Surgical approaches for dislocations of the neck bones

The part of the back bone found in the neck is called the cervical spine. It consists of seven bones (or vertebrae). The relative movement of these vertebrae is mainly via small joints (called facet joints) located between each vertebrae. The facet joints in the cervical spine facilitate good movement of the neck, but they are vulnerable to dislocation. Typically, cervical spine facet dislocations are caused by high-energy traumas such as road traffic accidents or violent attacks. Approximately half of people with such dislocations sustain an injury to the spinal cord carried within the spine. This can result in significant impairment of function (e.g. paralysis). Surgery is usually needed for these serious injuries in order to keep the neck bones in place.

What are the different surgical approaches?
There are two main stages to surgery: reduction and fixation. Reduction is the restoration of an injured or dislocated bone or joint to its normal anatomical position, and can be achieved either with surgery or through closed reduction, which is performed with traction or manipulation. Fixation is the medical procedure used to stabilise one or more joints, or a fractured bone, usually by surgically inserting devices such as wires, screws, plates and rods. Fixation of the injury is generally accomplished by either an anterior or posterior surgical approach. With an anterior cervical approach the surgery is performed through an incision over the front surface of the neck, while the posterior cervical approach consists of a lengthwise midline incision over the back part of the neck and dissection through muscle to the cervical vertebrae. This approach gives direct access to the dislocated facet joints.

Description of the studies included in the review
We searched the medical literature until May 2014 and found two relevant studies that included a total of 94 adults with cervical spine facet dislocations. One trial included individuals with spinal cord injuries and the other included individuals without spinal cord injuries. Both studies compared the anterior versus posterior surgical approach.

Quality of the evidence
The two studies were small and both were at high risk of bias. We therefore judged the quality of the evidence to be very low.

Summary of the evidence
Neither study found differences between the two approaches in neurological status and pain at one year. One study also found no differences between the two approaches in patient-reported quality of life. Although one study found that the anterior approach resulted in more normal curvature of the neck, the other study reported finding no difference between the two approaches with regard to the alignment of the neck vertebrae. The evidence was insufficient to indicate differences between the two approaches in medical adverse events, rates of instrumentation failure and infection. Although over half (11) of 20 people in the anterior approach group in one study had voice and swallowing disorders, these all resolved by three months.

Conclusion
The quality of the evidence was very low, meaning that we are very uncertain about the direction and size of effect. Thus we are unable to say whether either an anterior or posterior approach to the surgical management of individuals with dislocations to the cervical spine facet joints is better than the other. We suggest that further research is needed to inform the choice of surgical approach.

Authors' conclusions: 

Very low quality evidence from two trials indicated little difference in long-term neurological status, pain or patient-reported quality of life between anterior and posterior surgical approaches to the management of individuals with subaxial cervical spine facet dislocations. Sagittal alignment may be better achieved with the anterior approach. There was insufficient evidence available to indicate between-group differences in medical adverse events, rates of instrumentation failure and infection. The disorders of the voice and swallowing that occurred exclusively in the anterior approach group all resolved by three months. We are very uncertain about this evidence and thus we cannot say whether one approach is better than the other. There was no evidence available for other approaches. Further higher quality multicentre randomised trials are warranted.

Read the full abstract...
Background: 

The choice of surgical approach for the management of subaxial cervical spine facet dislocations is a controversial subject amongst spine surgeons. Reasons for this include differences in the technical familiarity and experience of surgeons with the different surgical approaches, and variable interpretation of image studies regarding the existence of a traumatic intervertebral disc herniation and of the neurological status of the patient. Moreover, since the approaches are dissimilar, important variations are likely in neurological, radiographical and clinical outcomes.

Objectives: 

To compare the effects (benefits and harms) of the different surgical approaches used for treating adults with acute cervical spine facet dislocation.

Search strategy: 

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (9 May 2014), The Cochrane Central Register of Controlled Trials (The Cochrane Library, 2014 Issue 4), MEDLINE (1946 to April Week 5 2014), MEDLINE In-Process & Other Non-Indexed Citations (8 May 2013), EMBASE (1980 to 2014 Week 18), Latin American and Caribbean Health Sciences (9 May 2014), trial registries, conference proceedings and reference lists of articles to May 2014.

Selection criteria: 

We included randomised and quasi-randomised controlled trials that compared surgical approaches for the management of adults with acute cervical spine facet dislocations with and without spinal cord injury.

Data collection and analysis: 

Two review authors independently selected studies, assessed risk of bias and extracted data.

Main results: 

We included one randomised and one quasi-randomised controlled trial involving a total of 94 participants and reporting results for a maximum of 84 participants. One trial included patients with spinal cord injuries and the other included patients without spinal cord injuries. Both trials compared anterior versus posterior surgical approaches. Both trials were at high risk of bias, including selection bias (one trial), performance bias (both trials) and attrition bias (one trial). Data were pooled for one outcome only: non-union. Reflecting also the imprecision of the results, the evidence was deemed to be of very low quality for all outcomes; which means that our level of uncertainty about the estimates is high.

Neither trial found differences between the two approaches in neurological recovery or status, as shown in one study by small clinically insignificant differences in NASS (Northern American Spine Society) neurological scores (0 to 100: optimal score) at one year of follow-up: anterior mean score: 85.23 versus posterior mean score: 83.86; mean difference (MD) 1.37 favouring anterior approach, 95% confidence interval (CI) -9.76 to 12.50; 33 participants; 1 study). The same trial found no relevant between-approach differences at one year in patient-reported quality of life measured using the 36-item Short Form Survey physical (MD -0.08, 95% CI -7.26 to 7.10) and mental component scores (MD 2.88, 95% CI -3.32 to 9.08). Neither trial found evidence of significant differences in long-term pain, or non-union (2/38 versus 2/46; risk ratio (RR) 1.18, 95% CI 0.04 to 34.91). One trial found better sagittal and more 'normal' alignment after the anterior approach (MD -10.31 degrees favouring anterior approach, 95% CI -14.95 degrees to -5.67 degrees), while the other trial reported no significant differences in cervical alignment. There was insufficient evidence to indicate between-group differences in medical adverse events, rates of instrumentation failure and infection. One trial found that the several participants had voice and swallowing disorders after anterior approach surgery (11/20) versus none (0/22) in the posterior approach group: RR 25.19, 95% CI 1.58 to 401.58); all had recovered by three months.

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