Prevention of bone infection after open fracture using a chitosan with ciprofloxacin implant in animal model

Bacterial Contamination of Open Fractures: Pathogens and Antibiotic Resistance Patterns in East China

Bacterial contamination of soft tissue in open fractures leads to high infection rates. Pathogens and their resistance against therapeutic agents change with time and vary in different regions. The purpose of this study was to characterize the bacterial spectrum present in open fractures and analyze the bacterial resistance to antibiotic agents based on five trauma centers in East China. A retrospective multicenter cohort study was conducted in six major trauma centers in East China from January 2015 to December 2017. Patients who sustained open fractures of the lower extremities were included. The data collected included the mechanism of injury, the Gustilo-Anderson classification, the isolated pathogens and their resistance against therapeutic agents, as well as the prophylactic antibiotics administered. In total, 1348 patients were included in our study, all of whom received antibiotic prophylaxis (cefotiam or cefuroxime) during the first debridement at the emergency room. Wound cultures were taken in 1187 patients (85.8%); the results showed that the positive rate of open fracture was 54.8% (651/1187), and 59% of the bacterial detections occurred in grade III fractures. Most pathogens (72.7%) were sensitive to prophylactic antibiotics, according to the EAST guideline. Quinolones and cotrimoxazole showed the lowest rates of resistance. The updated EAST guidelines for antibiotic prophylaxis in open fracture (2011) have been proven to be adequate for a large portion of patients, and we would like to suggest additional Gram-negative coverage for patients with grade II open fractures based on the results obtained in this setting in East China.

Fabrication and evaluation of customized implantable drug delivery system for orthopedic therapy based on 3D printing technologies

A customized implantable drug delivery system with the dual functions of playing a supporting role and providing continuous bacteriostasis is of great importance during the treatment of bone defect diseases. The main objective of this study was to explore the potential of using three-dimensional (3D) printing technologies to fabricate customized implants. Ciprofloxacin hydrochloride (Cipro) was chosen as the model drug, and two printing technologies, semisolid extrusion (SSE) and fused deposition modeling (FDM) were introduced. Six kinds of implants with customized irregular shapes were printed via FDM technology. Two kinds of implants with customized dosages were constructed via SSE technology. In addition, three kinds of implants with customized internal structures were produced via FDM and SSE technologies. The data for morphology, dimensions and mechanical properties demonstrated satisfactory printability and good printing accuracy when applying SSE and FDM technologies to produce the customized implants. The dissolution curves indicated that the desired customized drug release could be achieved by designing the specific internal structures. The biocompatibility examination showed that the printed implants possessed outstanding biocompatibility. In conclusion, all results suggested that 3D printing technologies provide a feasible method and novel strategy to fabricate customized implantable drug delivery systems.

Biomaterial design strategies to address obstacles in craniomaxillofacial bone repair

Biomaterial design to repair craniomaxillofacial defects has largely focused on promoting bone regeneration, while there are many additional factors that influence this process. The bone microenvironment is complex, with various mechanical property differences between cortical and cancellous bone, a unique porous architecture, and multiple cell types that must maintain homeostasis. This complex environment includes a vascular architecture to deliver cells and nutrients, osteoblasts which form new bone, osteoclasts which resorb excess bone, and upon injury, inflammatory cells and bacteria which can lead to failure to repair. To create biomaterials able to regenerate these large missing portions of bone on par with autograft materials, design of these materials must include methods to overcome multiple obstacles to effective, efficient bone regeneration. These obstacles include infection and biofilm formation on the biomaterial surface, fibrous tissue formation resulting from ill-fitting implants or persistent inflammation, non-bone tissue formation such as cartilage from improper biomaterial signals to cells, and voids in bone infill or lengthy implant degradation times. Novel biomaterial designs may provide approaches to effectively induce osteogenesis and new bone formation, include design motifs that facilitate surgical handling, intraoperative modification and promote conformal fitting within complex defect geometries, induce a pro-healing immune response, and prevent bacterial infection. In this review, we discuss the bone injury microenvironment and methods of biomaterial design to overcome these obstacles, which if unaddressed, may result in failure of the implant to regenerate host bone.