Extraforaminal Lumbar Interbody Fusion for Cage Migration after Screw Removal: A Case Report
A 55-year-old man initially presented with disabling pain in both legs with claudication of 5 months duration. Radiological studies, including simple radiographs and magnetic resonance imaging (MRI) studies, revealed right foraminal stenosis at the L4-L5 level. Preoperative laboratory tests and bone marrow densitometry (BMD) results were all within normal ranges. He underwent L4-L5 PLIF using Stryker titanium-threaded cages (length 25mm, height 9mm) with autogenous local bone chips following posterior instrumentation. Radiographs obtained immediately after surgery showed appropriate positioning of the cages, and his presenting symptoms were much improved. At his 12-month follow-up, the leg pain and claudication symptoms had resolved, but he complained of back pain, late-onset back discomfort, and a reduced range of motion (ROM). He requested implant removal. Plain radiographs showed that cage positions had been well-maintained (). Because he was believed to have solid arthrodesis and no other pain generator, such as, adjacent segment degeneration, flat back deformity, or pseudoarthrosis, we considered that spine implant removal would relieve the back pain and discomfort, which were responsive to injections of lidocaine. Pedicular screws were removed at 12 months after PLIF (). However, one month after screw removal, the pain in both legs severely worsened in spite of aggressive analgesic administration. Plain radiographs and MRI showed that posterior migration of the inserted into the disc space (). Patient was scheduled for extraforaminal lumbar inter-body fusion (ELIF) with percutaneous screw fixation, which enables facile exposure of the exiting nerve root for cage removal without violating previous posterior musculoligamentous structures or bony stabilizers of the spine. During revision surgery, after removing both offending cages, two peek cages (length 25mm, height 9mm) were inserted into the disc space, and percutaneous screw fixation with compression was applied to the disc space to prevent further cage migration. Dramatic improvements of severe back and radiating pain were achieved immediately after revision surgery (). At his 6-month follow-up, he was symptom free and plain radiographs and MR images showed that cage positions had not changed.