📑
Chapter Summary
• Context: Postoperative surgical site infections (SSI) represent one of the most critical complications in spine surgery due to their potential to increase morbidity, prolong hospitalization, and necessitate reoperations, including implant management. Incidence varies according to procedure type, patient profile, and surgical complexity. Extensive deformity surgeries, instrumentation, and comorbidities increase risk. Presentation is heterogeneous: acute early infections show overt local signs, whereas delayed late infections present insidiously, linked to implant colonization and biofilm formation. The clinical challenge consists of early recognition, differentiating superficial from deep involvement, and eradicating infection without unnecessarily compromising spinal stability or deformity correction.
• Chapter Objective: To enable the reader to recognize epidemiological, clinical, and microbiological features of postoperative spine infections, identify risk factors, apply classifications, and utilize laboratory and imaging studies appropriately. Principles of early and late infection management, the role of instrumentation retention vs. removal, and evidence-based preventive measures are detailed.
• Classification and Risk FactorsInfections are classified by timing (early < 30-90 days vs. late > 90 days) and anatomical depth (superficial vs. deep / organ-space). Chronology directly impacts presentation and implant management. Risk factors include obesity, diabetes, frailty, malnutrition, prolonged operative time, revision surgery, and instrumentation density. Multifactorial risk profiles require heightened clinical suspicion.
• Microbiology and Biofilm DynamicsStaphylococcus aureus and Staphylococcus epidermidis predominate. Neuromuscular deformity patients frequently show gram-negative and polymicrobial flora. In late infections, low-virulence organisms (Cutibacterium acnes, coagulase-negative staphylococci) form mature biofilms on metal implants, perpetuating infection despite subtle systemic signs.
• Diagnostic StrategyClinical suspicion is central. Erythema, wound drainage, pain, dehiscence, and fever characterize acute infections. Late infections may present only as persistent axial pain, mild swelling, or sinus tract drainage. Serial CRP, ESR, and CBC monitoring, alongside sterile wound cultures, guide diagnosis. Contrast-enhanced MRI and CT evaluate fluid collections, bone erosion, pseudarthrosis, and screw loosening.
• Treatment and PreventionAcute deep infections are treated with urgent surgical irrigation, debridement, targeted intravenous antimicrobials, and hardware retention whenever stable. In late infections with established biofilms, management depends on fusion maturity: if fused, hardware removal is curative; if ununited, single-stage or two-stage hardware exchange is indicated. Prevention hinges on bundle protocols: glycemic control, weight optimization, antiseptic skin prep, timely antibiotic prophylaxis, wound irrigation, and intrawound vancomycin powder.
• Clinical Application: Postoperative infection presents with diverse phenotypes. Acute wound breakdown requires aggressive early debridement and culture-directed antibiotics while preserving stable implants. Late-onset indolent pain around an instrumented spine warrants workup for low-virulence biofilm colonization. Laboratory markers must be evaluated serially. Deciding whether to retain, exchange, or remove implants requires assessing fusion solidity: removing hardware from an unhealed spine causes catastrophic loss of correction and pseudarthrosis.
