Executive Summary: State-of-the-Art Review: Diagnosis and Management of Spinal Implant Infections

Spinal implant infections are serious complications of instrumented spinal fusion surgeries, carrying high morbidity and complex management challenges. These infections can manifest in the early postoperative period or present chronically over time. Early postoperative infections occur within 90 days after surgery and are characterized by worsening back pain, wound healing issues, fever, or other systemic symptoms. Magnetic resonance imaging is the preferred imaging modality, although its utility can be limited by metal artifacts from the implant. Early infections necessitate surgical debridement. Implants may be retained if stable. This surgical intervention should be coupled with at least 12 weeks of antibiotic therapy. Ideally, biofilm-active antibiotics should be used for staphylococcal infections. Accurate microbiological diagnosis through intraoperative aerobic and anaerobic bacterial cultures is critical to guide targeted antimicrobial treatment. The majority of infections are caused by gram-positive organisms such as Staphylococcus aureus. Gram-negative bacilli are more common in lumbosacral infections. Intravenous antibiotics are commonly initiated due to their rapid onset and predictable pharmacokinetics, but highly bioavailable oral regimens can be used to complete therapy. Remission rates with implant retention approach 70%. There is no strong evidence to support routine suppressive antibiotic therapy. However, it may be considered for patients who received no debridement, underwent incomplete or delayed debridement, or are poor candidates for additional surgery. In contrast, chronic spinal implant infections typically present insidiously with implant failure, pseudarthrosis, or indolent pain. These infections are often diagnosed intraoperatively during revision surgery intended to address presumed aseptic loosening. Cutibacterium acnes is the predominant pathogen in chronic cases. Management generally requires implant removal, especially in the setting of hardware failure. Sonication of removed implants can improve microbiologic diagnosis by sampling surface biofilms. However, there are limited data on optimal antimicrobial regimens, with some evidence suggesting oral therapy may be adequate. In conclusion, spinal implant infections require a nuanced, multidisciplinary approach that carefully balances eradication of infection with preservation of spinal stability and is tailored to each patient's unique circumstances. Further research is needed to optimize diagnostic strategies and antimicrobial regimens, including better defining the role of suppressive antibiotic therapy.