[SECURITY OF FRACTURED VERTEBRAL PEDICLE SCREW IN DIFFERENT TYPES OF PEDICLE FRACTURES].

OBJECTIVE: To investigate the security of pedicle screw fixation in fractured vertebra in treatment of thoracolumbar fractures by comparing with routine fixation cross fractured vertebra.

METHODS: A total of 101 cases of single segmental thoracolumbar fracture were selected between June 2008 and June 2011. Of them, 56 cases underwent pedicle screw fixation in fractured vertebra (group A), and 45 cases received routine fixation cross fractured vertebra (group B). There was no significant difference in gender, age, causes of injury, fracture type, fracture segment, Frankel grading, time of injury to operation, and the preoperative anterior vertebral height compression ratio and the canal occupation rate between 2 groups (P > 0.05). There were 34 cases of junction fracture of pedicle and vertebra (type I), 2 cases of pedicle waist fracture (type II), and 20 cases of junction fracture of pedicle and lamina (type III) in group A. The position of fractured vertebral pedicle screw was observed; the anterior vertebral height compression ratio, canal occupation rate, and surgical complications were compared between 2 groups.

RESULTS: A total of 103 pedicle screws were placed in 54 patients of group A, except 2 patients of type II fracture; 96 screws were placed in the bone cortex completely and 7 screws deviated. The operation time of group A was significantly longer than that of group B (t = 4.339, P = 0.000), but there was no significant difference in intraoperative blood loss between 2 groups (t = -0.089, P = 0.929). All 101 patients were followed up 6-16 months (mean, 8.5 months). The patients of 2 groups achieved nerve functional recovery. Fixation-related complications occurred in 1 case of 2 groups respectively, showing no significant difference (P = 1.000). At last follow-up, according to Denis lumbago classification, 51 cases were rated as P1 level and 5 cases as P2 level in group A; 35 cases were rated as P1 level, 8 cases as P2 level, and 2 cases as P3 level in group B; and there was no significant difference between 2 groups (Z = -1.836, P = 0.066). There was no significant difference between 2 groups in canal occupation rate at immediate after operation and at last follow-up (P > 0.05), and in the anterior vertebral height compression ratio at immediate after operation (P > 0.05), but the anterior vertebral height compression ratio of group B was significantly higher that of group A at last follow-up (P < 0.05).

CONCLUSION: Single segmental thoracolumbar fracture treated by pedicle screw fixation in fractured vertebra through posterior approach is safe and feasible according to different pedicle fracture types to guide fixation.