(a)
(b)
(c)
Figure 5: Postoperative images obtained from a 69-year-old female patient who underwent dynamic stabilization at the level of L4/5. (a) Plain radiograph on postoperative day 3. (b) Postoperative plain radiograph 6 months after surgery documented the halo sign (arrow) which was indicative of screw loosening. (c) CT scan performed 19 months after surgery documented the presence of screw loosening (circle).