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Aims As a proven and comprehensive molecular technique, metagenomic next-generation sequencing (mNGS) has shown its potential in the diagnosis of pathogens in patients with periprosthetic joint infection (PJI), using a single type of specimen. However, the optimal use of mNGS in the management of PJI has not been explored. In this study, we evaluated the diagnostic value of mNGS using three types of specimen with the aim of achieving a better choice of specimen for mNGS in these patients. Methods In this prospective study, 177 specimens were collected from 59 revision arthroplasties, including periprosthetic tissues, synovial fluid, and prosthetic sonicate fluid. Each specimen was divided into two, one for mNGS and one for culture. The criteria of the Musculoskeletal Infection Society were used to define PJI (40 cases) and aseptic failure (19 cases). Results The sensitivity and specificity of mNGS in the diagnosis of PJI were 95% and 94.7%, respectively, for all types of specimen. The sensitivity and specificity were 65% and 100%, respectively, for periprosthetic tissues, 87.5% and 94.7%, respectively, for synovial fluid, and 92.5% and 94.7%, respectively, for prosthetic sonicate fluid. The mNGS of prosthetic sonicate fluid outperformed that for other types of specimen in the rates of detection of pathogens (84.6%), sequencing reads (> ten-fold) and the rate of genome coverage (> five-fold). Conclusion mNGS could serve as an accurate diagnostic tool in the detection of pathogens in patients with a PJI using three types of specimen. Due to its superior perfomance in identifying a pathogen, mNGS of prosthetic sonicate fluid provides the most value and may partly replace traditional tests such as bacteriological culture in these patients. Cite this article: Bone Joint J 2021;103-B(5):923–930.

Lower limb alignment and soft tissue balance are important factors affecting patient satisfaction, clinical functional outcome, and prosthetic long-term survival rate after total knee arthroplasty (TKA). Robot-assisted TKA (rTKA) has the advantages of achieving precise osteotomy and soft tissue balance. However, rTKA under the guidance of classic mechanical alignment principles does not significantly improve the functional outcome after operation. The new TKA alignment principles, such as kinematic alignment (KA) and functional alignment (FA), can better consider the patient's own knee joint morphology and kinematic characteristics, which may help improve the clinical results of TKA. With the help of more objective and accurate soft tissue balance assessment tool such as pressure sensors, KA and FA have been proven to better achieve soft tissue balance. rTKA can achieve non-neutral alignment goals such as KA or FA more accurately and reproducibly. The use of these lower limb alignment and soft tissue balancing strategies will be expected to further increase the patients' satisfaction rate after rTKA.下肢对线和膝关节软组织平衡是影响人工全膝关节置换术（total knee arthroplasty，TKA）术后患者满意度、临床功能结局和假体远期生存率的重要因素。机器人辅助 TKA（robot-assisted TKA，rTKA）具有实现精准截骨和软组织平衡的优势，然而在经典机械力学对线原则指导下的 rTKA 并未显著改善术后膝关节功能结局。运动学对线（kinematical alignment，KA）和功能性对线（functional alignment，FA）等新的 TKA 对线原则由于能够更好考虑患者自身膝关节形态和运动学特点，可能有助于 TKA 临床结果的提升。借助于压力感应器等更加客观准确的软组织平衡评估手段，KA 和 FA 已被证实能够更好地实现软组织平衡。rTKA 能够更加精准和可重复地实现 KA 或 FA 等非中立位对线目标，采用这些下肢对线和软组织平衡策略，有望进一步提高 rTKA 术后满意率。.

Background: Vascularized fibula graft (VFG) transfer is an established method of repairing large skeletal defects resulting from trauma, tumor resection, or infection. It obviates the process of creeping substitution that conventional bone grafts undergo and therefore exhibits better healing and improved strength. The aim of this study is to evaluate hypertrophy in VFG. Methods: We retrospectively reviewed patients undergoing VFG and studied immediate and late postoperative radiographs. Orthogonal views were measured for width of graft cortex and intramedullary canal, as well as adjacent recipient bone. Changes were measured for total cross sectional area, cortical area, intramedullary area, and graft width. Results: Thirty patients were included in the analysis, with recipient sites including 3 forearm, 4 humerus, 12 tibia, and 11 femur. Mean follow-up was 7.6 years (0.5-24.9 years). Patients’ mean age was 31 (16-59 years). Average hypertrophy was 254% in early postoperative period and 340% in the late postoperative period. There was rapid graft hypertrophy in early postoperative period that plateaued with time. The width of the graft increased over time but didn’t exceed the width of the adjacent recipient bone. In the later postoperative period, the size of graft intramedullary canal increased. Upper and lower extremity grafts showed similar hypertrophy. Conclusions: Using VFG to treat large skeletal defects is an attractive option in part due to the graft’s ability to hypertrophy. We describe an early period of periosteal hypertrophy, followed by endosteal hypertrophy. These processes have relevance to function, mechanical strength, and surgical decision-making.

Background Diagnosing acute periprosthetic joint infection remains a challenge. Several studies have proposed different acute cutoffs resulting in the International Consensus Meeting recommending a cutoff of 100 mg/L, 10,000 cell/μL and 90% for serum C-reactive protein (CRP), synovial white blood cell count (WBC), and polymorphonuclear percentage (PMN%), respectively. However, establishing cutoffs are difficult as the control group is limited to rare early aseptic revisions, and performing aspiration in asymptomatic patients is difficult because of a fear of seeding a well-functioning joint arthroplasty. This study (1) assessed the sensitivity of current thresholds for acute periprosthetic joint infection (PJI) and (2) identified associated factors for false negatives. Methods We retrospectively reviewed patients with acute PJIs (n = 218), defined as less than 6 weeks from index arthroplasty, treated between 2000 and 2017. Diagnosis of PJI was based on 2 positive cultures of the same pathogen from the periprosthetic tissue or synovial fluid samples. Sensitivities of International Consensus Meeting cutoff values of CRP, synovial WBC, and PMN% were evaluated according to organism type. Multiple logistic regression analysis was performed to determine associated factors for false negatives. Results Overall, the sensitivity of CRP, synovial WBC, and PMN% for acute PJI was 55.3%, 59.6%, and 50.5%, respectively. Coagulase-negative Staphylococcus (CNS) demonstrated the lowest sensitivity for both CRP (37.5%) and WBC (55.6%). CNS infection was identified as an independent risk factor for false-negative CRP. Conclusions Current thresholds for acute PJI may be missing approximately half of PJIs. Low virulent organisms, such as CNS, may be responsible for these false negatives. Current thresholds for acute PJI must be reexamined.

ObjectivesThe optimal protocol for antibiotic loading in the articulating cement spacers for the treatment of prosthetic joint infection (PJI) remains controversial. The objective of the present study was to investigate the effectiveness of articulating cement spacers loaded with a new combination of antibiotics.MethodsA retrospective cohort study involving 114 PJI cases treated with implantation of an articulating cement spacer between 2005 and 2016 was performed. The treatment outcomes of the conventional protocol (i.e. gentamicin and vancomycin (GV protocol)) were compared with those reported using the sophisticated antibiotic-loading protocol (i.e. vancomycin, meropenem, and amphotericin (VMA protocol)).ResultsThere were 62 and 52 PJI cases treated with the GV and VMA protocols, respectively. Antimicrobial susceptibility testing revealed that 22/78 of all isolates (28.2%) in this series were resistant to gentamicin, whereas there were no vancomycin-, meropenem-, or amphotericin-resistant strains. The overall infection recurrence rates were 17.7% (11/62) and 1.9% (1/52), respectively (p = 0.006). In patients with a negative preoperative culture, there was no infection recurrence reported in the VMA cohort (0/45 (0%) vs 10/54 (18.5%) in the GV cohort; p = 0.002). Multivariate analysis indicated that the VMA protocol correlated with a decreased risk of infection recurrence compared with the GV protocol (p = 0.025).ConclusionThe sophisticated VMA protocol for the loading of antibiotics in articulating cement spacers, as part of a two-stage exchange, was associated with a reduced rate of infection recurrence. This proposed protocol appears to be safe and effective, especially in patients with negative culture results prior to the first-stage operation.Cite this article: Bone Joint Res 2019;8:526–534.

Tantalum (Ta) has been shown to enhance osseointegration in clinical practice, yet little is known about whether Ta nanofilms can be used as antimicrobial coatings in vivo. A highly biocompatible Ta nanofilm was developed using magnetron sputtering technology to further study the mechanism of its antibacterial effects in vivo and elucidate its potential for clinical translation. The Ta nanofilms exhibited effective antimicrobial activity against soft tissue infections but did not show an intrinsic antimicrobial effect in vitro. This inconsistency between the in vivo and in vitro antimicrobial effects was further investigated using ex vivo models. The Ta nanofilms could enhance the phagocytosis of bacteria by polymorphonuclear neutrophils (PMNs, neutrophils), reduce the lysis of neutrophils and enhance the proinflammatory cytokine release of macrophages. This accumulative enhancement of the local host defenses contributed to the favorable antibacterial effect in vivo. The alleviated osteolysis observed in the presence of the Ta nanofilms in the osteomyelitis model further proved the practicality of this antibacterial strategy in the orthopedic field. In summary, Ta nanofilms show excellent biocompatibility and in vivo antimicrobial activity mediated by the enhancement of local innate immunity and are promising for clinical application. STATEMENT OF SIGNIFICANCE: In this study, Ta nanofilms were deposited on titanium substrate by magnetron sputtering. Ta nanofilms exhibited excellent in vivo and in vitro biocompatibility. In vivo antimicrobial effects of Ta nanofilms were revealed by soft tissue infection and osteomyelitis models, while no direct antibacterial activity was observed in vitro. Comprehensive ex vivo models revealed that Ta nanofilms could enhance the phagocytosis of bacteria by neutrophils, reduce the lysis of neutrophils and promote the release of proinflammatory cytokines from macrophages. This immunomodulatory effect helps host to eliminate bacteria. In contrast to traditional antimicrobial nanocoatings which apply toxic materials to kill bacteria, this work proposes a safe, practical and effective Ta nanofilm immunomodulatory antimicrobial strategy with clinical translational prospect.

Metabolic homeostasis is vital for individual cells to keep alive. Stronger metabolic homeostasis allows bacteria to survive in vivo and do persistent harm to hosts, which is especially typical in implant-associated infection (IAI) with biofilm intervention. Herein, based on the competitive role of selenium (Se) and sulfur (S) in bacteria metabolism as congeners, a congener-induced sulfur-related metabolism interference therapy (SMIT) eradicating IAI is proposed by specific destruction of bacteria metabolic homeostasis. The original nanodrug manganese diselenide (MnSe2 ) is devised to generate permeable H2 Se in bacteria, triggered by the acidic microenvironment. H2 Se, the congener substitution of H2 S, as a bacteria-specific intermediate metabolite, can embed itself into the H2 S-utilization pathway and further alternatively disrupt the downstream sulfur-related metabolism state inside bacteria. A proteomic study indicates ribosome-related proteins are heavily downregulated and the basic metabolic pathways are mainly disordered after SMIT, revealing the destruction of bacteria metabolic homeostasis. The efficiency of SMIT is significantly promoted with the mild temperature sensitization provided by the photothermal treatment (PTT) of MnSe2 nanoparticles, verified by the proteomic study and the anti-IAI effect in vitro and in vivo. With the intelligent nanodrug, a PTT-promoted SMIT strategy against IAI is provided and a new insight into the interference design toward metabolic homeostasis with biochemical similarity is demonstrated.

Biofilms formed by Staphylococcus aureus are one of the predominant causes of implant-associated infections (IAIs). Previous studies have found that S. aureus nucleases nuc1 and nuc2 modulate biofilm formation. In this study, we found low nuc1/nuc2 expression and high biofilm-forming ability among IAI isolates. Furthermore, in a mouse model of exogenous IAIs, Δnuc1/2 exhibited higher bacterial load on the surface of the implant than that exhibited by the other groups (WT, Δnuc1, and Δnuc2). Survival analysis of the hematogenous IAI mouse model indicated that nuc1 is a virulence factor related to mortality. We then detected the influence of nuc1 and nuc2 on biofilm formation and immune evasion in vitro. Observation of in vitro biofilm structures with scanning electron microscopy and evaluation of bacterial aggregation with flow cytometry revealed that both nuc1 and nuc2 are involved in biofilm structuring and bacterial aggregation. Unlike nuc1, which is reported to participate in immune evasion, nuc2 cannot degrade neutrophil extracellular traps. Moreover, we found that nuc1/nuc2 transcription is negatively correlated during S. aureus growth, and a possible complementary relationship has been proposed. In conclusion, nuc1/nuc2 are complementary genes involved in biofilm formation in exogenous IAIs. However, nuc2 contributes less to virulence and is not involved in immune evasion.

A magnesium scaffold is a promising biodegradable bone repair material. However, its poor corrosion resistance limits its clinical application. In this study, we improved the corrosion resistance, biocompatibility and osteointergration ability of magnesium by alloying it with neodymium (Nd) and zinc (Zn), then fabricated a novel open-porous Mg–Nd–Zn (P-MNZ) alloy using a titanium wire space holder (TWSH) method. An in vitro corrosion experiment showed that corrosion resistance was enhanced. Both in vitro and in vivo experiments were performed to evaluate the biocompatibility and osteointergration ability of P-MNZ. The cell viability, cytoskeleton staining, ALP activity and osteogenic related gene expression confirm that the P-MNZ scaffold exhibits better biocompatibility and osteoblast differentiation properties in vitro. As for the in vivo experiment, the analysis of micro-CT scanning, Van Gieson staining and sequential polychrome labelling demonstrated that P-MNZ stimulates new bone formation and enhances the corrosion resistance of the P-MNZ scaffold. The results indicate that the P-MNZ alloy is a promising biodegradable bone repair material.

Lack of peri-operative microbiological evidence is an unfavourable factor in one-stage revision. The objective of this study was to figure out whether being culture-negative was an unfavourable factor for periprosthetic hip joint infection (PHJI) in patients undergoing two-stage revision. Records of PHJI patients treated between October 2003 and December 2016 were reviewed at our institution. Information such as microbiological data, clinical outcomes, and other details of patients’ clinical courses were recorded. A total of the 58 cases were reviewed. The median follow-up duration was 68.5 months. The infection control rate of PHJI was 93.1% after two-stage revision. Kaplan–Meier analysis showed no significant difference in infection control rates between culture-negative and culture-positive groups. Culture-positive sinus secretions were significantly associated with an increased rate of reinfection (P = 0.039). Two-stage revision had a high success rate for eradication of PHJI. Culture-negative PHJI had a comparable outcome with culture-positive PHJI.

An entangled titanium wire porous (ETP) scaffold shows similar mechanical properties of cancellous bone and is a promising bone repair material. However, the ETP scaffold's inert biocompatibility and poor osteogenic ability limit its clinical application. In this study, a Li-containing nanoporous coating was added on ETP by micro-arc oxidation (MAO). The SEM results indicated that a hierarchical and compact coating was formed on the Li-MAO-ETP scaffold. In vitro cell tests showed improved osteoblast morphology, adhesion, and viability in the Li-MAO-ETP group. Moreover, the Li-MAO-ETP scaffold exhibited improved osteogenic differentiation properties by activating the Wnt/β-catenin signal pathway based on the western blotting and RT-PCR results. The push-out test, sequential fluochrome labeling, and toluidine staining demonstrated that the Li-MAO-ETP scaffold contained improved osteogenic ability in vivo. The in vitro and in vivo experiments showed that the Li incorporated entangled porous titanium could be a suitable biomaterial for bone defect repair.

The optimal administration route of tranexamic acid (TXA) in total knee arthroplasty (TKA), and the effect of TXA on hidden blood loss and total blood loss are undetermined. The purpose of this study was to compare the effectiveness of intravenous versus intra-articular application of tranexamic acid in patients undergoing knee arthroplasty.A total of 150 patients undergoing primary unilateral total knee arthroplasty were randomly distributed to 3 groups (IV, intra-articular, and control group; each 50 patients) and administrated TXA (1 g IV and 50 mL intra-articular saline, 1 g intra-articularly and 50 mL intra-articular saline, and 0 g and 50 mL intra-articular saline, respectively). The amount of total and hidden blood loss (HBL), drainage, transfusion, changes in hemoglobin levels, and complications were recorded.Intra-articular use of TXA reduced more total blood loss (P = .011) and reduced more total 48 hours drainage volume than IV use of TXA (P.001). Two patients received transfusion in IV and control group. No deep venous thrombosis or other severe complications had occurred. The HBL volume had no significant difference among the control, IV, and intra-articular groups (708.6 ± 308.2, 651.7 ± 302.9, and 625.2 ± 252.1 mL, respectively; which was 65.6%, 70.8%, and 81.1% of the total loss).Intra-articular administration of TXA significantly reduced total blood loss and drainage volume to a greater degree than IV injection in total knee arthroplasty without reduction of HBL.

Supplemental material, Supplemental_material for Bony Hypertrophy in Vascularized Fibular Grafts by Lewis L. Shi, Rohit Garg, Andrew Jawa, Qiaojie Wang, Yimin Chai, Bingfang Zeng and Jesse B. Jupiter in HAND

Magnesium is an attractive candidate for orthopedic implants due to its similar mechanical properties to human bone and biodegradability. However, the high corrosion rate of magnesium accompanying with high pH value and poor osteogenic activity hinder its further application. In this study, we employed micro arc oxidation (MAO) to improve corrosion resistance by introduce nanoporous coating on AZ91 magnesium. Meanwhile, we added lithium, an angiogenic and osteogenic element, to the coating (named as Li-MAO) by reaction in a lithium-containing electrolyte to simultaneously enhance angiogenic and osteogenic activity of AZ91. The favorable corrosion resistance of Li-MAO was verified by electrochemical and immersion test in vitro. Better biocompatibility was observed in Li-MAO samples by cell counting kit-8 (CCK-8) and live/dead assay. The in vitro results of immunofluorescence staining, Alizarin red staining and osteogenic-related genes expression indicated better osteogenic ability of Li-MAO group, which may result from the activation the Wnt/β-catenin pathway. In vitro angiogenic tests also demonstrated better angiogenesis in Li-MAO group. A bone defect repair model was built to evaluate the in vivo osseointegration of samples. The outcomes of micro-computed tomography (Micro-CT) scanning, sequential fluorochrome labeling and Van Gieson staining suggested better in vivo bone repair ability of Li-MAO than other groups. Our promising results both in vitro and in vivo demonstrated that lithium-containing nanoporous coating can improve corrosion resistance, angiogenesis and osseointegration of magnesium alloy, which may forward the clinic application of Li-MAO magnesium.

Biomaterial-related bacterial infections cause patient suffering, mortality and extended periods of hospitalization, imposing a substantial burden on medical systems. In this context, understanding of nanomaterials-bacteria-cells interactions is of both fundamental and clinical significance. Herein, nano-MgF2 films were deposited on titanium substrate via magnetron sputtering. Using this platform, the antibacterial behavior and mechanism of the nano-MgF2 films were investigated in vitro and in vivo. It was found that, for S. aureus (CA-MRSA, USA300) and S. epidermidis (RP62A), the nano-MgF2 films possessed excellent anti-biofilm activity, but poor anti-planktonic bacteria activity in vitro. Nevertheless, both the traditional SD rat osteomyelitis model and the novel stably luminescent mouse infection model demonstrated that nano-MgF2 films exerted superior anti-infection effect in vivo, which cannot be completely explained by the antibacterial activity of the nanomaterial itself. Further, using polymorphonuclear leukocytes (PMNs), the critical immune cells of innate immunity, a complementary investigation of MgF2-bacteria-PMNs co-culturing revealed that the nano-MgF2 films improved the antibacterial effect of PMNs through enhancing their phagocytosis and stability. To our knowledge, this is the first time of exploring the antimicrobial mechanism of nano-MgF2 from the perspective of innate immunity both in vitro and in vivo. Based on the research results, a plausible mechanism is put forward for the predominant antibacterial effect of nano-MgF2in vivo, which may originate from the indirect immune enhancement effect of nano-MgF2 films. In summary, this study of surface antibacterial design using MgF2 nanolayer is a meaningful attempt, which can promote the host innate immune response to bacterial pathogens. This may give us a new understanding towards the antibacterial behavior and mechanism of nano-MgF2 films and pave the way towards their clinical applications.

Periprosthetic joint infection (PJI) is one of the formidable and recalcitrant complications after orthopedic surgery, and inhibiting biofilm formation on the implant surface is considered crucial to prophylaxis of PJI. However, it has recently been demonstrated that free-floating biofilm-like aggregates in the local body fluid and bacterial colonization on the implant and peri-implant tissues can coexist and are involved in the pathogenesis of PJI. An effective surface with both contact-killing and release-killing antimicrobial capabilities can potentially abate these concerns and minimize PJI caused by adherent/planktonic bacteria. Herein, Ag nanoparticles (NPs) are embedded in titania (TiO2) nanotubes by anodic oxidation and plasma immersion ion implantation (PIII) to form a contact-killing surface. Vancomycin is then incorporated into the nanotubes by vacuum extraction and lyophilization to produce the release-killing effect. A novel clinical PJI model system involving both in vitro and in vivo use of methicillin-resistant Staphylococcus aureus (MRSA) ST239 is established to systematically evaluate the antibacterial properties of the hybrid surface against planktonic and sessile bacteria. The vancomycin-loaded and Ag-implanted TiO2 nanotubular surface exhibits excellent antimicrobial and antibiofilm effects against planktonic/adherent bacteria without appreciable silver ion release. The fibroblasts/bacteria cocultures reveal that the surface can help fibroblasts to combat bacteria. We first utilize the nanoarchitecture of implant surface as a bridge between the inorganic bactericide (Ag NPs) and organic antibacterial agent (vancomycin) to achieve total victory in the battle of PJI. The combination of contact-killing and release-killing together with cell-assisting function also provides a novel and effective strategy to mitigate bacterial infection and biofilm formation on biomaterials and has large potential in orthopedic applications.

Implant-related infections (IRIs) and implant osseointegration disorders are the most common and catastrophic complications after total joint arthroplasty (TJA). Macrophages play a vital role in the development of these complications. Herein, tailored to the immunological characteristics of IRIs and implant osseointegration disorders, we proposed a sequential immunomodulatory strategy to cope with the complications, using Cu-Zn bi-layer nanofibrous membranes synthesized via a facile electrospinning process and a hot-pressed method. It was found that Cu-Zn bi-layer nanofibrous membranes exhibited a desirable controlled release of Cu2+ and Zn2+, and could sequentially regulate macrophage phenotype shift from M1 to M2 through alternately activating the MAPK and mTOR signaling pathways. Moreover, the dual-temporal bidirectional immunomodulatory effect endowed the Cu-Zn bi-layer nanofibrous membranes excellent anti-infection and osteogenic abilities in vitro and in vivo. To our knowledge, this is the first dual-temporal bidirectional immunomodulatory biomaterial specifically designed for the immune requirements of IRIs and implant osseointegration disorders. This is a meaningful attempt, which may pave a new way for exploring novel immunomodulatory biomaterials to solve the clinical challenges.

Key Points Question Is the use of laminar airflow during total joint arthroplasty procedures associated with reduced risk of subsequent periprosthetic joint infection? Findings In this cohort study of 6972 patients, the rate of periprosthetic joint infection was similar in procedures performed in operating rooms with or without laminar airflow (0.5% vs 0.4%). Meaning This study suggests that laminar airflow may not play a role in prevention of periprosthetic joint infection., Importance Whether laminar airflow (LAF) in the operating room is effective for decreasing periprosthetic joint infection (PJI) after total joint arthroplasty remains a clinically important yet controversial issue. Objective To investigate the association between operating room LAF ventilation systems and the risk of PJI in patients undergoing total joint arthroplasty. Design, Setting, and Participants A retrospective cohort study was conducted of 6972 consecutive patients undergoing primary total knee arthroplasty or total hip arthroplasty at 2 surgical facilities within a single institution from January 1, 2013, to September 15, 2017, with a minimum of 1 year of follow-up. All procedures were performed by 5 board-certified arthroplasty surgeons. Statistical analysis was performed from January 1, 2014, to September 15, 2018. Exposure Patients underwent total joint arthroplasty in operating rooms equipped with either LAF or turbulent airflow. Main Outcomes and Measures Patient characteristics were extracted from clinical records. Periprosthetic joint infection was defined according to Musculoskeletal Infection Society criteria within 1 year of the index arthroplasty. A multivariable logistic regression model was performed to explore the potential association between LAF and risk of PJI at 1 year, and then a sensitivity analysis using propensity score matching was performed to further validate the findings. Results A total of 6972 patients (2797 who underwent total knee arthroplasty and 4175 who underwent total hip arthroplasty; 3690 women [52.9%]; mean [SD] age, 63.9 [10.7] years) were included. The incidence of PJI within 1 year for patients from the facility without LAF was similar to that of patients from the facility with LAF (0.4% [12 of 3027] vs 0.5% [21 of 3945]). In the multivariable logistic regression analysis, after all confounding factors were taken into account, the use of LAF was not associated with a reduction of the risk of PJI (adjusted odds ratio, 0.94; 95% CI, 0.40-2.19; P = .89). After propensity score matching, there was no significant difference in the incidence of PJI within 1 year for patients who underwent total joint arthroplasty at these 2 sites. Conclusions and Relevance This study suggests that the use of LAF in the operating room was not associated with a reduced incidence of PJI after primary total joint arthroplasty. With an appropriate perioperative protocol for infection prevention, LAF does not seem to play a protective role in PJI prevention., This cohort study examines the association between operating room laminar airflow ventilation systems and the risk of periprosthetic joint infection in patients undergoing total joint arthroplasty.

Background Two-stage exchange arthroplasty remains a popular surgical treatment for patients with chronic periprosthetic joint infection (PJI). Patients who do not receive reimplantation were largely overlooked in the current literature. We aimed at investigating the clinical outcomes of these patients. Methods Our institutional PJI database was retrospectively reviewed to identify 616 patients (237 hips, 379 knees) who were treated with an intended 2-stage exchange. Of them, 111 (18%) did not receive reimplantation within a minimum follow-up of 1 year. Chart review and targeted interviews were performed to elucidate the cause of attrition. Patients were considered to have failed treatment in the absence of reimplantation if they remained medically unfit for reimplantation, underwent a salvage procedure, or died during the study period. Results Of the 111 patients without reimplantation, 29 (26.1%) did well with their retained spacer and were unwilling to proceed with reimplantation, 23 (20.7%) underwent salvage procedures, and the remaining 59 (53.2%) were considered medically unfit for reimplantation, with 34 of them dying within 1 year of initial spacer insertion. The overall success rate for 2-stage exchange cohort at 2 years was 65.7% when treatment failure without reimplantation was taken into account. Several factors associated with increased risk of treatment failure without reimplantation were identified using a multivariate regression model. Conclusion Almost 1 in 5 patients may never receive the intended reimplantation. Among many reasons for attrition, mortality appears to be a relatively common event. The current definition of treatment success does not take into account the attrition group and thus inflates the relative success of 2-stage exchange arthroplasty.

Whether prolonged operative time is an independent risk factor for subsequent surgical site infection (SSI) and periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) remains a clinically significant and underexplored issue. The aim of this study is to investigate the association between operative time and the risk of subsequent SSI and PJI in patients undergoing primary TJA.We retrospectively reviewed 17,342 primary unilateral total knee arthroplasty and total hip arthroplasty performed at a single institution between 2005 and 2016, with a minimum follow-up of 1 year. A multivariate logistic regression model was conducted to identify the association between operative time and the development of SSI within 90 days and PJI within 1 year.Overall, the incidence of 90-day SSI and 1-year PJI was 1.2% and 0.8%, respectively. Patients with an operative time of90 minutes had a significantly higher incidence of SSI and PJI (2.1% and 1.4%, respectively) compared to cases lasting between 60 and 90 minutes (1.1% and 0.7%), and those lasting ≤60 minutes (0.9% and 0.7%, P.01). In the multivariate model, the risk for infection increased by an odds ratio of 1.346 (95% confidential interval 1.114-1.627) for 90-day SSI and 1.253 (95% confidential interval 1.060-1.481) for 1-year PJI for each 20-minute increase in operative time.In patients undergoing primary TJA, each 20-minute increase in operative time was associated with nearly a 25% increased risk of subsequent PJI. We advocate that surgeons pay close attention to this underappreciated risk factor while maintaining safe operative practices, which minimize unnecessary steps and wasted time in the operating room.

Metal ions or nanoparticles are believed to be promising additives in developing antibacterial biomaterials, owing to possessing favorable bactericidal effects against antibiotic-resistant bacteria. However, the immunomodulatory antibacterial activity of metal ions has seldom been reported. Herein, a porous microstructure designed to trap methicillin-resistant Staphylococcus aureus (MRSA) is fabricated on polyetheretherketone biomaterial surface through sulfonation (SPEEK), following which copper (Cu) nanoparticles, which can kill the trapped MRSA, are immobilized on SPEEK surface using a customized magnetron sputtering technique. In vitro antibacterial and immunological experiments indicate that the Cu-incorporated SPEEK can exert a desirable bactericidal effect against MRSA through the combination of "trap killing" and "contact killing" actions; meanwhile, macrophages cultured on the Cu-incorporated SPEEK can be activated and polarized to a pro-inflammatory phenotype along with improved phagocytic ability on the MRSA. Further in vivo implant-associated infection models evidence the superior antibacterial activity of the Cu-incorporated SPEEK. These results demonstrate multimodal antibacterial actions of the Cu-incorporated SPEEK, which is capable of imposing direct antibacterial and indirect immunomodulatory antibacterial effects simultaneously, in order to prevent and cure MRSA infection. It is believed that this study may shed light on developing novel biomaterial implants that combine antibacterial and immunomodulatory functions.

SPOC is a mixed teaching mode combining MOOC with classroom teaching. It not only preserves the idea of open education in MOOC and advanced teaching design ideas, but also combines the advantages of face-to-face classroom teaching, so it can provide a complete learning experience for the learners and guarantee the quality of teaching. This paper explores and constructs a SPOC mixed teaching mode suitable for the teaching of university courses to understand the students' attitudes and views on the development of the SPOC based hybrid learning model. The results show that the students' recognition, participation and satisfaction of the SPOC mixed teaching mode are highly evaluated. A mixed teaching mode based on SPOC has been developed to improve the students' enthusiasm for learning and the effect of teaching is obviously improved in university.

Prevention of implant-associated infection (IAI) by inhibiting biofilm formation on implants is crucial to orthopedic surgery. In this work, the anti-biofilm activity of magnesium (Mg) is assessed using Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus epidermidis (S. epidermidis), two biofilm producing strains, in vitro, and using S. epidermidis in vivo. The effects of high Mg2+ concentration and alkaline pH on biofilm are evaluated in two separate experiments in vitro. Mg shows biofilm resistance proportional to the degradation of Mg in vitro, which is better than that of the corresponding alkaline pH, and high Mg2+ concentration has no such effect. Microbiological cultures and histological results demonstrate the ability of Mg against bacterial infection to reduce the risk of IAI in vivo. The results demonstrate that Mg prevents bacteria biofilm formation by high alkalinity at its surface rather than by high Mg2+ concentration, thus providing a promising new strategy for combating IAI.

Tranexamic acid decreases blood loss in primary total knee arthroplasty, and no related prospective randomized clinical trials have been conducted to evaluate the effectiveness and safety of tranexamic acid in revision total knee arthroplasty. Thus, we conducted this work to evaluate the synergistic effects of intravenous plus intra-articular tranexamic acid on reducing hemoglobin loss compared with intra-articular tranexamic acid alone in revision total knee arthroplasty.This prospective, controlled study randomized 96 patients undergoing revision total knee arthroplasty into two groups: an intravenous plus intra-articular tranexamic acid group (48 patients who received 20 mg/kg intravenous tranexamic acid and 3.0 g intra-articular tranexamic acid); and an intra-articular tranexamic acid alone group (48 patients who received the same intravenous volume of normal saline and 3.0 g intra-articular tranexamic acid). The primary outcome was hemoglobin loss. Secondary outcomes included the volume of drain output, the percentage of patients who received transfusions, the number of units transfused, and thromboembolic events.The baseline data, preoperative hemoglobin, and tourniquet time were similar in both groups. There was significantly less hemoglobin loss in the intravenous plus intra-articular tranexamic acid group compared with the intra-articular tranexamic acid alone group (2.7 ± 0.6 g/dL and 3.7 ± 0.7 g/dL; p 0.001). Compared with the intra-articular tranexamic acid alone group, the intravenous plus intra-articular tranexamic acid group also had significantly less drain output, fewer patients who received transfusions, and fewer units transfused (all p 0.05). There were no significant differences in thromboembolic events in the two groups during the 3-month follow-up.Compared with intra-articular tranexamic acid alone, combined intravenous plus intra-articular tranexamic acid significantly reduced hemoglobin loss and the need for transfusion without an apparent increase in thromboembolic events in patients who underwent revision total knee arthroplasty.

Patients with periprosthetic joint infection (PJI) undergoing 2-stage exchange arthroplasty may undergo an interim spacer exchange for a variety of reasons including mechanical failure of spacer or persistence of infection. The objective of this study is to understand the risk factors and outcomes of patients who undergo spacer exchange during the course of a planned 2-stage exchange arthroplasty.Our institutional database was used to identify 533 patients who underwent a 2-stage exchange arthroplasty for PJI, including 90 patients with a spacer exchange, from 2000 to 2017. A retrospective review was performed to extract relevant clinical information. Treatment outcomes included (1) progression to reimplantation and (2) treatment success as defined by a Delphi-based criterion. Both univariate and multivariate Cox regression models were performed to investigate whether spacer exchange was associated with failure. Additionally, a propensity score analysis was performed based on a 1:2 match.A spacer exchange was required in 16.9%. Patients who underwent spacer exchanges had a higher body mass index (P.001), rheumatoid arthritis (P = .018), and were more likely to have PJI caused by resistant (0.048) and polymicrobial organisms (P = .007). Patients undergoing a spacer exchange demonstrated lower survivorship and an increased risk of failure in the multivariate and propensity score matched analysis compared to patients who did not require a spacer exchange.Despite an additional load of local antibiotics and repeat debridement, patients who underwent a spacer exchange demonstrated poor outcomes, including failure to undergo reimplantation and twice the failure rate. The findings of this study may need to be borne in mind when managing patients who require spacer exchange.