Prosthetic joint infection

Alternating Magnetic Fields AMF) and Linezolid Reduce Staphylococcus aureus Biofilm in a Large Animal Implant Model

OBJECTIVES

We aimed to evaluate the effectiveness of alternating magnetic fields AMF) combined with antibiotics in reducing Staphylococcus aureus biofilm on metal implants in a large animal model, compared to antibiotics alone.

METHODS

Metal plates were inoculated with a clinical MRSA strain and then implanted into thirty-three ewes divided into three groups: positive control, linezolid only, and a combination of linezolid and AMF. Animals had either titanium or cobalt-chrome plates and were sacrificed at 5- or 21-days post-implantation. Blood and tissue samples were collected at various time points post-AMF treatment.

RESULTS

In vivo efficacy studies demonstrated significant biofilm reduction on titanium and cobalt-chrome implants with AMF-linezolid combination treatment compared to controls. Significant bacterial reductions were also observed in surrounding tissues and bones. Cytokine analysis showed improved inflammatory responses with combination therapy, and histopathology confirmed reduced inflammation, necrosis, and bacterial presence, especially at 5 days post-implantation.

CONCLUSIONS

This study demonstrates that combining AMF with antibiotics significantly reduces biofilm-associated infections on metal implants in a large animal model. Numerical simulations confirmed targeted heating, and in vivo results showed substantial bacterial load reduction and reduced inflammatory response. These findings support the potential of AMF as a non-invasive treatment for prosthetic joint infections.

Microbiology, Treatment, and Postoperative Outcomes of Gram-Negative Prosthetic Joint Infections-A Systematic Review of the Literature

INTRODUCTION

Gram-negative prosthetic joint infections (PJIs) represent 10% to 25% of all PJIs and are associated with worse outcomes than gram-positive infections. We sought to assess the microbiology, surgical treatment, and outcomes of patients with gram-negative PJIs.

METHODS

A systematic review using the PubMed and Embase databases was conducted. Our study was conducted following the PRISMA guidelines. Included studies were assessed for quality using the STROBE checklist. The primary outcome of analysis was treatment failure.

RESULTS

A total of 593 patients with gram-negative PJIs were included. Two-year survival free of treatment failure for hip and knee PJIs was 66% and 68% for acute infections, 39% and 78% for acute hematogenous infections, and 75% and 63% for chronic infections, respectively. Two-year survival free of treatment failure for acute infections treated with débridement, antibiotics, and implant retention was 65% and 67% for hip and knee PJIs, respectively. Exchange of the polyethylene during débridement, antibiotics, and implant retention was associated with higher treatment success (P = 0.045). Chronic PJIs treated with two-stage revision had a two-year treatment success rate of 87% and 65% for the hip and knee, respectively. Risk factors of treatment failure were chronic obstructive pulmonary disease and C-reactive protein ≥30 mg/L in acute PJIs and female sex, knee infection, and previously revised implant in chronic PJIs. Acute PJIs caused by Pseudomonas spp. were associated with lower treatment failure rates.

CONCLUSION

Gram-negative PJIs are associated with a high treatment failure rate. Patient comorbidities, preoperative biochemical tests, microorganism etiology, and PJI characteristics affected the treatment success rate.

Extended Prophylactic Antibiotics for Primary and Aseptic Revision Total Joint Arthroplasty: A Meta-Analysis

BACKGROUND

There is growing interest in extended antibiotic prophylaxis (EAP) following total joint arthroplasty (TJA); however, the benefit of EAP remains controversial. For this investigation, both oral and intravenous antibiotic protocols were included in the EAP group.

METHODS

The Cochrane Database of Systematic Reviews, Cochrane Register of Controlled Trials, PubMed, MEDLINE, Web of Science, Ovid Embase, Elton B. Stephens CO, and Cumulative Index to Nursing and Allied Health Literature were queried for literature comparing outcomes of primary and aseptic revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients who were treated with either ≤24 hours of postoperative antibiotic prophylaxis (standard of care [SoC]) or >24 hours of EAP. The primary outcome was periprosthetic joint infection (PJI). A pooled relative-risk random-effects Mantel-Haenszel model was implemented to compare cohorts.

RESULTS

There were 18 studies with a total of 19,153 patients included. There was considerable variation in antibiotic prophylaxis protocols with first-generation cephalosporins being the most commonly implemented antibiotic for both groups. Patients treated with EAP were 35% less likely to develop PJI relative to the SoC (P = .0004). When examining primary TJA, patients treated with EAP were 39% and 40% less likely to develop a PJI for TJA (P = .0008) and THA (P = .02), respectively. There was no significant difference for primary TKA (P = .17). When examining aseptic revision TJA, EAP led to a 36% and 47% reduction in the probability of a PJI for aseptic revision TJA (P = .007) and aseptic revision TKA (P = .008), respectively; there was no observed benefit for aseptic revision THA (P = .36).

CONCLUSIONS

This meta-analysis demonstrated that patients treated with EAP were less likely to develop a PJI relative to those treated with the SoC for all TJA, primary TJA, primary THA, aseptic revision TJA, and aseptic revision TKA. There was no significant difference observed between EAP and SoC for primary TKA or aseptic revision THA.

Dysregulated neutrophil extracellular traps and haemostatic biomarkers as diagnostic tools and therapeutic targets in periprosthetic joint infection

Aims

Bacterial infection activates neutrophils to release neutrophil extracellular traps (NETs) in bacterial biofilms of periprosthetic joint infections (PJIs). The aim of this study was to evaluate the increase in NET activation and release (NETosis) and haemostasis markers in the plasma of patients with PJI, to evaluate whether such plasma induces the activation of neutrophils, to ascertain whether increased NETosis is also mediated by reduced DNaseI activity, to explore novel therapeutic interventions for NETosis in PJI in vitro, and to evaluate the potential diagnostic use of these markers.

Methods

We prospectively recruited 107 patients in the preoperative period of prosthetic surgery, 71 with a suspicion of PJI and 36 who underwent arthroplasty for non-septic indications as controls, and obtained citrated plasma. PJI was confirmed in 50 patients. We measured NET markers, inflammation markers, DNaseI activity, haemostatic markers, and the thrombin generation test (TGT). We analyzed the ability of plasma from confirmed PJI and controls to induce NETosis and to degrade in vitro-generated NETs, and explored the therapeutic restoration of the impairment to degrade NETs of PJI plasma with recombinant human DNaseI. Finally, we assessed the contribution of these markers to the diagnosis of PJI.

Results

Patients with confirmed PJI had significantly increased levels of NET markers (cfDNA (p < 0.001), calprotectin (p < 0.001), and neutrophil elastase (p = 0.022)) and inflammation markers (IL-6; p < 0.001) in plasma. Moreover, the plasma of patients with PJI induced significantly more neutrophil activation than the plasma of the controls (p < 0.001) independently of tumour necrosis factor alpha. Patients with PJI also had a reduced DNaseI activity in plasma (p < 0.001), leading to a significantly impaired degradation of NETs (p < 0.001). This could be therapeutically restored with recombinant human DNaseI to the level in the controls. We developed a model to improve the diagnosis of PJI with cfDNA, calprotectin, and the start tail of TGT as predictors, though cfDNA alone achieved a good prediction and is simpler to measure.

Conclusion

We confirmed that patients with PJI have an increased level of NETosis in plasma. Their plasma both induced NET release and had an impaired ability to degrade NETs mediated by a reduced DNaseI activity. This can be therapeutically restored in vitro with the approved Dornase alfa, Pulmozyme, which may allow novel methods of treatment. A combination of NETs and haemostatic biomarkers could improve the diagnosis of PJI, especially those patients in whom this diagnosis is uncertain.

The Effect of Nutritional Status in the Treatment of Periprosthetic Joint Infections in Total Hip Arthroplasty

BACKGROUND

Periprosthetic joint infections (PJIs) continue to be a complication that plagues arthroplasty. Albumin is a surrogate marker for nutrition as well as chronic inflammation, and hypoalbuminemia increases the risk of complications in arthroplasty. Patients with PJI are at increased risk for malnutrition and complications. This study's objective was to analyze patients who underwent treatment of PJI following total hip arthroplasty and investigate the outcome with regards to albumin levels.

METHODS

Overall, 48 patients who underwent surgery for a total hip PJI at 1 institution were reviewed. Albumin and C-reactive protein were recorded preoperatively and 2 to 3 weeks postoperatively. Treatment failure was determined by further surgical treatment for PJI or repeat infection, as determined by Musculoskeletal Infection Society guidelines.

RESULTS

A debridement, antibiotics, and implant retention procedure was performed in 39 patients, and explant with the placement of an antibiotic spacer was performed in 9. Preoperative mean albumin levels were significantly decreased in patients who failed to clear their infection compared to patients who remained infection-free (2.5 versus 3.3, P < .001). Postoperative albumin levels decreased in this same population (2.6 versus 3.8, P < .001). C-reactive protein was elevated in patients who failed to clear their infection preoperatively (19.9 versus 7.5, P < .001) and postoperatively (7.0 versus 1.7, P < .001). The average time to repeat surgical treatment for their PJI was 9 months CONCLUSIONS: Lower albumin levels are observed in patients with PJI who failed to remain infection-free after surgery. Albumin is a surrogate marker for nutrition, and low albumin is associated with poor immune function. Hypoalbuminemia is found with chronic inflammation as well as malnutrition. Nutritional reserves are diverted to the acute inflammatory response during an infection, which can lead to a deficient state. Further research may develop treatments to alter this modifiable risk factor.

LEVEL OF EVIDENCE

Level 4.

Sticking together: independent evolution of biofilm formation in different species of staphylococci has occurred multiple times via different pathways

BACKGROUND

Staphylococci cause a wide range of infections, including implant-associated infections which are difficult to treat due to the presence of biofilms. Whilst some proteins involved in biofilm formation are known, the differences in biofilm production between staphylococcal species remains understudied. Currently biofilm formation by Staphylococcus aureus is better understood than other members of the genus as more research has focused on this species.

RESULTS

We assembled a panel of 385 non-aureus Staphylococcus isolates of 19 species from a combination of clinical sources and reference strains. We used a high-throughput crystal violet assay to assess the biofilm forming ability of all strains and assign distinct biofilm formation categories. We compared the prevalence of Pfam domains between the categories and used machine learning to identify amino acid 20-mers linked to biofilm formation. This identified some domains within proteins already linked to biofilm formation and important domains not previously linked to biofilm formation in staphylococci. RT-qPCR confirmed the expression of selected genes predicted to encode important domains within biofilms in Staphylococcus epidermidis. The prevalence and distribution of biofilm associated domains showed a link to phylogeny, suggesting different Staphylococcus species have independently evolved different mechanisms of biofilm production.

CONCLUSIONS

This work has identified different routes to biofilm formation in diverse species of Staphylococcus and suggests independent evolution of biofilm has occurred multiple times across the genus. Understanding the mechanisms of biofilm formation in any given species is likely to require detailed study of relevant strains and the ability to generalise across the genus may be limited.

Nanoparticle ultrasonication outperforms conventional irrigation solutions in eradicating Staphylococcus aureus biofilm from titanium surfaces: an in vitro study

PURPOSE

Bacterial biofilms create a challenge in the treatment of prosthetic joint infection (PJI), and failure to eradicate biofilms is often implicated in the high rates of recurrence. In this study, we aimed to compare the effectiveness of a novel nanoparticle ultrasonication technology on Staphylococcus aureus biofilm eradication compared to commonly used orthopedic irrigation solutions.

METHODS

Twenty-four sterile, titanium alloy discs were inoculated with a standardized concentration of methicillin-resistant S. aureus and cultured for seven days to allow for biofilm formation. Discs were then treated with either ultrasonicated nanoparticle therapy or irrigation with chlorhexidine gluconate, povidone-iodine or normal saline. The remaining bacteria on each surface was subsequently plated for colony-forming units of S. aureus. Bacterial eradication was reported as a decrease in CFUs relative to the control group. Mann-Whitney U tests were used to compare between groups.

RESULTS

Treatment with ultrasonicated nanoparticles resulted in a significant mean decrease in CFUs of 99.3% compared to controls (p < 0.0001). Irrigation with povidone-iodine also resulted in a significant 77.5% reduction in CFUs compared to controls (p < 0.0001). Comparisons between ultrasonicated nanoparticles and povidone-iodine demonstrated a significantly higher reduction in bacterial CFUs in the nanoparticle group (p < 0.0001).

CONCLUSION

Ultrasonicated nanoparticle were superior to commonly used bactericidal irrigation solutions in the eradication of S. aureus from a titanium surface. Future clinical studies are warranted to evaluate this ultrsonication technology in the treatment of PJI.

Diagnosing periprosthetic hip joint infection with new-generation 0.55T MRI

PURPOSE

To assess the accuracy of 0.55 T MRI in diagnosing periprosthetic joint infection (PJI) in patients with symptomatic total hip arthroplasty (THA).

MATERIAL AND METHODS

0.55 T MRI of patients with THA PJI (Group A) and noninfected THA (Group B), including aseptic loosening (Group C, subgroup of B) performed between May 2021 and July 2023 were analysed retrospectively. Two musculoskeletal fellowship-trained radiologists independently identified MRI bone and soft tissue changes including: marrow oedema, periosteal reaction, osteolysis, joint effusion, capsule oedema and thickening, fluid collections, muscle oedema, bursitis, inguinal adenopathy, and muscle tears. The diagnostic performance of MRI discriminators of PJI was evaluated using Fisher's exact test (p < 0.05) and interrater reliability was determined. 61 MRI scans from 60 THA patients (34 female, median age 68, range 41-93 years) in Group A (n = 9; female 4; median age 69, range 56-82 years), B (n = 51; 30; 67.5, 41-93 years), and C (10; 6; 67; 41-82 years) were included.

RESULTS

Capsule oedema (sensitivity 89 %, specificity 92 %,), intramuscular oedema (89 %, 82 %) and joint effusion (89 %, 73 %) were the best performing discriminators for PJI diagnosis (p ≤ 0.001), when viewed individually and had combined 70 % sensitivity and 100 % specificity for PJI diagnosis in parallel testing. For the differentiation between PJI and aseptic loosening, intramuscular oedema (89 %, 80 %) and capsule oedema (89 %, 80 %) were significant discriminators (p ≤ 0.001) with combined 64 % sensitivity and 96 % specificity for PJI.

CONCLUSIONS

New generation 0.55 T MRI may aid in the detection of PJI in symptomatic patients. Oedema of the joint capsule, adjacent muscles as well as joint effusion were indicative of the presence of PJI.

The myocutaneous gastrocnemius flap for periprosthetic joint infection of the knee

Purpose

Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) presents significant challenges, especially in elderly and comorbid patients, often necessitating revision surgeries. We report on a series of patients with confirmed PJI of the knee and concomitant soft-tissue/extensor apparatus defects, treated by using pedicled myocutaneous medial or lateral sural artery perforator (MSAP/LSAP) gastrocnemius flaps.

Methods

Our retrospective study at the Center for Musculoskeletal Infections, included patients with knee PJI undergoing pedicled myocutaneous MSAP/LSAP gastrocnemius flap reconstruction for combined soft tissue and extensor apparatus defects. The tendinous back of the gastrocnemius muscle was used and, if required, the Achilles tendon for extensor apparatus reconstruction, with the skin island addressing the cutaneous defect. Perioperative complications and postoperative outcomes after 1 year were evaluated, including functional and clinical assessments with the American Knee Society Score (AKSS).

Results

Eight patients (mean age 73 years; five female) were included, predominantly with Staphylococcus aureus infections. Six patients involved isolated MSAP flaps, two were extended with the Achilles tendon. The median time for wound healing was 9 days. Short-term follow-up showed successful reconstruction in seven patients, with minor wound dehiscence in one patient. One patient required flap revision for a perigenicular haemato-seroma and two patients were diagnosed with new haematogenous PJI infection. Significant improvement in AKSS scores after surgery was observed (functional AKSS: median 33-85; clinical AKSS: median 64-91, p = 0.001).

Conclusion

Pedicled myocutaneous MSAP/LSAP gastrocnemius flaps offer a safe, reliable and versatile option for reconstructing combined soft tissue and extensor apparatus defects in PJI after TKA. This approach yields excellent functional outcomes with minimal peri- and postoperative complications, which is particularly beneficial in elderly and comorbid patients and feasible in settings without microsurgical availability.

Level of evidence

Level IV.

Sonication protocols and their contributions to the microbiological diagnosis of implant-associated infections: a review of the current scenario

Addressing the existing problem in the microbiological diagnosis of infections associated with implants and the current debate about the real power of precision of sonicated fluid culture (SFC), the objective of this review is to describe the methodology and analyze and compare the results obtained in current studies on the subject. Furthermore, the present study also discusses and suggests the best parameters for performing sonication. A search was carried out for recent studies in the literature (2019-2023) that addressed this research topic. As a result, different sonication protocols were adopted in the studies analyzed, as expected, and consequently, there was significant variability between the results obtained regarding the sensitivity and specificity of the technique in relation to the traditional culture method (periprosthetic tissue culture - PTC). Coagulase-negative Staphylococcus (CoNS) and Staphylococcus aureus were identified as the main etiological agents by SFC and PTC, with SFC being important for the identification of pathogens of low virulence that are difficult to detect. Compared to chemical biofilm displacement methods, EDTA and DTT, SFC also produced variable results. In this context, this review provided an overview of the most current scenarios on the topic and theoretical support to improve sonication performance, especially with regard to sensitivity and specificity, by scoring the best parameters from various aspects, including sample collection, storage conditions, cultivation methods, microorganism identification techniques (both phenotypic and molecular) and the cutoff point for colony forming unit (CFU) counts. This study demonstrated the need for standardization of the technique and provided a theoretical basis for a sonication protocol that aims to achieve the highest levels of sensitivity and specificity for the reliable microbiological diagnosis of infections associated with implants and prosthetic devices, such as prosthetic joint infections (PJIs). However, practical application and additional complementary studies are still needed.

The Financial Burden of Aspirin versus Oral Factor Xa Inhibitors for Thromboprophylaxis Following Total Knee Arthroplasty

BACKGROUND

Aspirin and oral factor Xa inhibitor thromboprophylaxis regimens are associated with similarly low rates of venous thromboembolism following total knee arthroplasty (TKA). However, the rate of prosthetic joint infection (PJI) is lower with aspirin use. This study aimed to compare the cost differential between aspirin and factor Xa inhibitor thromboprophylaxis with respect to PJI management.

METHODS

We used previously published rates of PJI following aspirin and factor Xa inhibitor thromboprophylaxis in primary TKA patients at a single, large institution. Prices for individual drugs were obtained from our hospital's pharmacy service. The cost of PJI included that of 2-stage septic revision, with or without the cost of 1-year follow-up. National data were obtained to determine annual projected TKA volume.

RESULTS

The per-patient costs associated with a 28-day course of aspirin versus factor Xa inhibitor thromboprophylaxis were $17.36 and $3,784.20, respectively. Including cost of follow-up, per-patient costs for a 28-day course of aspirin versus factor Xa inhibitors increased to $73,358.76 and $77,125.60, respectively. The weighted average per-patient costs for a 28-day course were $237.38 and $4,370.93, respectively. The annual cost difference could amount to over $14.1 billion in the United States by 2040.

CONCLUSIONS

The per-patient cost associated with factor Xa inhibitor thromboprophylaxis is as much as 1,980.6% higher than that of an aspirin regimen due to increased costs of primary treatment, differential PJI rates, and high costs of management. In an era of value-based care, the use of aspirin is associated with major cost advantages.

How Reliable Is the Absolute Synovial Polymorphonuclear Neutrophil Cell Count in Diagnosing Periprosthetic Joint Infection?

BACKGROUND

Diagnosing periprosthetic joint infection (PJI) is a daunting task for even the most experienced orthopedic surgeons, as there is currently no test available that can provide absolute accuracy. Utilizing an established synovial indicator for detecting PJI without incurring additional costs or resources would be the optimal solution for predicting the presence of infection. Therefore, we hypothesized that synovial absolute neutrophil count (ANC) would improve the diagnostic accuracy of chronic knee and hip PJI.

METHODS

The study included 260 patients (134 men and 126 women, mean age of 70 years [range, 26 to 89]) who underwent aspiration during preoperative workup. Of these, 109 patients (41.9%) were diagnosed with chronic PJI (50 knees, 59 hips), and 151 patients (58.1%) were diagnosed as aseptic (94 knees, 57 hips). Data obtained from all patients included age, sex, procedure type (total hip or total knee arthroplasty), operation side, synovial white blood cell count (cells/μL), synovial polymorphonuclear cells percentage, and synovial α-defensin immunoassay value at the admission were retrieved from the electronic medical record.

RESULTS

The calculated optimal threshold for synovial ANC of 1,415.5 cells/μL was associated with an area under the receiver operating characteristic curve (AUC) of 0.930 for chronic knee PJI diagnosis. The calculated optimal threshold for synovial ANC of 2,247 cells/μL was associated with an AUC of 0.905 for chronic hip PJI diagnosis.

CONCLUSIONS

This study has conclusively shown that the synovial ANC serves as a valuable marker in the complicated diagnosis of PJI. This highly effective and efficient approach should be utilized for obtaining further information through standard tests, thereby ruling out the possibility of PJI.

LEVEL OF EVIDENCE

III.

Effect of Taiwan's Diabetes Shared Care Program on the risk of periprosthetic joint infection after total joint arthroplasty in patients with type 2 diabetes mellitus: an eight-year population-based study

BACKGROUND

Periprosthetic joint infection (PJI) is a significant post-arthroplasty complication for diabetic patients, with uncontrolled diabetes identified as a PJI risk factor. Taiwan's Diabetes Shared Care Program (DSCP) was established for holistic diabetes care.

AIM

To evaluate the DSCP's impact on PJI incidence and patients' medical costs.

METHODS

Data were analysed from Taiwan's National Health Insurance Research Database from 2010 to 2020, focusing on type 2 diabetes mellitus (DM) patients who had undergone arthroplasty. The study group involved DSCP participants, while a comparison group comprised non-participants with matched propensity scores for age, sex, and comorbidities. The primary outcome was the PJI incidence difference between the groups; the secondary outcome was the medical expense difference.

FINDINGS

The study group consisted of 11,908 type 2 DM patients who had arthroplasty and joined the DSCP; PJI occurred in 128 patients. Among non-participants, 184 patients had PJI. The PJI incidence difference between the groups was statistically significant (1.07% vs 1.55%). The study group's medical costs were notably lower, regardless of PJI incidence. Multivariate regression showed higher PJI risk in patients in comparison group, aged >70 years, male, or who had obesity, anaemia.

CONCLUSION

The study indicates that DSCP involvement reduces PJI risks and decreases annual medical costs for diabetic patients after arthroplasty. Consequently, the DSCP is a recommendable option for such patients who are preparing for total joint arthroplasty.

Developing an antibiogram for empiric antibiotic prescribing for adult non-spinal orthopaedic infections in a developing world setting

PURPOSE

Empiric antibiotic strategies in the treatment of fracture-related infections, chronic osteomyelitis, prosthetic joint infection, and septic arthritis should be based on local microbiological antibiograms. This study aims to describe the microbiology and review the antibiogram profiles of bacterial isolates from patients undergoing surgical treatment for non-spinal orthopaedic infections, to identify the most appropriate empiric antibiotic strategy.

METHODS

A retrospective review was performed of all cases of non-spinal orthopaedic infections treated surgically from 1 January 2018 to 31 December 2018. The National Health Laboratory Service microbiology database was used to identify all intra-operative microbiological specimens obtained from orthopaedic patients, and data were correlated with the orthopaedic surgical database. Cases were divided into fracture-related infections, chronic osteomyelitis, prosthetic joint infection, and septic arthritis. Antibiotic susceptibility data were used to predict the efficacy of different empiric antibiotic regimens.

RESULTS

A total of 107 cases were included in the study; 184 organisms were cultured. Overall, the most common organism cultured was Staphylococcus aureus (25%) followed by Acinetobacter baumannii (9%), Enterococcus faecalis (7%) and Enterobacter cloacae (5%). Across all categories the oral antibiotic combination with the highest effectiveness (81%) would have been a combination of co-trimoxazole, ciprofloxacin and amoxicillin. The most effective intravenous antibiotic combination would have been either piperacillin-tazobactam, amikacin and vancomycin or meropenem and vancomycin; 90% of tested isolates were susceptible to either of these combinations.

CONCLUSION

Antibiogram profiles can serve to guide to empiric antibiotic choice in the management of different categories of non-spinal orthopaedic infections.

Extraction, characterization, and therapeutic potential of Omega-3 fatty acids from Belone belone skin

This study provides the fatty acid profile, presence of Omega 3 fatty acids (ω3FAs) and therapeutic potential of the skin of Garfish (Belone belone), a highly nutritious fish. The ω3FAs were obtained using the urea crystallization method and confirmed by UV VIS spectroscopy, HPLC, FT-IR, and NMR. Additionally, the therapeutic potential of the ω3FAs was assessed through antioxidant, antimicrobial, antibiofilm, and toxicity assays. The oil extracted from Garfish skin (GS) predominantly contains ω3FAs, palmitic acids, and oleic acids. The ω3FAs exhibit high anti-free radical activity and ferric reducing activity. It reduces nitric oxide production as well as lipid peroxidation under certain time. They also demonstrate effective antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pneumoniae. The biofilm formation is efficiently reduced by ω3FAs and eradication effects on biofilm are higher at 4000 µg/mL of concentration. When tested against brine shrimp larvae, ω3FAs were found to be non-toxic. The study indicates that GS skin oil contains a significant amount of omega-3 fatty acids and has potential therapeutic benefits due to its antioxidant and antibacterial properties, without causing any toxic effects. Omega-3 fatty acids have the potential to enhance the treatment of infections caused by harmful bacteria and their biofilm formation. Further research is needed to understand how omega-3 fatty acids work to kill bacteria and how they affect bacterial gene expression.

Utility of Debridement, Antibiotics, and Implant Retention for Acute Periprosthetic Joint Infection in Revision Total Knee Arthroplasty

Background

Periprosthetic joint infection (PJI) in revision arthroplasty presents as a challenging complication that is difficult to manage. Debridement, antibiotics, and implant retention (DAIR) is a recognized treatment option, although few studies have investigated success rates in addition to eventual amputation rates for failed cases.

Methods

A retrospective review of 365 DAIR cases was performed at a single institution from 2008-2020. Patient records were thoroughly reviewed for inclusion and exclusion criteria by multiple members of the research team, discovering 45 cases met criteria for the study cohort. Demographic information, medical history, culture data, and surgical history, were recorded. DAIR's overall survivorship was evaluated with a Kaplan-Meier (KM) survival curve. Additional KM curves were constructed to compare acute postoperative versus acute hematogenous infections as well as DAIR survivorship relative to infecting organism.

Results

DAIR's success rate in revision TKA was 77% at 0.5 years, 56% at 2 years and 46% at 5 years. No significant difference was noted in survivorship when comparing acute postoperative and acute hematogenous cases at 5 years (29 vs 51%, P=0.64). No significance differences in survivorship were noted according to infecting organism (P =0.30). Median follow up duration was significantly lower in the failed DAIR cohort with a median time of 0.5 years in comparison to 1.7 years for the successful DAIR group (P =0.012). There were 20 DAIR cases that failed, 10 of which resulted in eventual amputation.

Conclusion

DAIR's success rate for managing acute PJI in revision arthroplasty cases was 46% at 5 years. Of the 20 failed DAIR cases, 10 resulted in eventual amputation. DAIRs utility in managing these complicated PJI cases in the setting of revision arthroplasty is concerning with low success rates and high rates of amputation in failed cases. Level of Evidence: III.

Proceedings of the United Kingdom Periprosthetic Joint Infection Meeting 2022: Combined and Arthroplasty Sessions

Considerable variation in practice exists in the prevention, diagnosis, and treatment of periprosthetic joint infection (PJI), which is a devastating complication for patients and surgeons. The consensus principle has been increasingly embraced by the orthopaedic community to help guide practice, especially where high-level evidence remains unavailable. The third United Kingdom Periprosthetic Joint Infection (UK PJI) Meeting was held in Glasgow on April 1, 2022, with more than 180 delegates in attendance, representing orthopaedics, microbiology, infectious diseases, plastic surgery, anesthetics, and allied health professions, including pharmacy and arthroplasty nurses. The meeting comprised a combined session for all delegates, and separate breakout sessions for arthroplasty and fracture-related infection. Consensus questions for each session were prepared in advance by the UK PJI working group, based upon topics that were proposed at previous UK PJI Meetings, and delegates participated in an anonymized electronic voting process. We present the findings of the combined and arthroplasty sessions of the meeting in this article, and each consensus topic is discussed in relation to the contemporary literature.

What is the diagnostic accuracy of neutrophil to lymphocyte ratio and monocyte to lymphocyte ratio in detecting acute periprosthetic joint infections? A gender-specific analysis

PURPOSE

The accurate and timely diagnosis of periprosthetic joint infection (PJI) is critical for guiding optimal treatment management and success, highlighting the requirement of readily available inexpensive serum biomarkers to increase the diagnostic accuracy for PJI. Many studies have investigated the diagnostic accuracy of neutrophil to lymphocyte ratio (NLR) and monocyte to lymphocyte ratio (MLR). However, there is a lack of existing literature regarding optimal thresholds for acute PJI. The purpose of this study was to reveal the most appropriate cut-off values for MLR and NLR in detecting acute PJI with a gender specific analysis.

METHODS

Patients were classified as having an acute PJI if they met the International Consensus Meeting (ICM) 2018 modified criteria. Patients who had a negative clinical and diagnostic workup for a PJI and the presence of erythema on the index surgical area were included in the erysipelas group (control group). Data obtained from all patients included age, sex, body mass index (BMI), Charlson Comorbidity Index (CCI), procedure type (THA or TKA), serum C-reactive protein (CRP), and blood studies at the admission and culture results were retrieved from the electronic medical record.

RESULTS

ROC curve analysis was used to determine the gender-specific optimal threshold values for CRP, NLR, and MLR. Comparing the sensitivities and specificities of NLR and MLR at the identified best thresholds in males and females, the study found similar sensitivities of NLR in males and females with 0.84 and 0.84, respectively. On the other hand, an MLR of 0.67 or more reported a notably higher specificity in male patients [0.90 (95% CI 0.75-0.96) versus 0.70 (95% CI 0.56-0.80)].

CONCLUSION

NLR and MLR represent commonly ordered, low-cost, simple, and readily available complete cell count laboratory values and should be used as adjunct tests with reasonable diagnostic accuracy in detecting acute PJIs. Moreover, with its excellent specificity and PPV, MLR could provide valuable insight in diagnosing acute PJI, particularly in male patients.

LEVEL OF EVIDENCE

Level III Retrospective Cohort analysis.

Day-case hip and knee arthroplasty: stages of care and the development of an institutional pathway

Day-case, or outpatient, arthroplasty is growing and has been adopted in healthcare systems because of its cost-effectiveness. A number of studies that reported on day-case total hip arthroplasty, total knee arthroplasty and unicompartmental knee arthroplasty have shown that they can be performed successfully in a select group of patients. However, safety remains a concern, as a clear pathway, including discharge criteria, is not well described in the literature. This article outlines the stages of care involved in day-case hip and knee arthroplasty and gives insights from University College London Hospital's own evidence-based day-case arthroplasty pathway.

The use of intra-articular vancomycin is safe in primary hip and knee arthroplasty

Background

The use of a single dose of intra-articular antibiotic (IAA) has been reported in reducing the rate of prosthetic joint injection after total hip and knee arthroplasty. We examine the safety of IAA in primary hip and knee replacement surgery and the blood levels and joint fluid levels of vancomycin utilising this technique.

Methods

From August to October 2021, 68 patients undergoing primary total joint arthroplasty (THA & TKA) were given 1g vancomycin intra-articularly (IA)after closure of the fascia. All patients received 2g cefazolin intravenously (IV) 30 min prior to the procedure as is our standard prophylaxis, and 21 of the patients (IA + IV) were also administered an additional 1 gm vancomycin IV. Post-operative blood vancomycin, creatinine land eGFR level monitoring was performed d1 and d3. To determine the post-operative intra-articular vancomycin levels, surgical drain fluid was sampled at day 1 and 2, in 10 patients.

Results

All patients had serum vancomycin levels measured on day 1 and 3. In the group where vancomycin was injected after fascial closure, the average blood vancomycin level day 1 was 5.2 μg/ml (range 2.0-10.9) and day 3 was <1.4 μg/ml. The average pre-op creatinine levels were 69.4 μmol/L (56.1-82.6) compared to 70.2 μmol/L (57.0-83.4) on day 1 and 66.1 μmol/L (52.6-79.6) on day 3, (p = 0.663). The average pre-op eGFR levels (ml/min/1.73 m2) were 82.2 (76.0-88.3) compared to 81.7 (75.6-87.8) on day 1 and 83.0 (76.8-89.2) on day 3 (p = 0.736). Samples of joint fluid aspirated from surgical drains on day 1 and day 2 showed average vancomycin levels of 224 μg/ml and 51 μg/ml respectively, significantly higher than the MIC for Staph aureus.

Conclusions

The use of intra-articular vancomycin is safe in primary TJA, with no renal damage and delivers levels within the joint which are highly therapeutic for at least 48 h post injection.

Surgical helmet systems in total joint arthroplasty: assessment of hood sterility and donning technique

BACKGROUND

The incidence of prosthetic joint infection (PJI) is increasing, coincident with the rising volume of joint arthroplasty being performed. With recent controversy regarding the efficacy of surgical helmet systems (SHS) in preventing infection, the focus has turned to the correct donning techniques and usage of surgical hoods. The aim of this study was to compare the bacterial contamination of the operating surgeon's gloves after two common donning techniques of SHS hoods. We also evaluated the baseline sterility of the SHS hoods at the beginning of the procedure.

METHODS

The bacterial contamination rate was quantified using colony-forming units (CFUs), with 50 trials performed per donning technique. Samples were cultured on 5% Columbia blood agar in ambient air at 37 °C for 48 h and all subsequent bacterial growth was identified using a MALDI-TOF mass spectrometer. In Group 1, the operating surgeon donned their colleague's hood. In Group 2, the operating surgeon had their hood applied by a non-scrubbed colleague. After each trial, the operating surgeon immediately inoculated their gloves onto an agar plate. The immediate sterility of 50 SHS hoods was assessed at two separate zones-the screen (Zone 1) and the neckline (Zone 2).

RESULTS

There was no significant difference in contamination rates between the two techniques (3% vs. 2%, P = 0.99) or between right and left glove contamination rates. Immediately after donning, 6/50 (12%) of SHS hoods cultured an organism. Contamination rates at both the face shield and neckline zones were equivalent. The majority of bacteria cultured were Bacillus species.

DISCUSSION

We found no significant difference in the operating surgeon's glove contamination using two common SHS hood-donning techniques when they were performed under laminar airflow with late fan activation. We suggest the SHS hood should not be assumed to be completely sterile and that gloves are changed if it is touched intraoperatively.

Treatment and Outcomes of Fungal Prosthetic Joint Infections: A Systematic Review of 225 Cases

BACKGROUND

Fungal prosthetic joint infections (PJIs) after a total joint arthroplasty are a rare, yet severe, occurrence not often reported in the literature. Unlike in bacterial PJIs, no clear consensus exists on fungal PJI optimal management.

METHODS

A systematic review was performed using the PubMed and Embase databases. Manuscripts were assessed for inclusion and exclusion criteria. The Strengthening the Reporting of Observational Studies in Epidemiology checklist was applied for quality assessment. Individual demographic, clinical, and treatment information was retrieved from included manuscripts.

RESULTS

Seventy one patients who had a PJI of the hip and 126 of the knee were included. Infection recurrence occurred in 29.6% and 18.3% of patients with hip or knee PJI, respectively. Patients who had knee PJIs recurrence had a significantly higher Charlson Comorbidity Index (CCI). For knee PJIs, infection recurrence was more common in patients with Candida albicans (CA) PJIs (P = .022). Two-stage exchange arthroplasty was the most common procedure in both joints. Multivariate analysis found that CCI ≥ 3 was associated with an 18.5-fold increase in the risk of knee PJI recurrence (Odds ratio [OR] = 18.57). Additional risk factors for recurrence in the knee included CA etiology (OR = 3.56) and C-reactive protein at presentation ≥ 6 (OR = 6.54). Compared to debridement, antibiotics, and implant retention, 2-stage procedure was a protective factor for PJI recurrence in the knee (OR = 0.18). No risk factors were found in patients who had hip PJIs.

CONCLUSION

Treatment of fungal PJIs varies widely, but 2-stage revision is the most common. Risk factors for knee fungal PJI recurrence include elevated CCI, infection by CA, and high C-reactive protein at presentation.

Rank-Ordered List of Cost-effective Strategies for Preventing Prosthetic Joint Infection in Total Joint Arthroplasty in an Academic US Hospital

Although the overall rate of prosthetic joint infection (PJI) is low, it remains a major complication associated with total joint arthroplasty (TJA). PJI represents a significant economic burden to the health care system that is projected to increase commensurate with increasing joint replacement volumes. This review provides a rank-ordered list of cost-effective strategies that are performable intraoperatively and have data supporting their efficacy at preventing PJI after TJA. This study may be helpful in assisting surgeons, ambulatory surgery center owners, and hospital acquisition committees to make reasonable and cost-conscious decisions in the face of changing reimbursement. [Orthopedics. 2023;46(6):327-332.].

National variation in prophylactic antibiotic use for elective primary total joint replacement

Aims

Prophylactic antibiotic regimens for elective primary total hip and knee arthroplasty vary widely across hospitals and trusts in the UK. This study aimed to identify antibiotic prophylaxis regimens currently in use for elective primary arthroplasty across the UK, establish variations in antibiotic prophylaxis regimens and their impact on the risk of periprosthetic joint infection (PJI) in the first-year post-index procedure, and evaluate adherence to current international consensus guidance.

Methods

The guidelines for the primary and alternative recommended prophylactic antibiotic regimens in clean orthopaedic surgery (primary arthroplasty) for 109 hospitals and trusts across the UK were sought by searching each trust and hospital's website (intranet webpages), and by using the MicroGuide app. The mean cost of each antibiotic regimen was calculated using price data from the British National Formulary (BNF). Regimens were then compared to the 2018 Philadelphia Consensus Guidance, to evaluate adherence to international guidance.

Results

The primary choice and dosing of the prophylactic antimicrobial regimens varied widely. The two most used regimens were combined teicoplanin and gentamicin, and cefuroxime followed by two or three doses of cefuroxime eight-hourly, recommended by 24 centres (22.02%) each. The alternative choice and dosing of the prophylactic antimicrobial regimen also varied widely across the 83 centres with data available. Prophylaxis regimens across some centres fail to cover the likeliest causes of surgical site infection (SSI). Five centres (4.59%) recommend co-amoxiclav, which confers no Staphylococcus coverage, while 33 centres (30.28%) recommend cefuroxime, which confers no Enterococcus coverage. Limited adherence to 2018 Philadelphia Consensus Guidance was observed, with 67 centres (61.50%) not including a cephalosporin in their guidance.

Conclusion

This analysis of guidance on antimicrobial prophylaxis in primary arthroplasty across 109 hospitals and trusts in the UK has identified widespread variation in primary and alternative antimicrobial regimens currently recommended.

Utility of Blood Cell Ratio Combinations for Diagnosis of Periprosthetic Joint Infection

Background

Periprosthetic joint infection (PJI) is a serious complication following joint replacement surgery, and its diagnosis can be challenging due to the similarity of symptoms to other conditions and the lack of confirmatory imaging tests. Platelet/mean platelet volume ratio (PVR), platelet/lymphocyte ratio, monocyte/lymphocyte ratio, and neutrophil/lymphocyte ratio have been proposed as potential markers to aid in the diagnosis of PJI. This study aimed to further assess the utility of these blood cell ratio combinations for the diagnosis of PJI.

Methods

A retrospective chart review was conducted on patients who presented to a university hospital for evaluation for PJI or underwent aseptic revision surgery. All patients were reviewed for inclusion in the study. Data were collected on several markers, including complete blood counts, synovial fluid white blood cell count, and polymorphonuclear percentage. Receiver operator characteristic curve analysis was used to evaluate the diagnostic capabilities of the markers and marker combinations.

Results

The combination of erythrocyte sedimentation rate, C-reactive protein, synovial white blood cell count, and synovial polymorphonuclear percentage, with PVR, had the highest area under the curve of 0.97, with a sensitivity of 94.3% and a specificity of 88.9%, and a positive predictive value of 97.1% and a negative predictive value of 80.0%.

Conclusions

This study further supports the use of PVR calculated from complete blood count commonly ordered laboratory values obtained during routine complete blood counts when combined with established serum and synovial markers to increase the diagnostic accuracy for diagnosing PJI.

Longitudinal rates, risk factors, and costs of superficial and deep incisional surgical-site infection (SSI) after primary and revision total knee arthroplasty: A US retrospective claims database analysis

OBJECTIVE

We evaluated longitudinal rates, risk factors, and costs of superficial and deep incisional surgical-site infection (SSI) 6 months after primary total knee arthroplasty (pTKA) and revision total knee arthroplasty (rTKA).

METHODS

Patients were identified from January 1, 2016 through March 31, 2018, in the IBM MarketScan administrative claims databases. Kaplan-Meier survival curves evaluated time to SSI over 6 months. Cox proportional hazard models evaluated SSI risk factors. Generalized linear models estimated SSI costs up to 12 months.

RESULTS

Of the 26,097 pTKA patients analyzed (mean age, 61.6 years; SD, 9.2; 61.4% female; 60.4% commercial insurance), 0.65% (95% CI, 0.56%-0.75%) presented with a deep incisional SSI and 0.82% (95% CI, 0.71%-0.93%) with a superficial incisional SSI. Also, 3,663 patients who had rTKA (mean age, 60.9 years; SD, 10.1; 60.6% female; 53.0% commercial insurance), 10.44% (95% CI, 9.36%-11.51%) presented with a deep incisional SSI and 2.60% (95% CI, 2.07%-3.13%) presented with a superficial incisional SSI. Infections were associated with male sex and multiple patient comorbidities including chronic pulmonary disease, pulmonary circulatory disorders, fluid and electrolyte disorders, malnutrition, drug abuse, and depression. Adjusted average all-cause incremental commercial cost ranged from $14,298 to $29,176 and from $41,381 to 59,491 for superficial and deep incisional SSI, respectively.

CONCLUSIONS

SSI occurred most frequently following rTKA and among patients with pulmonary comorbidities and depression. The incremental costs associated with SSI following TKA were substantial.

Incidence of Rifampicin Resistance in Periprosthetic Joint Infection: A Single-Centre Cohort Study on 238 Patients

BACKGROUND

Rifampicin is a pillar in the treatment of periprosthetic joint infection (PJI). However, rifampicin resistance is an increasing threat to PJI treatment. This study explores the incidence of rifampicin-resistant bacteria over time in a Swedish tertiary referral centre and the association of rifampicin resistance with infection-free survival after PJI.

METHODS

The study included 238 staphylococcal PJIs treated between 2001 and 2020 for which susceptibility data for rifampicin were available. Data on causative bacteria, rifampicin resistance, treatment, and outcome were obtained. Kaplan-Meier survival analysis and Cox regression modelling estimated the infection-free cumulative survival and adjusted hazard ratios (HRs) for the risk of treatment failure.

RESULTS

Rifampicin-resistant causative bacteria were identified in 40 cases (17%). The proportion of rifampicin-resistant agents decreased from 24% in 2010-2015 to 12% in 2016-2020. The 2-year infection-free survival rates were 78.6% (95% CI, 66.4-93.1%) for the rifampicin-resistant group and 90.0% (95% CI, 85.8-94.4%) for the rifampicin-sensitive group. Patients with PJI caused by rifampicin-resistant bacteria had an increased risk of treatment failure (adjusted HR, 4.2; 95% CI, 1.7-10.3).

CONCLUSIONS

The incidence of PJI caused by rifampicin-resistant bacteria did not increase over the past 20 years. The risk of treatment failure in PJI caused by rifampicin-resistant bacteria is more than four times that caused by rifampicin-sensitive bacteria, highlighting the importance of limiting the development of rifampicin resistance.

Safety and tolerability of tedizolid as oral treatment for bone and joint infections

Bone and joint infections (BJIs) are common infections increasingly managed with oral therapy. However, there are limited safe oral options for many Gram-positive pathogens. In animal studies and short-term human use, tedizolid lacks the hematologic and neurologic toxicity of the other available oxazolidinone, linezolid. However, there are limited prospective safety data. We conducted an open-label, non-comparative trial of oral tedizolid for BJI treatment. Primary outcomes were safety and cure rate. Eligible patients had a BJI caused by documented or suspected Gram-positive pathogen, required 4-12 weeks of therapy, and did not have myelosuppression or peripheral/optic neuropathy. Subjects underwent weekly evaluation for cytopenias and neuropathy. We enrolled 44 subjects; five were lost to follow-up. Two subjects did not complete planned treatment because of rash (n = 1) and urgent surgery (n = 1). Of 37 patients with evaluable outcomes, 17 (46%) had hardware-associated infection, 13 (35%) had osteomyelitis, 5 (14%) had prosthetic joint infection, and 2 (5%) had other BJIs. Median (mean, range) treatment duration was 12 (10.1, 4-12) weeks. There were no cases of cytopenias or peripheral or optic neuropathy. Treatment cure occurred in 13 (35%); 19 (51%) required antibiotic continuation after 12 weeks of tedizolid related to retained hardware at the BJI site, and failure occurred in four (11%), two unlikely, one possibly, and one probably due to tedizolid. We found that oral tedizolid was well tolerated for prolonged BJI treatment without significant toxicity. Clinical failure rate was similar to that of other published BJI investigations. (This study has been registered at Clinicaltrials.gov under identifier NCT03009045.) IMPORTANCE Bone and joint infections are common infections with limited effective and safe oral options for Gram-positive infections. The largest prospective clinical trial of tedizolid therapy for bone and joint infections enrolled 44 patients and tested each in person weekly with detailed safety monitoring including tests for leukopenia, anemia, thrombocytopenia, peripheral neuropathy, and optic neuropathy for up to 12 weeks. Findings demonstrated tedizolid was generally well tolerated and there were no incident cases of cytopenias or neuropathy. Cure rates were similar to that in other bone and joint infection studies. In summary, oral tedizolid appears to be a well-tolerated oral option for Gram-positive bone and joint infections.

Staphylococcus aureus colonization and periprosthetic joint infection in patients undergoing elective total joint arthroplasty: a narrative review

Peri-prosthetic joint infections (PJIs) following total joint arthroplasty (TJA) are associated with higher treatment costs, longer hospital admissions and increased morbidity and mortality. Colonization with Staphylococcus aureus is an independent and modifiable risk factor for PJIs and carriers of S. aureus are ten times more likely than non-carriers for post-operative infections. Screening and targeted decolonization, vs universal decolonization without screening, remains a controversial topic. We recommend a tailored approach, based on local epidemiological patterns, resource availability and logistical capacity. Universal decolonization is associated with lower rates of SSI and may reduce treatment costs.

Prosthetic knee joint infection caused by α-hemolytic Streptococcus species: a case report

BACKGROUND

Knee arthroplasty is an orthopedic surgical procedure in which a damaged joint is replaced with an artificial one. It is estimated that 1-2% of knee arthroplasties will encounter infection over their lifetime. Although α-hemolytic Streptococcus species play an important role in prosthetic joint infection, they are less common than staphylococcal species.

CASE PRESENTATION

In this report, a 50-year-old Iranian woman was diagnosed with prosthetic knee joint infection based on clinical, radiological, and laboratory findings. She was diabetic and had undergone a left total knee arthroplasty, which, 18 months after the surgery, presented pain, erythema, and edema in that knee. The primary culture of knee aspirate was positive for α-hemolytic Streptococcus species, but following antibiotic medication, culture was negative. The primary antibiotic regime was vancomycin and meropenem, which was changed to cefepime for the management of the infection based on the results of antimicrobial susceptibility testing.

CONCLUSIONS

This report indicated the clinical presentation and management of the patient with prosthetic joint infection in which the patient recovered without any severe complications or surgical intervention.

Periprosthetic knee infection in octogenarians: a single institution experience at midterm outcome

PURPOSE

Periprosthetic joint infections (PJI) of total knee arthroplasties (TKAs) in the elderly is among the clinically most challenging scenarios given multimorbidity combined with poor bone and soft tissue quality. Despite increasing prevalence, limited is known on PJI among this unique group of patients. As such, this study analyzed PJI characteristics, implant survivorship and non-surgical complications of octogenarians revised PJI for the knee.

METHODS

We identified 31 patients that were revised for PJIs of the knee between 2010 and 2019 using a single university-based registry. Mean age was 83 years (range 80-87), 48% were females, and mean BMI was 29 kg/m2. Mean age adjusted Charlson Comorbidity Index was 7, and mean ASA score was 3. Major causative pathogens included Coagulase-negative Staphylococci (26%), Staphylococcus aureus (13%), and Streptococci (13%). Two-stage exchange was performed in 30 patients, permanent resection arthroplasty in one joint. Kaplan-Meier survivorship analyses were performed. Mean follow-up was 4 years.

RESULTS

The 2-year survivorship free of any recurrent PJI was 96%, and there was one PJI relapse noted at 6 months. Moreover, there were three additional revisions for aseptic loosening, and one further revision for fracture. As such, the 2-year survivorship free of any revision was 87%. In addition to the aforementioned revisions, there was one additional plate osteosynthesis for a Vancouver C fracture, resulting in a 79% survivorship free of any reoperation at 2 years. Mean perioperative complication score according to the Clavien-Dindo classification was 2 out of 5. A total of three patients died: one patient 40 days after resection arthroplasty, two others 4 months and 8 months after reimplantation.

CONCLUSIONS

Octogenarians revised for PJI of the knee are at low risk of recurrent infection and overall revision at 2 years. However, moderate rates of perioperative complications and mortality at short term must acknowledge before deciding upon procedure.

LEVEL OF EVIDENCE

Therapeutic level IV.

Application of machine learning in the prevention of periprosthetic joint infection following total knee arthroplasty: a systematic review

BACKGROUND

Machine learning is a promising and powerful technology with increasing use in orthopedics. Periprosthetic joint infection following total knee arthroplasty results in increased morbidity and mortality. This systematic review investigated the use of machine learning in preventing periprosthetic joint infection.

METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed was searched in November 2022. All studies that investigated the clinical applications of machine learning in the prevention of periprosthetic joint infection following total knee arthroplasty were included. Non-English studies, studies with no full text available, studies focusing on non-clinical applications of machine learning, reviews and meta-analyses were excluded. For each included study, its characteristics, machine learning applications, algorithms, statistical performances, strengths and limitations were summarized. Limitations of the current machine learning applications and the studies, including their 'black box' nature, overfitting, the requirement of a large dataset, the lack of external validation, and their retrospective nature were identified.

RESULTS

Eleven studies were included in the final analysis. Machine learning applications in the prevention of periprosthetic joint infection were divided into four categories: prediction, diagnosis, antibiotic application and prognosis.

CONCLUSION

Machine learning may be a favorable alternative to manual methods in the prevention of periprosthetic joint infection following total knee arthroplasty. It aids in preoperative health optimization, preoperative surgical planning, the early diagnosis of infection, the early application of suitable antibiotics, and the prediction of clinical outcomes. Future research is warranted to resolve the current limitations and bring machine learning into clinical settings.

No Difference in the Rate of Periprosthetic Joint Infection in Patients Undergoing the Posterolateral Compared to the Direct Anterior Approach

BACKGROUND

There remains inconsistent data about the association of surgical approach and periprosthetic joint infection (PJI). We sought to evaluate the risk of reoperation for superficial infection and PJI after primary total hip arthroplasty (THA) in a multivariate model.

METHODS

We reviewed 16,500 primary THAs, collecting data on surgical approach and all reoperations within 1 year for superficial infection (n = 36) or PJI (n = 70). Considering superficial infection and PJI separately, we used Kaplan-Meier survivorship to assess survival free from reoperation and a Cox Proportional Hazards multivariate models to assess risk factors for reoperation.

RESULTS

Between direct anterior approach (DAA) (N = 3,351) and PLA (N = 13,149) cohorts, rates of superficial infection (0.4 versus 0.2%) and PJI (0.3 versus 0.5%) were low and survivorship free from reoperation for superficial infection (99.6 versus 99.8%) and PJI (99.4 versus 99.7%) were excellent at both 1 and 2 years. The risk of developing superficial infection increased with high body mass index (BMI) (hazard ratio [HR] = 1.1 per unit increase, P = .003), DAA (HR = 2.7, P = .01), and smoking status (HR = 2.9, P = .03). The risk of developing PJI increased with the high BMI (HR = 1.04, P = .03), but not surgical approach (HR = 0.68, P = .3).

CONCLUSION

In this study of 16,500 primary THAs, DAA was independently associated with an elevated risk of superficial infection reoperation compared to the PLA, but there was no association between surgical approach and PJI. An elevated patient BMI was the strongest risk factor for superficial infection and PJI in our cohort.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Which Combination is Best? A Comparison of the Predictive Potential of Serum Biomarker Combinations to Diagnose Periprosthetic Joint Infection

BACKGROUND

Without a gold standard test, recent periprosthetic joint infections (PJI) literature has explored the utility of combining serological results, with promising findings. However, previous studies evaluated fewer than 200 patients and often studied only 1 to 2 test combinations. The purpose of this study was to accumulate a large single institution cohort of revision total joint arthroplasty (rTJA) patients to determine the diagnostic utility of combination serum biomarkers to identify PJI.

METHODS

A single institution longitudinal database was assessed to identify all patients who underwent rTJA from 2017 to 2020. There were 1,363 rTJA patients (715 rTKA patients and 648 rTHA patients) including 273 PJI cases (20%) analyzed. The PJI was diagnosed post-rTJA utilizing 2011 Musculoskeletal Infection Society (MSIS) criteria. Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), D-dimer, and interleukin 6 (IL-6) were systematically collected for all patients.

RESULTS

The rTKA combination markers of CRP+ESR (sensitivity: 78.3%, specificity: 88.8%, positive predictive value (PPV): 70.0%, negative predictive value (NPV): 92.5%), CRP+D-dimer (sensitivity: 60.5%, specificity: 92.6%, PPV: 63.4%, NPV: 91.7%), and CRP+IL-6 (sensitivity: 38.5%, specificity: 100.0%, PPV: 100.0%, NPV: 92.9%) all yielded higher specificity than CRP alone (sensitivity: 94.4%, specificity: 75.0%, PPV: 55.5%, NPV: 97.6%). Similarly, the rTHA combination markers of CRP+ESR (sensitivity: 70.1%, specificity: 88.8%, PPV: 58.1%, NPV: 93.1%), CRP+D-dimer (sensitivity: 57.1%, specificity: 90.1%, PPV: 43.2%, NPV: 94.1%), and CRP+IL-6 (sensitivity: 21.4%, specificity: 98.4%, PPV: 60.0%, NPV: 91.7%) all yielded higher specificity than CRP alone (sensitivity: 84.7%, specificity: 77.5%, PPV: 45.4%, NPV: 95.8%).

CONCLUSIONS

Overall, in diagnosing PJI for both rTKA and rTHA, two marker combinations yielded higher specificity, while three marker combinations yielded higher sensitivity compared to CRP alone. However, compared to all two and three marker combinations, CRP demonstrated superior overall diagnostic utility. These findings suggest that routine combination testing of markers for PJI diagnosis may be excessive and an unnecessary use of resources, especially in resource-limited situations.

Acute kidney injury in the context of staged revision arthroplasty and the use of antibiotic-laden cement spacers: a systematic review

BACKGROUND

The most common cause of revision arthroplasty is prosthetic joint infection (PJI). Chronic PJI is commonly treated with two-stage exchange arthroplasty involving the placement of antibiotic-laden cement spacers (ACS) in the first stage, often containing nephrotoxic antibiotics. These patients often have significant comorbidity burdens and have higher rates of acute kidney injury (AKI). This systematic review aims to assess the current literature to identify (1) AKI incidence, (2) associated risk factors, and (3) antibiotic concentration thresholds in ACS that increase AKI risk following first-stage revision arthroplasty.

METHODS

An electronic search was performed of the PubMed database of all studies involving patients undergoing ACS placement for chronic PJI. Studies assessing AKI rates and risk factors were screened by two authors independently. Data synthesis was performed when possible. Significant heterogeneity prevented meta-analysis.

RESULTS

Eight observational studies consisting of 540 knee PJIs and 943 hip PJIs met inclusion criteria. There were 309 (21%) cases involving AKI. The most commonly reported risk factors included perfusion-related factors (lower preoperative hemoglobin, transfusion requirement, or hypovolemia), older age, increased comorbidity burden, and nonsteroidal anti-inflammatory drug consumption. Only two studies found increased risk with greater ACS antibiotic concentration (> 4 g vancomycin and > 4.8 g tobramycin per spacer in one study, > 3.6 g of vancomycin per batch or > 3.6 g of aminoglycosides per batch in the other); however, these were reported from univariate analyses not accounting for other potential risk factors.

DISCUSSION

Patients undergoing ACS placement for chronic PJI are at an increased risk for AKI. Understanding the risk factors may lead to better multidisciplinary care and safer outcomes for chronic PJI patients.

LEVEL OF EVIDENCE III

Genomic Sequencing to Diagnose Prosthetic Joint Infection in the Knee: A Case Report

There is currently no "gold-standard" method to diagnose prosthetic joint infections (PJI), and the current practice of using microbiological cultures has many limitations. The identification of the bacterial species causing the infection is crucial to guide treatment; therefore, a robust method needs to be developed. Here, we attempt to use genomic sequencing with the MinION device from Oxford Nanopore Technologies to identify the species of bacteria causing PJI in a 61-year-old male. Genomic sequencing with the MinION presents an opportunity to produce species identification in real-time and at a smaller cost than current methods. By comparing results with standard hospital microbiological cultures, this study suggests that nanopore sequencing using the MinION could be a faster and more sensitive method to diagnose PJI than microbiological cultures.

Acetabular Wall Weakening in Total Hip Arthroplasty: A Pilot Study

Total hip arthroplasty is a widely performed operation allowing disabled patients to improve their quality of life to a degree greater than any other elective procedure. Planning for a THA requires adequate patient assessment and preoperative characterizations of acetabular bone loss via radiographs and specific classification schemes. Some surgeons may be inclined to ream at a larger diameter thinking it would lead to a more stable press-fit, but this could be detrimental to the acetabular wall, leading to intraoperative fracture. In the attempt to reduce the incidence of intraoperative fractures, the current study aims to identify how increased reaming diameter degrades and weakens the acetabular rim strength. We hypothesized that there is proportionality between the reaming diameter and the reduction in acetabular strength. To test this hypothesis, this study used bone surrogates, templated from CT scans, and reamed at different diameters. The obtained bone surrogate models were then tested using an Intron 8874 mechanical testing machine (Instron, Norwood, MA) equipped with a custom-made fixture. Analysis of variance (ANOVA) was used to identify differences among reamed diameters while linear regression was used to identify the relationship between reamed diameters and acetabular strength. We found a moderate correlation between increasing reaming diameter that induced thinning of the acetabular wall and radial load damage. For the simplified acetabular model used in this study, it supported our hypothesis and is a promising first attempt in providing quantitative data for acetabular weakening induced by reaming.

Increased Incidence of Methicillin-Resistant Staphylococcus aureus in Knee and Hip Prosthetic Joint Infection

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication of knee and hip arthroplasty. Past literature has shown that gram-positive bacteria are commonly responsible for these infections, although limited research exists studying the changes in the microbial profile of PJIs over time. This study sought to analyze the incidence and trends of pathogens responsible for PJI over three decades.

METHODS

This is a multi-institutional retrospective review of patients who had a knee or hip PJI from 1990 to 2020. Patients with a known causative organism were included and those with insufficient culture sensitivity data were excluded. There were 731 eligible joint infections from 715 patients identified. Organisms were divided into multiple categories based on genus/species and 5-year increments were used to analyze the study period. The Cochran-Armitage trend tests were used to evaluate linear trends in microbial profile over time and a P-value <.05 was considered statistically significant.

RESULTS

There was a statistically significant positive linear trend in the incidence of methicillin-resistant Staphylococcus aureus over time (P = .0088) as well as a statistically significant negative linear trend in the incidence of coagulase-negative staphylococci over time (P = .0018). There was no statistical significance between organism and affected joint (knee/hip).

CONCLUSION

The incidence of methicillin-resistant Staphylococcus aureus PJI is increasing over time, whereas, coagulase-negative staphylococci PJI is decreasing, paralleling the global trend of antibiotic resistance. Identifying these trends may help with the prevention and treatment of PJI through methods such as remodeling perioperative protocols, modifying prophylactic/empiric antimicrobial approaches, or transitioning to alternative therapeutic strategies.

The promising role of bacteriophage therapy in managing total hip and knee arthroplasty related periprosthetic joint infection, a systematic review

PURPOSE

Total hip and knee arthroplasty periprosthetic joint infection (PJI) poses a management dilemma owing to the emergence of resistant organisms. A promising option is Bacteriophage therapy (BT) was used as an adjuvant for PJI management, aiming at treating resistant infections, decreasing morbidity, and mortality. The current review aimed to demonstrate the role and safety of using BT as an adjuvant to treat PJIs.

METHODS

A systematic search was performed through four databases (Embase, PubMed, Web of Science, and Scopus) up to March 2022, according to the predetermined inclusion and exclusion criteria.

RESULTS

Our systematic review included 11 case reports of 13 patients in which 14 joints (11 TKAs and three THAs) were treated. The patients' average age was 73.7 years, underwent an average of 4.5 previous surgeries. The most common organism was the Staphylococcus aureus species. All patients underwent surgical debridement; for the 13 patients, eight received a cocktail, and five received monophage therapy. All patients received postoperative suppressive antibiotic therapy. After an average follow-up of 14.5 months, all patients had satisfactory outcomes. No recurrence of infection in any patient. Transaminitis complicating BT was developed in three patients, needed stoppage in only one, and the condition was reversible and non-life-threatening.

CONCLUSION

BT is a safe and potentially effective adjuvant therapy for treating resistant and relapsing PJIs. However, further investigations are needed to clarify some BT-related issues to create effective and reproducible therapeutics. Furthermore, new ethical regulations should be implemented to facilitate its widespread use.

Is Topical Vancomycin an Option? A Randomized Controlled Trial to Determine the Safety of the Topical Use of Vancomycin Powder in Preventing Postoperative Infections in Total Knee Arthroplasty, as Compared With Standard Postoperative Antibiotics

BACKGROUND

The demand for total knee arthroplasties (TKAs) is expected to rise in the coming decades, increasing the burden of periprosthetic joint infections (PJIs). The use of intrawound vancomycin powder (VP) has proven to be effective in reducing the incidence of PJIs after spinal surgery. That said, its effectiveness in TKA remains unclear. This trial aims to examine the efficacy of intrawound vancomycin powder first versus standard postoperative antibiotics in preventing PJIs after TKA.

METHODS

This study was a double-blinded, noninferiority, randomized controlled trial. All participants received standard preoperative intravenous (IV) antibiotics (Cefazolin/Vancomycin) within 60 minutes of skin incision. Patients in the treatment group received 1 gram of VP applied intraoperatively by the orthopedic surgeon (500 mg directly on the prosthesis, 500 mg above the closed joint capsule). These patients did not receive postoperative antibiotics. Patients in the control group received standard postoperative IV antibiotics. The primary outcome was the incidence of acute surgical site infection within 42 days of procedure.

RESULTS

There were 80 patients randomized to the treatment group and 85 patients randomized to the control. Groups were matched with respect to baseline characteristics, including average age (66 versus 64), BMI (35.7 versus 33.4), and diabetics (16 versus 13). The trial was halted at 1 year as a significantly greater proportion (P = .03) of patients in the treatment group (n = 3, 3.75%) were diagnosed with PJIs compared to the control (n = 0).

CONCLUSION

Our trial demonstrated the intrawound application of VP to be inferior to standard postoperative IV antibiotics in reducing the incidence of PJIs after TKA.

One- or two-stage reimplantation for infected total knee prosthesis?

A prosthetic joint infection (PJI) is possibly the most significant potential complication of total knee arthroplasty (TKA) and is associated with substantial morbidity and socioeconomic burden. It is a devastating complication for both the patient and the surgeon alike. A two-stage revision approach for infected TKA has been the standard for surgical management; however, there is growing interest in single-stage revision surgery due to fewer procedures, reduced inpatient hospital stay and reduced costs to healthcare systems. A one-stage exchange is indicated when there is no sign of systemic sepsis and in cases where a microorganism has been isolated. It involves removal of the old prosthesis, debridement of all infected tissue, a copious washout and re-draping, and finally, re-implantation of a new prosthesis. The two-stage approach involves the use of an antibiotic spacer before the second stage is carried out. The length of time between the stages is discussed. Patients with a PJI should be managed by a multidisciplinary team. We recommend these patients are managed in specialist arthroplasty centres by high volume revision arthroplasty specialists.

Influence of surface characteristics of implant materials on MRSA biofilm formation and effects of antimicrobial treatment

Introduction

One of the main causes of treatment failure in bacterial prosthetic joint infections (PJI) is biofilm formation. The topography of the biofilm may be associated with susceptibility to antimicrobial treatment. The aims of this study were to assess differences in topography of biofilms on different implant materials and the correlation thereof with susceptibility to antimicrobial treatment.

Methods

Methicillin-resistant Staphylococcus aureus (MRSA) 7-day mature biofilms were generated on disks made from titanium alloys (Ti-6Al-7Nb and Ti-6Al-4V), synthetic polymer and orthopedic bone cement, commonly used in implant surgery. The surface topography of these implant materials and the biofilms cultured on them was assessed using atomic force microscopy. This provided detailed images, as well as average roughness (Ra) and peak-to-valley roughness (Rt) values in nanometers, of the biofilm and the material surfaces. Bacterial counts within biofilms were assessed microbiologically. Antimicrobial treatment of biofilms was performed by 24-h exposure to the combination of rifampicin and ciprofloxacin in concentrations of 1-, 5- and 10-times the minimal bactericidal concentration (MBC). Finally, treatment-induced differences in bacterial loads and their correlation with biofilm surface parameters were assessed.

Results

The biofilm surfaces on titanium alloys Ti-6Al-7Nb (Ra = 186 nm) and Ti-6Al-4V (Ra = 270 nm) were less rough than those of biofilms on silicone (Ra = 636 nm). The highest roughness was observed for biofilms on orthopedic bone cement with an Ra of 1,551 nm. Interestingly, the roughness parameters of the titanium alloys themselves were lower than the value for silicone, whereas the surface of the bone cement was the roughest. Treatment with 1- and 5-times the MBC of antibiotics resulted in inter-material differences in colony forming units (CFU) counts, ultimately showing comparable reductions of 2.4-3.0 log CFU/mL at the highest tested concentration. No significant differences in bacterial loads within MRSA biofilms were observed between the various implant materials, upon exposure to increasing concentrations of antibiotics.

Discussion

The surface parameters of MRSA biofilms were determined by those of the implant materials on which they were formed. The antibiotic susceptibility of MRSA biofilms on the various tested implant materials did not differ, indicating that the efficacy of antibiotics was not affected by the roughness of the biofilm.

Femoral head and neck autograft in arthroplasty for developmental dysplasia of the hip: a systematic review of long-term outcomes

PURPOSE

Total hip arthroplasty (THA) with an acetabular component and an autogenous femoral head graft for acetabular reconstruction in developmental dysplasia of the hip was first described by Harris et al. in 1977. While a number of studies have addressed the aforementioned scenario over the last decades, most lack sufficient numbers and follow-up. As such, we analyzed long-term outcomes of THAs with femoral autograft for arthrosis secondary to hip dysplasia.

METHODS

A systematic review was performed using a structured PubMed, Web of Science, Ovid MEDLINE, and Cochrane analysis, based on the PRISMA criteria. All original studies from 1977 to 2022 with a mean follow-up of 10 or more years were included. Methodological Index for Nonrandomized Studies (MINORS) were used for quality assessment.

RESULTS

A total of 26 studies with 1316 patients (87% females) undergoing 1543 THAs with femoral autograft (2 times neck graft, 24 times head graft) were included. Mean age was 52 years (range, 28-73) and the mean follow-up was 13 years (range, 9-18). The revision rate was 8.3% (n = 129), and 73% of revisions were for loosening. Rate of infection (0.5%) and dislocations (1%) were low. Radiographic analysis revealed 167 loose acetabular components (11%) and 118 cases of graft resorption (7.6%). Mean Harris Hip Score increased from 42 to 85. Mean MINORS score was 11, and no study was level of evidence I or II.

CONCLUSIONS

Femoral autograft with THA may be a viable long-term option for hip reconstruction in developmental dysplasia of the hip. However, moderate loosening rates and low level of evidence must be acknowledged before drawing the final conclusions.

LEVEL OF EVIDENCE

Therapeutic Level III.

Clinical Use of a 16S Ribosomal RNA Gene-Based Sanger and/or Next Generation Sequencing Assay to Test Preoperative Synovial Fluid for Periprosthetic Joint Infection Diagnosis

Preoperative pathogen identification in patients with periprosthetic joint infection (PJI) is typically limited to synovial fluid culture. Whether sequencing-based approaches are of potential use in identification of pathogens in PJI, and if so which approach is ideal, is incompletely defined. The objective of the study was to analyze the accuracy of a 16S rRNA (rRNA) gene-based PCR followed by Sanger sequencing and/or targeted metagenomic sequencing approach (tMGS) performed on synovial fluid for PJI diagnosis. A retrospective study was conducted, analyzing synovial fluids tested between August 2020 and May 2021 at a single center. Subjects with hip, knee, shoulder, and elbow arthroplasties who had synovial fluid aspirated and clinically subjected to sequence-based testing and conventional culture were studied. A total of 154 subjects were included in the study; 118 had noninfectious arthroplasty failure (NIAF), while 36 had PJI. Clinical sensitivity and specificity for diagnosis of PJI were 69% and 100%, respectively, for the sequencing-based approach and 72% and 100%, respectively, for conventional culture (P = 0.74). The combination of both tests was more sensitive (83%) than culture alone (P = 0.04). Results of sequencing-based testing led to changes in treatment in four of 36 (11%) PJI subjects. Microbial identification was achieved using Sanger and next generation sequencing in 19 and 6 subjects, respectively. When combined with culture, the described 16S rRNA gene sequencing-based approach increased sensitivity compared to culture alone, suggesting its potential use in the diagnosis of PJI when synovial fluid culture is negative. IMPORTANCE Periprosthetic joint infection (PJI) is a dreadful complication of joint replacement. Noninvasive identification of infectious pathogens has been traditionnally limited to culture-based testing of synovial fluid which has poor sensitivity. Sanger and Next-generation sequencing (NGS) may be used for synovial fluid testing in PJI, but experience in routine practice is sparse. We used a targeted metagenomic sequencing approach for routine testing of synovial fluid involving NGS when Sanger sequencing had failed or was likely to fail. The objective of this study was to analyze the approach's performance for diagnosis of PJI in comparison to culture for testing synovial fluid. Overall, the sequencing-based approach was not superior to culture for diagnosis of PJI, but yielded positive results in some culture-negative samples.

Sterilization Procedures for Titanium Alloy Surfaces Leads to Higher Expression of Biofilm-Related Staphylococcus aureus Genes

Background: Around 1-2% of all implantation surgeries lead to implant-related infections, incurring costs of $40,000-$160,000 per total hip PJI. The 5-year mortality rate of prosthetic joint infections is up to 21%. To prevent infections during surgery, sterile surgery rooms and procedures have been developed and certified standards have been established. To guarantee the sterility, implants can be acquired already sterile from manufacturers. Some titanium implants can be delivered unsterilized with a manual for sterilization procedure in compliance with ISO 17664. The aim of this study is to evaluate if the most used sterilization methods (steam sterilization in an autoclave and UV light sterilization) of titanium alloys, can influence the biofilm forming capacity of Staphylococcus aureus. In this study, we examined the influence of sterilization methods on the gene expression of biofilm-associated genes and regulators. Methods: We compared gene expression of icaADBC, SarA, SigB, and SodA on titanium CP4 and Ti6Al4V alloys sterilized by UV-light and pressurized saturated steam sterilization. We performed RT-qPCR after RNA extraction of Staphylococcus aureus ATCC 29213. In addition, bacterial cell growth on the sterilized titanium surfaces was examined by colony forming unit counting on agar plates after 24 h of incubation. Results: Colony forming units of S. aureus on titanium CP4 samples showed a higher tendency in colony counts when sterilized with UV light than with pressurized saturated steam (autoclaved). Similarly, colony forming unit counts on Ti6Al4V samples showed tendencies of higher numbers on UV light sterilized samples than on autoclaved samples. Gene expression of icaADBC, SarA and SodA between steamed samples and UV light sterilized samples showed no difference on titanium CP4 samples, whereas SigB showed higher gene expression on titanium CP4 samples when sterilized with UV light than in an autoclave. On autoclaved Ti6Al4V samples, all examined genes showed 4 to 9 times higher fold changes in gene expression than on UV light sterilized samples. Conclusions: This study indicates that steam sterilization of Ti6Al4V can increase biofilm formation of S. aureus on its surface. The significantly increased gene expression of biofilm responsible genes may indicate a modification of titanium surfaces on alloy components. This may promote biofilm formation that can lead to implant-infections in vivo.

Techniques for Decreasing Bacterial Load for Open Shoulder Surgery

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Benzoyl peroxide (BPO) 5% has been shown to reduce Cutibacterium acnes load on the skin. BPO 5% with miconazole nitrate (MN) 2% may be beneficial, whereas BPO 5% with clindamycin cream 1% to 1.2% does not seem to have additive effects when compared with BPO 5% alone. Chlorhexidine gluconate solutions reduce the total bacterial load on the skin, but do not seem to have a significant effect on C. acnes.

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ChloraPrep seems to be the best surgical skin preparation to decrease overall positive skin cultures. Preincisional hydrogen peroxide 3% application has been shown to be a cost-effective practice to inhibit growth of C. acnes. Vancomycin powder before deltopectoral interval closure has antimicrobial effects against C. acnes and is a cost-effective practice. Finally, Bactisure surgical lavage is protective against the formation of biofilms.

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IV cefazolin has been shown to be more effective for shoulder arthroplasty infection prophylaxis than antibiotic alternatives such as vancomycin. Thus, patients with a questionable history of penicillin allergy should undergo additional testing.

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For shoulder surgery infection prophylaxis, we recommend the use of BPO 5% cream for 5 days preoperatively with chlorhexidine wipes the night before and the morning of surgery. IV cefazolin should be administered perioperatively, and patients with a questionable history of penicillin allergy should be tested. Surgeons should consider preincisional application of hydrogen peroxide 3% for 5 minutes, followed by standard ChloraPrep preparation. Normal saline should be used for preclosure lavage. Finally, application of vancomycin powder deep to the deltopectoral interval closure should be considered.

The Timing of Preoperative Urinary Tract Infection Influences the Risk of Prosthetic Joint Infection Following Primary Total Hip and Knee Arthroplasty

BACKGROUND

The importance of preoperative urinary tract infection (UTI) in total hip and knee arthroplasty (THA and TKA) is controversial. The purpose of this study was to investigate the timing of preoperative UTI diagnosis and association with prosthetic joint infection (PJI) and determine if antibiotics impact this risk.

METHODS

A national database was used to analyze patients undergoing THA and TKA diagnosed with a preoperative UTI. Timing of diagnosis was categorized by 1-week intervals prior to surgery. Matched cohorts without UTI were collected, and PJI rates within 2 years of surgery were compared. Patients who received antibiotic prescriptions were identified and compared to no prescription.

RESULTS

Preoperative UTI within 1 week of TKA was associated with higher rates of PJI (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.26-1.43, P < .001). Preoperative UTI within 1 week of THA (OR 1.56, 95% CI 1.44-1.68, P < .001) and between 1-2 weeks prior to THA (OR 1.12, 95% CI 1.02-1.22, P = .022) was associated with significantly higher rates of PJI. UTI diagnosis at any other time interval did not reach statistical significance. Antibiotic prescription was not associated with lower rates of PJI.

CONCLUSION

Patients with preoperative UTI within 1 week of TKA or within 2 weeks of THA have an increased risk of postoperative PJI. Antibiotics do not appear to mitigate risk.

LEVEL OF EVIDENCE

Level III; Retrospective, database comparison.

The Efficacy of Bone Wax in Reduction of Perioperative Blood Loss in Total Hip Arthroplasty via Direct Anterior Approach: A Prospective Randomized Clinical Trial

BACKGROUND

Perioperative blood management in total hip arthroplasty (THA) has become a prime focus of research. Given the morbidity, delayed recovery, and prolonged hospital stay associated with postoperative anemia, various measures have been proposed to reduce perioperative blood loss (PBL). In this trial, we studied the efficacy of bone wax application on the distal cut surface of the femoral neck in reducing PBL during THA through the direct anterior approach.

METHODS

In a randomized controlled clinical trial, 152 patients underwent THA through the direct anterior approach with use of bone wax (n = 75) or without bone wax (control) (n = 77). The study was triple-blinded. The primary outcomes were apparent PBL (blood in sponges and suction canister) and total PBL on postoperative days (PODs) 3 and 5 (as calculated with the Good and Nadler methods). Transfusion and complications were the secondary outcomes.

RESULTS

No significant difference was found between the 2 groups in terms of age, sex, body mass index, American Society of Anesthesiologists score, etiology, preoperative hematologic/coagulation profile, anesthesia, intraoperative mean arterial pressure, or operative time. Apparent PBL, total PBL on POD3, and total PBL, in milliliters, on POD5 were significantly lower in the wax group, with median values of 200 (interquartile range [IQR]: 115 to 310) versus 370 (IQR: 195 to 513.7), 505.2 (IQR: 409.2 to 637.6) versus 747 (IQR: 494.6 to 955.4), and 536.7 (IQR: 430.9 to 689.3) versus 767.8 (IQR: 537.8 to 1,021.9) in the wax and control groups, respectively (p < 0.001). No significant differences in the rates of transfusion and complications were found.

CONCLUSIONS

Bone wax on the cut surface of femoral neck can significantly reduce PBL during THA through the direct anterior approach. Bone wax is accessible and inexpensive and can be considered a routine part of the surgical technique in THA through the direct anterior approach. This intervention has no impact on complication or transfusion rates.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

The Impact of Sterile Instrument Set Wrapping Defects on Trauma and Orthopaedic Surgery Theatre Lists

Introduction Surgical site infections (SSIs) are a universally dreaded complication of any surgical procedure. The goal of this single-center study was to examine the issue of orthopaedic instrument wrapping defects with a focus on the importance of a high level of surveillance to enable identification of these defects in order to reduce the risk of instrument contamination. We also evaluated the impact on patient care, theatre staff, hospital finances and resource utilization during a defined study period in order to stimulate critical discussion and further research into potentially eliminating this problem via change in practice and advances in technology. To the best of our knowledge, this will be the first paper that looks at this problem from the above perspective within the United Kingdom National Health Service. Methods  We conducted a prospective service evaluation project over a 30-week period from December 2021 to July 2022 across our three hospital sites within the United Kingdom National Health Service. We collated data on defects found in orthopaedic instrument wrappings as detected by visual inspection under ambient or theater lighting and the resulting surgical case cancellations. Defect types included in the study were all puncture holes, abrasions or tears visible to the naked eye irrespective of their size.  Results  A total of 601 orthopaedic sets were rejected during the study period due to defects identified in the sterile instrument wrappings. Of these, 437 were due to holes/tears in the wrapping, 129 were due to wet inner wrappings and 35 were due to insecure wrappings. This directly resulted in same-day cancellation of 13 surgical cases or 0.27% of booked cases with extra sets required for the other affected cases. These 13 cases could not proceed as they involved loan kits where no remedial action could be taken. Remedial action was required for the other 588 operation list cases affected by the sterile wrapping defects. The majority of the identified defects and resulting theatre case cancellations (61.5%) were in hip and knee arthroplasty surgery. The calculated potential financial loss due to these problems was £145,000 over the seven-month study period. This financial cost is equivalent to the best practice top-up tariff in England for treating approximately 108 hip fracture patients based on £1,335 per patient.  Conclusion  Our study identified defects in the sterile instrument wrappings affecting both the inner with or without involving the outer wrapping layer and resulting in cancellation of elective and trauma orthopaedic cases with resultant clinical and financial implications. There is a need to be more vigilant in identifying defects in drapes. Further research is warranted to improve ways of identifying defects in sterile wrappings and devise new protective mechanisms during sterilisation that can eliminate the use of sterile instrument wrappings.