Epidural abscess and discitis complicating instrumented posterior lumbar interbody fusion: A case report

Study Design. A case of epidural abscess and discitis following instrumented PLIF using a single carbon fiber interbody cage is presented. Objective. To describe a previously unreported complication of epidural abscess and discitis following posterior lumbar interbody fusion using a single carbon fiber cage. Summary of Background Data. Various complications have been reported with PLIF. These include graft migration, pseudarthrosis, implant subsidence, epidural hemorrhage, incidental durotomy, arachnoiditis, transient or permanent neurologic deficits, persistence of pain, and wound infections. There are no reported cases of epidural abscess or refractory discitis associated with PLIF. Methods. A 35-year-old infantryman on active duty with chronic low back pain and single-level lumbar disc degeneration underwent instrumented PLIF after reporting no improvement with 3 years of extension-based physical therapy and nonsteroidal pain medications. His back pain was reported improved at 6 weeks after surgery. At 12 weeks after surgery, he presented to the emergency department with intense back pain and fevers. Laboratory data were remarkable for elevated erythrocyte sedimentation rate ( 118) and C-reactive protein ( 38). Initial imaging studies, including a lumbar MRI, did not demonstrate any abnormalities. The patient continued to spike fevers, and a repeat lumbar MRI 1 week later clearly demonstrated the presence of an epidural abscess at the level of the PLIF surgery. The patient was treated with surgical debridement and epidural abscess drainage. The interbody cage was left in place. Surgical cultures identified Staphylococcus aureus as the pathogen, and the patient was placed on intravenous vancomycin. During the ensuing 3 weeks, his clinical symptoms worsened and his radiographs demonstrated lucency in the region of his interbody cage. Repeat debridement was performed, and his interbody cage and pedicle screw instrumentation were removed 4 months after initial surgery. Results. The disc space infection resolved following removal of the implants. Radiographs at 6 months after instrumentation removal demonstrated solid bilateral posterolateral arthrodesis. The patient returned to active duty 1 year after his initial surgery, reporting that his back pain was reduced compared with his preoperative level. Conclusions. There is a paucity of literature on epidural abscess and discitis as complications associated with PLIF. In this case, the infection persisted despite surgical debridement and intravenous antibiotics. The patient ultimately required removal of the interbody implant and posterior instrumentation. The patient developed solid posterolateral arthrodesis despite the presence of deep infection, which led to early implant removal 4 months after the initial surgery. This case underscores the potential importance of concomitant posterolateral fusion, particularly following wide laminectomy and facet-ectomy required for PLIF.