Biomechanical Evaluation of Diagonal Transfixation in Pedicle Screw Instrumentation

In pedicle screw instrumentation, it is common to use one or more transfixators that crosslink the longitudinal rods horizontally. Such a horizontal transfixation (HTF) of the longitudinal rods was shown to provide an additional stability in axial rotation and lateral bending but not in flexion extension. Most significant contribution of HTF was noted in axial rotational stability because the torsional instability appeared to be most difficult to prevent using pedicle screw fixation. Recently, diagonal transfixation (DTF) has been suggested as a way to improve the overall biomechanical rigidity of the pedicle screw systems. However, the construct stiffness changes due to DTF has not been well investigated yet. The purpose of this study was to investigate biomechanical advantages of DTF compared with the HTF using flexibility tests and finite element (FE) analyses.