[Pedicle screw fixation and allograft bone in posterior spinal fusion for treatment of thoracolumbar vertebral fractures].

OBJECTIVE: To investigate the efficacy of the pedicle screw fixation and allograft bone in posterior spinal fusion for the treatment of thoracolumbar vertebral fractures.

METHODS: From September 2006 to March 2008, 105 cases of thoracolumbar vertebral fractures were treated with allograft bone in posterior spinal fusion after the pedicle screw fixation, including 75 males and 30 males aged 15-65 years (mean 37 years). The mixture which consisted of spinous process and vertebral plate sclerotin and homogeneity variant bone was used as bone graft to implant into articular process and processus transversus space or vertebral plate space. The time from injury to surgery varied from 8 hours to 21 days, with an average of 3 days. There were 52 cases of falling injuries from height, 35 cases of traffic accident injuries, 11 cases of bruise injuries and 7 cases of tumbling injuries. Before operation, the primary clinical symptoms of patients included local pain combined with limitation of activity, 30 cases complicated by various degrees of spinal cord and nerve root functional disturbance. According to Mcaffee classification, there were 7 cases of flexion depressed fractures, 86 cases of blow-out fractures, 9 cases of Chance fractures and 3 cases of dislocation-fracture. According to Frankel grade, there were 11 cases of grade A, 2 cases of grade B, 7 cases of grade C, 10 cases of grade D and 75 cases of grade E. The X-ray examination of all patients denoted that the bodies of injured vertebra were compressed and wedge-shaped, and the CT scan showed that 98 cases had spinal stenosis. After 2 weeks and 3, 6, 12 months, the X-ray films were taken to evaluate bone graft fusion. The Cobb angle was measured. The recovery of nerve function was analyzed.

RESULTS: The operation time was 55-180 minutes (mean 90 minutes) and the blood loss was 100-900 mL (mean 200 mL). All patients achieved healing by first intention with no complication. After operation, 93 cases were followed up for 6-15 months with an average of 11 months. Except for 11 patients who were at grade A before operation, one to two grade recover was observed in other patients. The average Cobb angle of injury segment was improved from preoperative 32.1 degrees to postoperative 5.2 degrees. The height of anterior border of injured vertebral body was recovered from the preoperative average compressed remaining height 61.5% to postoperative 96.8%. The vestigial degree of canalis spinalis anteroposterior diameter was recovered from preoperative 65.7% to postoperative 89.9%. Imageology examination showed that all the patient achieved bone union within 6 months. The fusion rate of bone graft in spinal fusion was 100%. No loosening and breaking of nails occurred.

CONCLUSION: Pedicle fixators can restore and fix the thoracolumbar fractures, and the combination of autograft and allograft bone transplantation is a safe, reliable and effective method.