Estimation of 3D location and orientation of human vertebral facet joints from standing digital radiographs.

This study provides a biplanar radiographic reconstruction method of volumes of interest to evaluate the location, dimensions and orientation of human facet joints. Visibility of facet anatomical landmarks and areas of interest was evaluated on digital radiographs of 20 idiopathic scoliotic adolescents. Areas of interest have provided the most reliable evaluation of facet joints on postero-anterior and lateral digital radiographs. Volumes of interest of a thoracic and lumbar spinal segment (T1 to L3) were computed using the proposed biplanar 3D reconstruction method and compared with serial tomographic reconstructed models. Differences of 1.5 +/- 0.7 mm in 3D location and 1.8 +/- 1.2 degrees in sagittal orientation of volumes of interest were observed between both representations. This in vivo geometric information on human vertebral facet joints will help us to understand their role in spinal disorders and will provide important data for personalised biomechanical simulations.