Fig. 4

a–c Representative case of the continuous posterior-annular fibrosus type. a CT image: A trabecular bone structure was frequently observed within the high-density area. b Three dimensional reconstruction image: The high-density area was observed as an elongation of the rim of the vertebral body. c Pathological image: These cases typically involved a projection with continuity with both marrow and the cortex of the bone to the enthesis. Calcification was observed in the connective tissue around the projection