Freehand Pedicle Screw Insertion in Spondylitis Tuberculosis Kyphosis Correction Using Cantilever Method: A Breach Rate Analysis of 168 Consecutive Screws.

Background: The cantilever method is a standard for two-dimensional deformity correction, as in spondylitis tuberculosis kyphotic deformity. An accurate and secured pedicle screw placement as part of the correction tools is essential to accommodate reduction while preventing screw-related complications. Many literatures have described the pedicle screw misplacement in cases with "normal" bone quality (ie, scoliosis, Scheuermann's kyphosis, ankylosing spondylitis, trauma) or in the obviously abnormal bone such as osteoporosis. However, to our knowledge, the pedicle screw accuracy in cases of deformity correction of tuberculous kyphosis was not previously reported.

Methods: This is a retrospective study of 168 pedicle screws in 14 consecutive cases of spondylitis tuberculosis with kyphotic deformity. The cantilever reduction method with freehand screw insertion technique was done in all cases to correct the deformity. Postoperative computed tomography (CT) evaluation was done to evaluate screw position and breach rates.

Results: Among the 168 screws, accurate pedicle screw placement was accomplished in 39.3% screws (Gertzbein-Robbins Grade A). The overall breach rate was 61.9%, which was most commonly occurred on the segment proximal to the apex of the deformity (p=0.001). The lateral breach was more common than the medial breach (52.3% vs 7.7%). The pedicle screw on the thoracal region has a greater breach incidence than those on the lumbar region especially those on T9, T10, and T11. There was no injury to the surrounding neurovascular and pleural structures. No revision surgeries were required.

Conclusion: Freehand pedicle screw insertion in spondylitis tuberculosis kyphotic reduction has proved to be safe. However, the accuracy should be improved to prevent long-term screw-related complications.