Fig. 1From: Associations between facet tropism and vertebral rotation in patients with degenerative lumbar diseasea The rotation angle is the angle between the midline of the vertebral body and the sagittal line. b The angle subtended by the plane of the facet with the sagittal plane in the midline of the vertebral body is the facet angle. c Diagram shows the measurement of rotation angle of L2 vertebral body and facet angle of L1/2 segmentBack to article page