OBJECTIVETo study the clinical effects and application value of intraoperative CT in treatment of severe scoliosis with posterior total pedicle screws.

METHODSThirty-two cases of severe scoliosis were retrospectively analysed in our hospital from June 2009 to June 2011,which were treated by posterior total pedicle screws with intraoperative CT including 12 males and 20 females with an average age of 16.8 years ranging from 10 to 38 years. There were 19 cases combined with thoracic kyphosis among 32 cases. Multiple planar reconstruction technology of intraoperative CT was applied to assess screw position. The numbers (rates) of pedicle screws were calculated and evaluated as different grades in upper thoracic vertebra (T1-T4) ,middle thoracic vertebra (T5-T8), lower thoracic vertebra (T9-T12) and lumbar vertebra. The pedicle screws of 2 grade and 3 grade were defined as malpositioned screws. Times of applicating intraoperative CT were calculated. Cobb angle of all cases and kyphosis angle of the cases combined with thoracic kyphosis were measured before and after surgery. Scoliosis correction rates and kyphosis correction rates were calculated.

RESULTSThere were 686 pedicle screws placed in thoracolumbar of 32 patients (including 544 thoracic pedicle screws,142 lumbar pedicle screws) and 14 patients underwent osteotomy. The rate of malpositioned screws in thoracolumbar was 7.3% by evaluating with intraoperative CT,and it respectively was 5.6%,11.1%, 6.7% and 4.3% in upper thoracic vertebra, middle thoracic vertebra,lower thoracic vertebra and lumbar vertebra. The malpositioned screws were amended in surgery. The mean times of intraoperative CT was 2.6 times (ranged from 2 times to 4 times). The mean preoperative Cobb angle was 95 degrees (ranged from 78 degrees to 123 degrees) and the mean postoperative Cobb angle was 340 (ranged from 19 degrees to 53 degrees). The mean correction rate of Cobb angle was 64%. The mean preoperative kyphosis angle of the patients combined with thoracic kyphosis was 69 degrees (ranged from 46 degrees to 82 degrees) and the mean postoperative kyphosis angle was 32 degrees (ranged from 22 degrees to 45 degrees). The mean correction rate of kyphosis angle was 54%. Four patients suffered cerebrospinal fluid leak after surgery. No infection, vascular lesion and nervous lesion were found. All patients had an average 18-month follow-up (ranged from 12 to 26 months). No broken nails, broken rods and pseudarthrosis were founded.

CONCLUSIONApplication of in traoperative CT in severe scoliosis with posterior total pedicle screws can detect and amend malpositioned screws timely in surgery, to avoid secondary surgery for malpositioned screws and protect the safety of surgery. The effects of surgery is satisfactory.