The Pedicle-to-Pedicle Distance Translation in Normal Lumbar Spine during Flexion-Extension and its Importance in Dynamic Stabilization

Abstract

Kinematic effects of pedicle-screw based posterior dynamic stabilization (PDS) devices are closely related to devices’ fatigue failure risk and pain relief function. Conventionally, such effects are assessed mainly by Range of angular Motion (ROM). However, angular ROM was found to be inadequate to explain fatigue failure of some recent PDS devices. The reason behind is normal segmental angular motion may involve changes in the Inter-Pedicular Distance (IPD), whereas PDS device may permit angular motion without permitting changes in the IPD distances.