[MINIMALLY INVASIVE PASSAGE IN POSTERIOR LAMINOTOMY DECOMPRESSION AND INTERVERTEBRAL BONE GRAFTING COMBINED WITH PERCUTANEOUS PEDICLE SCREW FIXATION FOR TREATMENT OF Denis TYPE B THORACOLUMBAR BURST FRACTURES].

OBJECTIVE

To evaluate the feasibility and the effectiveness of minimally invasive passage in posterior laminotomy decompression and intervertebral bone grafting combined with percutaneous pedicle screw fixation for the treatment of Denis type B thoracolumbar burst fractures.

METHODS

Between January 2013 and March 2015, 53 patients with Denis type B thoracolumbar burst fractures were treated by minimally invasive passage in posterior laminotomy decompression and intervertebral bone grafting combined with percutaneous pedicle screw fixation. There were 37 males and 16 females with a mean age of 43 years (range, 16-57 years). The causes included falling injury from height in 23 cases, traffic accident injury in 15 cases, heavy pound injury in 7 cases, and falling injury in 8 cases. The time between injury and operation was 7 hours to 12 days (mean, 6.7 days). The involved segments included T11 in 2 cases, T12 in 7 cases, L1 in 20 cases, L2 in 18 cases, and L3 in 6 cases; based on the neurological classification of spinal cord injury by American Spinal Injury Association (ASIA), 3 cases were rated as grade A, 5 cases as grade B, 12 cases as grade C, 24 cases as grade D, and 9 cases as grade E. The operation time, bleeding volume, and postoperative drainage were recorded; postoperative visual analogue scale (VAS) was used for pain evaluation, and ASIA for neurological function assessment; CT and X-ray films were taken to observe fracture healing, bone fusion, and grafted bone absorption; The vertebral canal patency rate was calculated; the relative height of fractured vertebrae and Cobb angle were measured.

RESULTS

The operation was successfully completed in all patients; the average operation time was 150 minutes (range, 90-240 minutes); the average bleeding volume was 350 mL (range, 50-500 mL); the average postoperative drainage was 80 mL (range, 20-150 mL); and the average VAS score was 2.3 (range, 1.5-4.7) at 3 days after operation. The incisions healed primarily. All the patients were followed up 12-19 months (mean, 15 months). All fractures healed at 3-9 months (mean, 6 months). No complications of broken nails, broken rod, and screw loosening occurred. At last follow-up, the vertebral canal patency rate was significantly improved when compared with preoperative value (t=27.395, P=0.000). The Cobb angle, and the anterior and posterior heights of of traumatic vertebra were significantly improved at 1 week, 1 year, and last follow-up when compared with preoperative ones (P<0.05), but there was no significant difference between different time points after operation (P>0.05). The neurological function was improved in different degrees; 1 case was rated as grade A, 4 cases as grade B, 7 cases as grade C, 15 cases as grade D, and 26 cases as grade E, showing significant difference when compared with preoperative one (Z=-5.477, P=0.000).

CONCLUSIONS

Minimally invasive passage in posterior laminotomy decompression, bone graft in the injured vertebrae combined with percutaneous pedicle screw fixation is an effective method to treat Denis type B thoracolumbar burst fractures, which not only can fully decompression, but also can effectively maintain the postoperative injured vertebral height, reduce the postoperative failure risk of internal fixation and decrease operation trauma.