Background context: A delayed infection after instrumented spine surgery can be difficult to diagnose because of its low incidence and variety of clinical symptoms.
Purpose: To describe four cases of delayed infection after instrumented spine surgery and to review the literature of such cases with regard to the clinical symptoms and risk factors, possible causes of infection and treatment.
Study design/setting: Personal review of cases and literature review.
Patient sample: Four cases in this report and 93 other cases reported in the literature.
Outcome measures: Not measured.
Methods: Summary of the clinical symptoms, risk factors, causes of infection and treatment regimens.
Results: Three possible causes of a delayed infection have been cited: intraoperative seeding, metal fretting causing a sterile inflammatory response or stimulating low-virulent organisms to fester and hematogenous seeding. A variety of clinical symptoms were found, but spontaneous drainage appears to be most common. Many patients had either a fluctuant mass, localized drainage or an abscess. Abscesses or drainage material is typically contiguous with the instrumentation and the fusion mass. Fever was present in only six patients. Effective treatment usually includes removal of the implants, irrigation and debridement, followed by the administration of antibiotics.
Conclusions: A high level of suspicion is needed to diagnose a delayed infection after instrumented spine surgery.