OBJECTIVETo explore the feasibility and effect of percutanuous cannulated pedicle screw AF system fixation for the treatment of thoracolumbar flexion-distraction fracture without neurologic impairment.

METHODSFrom June 2008 to June 2010,21 patients with thoracolumbar flexion-distraction fracture were treated with percutanuous cannulated pedicle screw fixation. There were 16 males and 5 females with the mean age of 32.7 years ranging from 23 to 55 years. Injured levels 5 cases was in T12, 13 was in L1, 3 was in L2. According to classification of AO, B1 was in 13 cases, B2 was in 8 cases. ASIA grade of all the patients were grade E. The mean operative time, bleeding volume, lengths of stay were evaluated. All the patients took the X-ray and three-dimensional CT reconstruction to observe the fracture healing and to measure the height of the anterior border of fracture vertebral body and the Cobb angle of kyphosis. The visual analogue scales (VAS) were compared preoperation and postoperation. The clinical effects were analyzed according to Oswestry Disability Index (ODI) from 10 aspects, including pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex life, social life, traveling.

RESULTSAll the operations were successful and the mean time was (109.0+/-16.0) min, blood loss was (90.0+/-15.0) ml, lengths of stay was (7.7+/-2.3) d. No postoperative neurological deficits or wound infection occured. One case occurred subcutaneous fluid of incision and 1 case occurred delayed healing of incision. Fifteen patients were followed up with an average of 16.7 months (12-33 months). The VAS score improved from preoperative 8.3+/-1.7 to 1.8+/-1.2 at final follow up (P<0.05). The ODI of last follow-up was (10.0+/-1.2)%. Three-dimensional CT reconstructions and X-rays showed the height of vertebral body increased from preoperative (54.0+/-17.1)% to (82.7 - 3.5)% at 12 months after operation (P<0.05). Cobb angle of kyphosis changed from preoperative (23.0+/-13.1) to (6.9+/-5.1) degrees at 12 months after operation (P<0.05). The healing time of fracture was (4.7+/-0.3) months. There were no significant loss of vertebral height or kyphosis correction between postoperative 1 months and last follow-up (P>0.05). There were satisfactory fracture reduction and good position of internal fixation,and no loss of reduction within 12 months and no fixation failure in follow-up.

CONCLUSIONThe minimally invasive percutaneous cannulated pedicle screw fixation technique is feasible in treatment of thoracolumbar flexion-distraction fracture without neurologic impairment. This technique can avoid re -injury of posterior ligaments and bone structure, and may rebuild posterior tension band structure with the advantages of less trauma, less bleeding,shorter operative time, rapid postoperative recovery and so on.