Study design: Retrospective.
Objective: To evaluate the clinical safety and accuracy of the Tai Chi ((Equation is included in full-text article.)) technique for placing pedicle screws, without intraoperative radiographic imaging, in severe scoliotic spines.
Summary of background data: The current techniques for pedicle screw placement have a number of drawbacks in cases of severe scoliosis, including difficulty or impossibility to use, delayed operative time, requiring the presence of trained personnel for the duration of the surgery, high cost issues, increased radiation exposure, and technical challenges. No previous report has described the application of the Tai Chi pedicle screw placement technique for severe scoliosis.
Material and methods: Between 2006 and 2008, the cases of 39 consecutive patients with severe scoliosis (Cobb angle >100 degrees) who underwent posterior correction and stabilization (from T1 to L5) using 992 transpedicular screws were examined. The mean patient age was 25.7 (range, 11 to 63) years at the time of surgery. Pedicle screws were inserted by the Tai Chi technique using anatomic landmarks and preoperative radiographs as a guide. Tai Chi drilling fully utilizes the natural anatomic and physical characteristics of pedicles and unconstrained circular force. By nature, a drill bit driven by unconstrained circular force would migrate within the pedicle along a path of least resistance, advancing along the central cancellous bone tunnel spontaneously. Accurate drilling was achieved by following the nature and sticking to the hand sensation when the drill bit broke through the cancellous bone. The total time for inserting all pedicle screws in each case was recorded. Postoperative computed tomography scans were performed to evaluate the position of the inserted pedicle screws. The screw position was classified as "in" or "out." The distance of perforation was measured.
Result: The average Cobb angle was 127 degrees (range, 100 to 153 degrees). The number of screws inserted at each level were as follows: T1 (n=10), T2 (n=34), T3 (n=46), T4 (n=53), T5 (n=61), T6 (n=69), T7 (n=75), T8 (n=76), T9 (n=76), T10 (n=77), T11 (n=76), T12 (n=78), L1 (n=77), L2 (n=68), L3 (n=56), L4 (n=38), and L5 (n=22). There were 923 (93%) "in" screws and 69 (7%) "out" screws. The overall accuracy of screw placement was 93%. There were no neurological, vascular, or visceral complications. No screws required postoperative repositioning. The average time for pedicle screw placement was 73 seconds.
Conclusions: Our findings suggest that the Tai Chi pedicle screw placement technique, which does not require intraoperative radiographic imaging, is an accurate, reliable, safe, and time-saving method of placing pedicle screws in severe scoliotic spines.