Abstract: 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. 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.

Plain-language summary: 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.