Insertion torque profile during pedicle screw insertion of the thoracic spine with and without violation of the pedicle wall: comparison between cylindrical and conical designs.

Study Design: Biomechanical study in human cadaveric thoracic spines.

Objective: To compare the insertion torque profile of cylindrical and conical screws with normal insertion tract, and with violation of the pedicle.

Summary Of Background Data: Previous studies revealed higher insertion torque for conical screws.