249. Traumatic subaxial cervical facet joint dislocation: predictors of spinal cord injury and surgical failure

BACKGROUND CONTEXT Approximately two thirds of cervical spine injuries affect the subaxial cervical spine, with fractures occurring most often at C6 and C7 and dislocations at C5-C6 and C6-C7. In the spectrum of these injuries, facet joint dislocation represents a severe injury, frequently associated with spinal cord injury (SCI). PURPOSE The purpose of this study was to analyze a cohort of surgically treated subaxial cervical spine dislocations and to identify factors associated with higher risk of SCI and predictors of surgical failure. METHODS All patients operated in a single institution during a 10-year period (2007-2016) for traumatic single-level cervical facet joint dislocation were retrospectively reviewed. Age, gender, injury characteristics (dislocation or subluxation, uni- or bilateral, level of injury and presence of associated facet fracture), mechanism of trauma, presence of SCI (determined by the American Spinal Injury Association Impairment Scale [ASIA]), surgical data and follow-up records were reviewed. All patients had a minimum follow-up of 2 years. RESULTS A total of 71 patients, 53 men and 18 women, with mean age of 57 ± 18 years (18-90) were identified. Motor-vehicle accidents were the most frequent trauma mechanism, followed by fall from height. Young adults were mostly represented among motor-vehicle accidents, whereas falls contributed to a majority of facet joint dislocations sustained by the elderly. The C6-C7 level was the most affected (37/71 cases). Forty-seven patients had unilateral and 24 bilateral dislocation, with 47 of these cases (66%) having associated facet fractures. Spinal cord injury was present in 37% of the cases. Rigid columns (p = 0.009) and bilateral dislocations (p = 0.004) were associated with the presence of spinal cord injury. Patients with bilateral dislocation were 4.7 times more likely to have a spinal cord injury (OR: 4.7, 95% CI = 1.6-13.8). The closed reduction with cranial traction was attempted in 51 cases, with a success rate of 86%. 59 cases were submitted to isolated anterior cervical arthrodesis and 7 to anterior cervical corpectomy. Five were submitted to combined anterior and posterior fixation (360°). There were 3 failures after the previous isolated fixation, which required revision surgery with 360 ° fusion. All cases of failure occurred after an isolated anterior fusion in the C7-T1 transition (p CONCLUSIONS Patients with rigid spines or with bilateral facet dislocations are at higher risk for SCI. After successful reduction, anterior discectomy and fusion, as a single procedure, offers an excellent surgical option in the management of many cervical facet fracture dislocations, has showed in this analysis. Failure occurred always at the C7-T1 level, suggesting that here; a 360 degree fusion may be needed. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.