Standard fluoroscopic views in cadavers for determining the entry point and depth of a guide needle for use in transpedicular procedures of the thoracolumbar spine.

The purpose of this study was to determine the entry point and the depth of a guide needle in a transpedicular procedure of the lower thoracic and lumbar spine on standard fluoroscopic views. Ten human cadaveric thoracolumbar spines (T9-L5) were anatomized into single vertebrae. The transpedicular puncturing needle was inserted and placed under the anterior cortex of the vertebrae along the center axis of the pedicle. The projection of the pedicle was divided into 12 sectors ("clock measurement") on the standard posterior-anterior (PA) view. We found that the ratio of the needle depth to the width of the vertebrae on the standard lateral view varied from 71.53%+/-5.72% to 93.28%+/-3.72% (mean+/-standard deviation). The entry point was located at the 9 o'clock to 11 o'clock position on the left pedicle projection and at the 1 o'clock to 3 o'clock position on the right pedicle projection on the PA view.