Intraoperative Cultures in Reimplantation of a Two-Stage Protocol: Only 1 vs. At Least 2 Positive Microbiological Results

Background:The main reason for using a two-stage exchange in Prosthetic Joint Infection (PJI) is that bacteria are completely eradicated in reimplantation surgery. However, reports of a positive culture in the second surgery are growing. The number of positive intraoperative cultures and their influence on final results is not well-established.Objectives:To compare epidemiological characteristics, infection recurrence and clinical evolution of patients with only onevs.at least two positive cultures based on our series of cases with positive cultures in reimplantation surgery.Material and Methods:Retrospective study of 55 patients was conducted prospectively. They were diagnosed with chronic PJI, treated with a two-stage protocol and at least three intraoperative cultures were obtained in the second stage. These cultures were negative in 28 patients. Fourteen patients showed two or more cultures with the same microorganism and they were denominated patients with positive cultures. Thirteen patients showed only one positive culture, and they were considered contaminated. Both groups of patients (positive cultures and contaminated ones) received the second cycle of oral antibiotics for 6 months. Functional results were evaluated with the Harris Hip Score (hips) or Knee Society Clinical Rating Score (KSCRS) (knees).Results:There were no significant differences between patients with positive or contaminated cultures for age (p=0.420) and sex (p=0.385). The knee was involved in 13/14 positive and in only 6/13 contaminated patients (p=0.013).Staphylococcus epidermidiswas the predominant isolate, but there were differences between positive (methicillin-resistant in 7/14 patients) and contaminated cultures (methicillin-sensitive in 6/13). There were no differences in the prevalence of polymicrobial cultures (p=0.785) or coincidence with cultures from the first stage (p=0.257). Three infection recurrences have appeared in patients with positive cultures (3/13, 21%) and none in patients with contaminated cultures. There are no differences in HSS or KSCRS when comparing final functional results between groups (p=0.411).Conclusion:The prevalence of positive cultures in reimplantation surgery is higher than expected (25%), and more frequent in women and in knee arthroplasties. The most frequently involved microorganism isStaphylococcus epidermidis, but antibiotic sensitivity varies between patients with positive cultures (methicillin-resistant) and those with contaminated cultures (methicillin-sensitive). There were no infection recurrences in patients with contaminated cultures, but those with positive cultures present a risk of over 20%.</jats:sec

Processing of membranes and 3D scaffolds based on n-TiO2 colloidally dispersed on a thermoplastic matrix for photocatalytic pollutant removal

[EN] One of the most promising technologies for water treatment today is photocatalytic membrane reactors (PMRs). Manufacturing efficient membranes is still challenging as many factors are involved, like the porosity, specific surface area, nature and size of particles. In this work, a colloidal method to self-support commercial nanoparticles (n-TiO) in a polymeric matrix of polylactic acid (PLA) is proposed allowing the fabrication of 2D and 3D structures with high inorganic content that can be adapted to the PMR configurations. Using a commercial filament of PLA loaded with up to 15 vol% of n-TiO2 as starting point, photocatalytic membranes have been manufactured by FFF. In addition, following a similar process, tapes with n-TiO2 particles up to 15 vol% have been processed by tape casting. Thermal characterisation (DTA) and dynamic rheometry evaluated the commercial filament for printing to determine the conditions used during the thermal extrusion and printing processes. FTIR and XRD technologies were used to determine the chemical interactions of PLA matrices with TiO nanoparticles. Porosity was measured by Archimedes's method for the filaments, by mercury intrusion for the membranes and by optical microscopy for the scaffolds. Finally, the microstructure of the 2D and 3D pieces was evaluated by scanning microscopy. 2D tape cast membranes were compared with individual filaments and 3D printed scaffolds in linear and gyroidal geometries. The catalytic activity results indicate that tape cast membranes show much higher kinetic constants than the individual filaments and the linear and gyroidal scaffolds. Regarding the two different printed scaffolds, in contrast to the kinetic values, gyroidal geometries achieve an average degradation time (t) of 6.1 h, which is a lower value than those observed for linear scaffold geometries. Methyl orange degradation tests after 24 h exposure under UV light showed degradation rates of 98% for membranes, 90% for commercial filaments, 80% for gyroidal scaffolds and 60% for linear patterns. Therefore, these results are promising as a solution for fabricating easily extractable self-supported membranes for water treatment in PMRs.This work has been supported by the Spanish Government (Agencia Estatal de Investigación) through the projects PID2019–106631 GB-C42 (MICRO@Mater) and TED2021–129920B-C41 (EC0FOOTPrint), both cofunded by AEI/10.13039/501100011033/Uni´on Europea NextGenerationEU/PRTR). Pablo Ortega Columbrans acknowledges the Comunidad de Madrid for the industrial doctorate support through the contract IND2022/IND-23603

Biocompatible colloidal feedstock for material extrusion processing of bioceramic-based scaffolds

Nowadays an enormous effort has been made to impulse the incorporation of additive manufacturing (AM) approaches in the biomedical sector. One of the most recognized biomaterials for this end is bioceramics such as hydroxyapatite (HA), but unfortunately, ceramics present a lack of accessible technologies based on AM. Consequently, the development of new methodologies which enable the manufacture of bioceramic-based scaffolds is imperative. A large number of publications on polymer–ceramic composite processed by Material Extrusion are available, so far, the maximum ceramic loading reached is still a parameter to improve. Recently an alternative colloidal processing technique to prepare ceramic-based composite feedstock for material extrusion has been proposed. It has been demonstrated that tailoring the surface of the ceramic particles enables the processing of high ceramic loading composites by AM. This article shows the potential of the colloidal approach to process biocompatible PLA/HA feedstock increasing the homogeneity of the bioceramic phase into the composite. The feedstock characterization shows that HA surface modification makes possible the successful dispersion and the ceramic load increase without modifying the biocompatibility. The ceramic load increase does not modify the melting properties of the polymeric matrix required for the 3D printing process. This methodology allows for the first time the development of a final 3D printed composite structure with contents up to 72 wt% of HA by Material Extrusion. This colloidal approach paves the way to transfer the use of additive manufacturing techniques mainly devoted to polymeric biomaterials to other types of biomaterials such as bioceramics. Highlights: A colloidal approach for 3D printing of PLA/HA composites is proposed. HA surface modification made possible a load increase with high dispersion. The characterization of a PLA/HA feedstock for 3D printing is established. Biocompatible PLA/HA feedstock is processed by AM in customized structures. Colloidal approach allows the processing of 3D structures with 72 wt% of HA. © 2024 The Authors. Polymer Composites published by Wiley Periodicals LLC on behalf of Society of Plastics Engineers.Comunidad de Madrid, Grant/AwardNumber: 2022-T1/IND-23973; SpanishGovernment (Agencia Estatal deInvestigación), Grant/Award Numbers:PID2022-137274NB-C31(3DPOSTPERFORM), TED2021-129920B-C41 (EC0FOOTPrint); FEDER, UE:PID2022-137274NB-C31(3DPOSTPERFORM) European Union“NextGeneration”/PRTR: TED2021-129920B-C41 (EC0FOOTPrint)Peer reviewe