5-Minute Summary: Beyond MIC: Biofilm Eradication, MBEC, and Sustained Intra-articular Antibiotic Delivery in Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) remains a challenging complication of total joint arthroplasty, in part because biofilm-associated bacteria demonstrate substantially greater antimicrobial tolerance than planktonic organisms. Although systemic antibiotics are central to PJI treatment, concentrations achieved within the joint may exceed the minimum inhibitory concentration (MIC) yet remain insufficient to reach the minimum biofilm eradication concentration (MBEC). This pharmacokinetic mismatch represents a fundamental limitation of conventional antimicrobial therapy. This narrative review examines biofilm biology, the limitations of MIC-based treatment, and the emerging role of MBEC in understanding biofilm eradication. Current local delivery strategies, including antibiotic-loaded polymethylmethacrylate spacers and beads, intra-wound antibiotic powders, and intraoperative irrigation, are reviewed, with emphasis on their limited ability to sustain biofilm-eradicating concentrations. Intra-articular antibiotic infusion offers a potential strategy to overcome these limitations by delivering sustained, high local antibiotic concentrations while maintaining comparatively modest systemic exposure. Available clinical series report encouraging infection-control rates across DAIR, single-stage revision, and salvage procedures; however, evidence remains largely retrospective and heterogeneous. Further comparative studies are needed to define optimal patient selection, antibiotic regimens, dosing strategies, and the clinical efficacy of intra-articular therapy in PJI.