91. Can the proposed posterior ligament-bone injury classification and severity score predict the failure of anterior-only surgery for subaxial cervical facet dislocations?

Abstract

BACKGROUND CONTEXT The approach selection for subaxial cervical fracture dislocations (SCFD) is controversial. While spinal surgeons increasingly prefer a single anterior approach, the complication of postoperative cervical kyphosis is worrisome. Hence, identification of suitable candidates requiring a second posterior reconstruction is necessary, thus preventing the failure of anterior-only surgery in patients with SCFD. PURPOSE To introduce a novel classification and scoring system called the posterior ligament-bone injury classification and severity (PLICS) score and verify whether this system can be generally utilized for the treatment of the SCFD to predict the failure of anterior-only surgery. STUDY DESIGN/SETTING A retrospective cohort study. PATIENT SAMPLE A total of 394 patients with SCFD who underwent anterior decompression, reduction, and fusion between January 2002 and December 2017 in one center were retrospectivelyenrolled in the study. The inclusion criteria included: 1. the preoperative magnetic resonance imaging (MRI) detected facture dislocation accompanying with an extruded disc, which deformed the dural sac beyond the line between the postero-inferior corner of cranial vertebrae and the postero-superior corner of caudal vertebrae; 2. the clinical level of neural dysfunction corresponds to the segment of reconstruction without the requirement of an extensive posterior decompression; 3. the reduction can be achieved under an attempt at the awake skull traction preoperatively or via anterior approach after the removal of herniated disc intraopertively. The exclusion criteria included: reduction can't be by preoperative skull traction, or by an anterior approach intraoperatively; the patients obtained a posterior reconstruction surgery when the intramedullary edema may extend beyond the segment of dislocation; severe traumatic cervical spondylolisthesis (over grade 3); the patients are accompanying by ankylosing spondylitis. OUTCOME MEASURES Clinical outcomes with respect to neck pain and function were recorded for each patient according to visual analog score (VAS) and the Neck Disability Index (NDI). We paired the equal number of patients between successful and unsuccessful groups to compare the difference in the clinical outcome. The American Spinal Injury Association (ASIA) impairment scale was recorded at each follow-up interval. Additionally, lateral radiography computed tomography (CT) and MRI were also recommended. METHODS Patients were divided into successful and unsuccessful groups according to whether failure of internal fixation was observed during follow-up. PLICS is based on the injury severity of the ligament-bone structure of three elements. Anatomically, the posterior column of cervical spine can be subdivided into three-column structure, including bilateral facet joints and the outside joint capsules, and posterior spinous processes and the attached ligament structures, so-called posterior ligamentous complex, including the supraspinal ligament and interspinous ligament. In this score system, a specific point value (0 - 3) is assigned to a particular variable within each element reflective of the severity of injury and its contribution to stability of posterior column of cervical spine. The preoperative PLICS score of all patients are recorded respectively. RESULTS Among 354 patients, 89.8% fulfilled the follow-up. Fifteen patients (4.2%) experienced hardware failure and progressive cervical kyphosis at the postoperative follow-up. The patients were divided into successful (15 patients) and unsuccessful (339 patients) groups. The average VAS score in the satisfactory group decreased from 6.7+0.8 to 1.3+0.6. The average VAS score in the unsatisfactory group decreased from 4.9+0.8 to 0.3+0.5. The average NDI score at the12-month follow-up was statistically low in the satisfactory group (6.2+2.1 vs 15.5+3.8, P= .028). It is worth noting that, except for only one patient with a PLICS score of 6, the PLICS score for the other 14 patients who experienced postoperative hardware failure was >7. However, the PLICS score for the other 339 patients (except for 2 cases) who obtained satisfactory radiological outcome was CONCLUSIONS When a PLICS score >7 is accompanied by severe lateral mass fracture, the risk of postoperative failure after an anterior-only reconstruction is high and supplemental posterior strengthening can be considered. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.