The impact of bilateral facetectomy on the instantaneous helical axis of the functional thoracic spinal unit T4-5 during axial rotation.

The location of the instantaneous helical axis (IHA) and the impact of the facet joints (FJ) on the kinematics in the thoracic spine remain inconclusive. This study aimed to examine the IHA in the functional spinal unit (FSU) T4-5 during axial rotation in intact conditions and after bilateral facetectomy. Four human T4-5 FSUs were examined with an established 6D measuring apparatus in intact conditions and after bilateral facetectomy.

Total disc arthroplasties alter the characteristics of the instantaneous helical axis of the cervical functional spinal units C3/C4 and C5/C6 during flexion and extension in in vitro conditions.

Total disc arthroplasty (TDA) increases the risk of adjacent segment disease (ASD). Kinematic analyses are necessary to compare the intact condition (IC) with alterations after TDA to develop better prostheses. A well-established 6D measuring apparatus (resolution < 2.

Evidence for IHA migration during axial rotation of a lumbar spine segment by using a novel high-resolution 6D kinematic tracking system.

The biomechanical properties of the lumbar spine have long been studied. However, despite its enormous importance, basic functional and morphological properties have been not well understood and require further experimental analysis since data concerning the spatial instantaneous segmental motions are hardly available. This study describes the theoretical background and the technical properties of an innovative method for tracking the instantaneous 3D motion of human spinal segments in vitro at high spatial resolution.