In vitro analysis of thoracic spinal motion segment flexibility during stepwise reduction of all functional structures

Purpose The aim of this study was to quantify the stabilizing effect of the passive structures in thoracic spinal motion segments by stepwise resections. These data can be used to calibrate finite element models of the thoracic spine, which are needed to explore novel surgical treatments of spinal deformities, fractures, and tumours. Method Six human thoracic spinal motion segments from three segmental levels (T2–T3, T6–T7, and T10–T11) were loaded with pure moments of 1 and 2.5 Nm in flexion/extension, lateral bending, and axial rotation. After each loading step, the ligaments, facet capsules, and the nucleus pulposus were stepwise resected from posterior to anterior direction, while the segmental relative motions were measured using an optical motion tracking system. Results Significant increases ( p