26dkou350 10.3205/26dkou350 urn:nbn:de:0183-26dkou3502 Meeting Abstract Rastegar Adib Rastegar Adib Fatemeh F

Experimental Trauma Surgery, Faculty of Medicine, Justus Liebig University of Gießen, Gießen, Deutschland

author Abu Mraheil Abu Mraheil Mobarak M

Institute of Medical Microbiology, German Centre for infection Giessen-Marburg-Langen Site, Justus-Liebig-University of Gießen, Gießen, Deutschland

author Jahed Jahed Vahid V

Experimental Trauma Surgery, Faculty of Medicine, Justus Liebig University of Gießen, Gießen, Deutschland

author Stötzel Stötzel Sabine S

Experimental Trauma Surgery, Faculty of Medicine, Justus Liebig University of Gießen, Gießen, Deutschland

author Heiß Heiß Christian C

Experimental Trauma Surgery, Faculty of Medicine, Justus Liebig University of Gießen, Gießen, Deutschland Clinic & Polyclinic for Trauma Surgery, University Hospital of Gießen-Marburg Justus Liebig University of Gießen, Germany, Gießen, Deutschland

author El Khassawna El Khassawna Thaqif T

Experimental Trauma Surgery, Faculty of Medicine, Justus Liebig University of Gießen, Gießen, Deutschland

author German Medical Science GMS Publishing House

Düsseldorf

610 20261020 engl This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. Dieser Artikel ist ein Open-Access-Artikel und steht unter den Lizenzbedingungen der Creative Commons Attribution 4.0 License (Namensnennung). M0659 350 Deutsche Gesellschaft für Orthopädie und Unfallchirurgie Deutsche Gesellschaft für Orthopädie und Orthopädische Chirurgie Deutsche Gesellschaft für Unfallchirurgie Berufsverband für Orthopädie und Unfallchirurgie Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2026) Grundlagenforschung | Infektion Berlin 20261020 20261023 DKOU26_Abs_2288 TextObjectives and questions: Bone infections, including osteomyelitis and post-surgical complications, remain a major challenge in orthopaedic and trauma surgery and can lead to implant failure, chronic inflammation, and impaired bone repair. Systemic antibiotics and surgical debridement are frequently insufficient due to recurrence and antibiotic resistance, motivating local sustained-release approaches. This study evaluated the antibacterial, antibiofilm, biocompatibility, and physicochemical performance of a novel injectable bone paste for infection-resistant bone repair applications.Material and methods: This in vitro experimental study evaluated antibacterial activity using agar diffusion (inhibition-zone) assays on standardized bacterial lawns (10⁶ CFU/mL) and quantitative killing assays against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and methicillin-resistant S. aureus (MRSA). Antibiofilm efficacy was assessed by disrupting 72 h mature biofilms and quantifying viable bacteria by CFU enumeration after 16–18 h exposure (detection limit: 10 CFU). Biocompatibility was examined using Cell Counting Kit-8 (CCK-8) on human bone marrow stem cells exposed to paste-conditioned medium (5–20 mg/mL) for 24–72 h, complemented by fluorescence imaging of F-actin and nuclei. Flowability/injectability was quantified by measuring injection force through a syringe at a constant rate over 21 days. Degradation and structural stability were assessed in PBS at 37 °C for up to 4 weeks. All experiments were performed with n = 5 independent replicates. Statistics: in Prism; t-tests or ANOVA/Tukey, α=0.05; data shown as mean±SD.Results: The bone paste produced inhibition zones of 23 ± 1.4 mm, 21 ± 1.2 mm, and 20 ± 1.1 mm against E. coli, S. aureus, and MRSA, respectively (n = 5). Conditioned medium (5–20 mg/mL) showed no cytotoxicity at 24, 48, or 72 h, with CCK-8 viability comparable to untreated controls (n = 5). Exposure to 10 mg/mL bone paste reduced viable counts by approximately 20,000-fold for E. coli, 60,000-fold for S. aureus, and 25,000-fold for MRSA (p ≤ 0.0001, n = 5). Biofilm disruption assays showed bacterial counts below the detection limit (<10 CFU) after overnight treatment with 10 mg/mL bone paste. Fluorescence imaging demonstrated normal cell morphology, intact nuclei, and well-organised F-actin across all tested concentrations. Injectability testing showed stable flow characteristics, with an injection force of 1.8 ± 0.2 N maintained over 21 days. Degradation testing showed preserved structural integrity for up to 4 weeks under physiological conditions.Discussion and conclusions: The injectable bone paste combined broad-spectrum antibacterial and antibiofilm activity with in vitro biocompatibility, sustained injectability, and structural stability under simulated physiological conditions. These properties support further evaluation as a local infection-resistant biomaterial for bone repair; confirmation of regenerative capacity requires dedicated osteogenic and/or in vivo bone-formation testing. 0 0 0 0