Fig. 3

A A 70-year-old man underwent L4–L5 fusion with screws and cage. An initial postoperative X-ray showed good locations of the implants. B One month after the surgery, a follow-up X-ray showed posterior migration of the L4–L5 cage and suspected L5 screw loosening, and conservative treatment with oral analgesics and brace protection was chosen. C Three months after the surgery, progressive posterior migration of the L4–L5 cage, erosion of the L4–L5 end plates, and L5 screw loosening were noted. D, E T1-weighted and T2-weighted magnetic resonance imaging revealed low signal changes in the abutting L4 and L5 vertebrae, and fluid accumulation in the L4–L5 disc space, respectively. F An anterior + posterior approach was chosen. Posterior surgery for the upper and lower extension of the instrumented level was performed, followed by anterior surgery with cage removal and interbody fusion with autologous iliac tricortical bone graft. An initial postoperative X-ray showed good alignment. G Fourteen months after the anterior + posterior surgery, an X-ray revealed L4–L5 solid interbody union. The patient also had improved clinical outcomes and adequate infection control.