =  rotational shear injury of the joint mass.

To remedy a lack of consensus on the classification of lower cervical spine injuries the Subaxial Injury Classification (SLIC) Scale was created [1]. This classification takes into account morphology; status of the disco-ligamentous complex and neurological assessment.



Table 1. Subaxial Injury Classification (SLIC) scale.
   
Morphology                                                                                                  Points
No abnormality                                                                                               0
Compression + burst                                                                                1 + 1  =  2
Distraction (e.g., facet perch or hyperextension)                                            3
Rotation or translation (e.g., facet dislocation, unstable teardrop,
or advanced-stage flexion-compression injury)                                              4

Disc-ligamentous complex
Intact                                                                                                               0
Indeterminate (e.g., isolated interspinous widening or MRI signal
change only)                                                                                                    1
Disrupted (e.g., widening of the anterior disk space or facet perch
or dislocation)                                                                                                  2

Neurological status
Intact                                                                                                              0
Root injury                                                                                                      1
Complete cord injury                                                                                      2
Incomplete cord injury                                                                                    3
Continuous cord compression (neuro-modifier in the setting of a
neurological deficit)                                                                                     + 1

Based on the above parameters, scores are assigned to each injury. Patients with a score lower than 4 will need nonsurgical treatment and patients with scores higher than 4 will require surgical treatment. Patients with a score of 4 can be treated surgically or nonsurgically depending on the experience of the surgeon.

Treatment of subaxial cervical spine fractures

Unfortunately, there is insufficient evidence to recommend treatment standards and there is also insufficient evidence to recommend treatment guidelines for subaxial cervical spine injuries [2]. The main principles of treatment include decompression of compressed neurological structures, restoration of vertebral column integrity, prevention and management of complications, and facilitation of rehabilitation [3].

Subaxial Injury Classification (SLIC) Scale has been introduced to help in decision making for treatment of subaxial injuries [1]. Generally, patients with a score lower than 4 are treated nonsurgically while patients with scores higher than 4 are treated with surgery. Patients with a score of 4 can be treated surgically or nonsurgically depending on the experience of the surgeon.
Many patients with cervical spine injuries can be treated nonoperatively. Options for conservative treatment include the use of a cervical orthosis or rigid stabilization with a halo jacket.

In patients with displaced cervical spine injury, a closed reduction can be carried out. It is safe to treat displaced subaxial fracture and subaxial subluxations and dislocations, by traction [3].

Lee et al [4] carried out a study involving 210 patients with unilateral and bilateral facet dislocations. They found that rapid traction under sedation using weights up to 150 pounds was safer than carrying out manipulation under anesthesia. They also found that early reduction of the dislocation in patients with neurological deficit gave them the best chance of neurological recovery.

Surgery is usually indicated in patients when a close reduction has failed, in patients with unstable injuries and when there is bilateral facet dislocation of more than 25% or 11°. Progressive neurological deterioration would be another indication for surgery. Kyphosis of 30° or more or loss of vertebral height of more than 50% is often associated with a high incidence of late complications, and this situation may warrant surgical intervention. Late instability and severe post-traumatic kyphosis may warrant surgical intervention [3].

In patients with partial neurological injury, early surgical intervention is usually recommended. There is some evidence that early surgical intervention (less than 24 hours) is safe and effective. Neurological recovery can also occur in some patients who have delayed decompression [4,5].
Some have claimed that 70% of patients with partial spinal cord injury improve one grade or more (American Spinal Injuries Association, International Medical Society of Paraplegia grades) if the surgery is carried within 6 hours after the injury [7]. When surgery is carried out after 6 hours only 12% of the patients show improvement. In patients with a complete spinal cord injury, the chances of neurological recovery is poor.

Decompression and/or stabilized of the cervical spine can be carried out via the anterior, posterior or a combination of both approaches, depending on the type of injury. The clinical success rates are higher with the anterior approach through the anterior approach is biomechanically inferior to the posterior approach [3].

Long term outcome of cervical spine injury treatment

There is a dearth of literature on the long term outcome of management of cervical spine injuries. The largest study with a long term follow up is the one by Fredø et al [8]. They followed up 256 patients with subaxial cervical spine injuries who were treated surgically. The surgical approach was anterior in 69% of the patients, posterior in 22% and combined in 9 % of the patients.
The mean follow-up period was 3.1 years with a range of 0.5–9.0 years. None of their patients had neurological deterioration after the surgery.

In patients who were operated within 24 hours, 48.8% showed improvement of their neurological grades, whereas in patients operated after 24 hours 53.1% showed improvement in their neurological grades. The improvement in AIS (American Spinal Injury Association impairment scale) grades between the two groups were not significantly different (p = 0.442). Of the patients with preoperative radiculopathy, 11 % of the patients continued to have radicular symptoms. There were four patients who developed radiculopathy after surgery, three of these patients were asymptomatic at follow-up.
Neck pain was assessed using the Visual Analog Scale (VAS). They found that the median VAS score for neck pain was 1 (range 0–10). Eighty percent of the patients had VAS scores ≤3, 15 % had VAS scores 4–6, and 5 % had VAS scores ≥7. There was no significant association between the surgical approach and neck pain [8].

They found that 26% of the patients had no neck stiffness, 63% had mild neck stiffness and 11% had severe neck stiffness. Neck stiffness was more common in patients who had fusion with posterior screw fixation.

Six percent of patients sustained hoarseness and 9% developed dysphagia after surgery. Of the 256 patients who were followed up with cervical CT scans, 98.4 % had a stable fusion, 0.4 % had a secondary loss of alignment, and in 1.2 % of the patients, there was loosening or fracture of their fixation device[8]. In this study, the surgical mortality(death within 30 days after surgery) was 2.3 %.
Koller et al. [9] carried out a retrospective review of 28 patients who had anterior cervical decompression, fusion, and plating (ACDFP) for unstable subaxial injuries without neurological deficit, to assess the mid- to long-term outcome. The mean follow up period was 5.5 years (range16–128 months). The self-rated clinical outcome was excellent or good in 81% of patients and moderate or poor in 19% of the patients.

Construct failure was seen in 31% of cases.  The fusion rate was 88.5%.  Adjacent-level degeneration progression was significantly influenced by a decreased plate-to-disc-distance. The motion of adjacent level intervertebral space was not altered due to the adjacent fusion, but it was reduced in the presence of advanced adjacent level degeneration.

Conclusion

There is a dearth of literature on the long term outcome of management of cervical spine injuries. The largest study with a long term follow up is the one by Fredø et al [8]. They followed up 256 patients with subaxial cervical spine injuries who were treated surgically. The mean follow-up period was 3.1 years with a range of 0.5–9.0 years. They obtained stable fusion in 98.4% of the patients, 0.4 % had a secondary loss of alignment, and in 1.2 % of the patients, there was implant failure. The surgical mortality (death within 30 days after surgery) was 2.3 %.

Koller et al. [9] carried out a small retrospective review of 28 patients who had anterior cervical decompression, fusion, and plating (ACDFP) for unstable subaxial injuries without neurological deficit, to assess the mid- to long-term outcome. The mean follow up period was 5.5 years (range16–128 months). Their results were not as good as the ones reported by Fredø et al [8]. Construct failure rates were very high with an incidence of 31%. Their fusion rates were lower at 88.5%.

To date, no other studies on the long term outcome of management of subaxial cervical spine injuries, have been published.

References

1. Dvorak MF, Fisher CG, Fehlings MG, Rampersaud YR, Oner FC, Aarabi B, et al. The surgical approach to subaxial cervical spine injuries: an evidence-based algorithm based on the SLIC classification system. Spine (Phila Pa 1976) 2007;32(23):2620–9.
2. Hadley MN, Walters BC, Grabb PA, Oyesiku NM, Przybylski GJ, Resnick DK, Ryken TC. Treatment of subaxial cervical spinal injuries. Neurosurgery. 2002 Mar;50(3 Suppl): S156-65.
3. O'Dowd JK. Basic principles of management for cervical spine trauma. Eur Spine J. 2010 Mar; 19(Suppl 1): 18–22.
4. Lee AS, MacLean JC, Newton DA. Rapid traction for reduction of cervical spine dislocations. J Bone Joint Surg Br. 1994 May;76(3):352-6.
5. La Rosa G, Conti A, Cardali S, Cacciola F, Tomasello F. Does early decompression improve neurological outcome of spinal cord injured patients? Appraisal of the literature using a meta-analytical approach. Spinal Cord 2004;42:503-12.
6. Fehlings MG, Perrin RG. The role and timing of early decompression for cervical spinal cord injury: Update with a review of recent clinical evidence. Injury 2005;36 Suppl 2:B13-26.
7. Fehlings M, Aarabi B, Dvorak M, et al. (2008) A prospective multicenter trial to evaluate the role and timing of decompression in patients with cervical spinal cord injury: initial one-year results of the STASCIS study. Paper presented at the AANS meeting in Chicago.
8. Fredø HL, Rizvi SAM, Rezai M, Rønning P, Lied B and Helseth E. Complications and long-term outcomes after open surgery for traumatic subaxial cervical spine fractures: a consecutive series of 303 patients. BMC Surg. 2016 Aug 15;16(1):56.
9. Koller H, Reynolds J, Zenner J, Forstner R, Hempfing A, Maislinger I, Kolb K, Tauber M, Resch H, Mayer M, Hitzl W. Mid- to long-term outcome of instrumented anterior cervical fusion for subaxial injuries. Eur Spine J. 2009 May;18(5):630-53.