| It has long been postulated that the facet joint geometry (FJG) has an important influence on lumbar segmental motion. Although their sagittal orientation has been described in detail, there are very few studies describing the three-dimensional (3D) FJG. None correlates the latter to segmental kinematics. In view, we developed a method to quantify 3D FJG and compared the results to segmental kinematics.;In the ex-vivo set-up, facets of individual cadaveric vertebrae taken from a previous biomechanical. study were digitized using a 3D morphometer and the geometry of the facet joints in respect to the vertebra's local coordinate system was quantified. In the in-vivo set-up, re-recruited subjects from a previous kinematic study had a MRI of their lumbar spine. The images were digitized and the facet joint's 3D geometry was evaluated. The two methods used for FJG measurements were validated. Kinematic data derived from both previous studies was correlated with their respective FJG.;We did not find a significant influence of the FJG or tropism on lumbar segmental kinematics. Different coupling patterns were measured in the ex-vivo and in in-vivo experiments. This is likely due to the absence of muscle activity in the cadaveric specimen. Future in-vivo studies should be done with simultaneous muscle activity recording to better understand the coupling patterns. Studying FJG in defined spinal pathologies may render valuable information on the etiology of spinal diseases. |
