Figure 1

Prevalence of MRI findings within Cluster 1. This cluster contained 51.6% of the 3155 vertebral motion-segments. (a) The vertical bars on the graph represent the proportion of vertebral motion segments present within each coding category for each MRI finding. The bars on the graph do not show the ‘category 0’ as that represents the presence of only normal findings. For pathologies with only one category it represents the presence of the pathology. For ‘disc signal intensity’, ‘disc height’ and ‘size of VESC’ the categories refer to increasing severity or size of pathology with ‘Category 1’ being the least severe. For ‘herniations’, the categories represent the following types: 1 = focal protrusion; 2 = broad-based protrusion; 3 = extrusion; 4 = sequestration. For ‘type of VESC’, the categories refer to the following types: 1 = Type I; 2 = Type II; 3 = Type III; 4 = mixed Type I/II; 5 = mixed Type II/III; 6 = mixed Type I/III. For ‘anterolisthesis’, the categories refer to the Meyerdings classification. Detailed information on proportions of categories of MRI findings is described in Additional file 2. (b) The mean age of the motion segments was 39 years (SD 10) and the proportion of women was 58%. (c) VESC = vertebral endplate signal change; Cat. = coding categories; EP = endplate.