Fig. 4

A Radiographical image of the lumbar spine on AP view. The solid arrow shows the partial defect of the vertebral arch of at the L5 level. The dashed arrow shows incomplete fusion of the spinous process at L5; higher lumbar levels are unaffected. B Ultrasonographic image of axial view at the level of L4/5. The solid arrow shows incomplete fusion of the vertebral arch at L5. The dashed arrow shows the incomplete fusion of the spinous process of the L5 vertebra