Bilateral ossification of the iliolumbar ligament from the transverse process of the fifth lumbar vertebra to the iliac crest. The enlarged left L5 transverse process forming a pseudo-articulation with the iliolumbar ligament calcified. Sacroiliac joints are fused. Bamboo shaped spine due to syndesmophyte formation laterally. Interspinous/supraspinous ligamentous calcification (dagger sign).