High Mortality After Total Knee Arthroplasty Periprosthetic Joint Infection is Related to Preoperative Morbidity and the Disease Process but Not Treatment

Effect of endolysin XZ.700 on monocyte differentiation into osteoclasts and foreign body giant cells

Periprosthetic joint infections due to biofilm formation are a major concern in orthopaedic and dental implant surgery. Current treatment options use antibiotics, but antibiotic-resistant bacteria in the biofilm cause treatment failure. Bacteriophage-derived endolysin XZ.700 is highly promising to fight anti-microbial resistance, since it exhibits potent anti-biofilm activity and low cell toxicity. However, whether it affects immunomodulatory cell formation is currently unknown. Therefore, this study aimed to determine whether endolysin XZ.700 affects monocyte differentiation into osteoclasts and/or foreign body giant cells in vitro. Formation of multinucleated osteoclasts and foreign body giant cells from CD14+ monocytes cultured without/with endolysin XZ.700 (25, 50, 75 μg/ml) was assessed after 7, 14, and 21 days, as well as differentiation, multinucleation, and cell activation-related gene expression. Endolysin XZ.700 decreased formation of osteoclasts with 3-5 nuclei/cell, but increased those with >10 nuclei/cell after 21 days, resulting in overall inhibition of total osteoclast formation. The formation of foreign body giant cells with 3-5 nuclei/cell, but not 6-10 or >10 nuclei/cell, was significantly decreased by endolysin XZ.700 at all time points. Only 25 μg/ml endolysin XZ.700 decreased total foreign body giant cell formation after 21 days. Endolysin XZ.700 downregulated differentiation-related gene expression, but upregulated cytokine-related gene expression in monocytes differentiating into osteoclasts or foreign body giant cells. In conclusion, the biofilm-reducing agent endolysin XZ.700 decreases the formation of immunomodulatory cells, i.e. foreign body giant cells and osteoclasts, indicating that it might be highly promising as a novel antimicrobial, with short term administration as the safest mode of treatment.

Extended oral antibiotic prophylaxis and PJI-free survivorship after primary total knee arthroplasty

INTRODUCTION

Recent evidence has emerged supporting the use of extended oral antibiotic (EOA) prophylaxis after primary total knee replacement (TKA) to reduce periprosthetic joint infection (PJI) in high-risk patients. However, much of the evidence stems from single-institution series with limited sample sizes. This study aimed to explore the impact of EOA on complications and infection-free survivorship in a large cohort of patients after primary TKA.

METHODS

A large national database was used to identify patients undergoing primary TKA from 2015 to 2022. Patients receiving 7-14 days of EOA were identified. Propensity-score matching, based on patient comorbidities, was used to match patients who received EOA and to control patients who did not. Three cohorts were created: any-risk, high-risk, and standard-risk. Complications at 90-days were assessed with univariate analysis and survivorship free of PJI to 2 years was analyzed with the Kaplan-Meier method and cox regression.

RESULTS

We identified 5,701 patients who received EOA: 3,628 (64%) with high-risk comorbidities and 2,073 (36%) standard risk. There were no significant reduction in hazard of PJI at 90-days (any-risk: HR: 1.65, 95% CI: 0.90-3.04, P = 0.11; high-risk: HR: 1.37, 95% CI: 0.69-2.70, P = 0.4; standard-risk: HR: 1.51, 95% CI: 0.53-4.26, P = 0.4), 1 year (P > 0.07), or 2 years (any-risk: HR: 1.42, 95% CI: 0.98-2.05, P = 0.065; high-risk: HR: 1.14, 95% CI: 0.76-1.73, P = 0.5; standard-risk: HR: 1.51, 95% CI: 0.76-2.98, P = 0.2) with EOA administration.

DISCUSSION

EOA prophylaxis was not associated with improved PJI-free survivorship at any measured time point following primary TKA in either high-risk or standard-risk risk patients. Given the observed widespread use of EOA, our study highlights the need for further investigation to delineate what specific populations may benefit from EOA prophylaxis.

Rates of Extended Oral Antibiotic Prophylaxis After Primary Total Knee Arthroplasty Among High-Risk and Standard-Risk Patients: 2009 to 2022

BACKGROUND

Recent evidence suggests extended courses of oral antibiotics (EOA) after total hip arthroplasty and total knee arthroplasty (TKA) may reduce the risk of periprosthetic joint infection in high-risk patients. EOA rates after total hip arthroplasty have risen significantly. However, there is a lack of epidemiologic data on EOA prophylaxis following TKA. Therefore, we investigated national trends in EOA prophylaxis for primary TKA and whether these rates were reflective of changes in patient risk or prescribing practices.

METHODS

Adult patients undergoing TKA between 2009 and 2022 were identified in a national insurance claims database. An EOA was defined as a 7 to 14-day course of a first-generation cephalosporin, cefdinir, clindamycin, doxycycline, or trimethoprim-sulfamethoxazole filled between 5 days preoperatively and 3 days postoperatively. Annual EOA rates were calculated and stratified by preoperative periprosthetic joint infection risk. Multivariable logistic regression was used to explore whether rates reflected changing patient characteristics. Future rates were predicted with time-series forecasting.

RESULTS

We identified 712,212 eligible TKA cases. EOA rates rose from 0.91% in 2009 to 7.95% in 2022. Rates increased by 686% among standard-risk patients and 786% among high-risk patients. Logistic regression models using patient comorbidities could not account for changes in EOA rates. EOA rates were projected to rise to 18.3% by 2030.

CONCLUSIONS

Rates of EOA prophylaxis after TKA rose significantly from 2009 to 2022. This trend could not be explained by changing patient characteristics, suggesting widespread changes in antibiotic prescribing practices, which may be reflective of recent studies favoring EOA use. There is a need for further high-quality research examining the safety, efficacy, and role of EOA prophylaxis in the primary TKA patient population.

Periprosthetic Joint Infection Mortality After Total Hip Arthroplasty Is Comparable to 5-Year Rates of Common Cancers: A Meta-Analysis

BACKGROUND

Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) is a rare, but devastating complication with elevated morbidity and mortality. While associated with increased mortality, the reported range is broad and most often reported after 2-stage exchange arthroplasty. This study aimed to report the overall mortality after PJI following primary THA, PJI mortality at one, three, and 12 months, and mortality after common PJI treatments. We hypothesized that mortality after THA PJI would be high, increase over time, and be highest after a 2-stage exchange.

METHODS

A meta-analysis of articles from six databases, queried from inception to December 2023, was performed. Full-length articles reporting mortality following PJI after primary THA were included. Articles with oncologic, infectious, or traumatic THA indications were excluded. Articles investigating high-risk patient populations, including those who had solid organ transplants, active cancer diagnoses, and synchronous PJI, were excluded. There were two independent reviewers who reviewed articles. Mortality over time and after treatment (debridement, antibiotics, and implant retention, 1-stage, and 2-stage exchange arthroplasty) was collected. A meta-analysis of proportions with inverse-variance proportion models was constructed for overall mortality.

RESULTS

A total of 19,917 patients who had PJI after THA from 20 studies were included. Overall mortality was 11.0% (95% CI [confidence interval]: five to 18.8) at a mean follow-up of 40.3 months (range, one to 240). Pooled mortality at one, three, and 12 months was 1.1, 3.7, and 10.0%, respectively. Mortality following treatment with debridement, antibiotics, and implant retention, 1-stage, and 2-stage exchange was 7.8% (95% CI: 2.3 to 15.9), 1.6% (95% CI: 0 to 14), and 9.2% (95% CI: 5.4 to 13.9), respectively. Considerable heterogeneity was present.

CONCLUSIONS

Mortality after THA PJI is high (11.0%) within three years of arthroplasty and comparable to 5-year rates of cancers, such as breast (11%) and prostate (1%) cancers. A multidisciplinary approach, like those adopted in the treatment of cancer, is warranted to reduce the burden of this devastating complication.

Simultaneous Periprosthetic Joint Infection and Infective Endocarditis: Prevalence, Risk Factors, and Clinical Presentation

BACKGROUND

Infective endocarditis (IE) and periprosthetic joint infections (PJI) occur due to hematogenous bacterial spread, theoretically increasing the risk for concurrent infections. There is a scarcity of literature investigating this specific association. We aimed to assess the prevalence, comorbidities, and clinical presentation of patients who have simultaneous PJI and IE.

METHODS

We retrospectively identified 655 patients (321 men, 334 women; 382 total hip arthroplasty, 273 total knee arthroplasty) who developed a PJI from July 1, 2015, to December 31, 2020, at one institution. There were two groups created: patients diagnosed with PJI with IE (PJI + IE) and PJI patients who did not have IE (PJI). We analyzed clinical outcomes and comorbidities.

RESULTS

There were nine patients who had PJI with IE (1.4% of PJI patients). The C-reactive protein (170.9 versus 78, P = 0.026), Elixhauser comorbidity score (P = 0.002), length of hospital stay (10.9 versus 5.7 days, P = 0.043), and the 2-year postdischarge mortality rate (55.6 versus 9.0%, P = 0.0007) were significantly greater in the PJI + IE group. Comorbidities such as iron deficiency anemia (P = 0.03), coagulopathy (P = 0.02), complicated diabetes mellitus (P = 0.02), electrolyte disorders (P = 0.01), neurologic disease (P = 0.004), paralysis (P = 0.04), renal failure (P = 0.0001), and valvular disease (P = 0.0008) occurred more frequently in the PJI + IE group. Modified Duke's criteria were met for possible or definite IE in eight of the nine patients.

CONCLUSIONS

Concurrent PJIs and IE, although rare, are a potentially devastating disease state with increased length of hospital stay and 2-year mortality rates. This emphasizes the need for appropriate IE workups in patients who have a PJI. The modified Duke's criteria are effective in establishing a diagnosis for IE in this scenario.

Impact of Preoperative Colonoscopy on Revision Surgery Risk in Primary Total Knee Arthroplasty: A Comprehensive Population-Based Analysis

BACKGROUND

In the same age group of patients undergoing total knee arthroplasty (TKA), colonoscopies are performed commonly as part of national colorectal cancer screening pathways. Several authors have reported periprosthetic joint infection (PJI) cases after colonoscopy, suggesting transient bacteremia as a potential mechanism for hematogenous seeding. However, the effect of preoperative colonoscopy on the risk of PJI in prospective TKA patients has been minimally studied. This study aimed to investigate the relationship between preoperative colonoscopy and reoperation and revision rates in TKAs performed for osteoarthritis, using data from Ontario's health care databases.

METHODS

This retrospective cohort study identified adults undergoing TKA for osteoarthritis in Ontario, Canada, between 2003 and 2022 through linked databases (CIHI, DAD, and OHIP). Propensity-score matching, Cox proportional hazards regression analysis, Nelson-Aalen curves, and log-log-survival curves were used to evaluate the effect of preoperative colonoscopy on the risk of reoperation and revision arthroplasty due to PJI.

RESULTS

Having a colonoscopy in the 3 months before TKA was associated with a significantly increased risk of TKA-related reoperation and revision TKA (rTKA) (hazard ratio [HR]: 2.20; 95% confidence interval [CI]: 1.05 to 4.63 and HR: 2.59; 95% CI 1.16 to 5.80, respectively). In addition, patients who underwent colonoscopy in the 12 months before TKA had a 1-year rTKA rate of 1.0% compared to 0.5% of patients who did not undergo a colonoscopy in the same time period (P = 0.020). However, having a colonoscopy in the 12 months before TKA was not associated with a significantly increased risk of TKA-related reoperation (HR: 1.43; CI: 0.88 to 2.32) or rTKA (HR: 1.62; CI: 0.94 to 2.78) on multivariate logistic regression analyses.

CONCLUSIONS

This study demonstrated a statistically significant association between having a colonoscopy in the 3 months preceding TKA and increased rates of both TKA-related reoperation and rTKA.

Declining Trends in Septic Revision Following Total Knee Arthroplasty From 2010 to 2019: A National Cohort Analysis

BACKGROUND

Periprosthetic joint infections (PJIs) following total knee arthroplasty (TKA) are associated with high patient morbidity, mortality, and health care costs. Methods to reduce the burden of PJI have been shown to be efficacious on a small scale. On a national scale, it is unknown whether these methods have reduced PJI rates.

METHODS

A retrospective trend analysis was conducted using a national database. The incidence of 2-year septic revision was observed for the entire cohort in patients who had high-risk comorbidities from 2010 to 2019. A multivariable logistic regression was performed to compare the odds ratios of 2-year septic revision rates from 2011 to 2019 to the reference year of 2010. Linear regression was used to compare the change in the overall and high-risk subanalysis groups.

RESULTS

Among the 860,185 patients, 5,589 underwent septic revision within 2 years. The 2-year septic revision rate decreased from 0.75% in 2010 to 0.69% in 2019 (compounded annual growth rate = -0.94%, P = 0.049). Multivariable logistic regressions demonstrated that the odds of septic revision in 2019 were significantly lower than those in 2010 (odds ratio: 0.83, 95% CI [confidence interval]: [0.70 to 0.96], P = 0.017). In high-risk patients, the septic revision rate decreased from 1.04 to 0.80% (compounded annual growth rate = -2.80%, P = 0.004), specifically in those who had a history of psychoses, Medicaid insurance, anemia, heart failure, obesity, liver disease, tobacco use, and drug abuse (P < 0.05 for all).

CONCLUSIONS

This study demonstrated a national reduction in the 2-year septic revision rate in all TKA patients, including patients considered at high risk for PJI. This suggests that current preventative methods may be efficacious on a national scale in TKA. Further research is needed to identify more modalities to reduce the national incidence of this morbid and costly complication.

Effect of Antiseptic Irrigation Solutions on Primary Human Knee Fibroblasts Cultured in Human Platelet Lysate

BACKGROUND

Native and periprosthetic joint infections are devastating conditions fraught with patient morbidity and mortality. Aseptic and septic joints are often debrided and irrigated to decrease bacterial loads when preventing or treating infection. However, the effect of clinically used irrigation solutions on the native cellular components of the synovial joint is unknown.

METHODS

Patients consented, and their suprapatellar knee tissue was surgically excised for fibroblast isolation. Cultured knee fibroblasts were treated with normal saline for three minutes or one of the following experimental solutions: acetic acid, chlorhexidine-gluconate, Dakin's solution, hydrogen peroxide, or povidone-iodine. The exposure time for the antiseptic solutions was one and three minutes. At 24 hours after irrigation treatment, metabolic activity was measured via MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] activity assay, and deoxyribonucleic acid content was assessed by Hoechst staining as a surrogate for cell number. Phase-contrast imaging elucidated proliferation potential, progressive cell loss, and cell morphology over a 5-day period. All experiments were repeated in triplicate.

RESULTS

All experimental antiseptic irrigation solutions, regardless of application time, caused a significant reduction in metabolic activity and DNA content, indicating extensive cell death. Phase-contrast imaging showed halted cellular proliferation, progressive cell loss, and distinct changes in cellular morphology, indicating decreased cellular viability and progressive cell death.

CONCLUSIONS

All antiseptic irrigation solutions investigated in this study were severely cytotoxic to human knee fibroblasts regardless of their chemical composition. The concentrations of these solutions are commonly used in orthopaedic surgery. Although these solutions have high bactericidal properties, it may be beneficial to use them in combination at lower doses to retain their effect on bacteria while remaining benign to native synovial cells.

The Efficacy of Defensive Antibacterial Coating (DAC™) Periprosthetic Joint Infection Prevention in the Hip: A Systematic Review

Background: Periprosthetic joint infections (PJIs) are a significant issue in joint replacement surgery patients, affecting results and mortality. Recent research focuses on developing hydrogels (HG) and antimicrobial coatings to reduce pressure injuries, with DAC™ HG showing lower infection risk in hip revision surgery. However, the effectiveness of DAC™ hydrogel in PIJs is still unknown. Here, we attempt to update the literature in this field, pointing out methodological flaws and providing guidance for further research. Methods: We conducted a systematic literature review using the PRISMA guidelines. Quality assessment was performed with the Newcastle-Ottawa Scale (NOS) and the Coleman Methodology Score (CMS). Results: Among 27 records from the initial search, 3 studies resulted eligible for final evaluation. It was observed that following the three surgical procedures performed in combination with DAC™ loaded with specific antibiotics, the quality of life of the treated patients had improved. No side effects associated with DAC™ treatment were in fact observed. Conclusions: The amount and quality of scientific evidence are yet insufficient to either encourage or dissuade the use of such hydrogels in hip prosthesis, despite some intriguing first results. These challenges will be better addressed by randomized controlled trials or longitudinal prospective investigations.

Benefits and Adverse Events Associated With Extended Antibiotic Use for One Year Following Periprosthetic Joint Infection in Total Knee Arthroplasty: A Prospective Cohort Analysis

BACKGROUND

Periprosthetic joint infections (PJIs) are common and serious complications following knee and hip arthroplasty. Our previous retrospective study suggested extended antibiotics following debridement, antibiotics, and implant retention (DAIR) decreased failure rates and were not associated with increased adverse events (AEs) as compared to a standard 6 weeks of antibiotic therapy. Further, extended antibiotics beyond one year did not provide additional benefits. These observations were tested in this prospective cohort study.

METHODS

A prospective cohort of patients who underwent DAIR for total knee arthroplasty PJI and received primary antibiotics were compared to patients who received primary antibiotics combined with extended antibiotics for one year. Participants had a minimum of 2-year follow-up after the final dose of antibiotics.

RESULTS

A prospective cohort of 79 patients was followed, where 39 participants (52.7%) received primary antibiotics and 35 participants (47.3%) received both primary and extended antibiotics following DAIR. Multivariable time-to-event analyses revealed that extended antibiotic use was an independent predictor of treatment success. Infection-free survival differed significantly between the two treatment regimens, as the hazard of PJI failure was significantly lower for extended antibiotics as compared to primary antibiotics alone (adjusted hazard ratio [HR] = 0.46 [0.24 to 0.87], P = 0.017). The AE rates did not significantly differ between patients treated with primary antibiotics only versus primary combined with extended antibiotics.

CONCLUSIONS

This prospective cohort study supports our previous observations that extended antibiotics for one year were associated with lower failure rates as compared to primary antibiotics alone. Extended antibiotics after primary antibiotics were not found to be associated with increased AEs as compared to only primary antibiotics.

Hypoalbuminemia is Highly Prevalent in Patients with Periprosthetic Joint Infection and Strongly Associated with Treatment Failure

OBJECTIVE

The role of hypoalbuminemia throughout the course of chronic periprosthetic joint infection (PJI) remains poorly understood. This study aimed to determine the prevalence and risk factors of hypoalbuminemia in periprosthetic joint infection (PJI) patients and to explore the association between hypoalbuminemia and treatment outcomes.

METHODS

This retrospective cohort study included 387 PJI cases who underwent two-stage exchange arthroplasty between January 2007 and August 2020, of which 342 were reimplanted. The mean follow-up period was 7.9 years. Multivariate logistic regression analyses were performed to identify risk factors for hypoalbuminemia and to assess the effect of hypoalbuminemia at 1st- and 2nd-stage exchange on the treatment outcome. Furthermore, the impact of dynamic changes in hypoalbuminemia was investigated.

RESULTS

The prevalence of hypoalbuminemia at 1st- and 2nd-stage exchange was 22.2% and 4.7%, respectively. Patients with age ≥ 68 years and those with isolation of Staphylococcus aureus, Streptococcus, or Gram-negative bacteria exhibited a higher risk of hypoalbuminemia. Hypoalbuminemia at 1st-stage was significantly related to treatment failure (OR = 3.3), while hypoalbuminemia at 2nd-stage raised the OR to 10.0. Patients with persistent hypoalbuminemia at both the 1st- and 2nd-stage exchanges had a significantly higher rate of treatment failure than patients with hypoalbuminemia at the 1st-stage but normal albumin levels at the 2nd-stage exchange (55.6% vs 20.0%, p = 0.036).

CONCLUSION

One in five patients with chronic PJI exhibits hypoalbuminemia. Hypoalbuminemia is more likely to develop in patients of advanced age and those infected by specific highly virulent organisms. Also, our results highlight the close association between hypoalbuminemia and treatment outcomes.

Antibiotic Laden Bone Cement Does Not Reduce Acute Periprosthetic Joint Infection Risk in Primary Total Knee Arthroplasty

BACKGROUND

Periprosthetic joint infection (PJI) can be a serious complication of total knee arthroplasty (TKA). A method believed to decrease the incidence of PJI is antibiotic-laden bone cement (ALBC). Current clinical practice guidelines do not recommend ALBC in primary TKA. The purpose of this study was to compare ALBC to plain cement (PC) in preventing PJI in primary TKA.

METHODS

This retrospective analysis included 109,242 Medicare patients in the American Joint Replacement Registry who underwent a cemented primary TKA from January 2017 to March 2021, and had at least 1 year of follow-up. Patients who received ALBC were compared to patients who received PC. Demographic and case-specific variables such as age, sex, race, body mass index, Charlson Comorbidity Index, anesthesia type, and operative time were used to create propensity scores. A logistic regression was run to predict the probability of receiving ALBC. Also, a multivariate model was run on the full unstratified population, using the same covariates as were used to create the propensity model. The primary outcome was differences in PJI rates.

RESULTS

Logistic regression analysis showed that a higher preoperative diagnosis of osteoarthritis, higher Charlson Comorbidity Index, higher body mass index, women, race, and anesthesia requirements increased a patient's probability of receiving ALBC. In the full unstratified multivariate model, ALBC did not show a statistically significant difference in risk of revision for infection compared to PC.

CONCLUSIONS

The use of ALBC in primary TKA has not been shown to be more efficacious in preventing PJI within the population of Medicare patients in the United States. However, this study is limited given it is a retrospective database study that may inherently have biases and the large dataset has a potential for overpowering the findings.

What Is the True Impact of Periprosthetic Joint Infection Diagnosis on Mortality?

BACKGROUND

Mortality is a quality indicator that may affect expenditures. Revisions for periprosthetic joint infection (PJI) are, on average, more expensive and exhibit higher morbidity than aseptic revisions, although reimbursement is similar. Therefore, we sought to determine (1) impact on mortality rates of revision total hip and/or knee arthroplasty performed for PJI diagnosis (septic) versus aseptic revisions, at any point in time, and (2) mortality predictors among PJI patients.

METHODS

Retrospective chart review of 978 consecutive patients who underwent revision at a single institution (January 2015 to November 2020). All revisions were evaluated, and it was determined whether patients had a revision for PJI at any point in time or not. Two groups were compared: (1) patients with septic revision(s) (n = 350) and (2) patients who only underwent aseptic revision(s) (n = 628). Demographics and mortality status at latest follow-up (mean 3 years, range: 0 to 18 years, from first revision ever) were assessed. Mortality status was also separately assessed among patients who exclusively had hip revision(s), or solely knee revision(s), or both. Multivariate regression analysis (Cox) was used to determine whether PJI diagnosis was an independent mortality predictor. Among PJI patients, potential mortality predictors were evaluated.

RESULTS

Overall, 65 patients died (6.6%). The septic cohort had significantly more men and American Society of Anesthesiologists (ASA) class-IV patients. Mortality rates were 10.9% and 4.3% (P < .0001) for septic and aseptic revision groups, respectively. After controlling for sex, ASA, and number of revisions, PJI diagnosis was a significant mortality predictor (hazard ratio [HR]: 2.69, 95% confidence interval [CI]: 1.5 to 4.7, P = .001). Among PJI patients, age (HR: 1.05, 95% CI: 1.01 to 1.08, P = .009) and ASA (HR: 4.02, 95% CI: 1.67 to 9.67, P = .002) were independent predictors.

CONCLUSIONS

Having a revision due to PJI diagnosis was associated with 2.5 times increased mortality. Therefore, more accurate coding capturing the complexity and morbidity of revisions for PJI diagnosis is needed.

Insight into antibacterial effect of titanium nanotubular surfaces with focus on Staphylococcus aureus and Pseudomonas aeruginosa

Materials used for orthopedic implants should not only have physical properties close to those of bones, durability and biocompatibility, but should also exhibit a sufficient degree of antibacterial functionality. Due to its excellent properties, titanium is still a widely used material for production of orthopedic implants, but the unmodified material exhibits poor antibacterial activity. In this work, the physicochemical characteristics, such as chemical composition, crystallinity, wettability, roughness, and release of Ti ions of the titanium surface modified with nanotubular layers were analyzed and its antibacterial activity against two biofilm-forming bacterial strains responsible for prosthetic joint infection (Staphylococcus aureus and Pseudomonas aeruginosa) was investigated. Electrochemical anodization (anodic oxidation) was used to prepare two types of nanotubular arrays with nanotubes differing in dimensions (with diameters of 73 and 118 nm and lengths of 572 and 343 nm, respectively). These two surface types showed similar chemistry, crystallinity, and surface energy. The surface with smaller nanotube diameter (TNT-73) but larger values of roughness parameters was more effective against S. aureus. For P. aeruginosa the sample with a larger nanotube diameter (TNT-118) had better antibacterial effect with proven cell lysis. Antibacterial properties of titanium nanotubular surfaces with potential in implantology, which in our previous work demonstrated a positive effect on the behavior of human gingival fibroblasts, were investigated in terms of surface parameters. The interplay between nanotube diameter and roughness appeared critical for the bacterial fate on nanotubular surfaces. The relationship of nanotube diameter, values of roughness parameters, and other surface properties to bacterial behavior is discussed in detail. The study is believed to shed more light on how nanotubular surface parameters and their interplay affect antibacterial activity.

The treatment of bacterial biofilms cultivated on knee arthroplasty implants using the bioelectric effect

Introduction: The formation of bacterial biofilms on knee arthroplasty implants can have catastrophic consequences. The aim of this study was to analyze the effectiveness of the bioelectric effect in the elimination of bacterial biofilms on cultivated knee arthroplasty implants. Methods: A novel device was designed to deliver a bioelectric effect on the surface of knee arthroplasty implants. 4-femoral prosthetic implants were cultivated with a staphylococcus aureus inoculum for 15 days. The components were divided into four different groups: A (not treated), B (normal saline 20-minutes), C (bioelectric effect 10-minutes), D (bioelectric effect 20-minutes). The implants were sonicated, and the detached colonies were quantified as the number of colony-forming unit (CFUs). The implants were sterilised and the process was repeated in a standardized manner four more times, to obtain a total of five samples per group. Results: The number of the CFUs after a 10-minute exposure to the bioelectric effect was of 208.2 ± 240.4, compared with 6,041.6 ± 2010.7 CFUs in group A, representing a decrease of 96.5% ± 4.3 (p = 0.004). And a diminution of 91.8% ± 7.9 compared with 2,051.0 ± 1,364.0 CFUs in group B (p = 0.109). The number of bacterial colonies after a 20-minute exposure to the bioelectric effect was 70 ± 126.7 CFUs, representing a decrease of 98.9% ± 1.9 (p = 0.000) compared with group A. And a decrease of 97.8% ± 3.0 (p = 0.019) compared with group B. Conclusions: The bioelectric effect was effective in the elimination of bacterial biofilm from knee arthroplasty implants. This method could be used in the future as part of conventional surgical procedures.

Current Concepts on the Clinical and Economic Impact of Periprosthetic Joint Infections

Total joint arthroplasty (TJA) is a common procedure performed throughout the entire world in hopes of alleviating debilitating hip or knee pain. The projected number of TJAs performed in the United States alone is projected to exceed 1.9 million by 2030 and 5 million by 2040. With the significant increase in TJA performed, more periprosthetic joint infections (PJIs) are likely to be encountered. PJIs are a devastating complication of TJA. The economic and clinical burden must be understood and respected to minimize occurrence and allow optimal patient outcomes.

Biofilm and How It Relates to Prosthetic Joint Infection

Prosthetic joint infection following total joint arthroplasty is a devastating complication, resulting in increased morbidity and mortality for the patient. The formation of a biofilm on implanted hardware contributes to the difficulty in successful identification and eradication of the infection. Antibiotic therapy and surgical intervention are necessary for addressing this condition; we present a discussion on different treatment options, including those that are not yet routinely utilized in the clinical setting or are under investigation, to highlight the present and future of PJI management.

Early-Outcome Differences between Acute and Chronic Periprosthetic Joint Infections-A Retrospective Single-Center Study

Periprosthetic joint infections (PJI) are serious complications after arthroplasty, associated with high morbidity, mortality, and complex treatment processes. The outcomes of different PJI entities are largely unknown. The aim of this study was to access the early outcomes of different PJI entities. A retrospective, single-center study was conducted. The characteristics and outcomes of patients with PJI treated between 2018 and 2019 were evaluated 12 months after the completion of treatment. Primary endpoints were mortality, relapse free survival (RFS) and postoperative complications (kidney failure, sepsis, admission to ICU). A total of 115 cases were included [19.1% early (EI), 33.0% acute late (ALI), and 47.8% chronic infections (CI)]. Patients with ALI were older (p = 0.023), had higher ASA scores (p = 0.031), preoperative CRP concentrations (p = 0.011), incidence of kidney failure (p = 0.002) and sepsis (p = 0.026). They also tended towards higher in-house mortality (ALI 21.1%, 13.6% EI, 5.5% CI) and admission to ICU (ALI 50.0%, 22.7% EI, 30.9% CI). At 12 months, 15.4% of patients with EI had a relapse, compared to 38.1% in ALI and 36.4% in CI. There are differences in patient characteristics and early outcomes between PJI entities. Patients with EI have better early clinical outcomes. Patients with ALI require special attention during follow-up because they have higher occurrences of relapses and postoperative complications than patients with EI and CI.

Do All Prosthetic Joint Infection Clinical Isolates Form Aggregates in Synovial Fluid That Are Resistant to Antibiotic Agents?

Background: Chronic prosthetic joint infections (PJI) are associated with substantial morbidity because conventional antibiotic agents lack activity to bacteria in biofilms that necessitates prosthetic removal to attempt definitive cure. However, these are complex infections that go beyond biofilms and bacteria can be present in various other different states such as synovial fluid aggregates. Consequently, the purpose of this study was to assess the propensity of historically preserved PJI clinical isolates to form synovial fluid aggregates and if aggregation occurred then what is proclivity to be tolerant to high doses of antibiotic agents. Patients and Methods: Historically preserved chronic PJI clinical isolates from 2021 were evaluated for their ability to form synovial fluid aggregates under static and dynamic conditions in 24-microwell plates. Tolerance to vancomycin, gentamicin, or amphotericin was conducted by adding high concentrations of these antibiotic agents to synovial fluid microbial aggregates. Results: All clinical isolates formed synovial fluid aggregates under dynamic conditions, which with the use of scanning electron microscopy showed dense collections of bacteria with synovial fluid polymers. However, under static conditions only Staphylococcus aureus formed aggregates. Importantly, all the microbes in these aggregates were tolerant to high concentrations of antibiotic agents. Conclusions: This study demonstrates that synovial fluid aggregation occurred with all bacterial and fungal species assessed. Therefore, the findings here have important clinical ramifications given the extent that this phenomenon occurs across microbial species and the propensity for the microbes in these aggregates to be tolerant to antibiotic agents.

Assessing the Mortality Rate After Primary Total Knee Arthroplasty: An Observational Study to Inform Future Economic Analysis

BACKGROUND

Previous research has focused on the perioperative or short-term (<1 year) mortality rate of total knee arthroplasty (TKA), leaving the long-term (>1 year) mortality rate unresolved. In this study, we calculated the mortality rate up to 15 years after primary TKA.

METHODS

Data from the New Zealand Joint Registry from April 1998 to December 2021 were analyzed. Patients aged 45 years or older who underwent TKA for osteoarthritis were included. Mortality data were linked with national records from births, deaths, and marriages. To determine the expected mortality rates in the general population, age-sex-specific life tables from statistics New Zealand were used. Mortality rate was presented as standardized mortality ratios (SMRs) - a comparison of relative mortality rate between the TKA and general populations. In total, 98,156 patients with a median follow-up of 7.25 years (range, 0.00 to 23.74) were included.

RESULTS

Over the entire follow-up period, 22,938 patients (23.4%) had died. The overall SMR for the TKA cohort was 1.08 (95% confidence interval (CI): 1.06 to 1.09), suggesting that TKA patients have an 8% higher mortality rate compared to the general population. However, a reduction in short-term mortality rate was observed for TKA patients up to 5 years post TKA (SMR 5 years post TKA; 0.59 95% CI: 0.57 to 0.60]). On the contrary, a significantly increased long-term mortality rate was observed in TKA patients with greater than 11 years of follow-up, particularly in men over the age of 75 years (SMR 11 to 15 years post TKA for males ≥ 75 years; 3.13 [95% CI: 2.95 to 3.31]).

CONCLUSION

The results suggest a reduction in short-term mortality rate for patients who undergo primary TKA. However, there is an increased long-term mortality rate particularly in men over the age of 75 years. Importantly, the mortality rates observed in this study cannot be causally attributed to TKA alone.

Concomitant malnutrition and frailty are significant risk factors for poor outcome following two-stage revision for chronic periprosthetic joint infection

BACKGROUND

Two-stage revision remains the gold standard for periprosthetic joint infection (PJI) treatment. Although previous studies have examined malnutrition and frailty independently, their cumulative effects are not clear. Therefore, this study aimed to assess the individual and combined influence of malnutrition and frailty on the two-stage revision surgery.

METHODS

Patients with chronic PJI undergoing two-stage revision were retrospectively included. The definition of PJI is completely consistent with the evidence-based definition of PJI recorded by the MSIS in 2018. Preoperative serum albumin levels and 11-item modified frailty index scores were collected. Four cohorts were created: (1) Normal (N), (2) Frail (F), (3) Malnourished (M), and (4) Malnourished and frail (MF). Demographic data, comorbidities, and postoperative complications were collected and compared between the four cohorts.

RESULTS

A total of 117 consecutive patients were enrolled, 48% of patients were healthy (27.4% F, 16.2% M, and 9.4% MF). MF group showed lower scores on the physical composite scale of the 12-item short-form health survey (SF12-PCS), mental composite summary (SF12-MCS), Harris hip score (HHS), and knee society score (KSS) (P < 0.05). The incidence of reinfection in the MF group was higher than that in all other groups (MF vs. N; odds ratio [OR] 3.7, 95% confidence interval [CI] 1.37 - 8.82, P = 0.032). The incidence of complications in the MF group was higher than that in all other groups (MF vs. N; OR 4.81, 95% CI 1.58-9.26, P = 0.018). Postoperative transfusion events (OR 2.92, 95% CI 1.27-3.09, P = 0.021), readmission at 60 days after the operation (OR 4.91, 95% CI 1.82-13.80, P = 0.012) was higher in the MF patients. In addition, the extended length of stay after the operation was highest in the MF patients, with an OR of 5.78 (95% CI 2.16-12.04, P = 0.003).

CONCLUSION

The concurrent presence of concomitant malnutrition and frailty in patients with PJI is related to poor prognosis and may be a predictor of the efficacy of two-stage revision. Future research will be needed to describe the benefits of improving these risk factors for patients with PJI.

Hydrogen Peroxide, Povidone-Iodine and Chlorhexidine Fail to Eradicate Staphylococcus aureus Biofilm from Infected Implant Materials

Hydrogen peroxide, povidone-iodine, and chlorhexidine are antiseptics that are commonly added to irrigants to either prevent or treat infection. There are little clinical data available that demonstrate efficacy of adding antiseptics to irrigants in the treatment of periprosthetic joint infection after biofilm establishment. The objective of the study was to assess the bactericidal activity of the antiseptics on S. aureus planktonic and biofilm. For planktonic irrigation, S. aureus was exposed to different concentrations of antiseptics. S. aureus biofilm was developed by submerging a Kirschner wire into normalized bacteria and allowing it to grow for forty-eight hours. The Kirschner wire was then treated with irrigation solutions and plated for CFU analysis. Hydrogen peroxide, povidone-iodine, and chlorhexidine were bactericidal against planktonic bacteria with over a 3 log reduction (p < 0.0001). Unlike cefazolin, the antiseptics were not bactericidal (less than 3 log reduction) against biofilm bacteria but did have a statistical reduction in biofilm as compared to the initial time point (p < 0.0001). As compared to cefazolin treatment alone, the addition of hydrogen peroxide or povidone-iodine to cefazolin treatment only additionally reduced the biofilm burden by less than 1 log. The antiseptics demonstrated bactericidal properties with planktonic S. aureus; however, when used to irrigate S. aureus biofilms, these antiseptics were unable to decrease biofilm mass below a 3 log reduction, suggesting that S. aureus biofilm has a tolerance to antiseptics. This information should be considered when considering antibiotic tolerance in established S. aureus biofilm treatment.

A mapping review on preoperative prognostic factors and outcome measures of revision total knee arthroplasty

To map literature on prognostic factors related to outcomes of revision total knee arthroplasty (rTKA), to identify extensively studied factors and to guide future research into what domains need further exploration. We performed a systematic literature search in MEDLINE, Embase, and Web of Science. The search string included multiple synonyms of the following keywords: "revision TKA", "outcome" and "prognostic factor". We searched for studies assessing the association between at least one prognostic factor and at least one outcome measure after rTKA surgery. Data on sample size, study design, prognostic factors, outcomes, and the direction of the association was extracted and included in an evidence map. After screening of 5,660 articles, we included 166 studies reporting prognostic factors for outcomes after rTKA, with a median sample size of 319 patients (30 to 303,867). Overall, 50% of the studies reported prospectively collected data, and 61% of the studies were performed in a single centre. In some studies, multiple associations were reported; 180 different prognostic factors were reported in these studies. The three most frequently studied prognostic factors were reason for revision (213 times), sex (125 times), and BMI (117 times). Studies focusing on functional scores and patient-reported outcome measures as prognostic factor for the outcome after surgery were limited (n = 42). The studies reported 154 different outcomes. The most commonly reported outcomes after rTKA were: re-revision (155 times), readmission (88 times), and reinfection (85 times). Only five studies included costs as outcome. Outcomes and prognostic factors that are routinely registered as part of clinical practice (e.g. BMI, sex, complications) or in (inter)national registries are studied frequently. Studies on prognostic factors, such as functional and sociodemographic status, and outcomes as healthcare costs, cognitive and mental function, and psychosocial impact are scarce, while they have been shown to be important for patients with osteoarthritis.

The superiority of immune-inflammation summary index for diagnosing periprosthetic joint infection

BACKGROUND

Accurate and rapid diagnosis of periprosthetic joint infections (PJI) is particularly challenging. This study aimed to evaluate the diagnostic value of a newly developed immune-inflammation summary index (IISI) for PJI.

METHODS

Our study enrolled 171 aseptic loosening (AL) and 172 PJI cases. Based on a biological-driven approach, the IISI was formulated as C-reaction protein (CRP) × globulin × neutrophil / [lymphocyte × albumin]. Receiver operating characteristic (ROC) curves were constructed to compare the diagnostic performance of IISI with other known serum markers. Subgroup analysis was also performed to explore the robustness of IISI. Restricted cubic splines were used to evaluate the dose-response association. Additionally, changes in IISI levels prior to reimplantation were investigated.

RESULTS

The levels of all tested biomarkers were significantly different between the PJI and AL groups (all P < 0.05). ROC analysis revealed that IISI outperformed any other marker in diagnosing PJI with an area under the curve (AUC) value of 0.890. The diagnostic performance of IISI was also optimal in the hip (0.898), knee (0.903), low-grade infection (0.841), and culture-negative (0.919) subgroups. The optimal cut-off value is stabilized at around 1.6. The nonlinear association between IISI scores and PJI was also confirmed (P < 0.001). The levels of IISI before reimplantation demonstrated a significant decrease (P < 0.001) and were comparable to those of the AL group (P = 0.143).

CONCLUSION

IISI can improve the utilization of serum indicators and is superior to other well-known biomarkers in diagnosing PJI. Further studies should evaluate its specific role in different infectious and inflammatory diseases.

The Impact of Hepatitis C on Complication Rates After Revision Total Knee Arthroplasty: A Matched Cohort Study

Background

It is unclear if hepatitis C (HCV) negatively impacts outcomes of revision total knee arthroplasty (rTKA). The purpose of this study was to compare complication rates after rTKA for patients with HCV vs matched controls.

Methods

A retrospective cohort study was conducted using the PearlDiver database (PearlDiver Inc., Colorado Springs, CO). Patients with HCV who underwent rTKA (n = 1448) were matched 1:4 with controls (n = 5792) on age, sex, and several comorbidities. Rates of medical complications within 90 days and prothesis-related complications within 2 years postoperatively were compared with logistic regression for (1) patients with vs without HCV and (2) HCV patients who underwent aseptic vs septic rTKA.

Results

Relative to controls, patients with HCV exhibited significantly higher rates of medical complications (27.7% vs 20.9%; odds ratio [OR] 1.47), periprosthetic fractures (2.3% vs 1.1%; OR 2.20), all-cause repeat rTKA (11.7% vs 9.4%; OR 1.29), and repeat rTKA for prosthetic joint infection (PJI) (6.7% vs 3.6%; OR 1.92). Within the HCV cohort, HCV patients with initial septic rTKA exhibited significantly higher rates of medical complications (41.7% vs 22.7%; OR 2.39), all-cause subsequent rTKA (15.9% vs 10.2%; OR 1.67), and repeat rTKA for PJI (15.9% vs 3.4%; OR 5.39). Conversely, HCV patients with initial aseptic rTKA exhibited significantly higher rates of aseptic loosening (2.6% vs 7.4%; OR 0.33).

Conclusions

Patients with HCV exhibited significantly higher rates of medical and prosthesis-related complications after rTKA than controls. Among patients with HCV, initial septic rTKA was associated with significantly higher rates of medical complications, repeat rTKA, and PJI.

Moderate-to-Severe Malnutrition Identified by the Controlling Nutritional Status (CONUT) Score Is Significantly Associated with Treatment Failure of Periprosthetic Joint Infection

The prevalence and role of malnutrition in periprosthetic joint infection (PJI) remain unclear. This study aimed to use measurable nutritional screening tools to assess the prevalence of malnutrition in PJI patients during two-stage exchange arthroplasty and to explore the association between malnutrition and treatment failure. Our study retrospectively included 183 PJI cases who underwent 1st stage exchange arthroplasty and had available nutritional parameters, of which 167 proceeded with 2nd stage reimplantation. The recently proposed Musculoskeletal Infection Society (MSIS) Outcome Reporting Tool was used to determine clinical outcomes. The Controlling Nutritional Status (CONUT), Nutritional Risk Index (NRI), and Naples Prognostic Score (NPS) were used to identify malnutrition at 1st and 2nd stage exchange, respectively. Multivariate logistic regression analyses were performed to determine the association between malnutrition and treatment failure. Restricted cubic spline models were further used to explore the dose−response association. Additionally, risk factors for moderate-to-severe malnutrition were evaluated. Malnourished patients identified by CONUT, NPS, and NRI accounted for 48.1% (88/183), 98.9% (181/183), and 55.7% (102/183) of patients at 1st stage, and 9.0% (15/167), 41.9% (70/167), and 43.1% (72/167) at 2nd stage, indicating a significant improvement in nutritional status. We found that poorer nutritional status was a predictor of treatment failure, with CONUT performing best as a predictive tool. Moderate-to-severe malnutrition at 1st stage identified by CONUT was significantly related to treatment failure directly caused by PJI (odds ratio [OR] = 5.86), while the OR was raised to 12.15 at 2nd stage (OR = 12.15). The linear dose−response associations between them were also confirmed (P for nonlinearity at both 1st and 2nd stage > 0.05). As for total treatment failure, moderate-to-severe malnutrition as determined by CONUT was associated with a 1.96-fold and 8.99-fold elevated risk at the 1st and 2nd stages, respectively. Age ≥ 68 years (OR = 5.35) and an increased number of previous surgeries (OR = 2.04) may be risk factors for moderate-to-severe malnutrition. Overall, the prevalence of malnutrition in PJI patients is very high. Given the strong association between moderate-to-severe malnutrition identified by CONUT and PJI treatment failure, COUNT could be a promising tool to evaluate the nutritional status of PJI patients to optimize treatment outcomes.

Synovial Fluid Interleukin Levels Cannot Distinguish between Prosthetic Joint Infection and Active Rheumatoid Arthritis after Hip or Knee Arthroplasty

Inflammatory arthritis affects the level of synovial inflammatory factors, which makes it more difficult to diagnose prosthetic joint infection (PJI) patients with inflammatory arthritis. The aim of this study was to analyze synovial interleukin levels to distinguish between PJI and active rheumatoid arthritis (RA) after a hip or knee arthroplasty. From September 2019 to September 2021, we prospectively enrolled patients with joint pain after arthroplasty due to aseptic prosthesis loosening (n = 39), acute RA (n = 26), and PJI (n = 37). Synovial fluid from the affected joint is obtained and tested with a standard enzyme-linked immunosorbent assay. Receiver operating characteristic curve (ROC) was analyzed for each biomarker. Interleukin (IL)-1β, IL-6, and IL-8 showed promising value in differentiating of aseptic loosening from PJI, with areas under the curves (AUCs) of 0.9590, 0.9506, and 0.9616, respectively. Synovial IL-1β, IL-6, and IL-8 showed limited value in distinguishing between PJI and acute episodes of RA after arthroplasty, with AUCs of 0.7507, 0.7069, and 0.7034, respectively. Interleukins showed satisfactory efficacy in differentiating aseptic loosening from PJI. However, when pain after arthroplasty results from an acute episode of RA, current synovial interleukin levels do not accurately rule out the presence of PJI.