McMaster Arthroplasty Collaborative (MAC). Risk Factors for Periprosthetic Joint Infection Following Primary Total Hip Arthroplasty: A 15-Year, Population-Based Cohort Study

Impact of fixation method on femoral bone loss: a retrospective evaluation of stem loosening in first-time revision total hip arthroplasty among two hundred and fifty five patients

PURPOSE

Implant loosening represent the most common indication for stem revision in hip revision arthroplasty. This study compares femoral bone loss and the risk of initial revisions between cemented and uncemented loosened primary stems, investigating the impact of fixation method at primary implantation on femoral bone defects.

METHODS

This retrospective study reviewed 255 patients who underwent their first revision for stem loosening from 2010 to 2022, receiving either cemented or uncemented stem implants. Femoral bone loss was preoperatively measured using the Paprosky classification through radiographic evaluations. Kaplan-Meier analysis estimated the survival probability of the original stem, and the hazard ratio assessed the relative risk of revision for uncemented versus cemented stems in the first postoperative year and the following two to ten years.

RESULTS

Cemented stems showed a higher prevalence of significant bone loss (type 3b and 4 defects: 32.39% vs. 2.72%, p < .001) compared to uncemented stems, which more commonly had type 1 and 2 defects (82.07% vs. 47.89%, p < .001). In our analysis of revision cases, primary uncemented stems demonstrated a 20% lower incidence of stem loosening in the first year post-implantation compared to cemented stems (HR 0.8; 95%-CI 0.3-2.0). However, the incidence in uncemented stems increased by 20% during the subsequent years two to ten (HR 1.2; 95%-CI 0.7-1.8). Septic loosening was more common in cemented stems (28.17% vs. 10.87% in uncemented stems, p = .001). Kaplan-Meier analysis indicated a modestly longer revision-free period for cemented stems within the first ten years post-implantation (p < .022).

CONCLUSION

During first-time revision, cemented stems show significantly larger femoral bone defects than uncemented stems. Septic stem loosening occurred 17.30% more in cemented stems.

Evaluating Modern Spacer Options and Outcomes in Revision Hip Arthroplasty

BACKGROUND

A 2-stage revision continues to be the standard treatment for periprosthetic joint infection (PJI) in hip arthroplasty. The use of "functional" spacers may allow patients to return to daily living while optimizing their health for revision surgery. We aimed to evaluate the clinical outcomes of different spacer types regarding infection eradication, mechanical complications, and functional outcomes.

METHODS

Patients who have complete Musculoskeletal Infection Society criteria for diagnosis of PJI that underwent one-stage or 2-stage revision were queried in an institutional surgical database between 2002 and 2022. Out of 286 patients, 210 met our inclusion criteria and were retrospectively reviewed for demographics, laboratory values, functional and patient-reported outcomes, and subsequent revisions. The study population had 54.3% women, a mean age of 61 years old, and a mean follow-up of 3.7 ± 3.2 years. There was no difference between age, body mass index, or Charlson Comorbidity Index scores between each cohort. Spacers were categorized as nonfunctional static, nonfunctional articulating, or functional articulating. Functional spacers were defined as those that allowed full weight bearing with no restrictions. Delphi criteria were used to define revision success, and failure was defined as a recurrent or persistent infection following definitive surgery.

RESULTS

There was a significantly lower reoperation rate after a definitive implant in the functional articulating cohort (P = .003), with a trending higher infection eradication rate and a lower rate of spacer failure compared to the nonfunctional spacer cohort. At 5 years, functional articulating spacers had a 94.1% survivorship rate, nonfunctional articulating spacers had an 81.2% survival rate, and nonfunctional static spacers had a 71.4% survival rate. In the functional articulating spacer cohort, 14.6% had yet to get reimplanted, with an average follow-up time of 1.4 years.

CONCLUSIONS

Within this large cohort of similar demographics, functional articulating spacers may result in better clinical outcomes and infection eradication during 2-stage revision arthroplasty for PJI.

Risk equations for prosthetic joint infections (PJIs) in UK: a retrospective study using the Clinical Practice Research Datalink (CPRD) AURUM and GOLD databases

BACKGROUND

Prosthetic joint infections (PJIs) are a serious negative outcome of arthroplasty with incidence of about 1%. Risk of PJI could depend on local treatment policies and guidelines; no UK-specific risk scoring is currently available.

OBJECTIVE

To determine a risk quantification model for the development of PJI using electronic health records.

DESIGN

Records in Clinical Practice Research Datalink (CPRD) GOLD and AURUM of patients undergoing hip or knee arthroplasty between January 2007 and December 2014, with linkage to Hospital Episode Statistics and Office of National Statistics, were obtained. Cohorts' characteristics and risk equations through parametric models were developed and compared between the two databases. Pooled cohort risk equations were determined for the UK population and simplified through stepwise selection.

RESULTS

After applying the inclusion/exclusion criteria, 174 905 joints (1021 developed PJI) were identified in CPRD AURUM and 48 419 joints (228 developed PJI) in CPRD GOLD. Patients undergoing hip or knee arthroplasty in both databases exhibited different sociodemographic characteristics and medical/drug history. However, the quantification of the impact of such covariates (coefficients of parametric models fitted to the survival curves) on the risk of PJI between the two cohorts was not statistically significant. The log-normal model fitted to the pooled cohorts after stepwise selection had a C-statistic >0.7.

CONCLUSIONS

The risk prediction tool developed here could help prevent PJI through identifying modifiable risk factors pre-surgery and identifying the patients most likely to benefit from close monitoring/preventive actions. As derived from the UK population, such tool will help the National Health Service reduce the impact of PJI on its resources and patient lives.

Culture-negative periprosthetic joint infections: Do we have an issue?

Culture-negative periprosthetic joint infection (PJI) poses a significant challenge in clinical settings. The lack of information on causative organism(s) leads to uncertainties regarding the choice of antimicrobial treatment, which can potentially adversely influence the outcome. Recent advances in molecular-based diagnostic methods have the potential to address the difficulties associated with culture-negative PJIs. These technologies offer a solution to the existing clinical dilemma by providing identification of pathogens and guiding appropriate antimicrobial treatment. In this narrative review, we provide information regarding: 1) incidence and risk factors for culture-negative PJI; 2) the optimal antimicrobial therapy and duration of treatment for culture-negative PJI; 3) outcome comparison between culture-positive and culture-negative PJI; and 4) utilization of novel molecular diagnostic methods in culture-negative PJI, including pathogen identification, and the implementation of an antibiotic stewardship program.

Effect of a national infection control programme in Sweden on prosthetic joint infection incidence following primary total hip arthroplasty: a cohort study

OBJECTIVES

Prosthetic joint infection (PJI) is a serious complication following total hip arthroplasty (THA) entailing increased mortality, decreased quality of life and high healthcare costs.The primary aim was to investigate whether the national project: Prosthesis Related Infections Shall be Stopped (PRISS) reduced PJI incidence after primary THA; the secondary aim was to evaluate other possible benefits of PRISS, such as shorter time to diagnosis.

DESIGN

Cohort study.

SETTING

In 2009, a nationwide, multidisciplinary infection control programme was launched in Sweden, PRISS, which aimed to reduce the PJI burden by 50%.

PARTICIPANTS

We obtained data on patients undergoing primary THA from the Swedish Arthroplasty Registry 2012-2014, (n=45 723 patients, 49 946 THAs). Using personal identity numbers, this cohort was matched with the Swedish Prescribed Drug Registry. Medical records of patients with ≥4 weeks' antibiotic consumption were reviewed to verify PJI diagnosis (n=2240, 2569 THAs).

RESULTS

The cumulative incidence of PJI following the PRISS Project was 1.2% (95% CI 1.1% to 1.3%) as compared with 0.9% (95% CI 0.8% to 1.0%) before. Cox regression models for the PJI incidence post-PRISS indicates there was no statistical significance difference versus pre-PRISS (HR 1.1 (95% CI 0.9 to 1.3)). There was similar time to PJI diagnosis after the PRISS Project 24 vs 23 days (p=0.5).

CONCLUSIONS

Despite the comprehensive nationwide PRISS Project, Swedish PJI incidence was higher after the project and time to diagnosis remained unchanged. Factors contributing to PJI, such as increasing obesity, higher American Society of Anesthesiology class and more fractures as indications, explain the PJI increase among primary THA patients.

Dyslipidaemia is associated with Cutibacterium acnes hip and knee prosthetic joint infection

PURPOSE

Optimization of medical factors including diabetes and obesity is a cornerstone in the prevention of prosthetic joint infection (PJI). Dyslipidaemia is another component of metabolic syndrome which has not been thoroughly investigated as an individual, modifiable risk factor. This study examined the association of dyslipidaemia with PJI caused by the lipophilic microbe Cutibacterium acnes (C. acnes).

METHODS

A retrospective chart review examined patients with positive C. acnes culture at hip or knee arthroplasty explantation. A control group with methicillin-sensitive Staphylococcus aureus (MSSA) positive cultures at explantation was matched for age, sex, and surgical site, as well as a second control group with no infection. A total of 80 patients were included, 16 with C. acnes, 32 with MSSA, and 32 with no infection. All patients had a lipid panel performed within one year of surgery. Lipid values and categories were compared using multinomial logistic regressions.

RESULTS

High or borderline triglycerides (TG) (relative risk ratio (RRR) = 0.13; P = 0.013) and low high-density lipoprotein (HDL) (RRR = 0.13; P = 0.025) were significantly associated with C. acnes PJI compared to MSSA-PJI. High or borderline TG (RRR = 0.21; P = 0.041) and low HDL (RRR = 0.17; P = 0.043) were also associated with a greater probability of C. acnes infection compared to no infection.

CONCLUSIONS

The presence of elevated TG and low HDL were both associated at a statistically significant level with C. acnes hip or knee PJI compared to controls with either MSSA PJI or no infection. This may represent a specific risk factor for C. acnes PJI that is modifiable.

What to Know about Antimicrobial Coatings in Arthroplasty: A Narrative Review

Periprosthetic joint infections (PJIs) are one of the most worrying complications orthopedic surgeons could face; thus, methods to prevent them are evolving. Apart from systemic antibiotics, targeted strategies such as local antimicrobial coatings applied to prosthetics have been introduced. This narrative review aims to provide an overview of the main antimicrobial coatings available in arthroplasty orthopedic surgery practice. The search was performed on the PubMed, Web of Science, SCOPUS, and EMBASE databases, focusing on antimicrobial-coated devices used in clinical practice in the arthroplasty world. While silver technology has been widely adopted in the prosthetic oncological field with favorable outcomes, recently, silver associated with hydroxyapatite for cementless fixation, antibiotic-loaded hydrogel coatings, and iodine coatings have all been employed with promising protective results against PJIs. However, challenges persist, with each material having strengths and weaknesses under investigation. Therefore, this narrative review emphasizes that further clinical studies are needed to understand whether antimicrobial coatings can truly revolutionize the field of PJIs.

Obesity and Primary Total Hip Arthroplasty: The Absolute versus Relative Risk of Periprosthetic Joint Infection at 15 Years

BACKGROUND

To make an informed decision about total hip arthroplasty (THA), surgeons and patients need to understand the absolute and relative risks of periprosthetic joint infection (PJI). We sought to evaluate the long-term risk of PJI following primary THA stratified by body mass index (BMI) and PJI-related risk factors.

METHODS

We identified 21,550 primary THAs performed from 2000 to 2021 at a single institution. Patients were stratified as having 0, 1, or ≥ 2 PJI risk factors (diabetes, chronic kidney disease, nonprimary osteoarthritis, immunosuppression, or active smoking) and into BMI categories. The 15-year cumulative risk of PJI was evaluated by BMI and PJI risk factors.

RESULTS

For the entire cohort, the 15-year absolute risk of PJI was 2%. For patients who did not have PJI risk factors, the absolute risk of PJI at 15 years was 1% in normal weight, 2% in class III obesity, and 4% in class IV obesity. Patients who had class III and IV obesity had a 3-times and 9-times higher relative risk of PJI, respectively (P = .03, P < .001). Among patients who had ≥ 2 PJI risk factors, the absolute risk of PJI at 15 years was 2% in normal weight, 4% in class III obesity, and 18% in class IV obesity.

CONCLUSIONS

Healthy patients who had class III and IV obesity had a 3-times and 9-times increased risk of PJI at 15 years relative to normal weight patients. However, the absolute risk of PJI at 15 years was 2 and 4%, respectively. Given emerging data questioning whether BMI modification decreases PJI risk, surgeons and patients must consider both a 3-times to 9-times increased relative risk of PJI and a 2 to 4% absolute risk of PJI at 15 years for healthy patients who had a BMI ≥ 40.

LEVEL OF EVIDENCE

IV.

Decreased Patellar Fractures and Subluxation with Patellar Component Replacement at Stage-One Spacer

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication of total knee arthroplasty (TKA) and is often treated with two-stage revision. We retrospectively assessed whether replacing the patellar component with articulating stage-one spacers was associated with improved outcomes compared to spacers without patellar component replacement.

METHODS

A total of 139 patients from a single academic institution were identified who underwent an articulating stage-one revision TKA and had at least 1-year follow-up. Of the 139 patients, 91 underwent patellar component removal without replacement, while 48 had a patellar component replaced at stage-one revision. Patellar fracture and reinfection at any point after stage-one were recorded. Knee range of motion (ROM), patellar thickness, lateral tilt, and lateral displacement were measured at six-weeks post stage-one. Chi-squared, Fisher's exact, and t-tests were utilized for comparisons. There were no significant demographic differences between groups.

RESULTS

Patellar component replacement at stage-one revision was associated with fewer patellar fractures (2.1 versus 12.1%, P = 0.046), less lateral patellar displacement (1.7 versus 16.0 mm, P < 0.01), and improved pre to postoperative knee ROM six weeks after stage-one (+5.9 versus -11.4°, P = 0.03). There was no difference in reinfections after stage-two revision for the replaced or unreplaced patellar groups (15.4 versus 15%, P = 1.000). While the mean time between stage-one and stage-two was not different (5.2 versus 4.5 months, P = 0.50), at one-year follow-up, significantly more patients in the patellar component replacement group were satisfied and refused stage-two revision (45.8% versus 3.3%, P < 0.001).

CONCLUSION

Replacing the patellar component at stage-one revision is associated with a decreased rate of patellar fracture and lateral patellar subluxation, improved ROM, and possible increased patient satisfaction, as reflected by nearly half of these patients electing to keep their spacer. There was no difference in reinfection rates between the cohorts.

Neutrophil Function Conversion Driven by Immune Switchpoint Regulator against Diabetes-Related Biofilm Infections

Reinforced biofilm structures and dysfunctional neutrophils induced by excessive oxidative stress contribute to the refractoriness of diabetes-related biofilm infections (DRBIs). Herein, in contrast to traditional antibacterial therapies, an immune switchpoint-driven neutrophil immune function conversion strategy based on a deoxyribonuclease I loaded vanadium carbide MXene (DNase-I@V2 C) nanoregulator is proposed to treat DRBIs via biofilm lysis and redirecting neutrophil functions from NETosis to phagocytosis in diabetes. Owing to its intrinsic superoxide dismutase/catalase-like activities, DNase-I@V2 C effectively scavenges reactive oxygen species (ROS) in a high oxidative stress microenvironment to maintain the biological activity of DNase-I. By increasing the depth of biofilm penetration of DNase-I, DNase-I@V2 C thoroughly degrades extracellular DNA and neutrophil extracellular traps (NETs) in extracellular polymeric substances, thus breaking the physical barrier of biofilms. More importantly, as an immune switchpoint regulator, DNase-I@V2 C can skew neutrophil functions from NETosis toward phagocytosis by intercepting ROS-NE/MPO-PAD4 and activating ROS-PI3K-AKT-mTOR pathways in diabetic microenvironment, thereby eliminating biofilm infections. Biofilm lysis and synergistic neutrophil function conversion exert favorable therapeutic effects on biofilm infections in vitro and in vivo. This study serves as a proof-of-principle demonstration of effectively achieving DRBIs with high therapeutic efficacy by regulating immune switchpoint to reverse neutrophil functions.

Cobalt and Chromium Ions Impair Macrophage Response to Staphylococcus aureus Infection

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co2+ and Cr3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co2+-exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co2+ and Cr3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.

Neutrophil-Lymphocyte Ratio and Lymphocyte-Monocyte Ratio correlate with Chronic Prosthetic Joint Infection but are not useful markers for diagnosis

PURPOSE

To investigate reported correlations between Neutrophil-to-Lymphocyte (NLR) and Lymphocyte-to-Monocyte (LMR) ratios and their value in diagnosis of chronic prosthetic joint infection (PJI) in a large cohort of patients from a single specialist hospital.

METHODS

Diagnostic aspirations of 362 patients under investigation for PJI were identified. Of the included patients 185 patients received a final diagnosis of PJI and 177 were classed as aseptic. Established criteria (ICM 2018) were employed to define PJI. Included in the analysis are differential white cell counts, C-Reactive Protein (CRP), Synovial Leukocyte Count, Synovial Alpha-defensin ELISA and Synovial Leukocyte esterase activity. Receiver-operator characteristic (ROC) curves were calculated for each of the available diagnostic tests together with the corresponding area under the curve values (AUC). Youden's index was utilized to identify the optimal diagnostic threshold point for the NLR and LMR. Other diagnostic tests were evaluated as per the threshold values previously defined in the literature and specified in the ICM criteria.

RESULTS

Using Youden's Index to identify the optimal NLR cut-off within our cohort we established a value of 2.93. This yielded a sensitivity of 0.60 and specificity of 0.64. The area under the curve (AUC) of a receiving operator characteristics (ROC) curve was 0.625. Regarding the LMR the results demonstrate similar findings; a positive correlation with a diagnosis of infection but poor sensitivity and specificity. The AUC for LMR was 0.633 and was not superior to NLR (P = 0.753).

CONCLUSIONS

There is a significant correlation between higher Neutrophil-Lymphocyte and Lymphocyte-Monocyte ratios, and a diagnosis of PJI. The sensitivity and specificity of this calculation is poor and the does not add value to the diagnostic algorithm for PJI.

LEVEL OF EVIDENCE

Level III Retrospective Cohort analysis.

Risk Factors and Management of Prosthetic Joint Infections in Megaprostheses-A Review of the Literature

Prosthetic joint infection (PJI) is the most common mode of failure of megaprostheses, yet the literature on the topic is scarce, and studies report conflicting data regarding the optimal treatment strategy. Patients with megaprostheses PJI are often immunosuppressed, and surgeons must balance the trade-off between treatment efficacy and morbidity associated with the surgery aiming for infection eradication. Our review on megaprostheses PJI focuses on two axes: (1) risk factors and preventative strategies; and (2) surgical strategies to manage this condition. Risk factors were classified as either unmodifiable or modifiable. Attempts to decrease the risk of PJI should target the latter group. Strategies to prevent PJI include the use of silver-coated implants, timely discontinuation of perioperative antibiotic prophylaxis, and adequate soft tissue coverage to diminish the amount of dead space. Regarding surgical treatment, main strategies include debridement, antibiotics, implant retention (DAIR), DAIR with modular component exchange, stem retention (DAIR plus), one-stage, and two-stage revision. Two-stage revision is the "gold standard" for PJI in conventional implants; however, its success hinges on adequate soft tissue coverage and willingness of patients to tolerate a spacer for a minimum of 6 weeks. DAIR plus and one-stage revisions may be appropriate for a select group of patients who cannot endure the morbidity of two surgeries. Moreover, whenever DAIR is considered, exchange of the modular components should be performed (DAIR plus). Due to the low volume of megaprostheses implanted, studies assessing PJI should be conducted in a multi-institutional fashion. This would allow for more meaningful comparison of groups, with sufficient statistical power. Level of evidence: IV.

The utilization of US-based large data in arthroplasty research: Bibiliometric analysis of trends and hotspots

Background

The accessibility of digital information has expanded orthopaedic surgery with expanded role of Big Databases. The increasing interest have led to creation of large databases with increasing utilization in retrospective studies. The aim of this study is to identify Big Database research and predict future hotspots.

Methods

Big Database publications between 1982 and 2022 were identified from the Web of Science Core Collection of Clarivate Analytics. Bibliometric indicators were obtained and imported for further analysis with VOSviewer and Bibliometrix to identify previous and ongoing trends within this field.

Results

Bibliometric sourcing identified 811 total articles that was associated with major databases. Twenty-eight countries published manuscript in the field with the United States as the largest contributor. The most relevant institutions were Cleveland Clinic and Harvard University. Mont MA was the most productive and influential author. Co-occurrence visualization and thematic map identified niche and major themes within the literature.

Conclusions

Large Database research continue to show an increasing trend since 2011 with contributions globally. United States institutions and authors are the leading contributors in big database research. This study identifies previous, current, and developing trends within this field for future hotspot development.

Diagnosing periprosthetic joint infection

Aims

The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI.

Methods

A retrospective review was conducted to assess the accuracy of different marker combinations for diagnosing chronic PJI. A total of 573 patients were included in the study, of which 124 knees and 122 hips had a diagnosis of chronic PJI. Complete blood count and synovial fluid analysis were collected. Recently published blood cell ratio cut-off points were applied to receiver operating characteristic curves for all markers and combinations. The area under the curve (AUC), sensitivity, specificity, and positive and negative predictive values were calculated.

Results

The results of the analysis showed that the combination of ESR, CRP, synovial white blood cell count (Syn. WBC), and polymorphonuclear neutrophil percentage (PMN%) with PVR had the highest AUC of 0.99 for knees, with sensitivity of 97.73% and specificity of 100%. Similarly, for hips, this combination had an AUC of 0.98, sensitivity of 96.15%, and specificity of 100.00%.

Conclusion

This study supports the use of PVR calculated from readily available complete blood counts, combined with established markers, to improve the accuracy in diagnosing chronic PJI in both total hip and knee arthroplasties.

Periprosthetic Joint Infection: Current Clinical Challenges

Over the last several decades, periprosthetic joint infection has been increasing in incidence and is occurring in more complex patients. While there have been advances in both surgical and medical treatment strategies, there remain important gaps in our understanding. Here, we share our current approaches to the diagnosis and management of periprosthetic joint infection, focusing on frequent clinical challenges and collaborative interdisciplinary care.

Routine use of antibiotic-laden bone cement in total knee arthroplasty is a cost-effective practice in the single-payer healthcare system

PURPOSE

The purpose of this study was to determine the cost-effectiveness of antibiotic-laden bone cement (ALBC) in primary total knee arthroplasty (TKA) from the perspective of a single-payer healthcare system.

METHODS

A cost-utility analysis (CUA) was performed over a 2-year time horizon comparing primary TKA with either ALBC or regular bone cement (RBC) from the perspective of the single-payer Canadian healthcare system. All costs were in 2020 Canadian dollars. Health utilities were in the form of quality-adjusted life years (QALYs). Model inputs for cost, utilities and probabilities were derived from the literature as well as regional and national databases. One-way deterministic sensitivity analysis was performed.

RESULTS

Primary TKA with ALBC was found to be more cost-effective compared to primary TKA with RBC with an incremental cost-effectiveness ratio (ICER) of -3,637.79 CAD/QALY. The use of routine ALBC remained cost-effective even with cost increases of up to 50% per bag of ALBC. TKA with ALBC was no longer cost-effective if the rate of PJI following this practice increased 52%, or the rate of PJI following the use of RBC decreased 27%.

CONCLUSIONS

The routine use of ALBC in TKA is a cost-effective practice in the single-payer Canadian healthcare system. This remains to be the case even with a 50% increase in the cost of ALBC. Policy makers and hospital administrators of single-payer healthcare systems can leverage this model to inform their local funding policies. Future prospective reviews and randomized controlled trials from the perspective of various healthcare models can further shed light on this issue.

LEVEL OF EVIDENCE

III.

Incidence of periprosthetic joint infection after primary total hip arthroplasty is underestimated: a synthesis of meta-analysis and bibliometric analysis

The American Musculoskeletal Society updated the diagnostic criteria for periprosthetic joint infection (PJI) in 2011 and 2018. However, the overall incidence of PJI since the introduction of these new standards has not been assessed. In order to fill this knowledge gap, a single-group meta-analysis was conducted using articles obtained from several databases, focusing on the incidence of PJI after primary total hip arthroplasty (THA). Our study revealed a significant difference in the incidence of PJI reported by different national or regional databases. Moreover, most cases of PJI were found to be underestimated. This highlights the crucial need for standardized diagnostic criteria and monitoring methods to accurately identify and track cases of PJI. Furthermore, a bibliometric analysis was conducted to provide a comprehensive overview of the current state of research on PJI after THA. This analysis explored the most productive countries, organizations, journals, and individuals in this research area. Additionally, it identified the research trends and hotspots of the last decade, highlighting the advancements and areas of focus in this field. By conducting these analyses, the study aims to contribute to the understanding of PJI after THA and provide valuable insights for clinicians, researchers, and policymakers involved in the management of this condition.

Managing early complications in total hip arthroplasty: the safety of immediate revision

PURPOSE

Immediate revision refers to a reoperation that involves resetting, draping, and exchanging the implant, after wound closure in total hip arthroplasty. The purpose of this study is to investigate the impact of immediate revision after total hip arthroplasty on subsequent infection and complication rates.

METHODS

A total of 14,076 primary total hip arthroplasties performed between 2010 and 2020 were identified in our institutional database, of which 42 underwent immediate revision. Infection rates were determined 2 years after the index arthroplasty. The cause and type of revision, duration of primary and revision surgeries, National Nosocomial Infections Surveillance score, implant type, changes in implants, complications, and preoperative and intraoperative antibiotic prophylaxis were all determined.

RESULTS

No infections were observed within 2 years after the index arthroplasty. Leg length discrepancy (88%, n = 37) and dislocation (7.1%, n = 3) were the main causes of immediate revision. In most cases of discrepancy, the limb was clinically and radiologically longer before the immediate revision. The mean operative time was 48 ± 14 min for the primary procedure and 23.6 ± 9 min for the revision. The time between the first incision and last skin closure ranged from 1 to 3 h. None of the patients were extubated between the two procedures. Two patients had a National Nosocomial Infections Surveillance score of 2, 13 had a score of 1, and 27 had a score of 0.

CONCLUSION

Immediate revision is safe for correcting clinical and radiological abnormalities, and may not be associated with increased complication or infection rates.

STUDY DESIGN

Retrospective cohort study; level of evidence, 3.

Finite element analysis of the mechanical strength of a new hip Spacer

BACKGROUND AND OBJECTIVE

At present, the influence of the internal metallic endoskeleton of Spacer on the biomechanical strength of Spacer remains unclear. The aim of this study was to analyze the mechanical stability of a novel Spacer applying a annular skeleton that mimics the structure of trabecular bone using finite element methods.

METHEDS

The femur models of three healthy individuals and skeletonless Spacer, K-Spacer, and AD-Spacer were assembled to create 15 3D models. Finite element analysis was performed in an Ansys Bench2022R1. Biomechanical parameters such as stress and strain of the Spacer, internal skeleton and femur were evaluated under three loads, which were applied with the maximum force borne by the hip joint (2100 N), standing on one leg (700 N), and standing on two legs (350 N). The mechanical properties of the new hip Spacer were evaluated.

RESULT

The stresses on the medial and lateral surfaces of the AD-Spacer and K-Spacer were smaller than the stresses in the state without skeletal support. The maximum stresses on the medial and lateral surfaces of the AD-Spacer were smaller than those of the inserted K-Spacer, and the difference gradually increased with the increase of force intensity. When the skeleton diameter was increased from 3 to 4 mm, the stresses in the medial and lateral sides of the AD-Spacer and K-Spacer necks decreased. The stress of both skeletons was concentrated at the neck, but the stress of the annular skeleton was evenly distributed on the medial and lateral sides of the skeleton. The mean stress in the proximal femur was higher in femurs with K-Spacer than in femurs with AD-Spacer.

CONCLUSIONS

AD-Spacer has lower stress and higher load-bearing capacity than K-Spacer, and the advantages of AD-Spacer are more obvious under the maximum load state of hip joint.

Survivorship and Etiologies of Failure in Single-stage Revision Arthroplasty for Periprosthetic Joint Infection: A Meta-analysis

INTRODUCTION

Single-stage revision arthroplasty for periprosthetic joint infection (PJI) may yield comparable infection-free survivorship with two-stage revision arthroplasty. It is unclear if the most common mode of failure of single-stage revision arthroplasty is infection or aseptic loosening. In this meta-analysis, we sought to (1) determine survivorship and (2) compare rates of different etiologies of failure of single-stage revision total hip arthroplasty (THA) and total knee arthroplasty (TKA).

METHODS

Preferred Reporting Items for Systematic Review and Meta-analyses guidelines search was done using search terms for "single stage revision," "exchange arthroplasty," "periprosthetic infection," "PJI," and "single stage." Patient demographics such as age, body mass index, and mean follow-up time were recorded. Overall survivorship and rates of revision surgery were aggregated using a random-effects model. Comparison of septic and aseptic loosening rates was done by risk difference and associated 95% confidence interval (CI) calculation.

RESULTS

Twenty-four studies were identified with 2,062 and 147 single-stage revision THA and TKA procedures performed between 1984 and 2019, respectively. The weighted mean follow-up and age were 69.8 months and 66.3 years, respectively, with 55% men overall. The all-cause revision surgery rate was 11.1% and 11.8% for THA and TKA, respectively. The revision surgery rate secondary to infection and aseptic loosening and associated 95% CI for the risk difference for THA and TKA was 5.5% and 3.3% (-1.7% to 5.0%), and 3% and 8.8% (-11.4% to 2.3%), respectively. Revision surgeries due to instability and fracture combined and mortality rate were both less than 3%.

DISCUSSION

Single-stage revision THA and TKA for PJI demonstrated overall high rates of survivorship, low mortality, and revision surgeries secondary to infection and aseptic loosening to be equivalent. Aseptic loosening after single-stage revision TKA might be higher than in primary TKA. As implant survivorship from infection improves in PJI, surgeons should be aware of aseptic loosening as an equally common mode of failure.

What is the Safe Distance Between Hip and Knee Implants to Reduce the Risk of Ipsilateral Metachronous Periprosthetic Joint Infection?

BACKGROUND

Periprosthetic joint infection (PJI), the most common cause of revision after TKA and THA, is a devastating complication for patients that is difficult to diagnose and treat. An increase in the number of patients with multiple joint arthroplasties in the same extremity will result in an increased risk of ipsilateral PJI. However, there is no definition of risk factors, micro-organism patterns, and safe distance between knee and hip implants for this patient group.

QUESTIONS/PURPOSES

(1) In patients with hip and knee arthroplasties on the same side who experience a PJI of one implant, are there factors associated with the development of subsequent PJI of the other implant? (2) In this patient group, how often is the same organism responsible for both PJIs? (3) Is a shorter distance from an infected prosthetic joint to an ipsilateral prosthetic joint associated with greater odds of subsequent infection of the second joint?

METHODS

We designed a retrospective study of a longitudinally maintained institutional database that identified all one-stage and two-stage procedures performed for chronic PJI of the hip and knee at our tertiary referral arthroplasty center between January 2010 and December 2018 (n = 2352). Of these patients, 6.8% (161 of 2352) had an ipsilateral hip or knee implant in situ at the time of receiving surgical treatment for a PJI of the hip or knee. The following criteria led to the exclusion of 39% (63 of 161) of these patients: 4.3% (seven of 161) for incomplete documentation, 30% (48 of 161) for unavailability of full-leg radiographs, and 5% (eight of 161) for synchronous infection. With regard to the latter, per internal protocol, all artificial joints were aspirated before septic surgery, allowing us to differentiate between synchronous and metachronous infection. The remaining 98 patients were included in the final analysis. Twenty patients experienced ipsilateral metachronous PJI during the study period (Group 1) and 78 patients did not experience a same-side PJI (Group 2). We analyzed the microbiological characteristics of bacteria during the first PJI and ipsilateral metachronous PJI. Calibrated, full-length plain radiographs were evaluated. Receiver operating characteristic curves were analyzed to determine the optimal cutoff for the stem-to-stem and empty native bone distance. The mean time between the initial PJI and ipsilateral metachronous PJI was 8 ± 14 months. Patients were followed for a minimum of 24 months for any complications.

RESULTS

The risk of ipsilateral metachronous PJI in the other joint secondary to a joint implant in which PJI develops can increase up to 20% in the first 2 years after the procedure. There was no difference between the two groups in age, sex, initial joint replacement (knee or hip), and BMI. However, patients in the ipsilateral metachronous PJI group were shorter and had a lower weight (1.6 ± 0.1 m and 76 ± 16 kg). An analysis of the microbiological characteristics of bacteria at the time of the initial PJI showed no differences in the proportions of difficult-to-treat, high virulence, and polymicrobial infections between the two groups (20% [20 of 98] versus 80% [78 of 98]). Our findings showed that the ipsilateral metachronous PJI group had a shorter stem-to-stem distance, shorter empty native bone distance, and a higher risk of cement restrictor failure (p < 0.01) than the 78 patients who did not experience ipsilateral metachronous PJI during the study period. An analysis of the receiver operating characteristic curve showed a cutoff of 7 cm for the empty native bone distance (p < 0.01), with a sensitivity of 72% and a specificity of 75%.

CONCLUSION

The risk of ipsilateral metachronous PJI in patients with multiple joint arthroplasties is associated with shorter stature and stem-to-stem distance. Appropriate position of the cement restrictor and native bone distance are important in reducing the risk of ipsilateral metachronous PJI in these patients. Future studies might evaluate the risk of ipsilateral metachronous PJI owing to bone adjacency.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Trends in Revision Hip Arthroplasty for Prosthetic Joint Infection: A Single-Center Study of 423 Hips at a High-Volume Center Between 2008 and 2021

BACKGROUND

Prosthetic joint infection (PJI) is one of the most devastating complications after total hip arthroplasty (THA), and comorbidities increase the risk. We examined whether there was a temporal change in the demographics, especially regarding comorbidities, of patients who have PJIs and were treated over a 13-year study period at a high-volume academic joint arthroplasty center. In addition, the surgical methods used and the microbiology of the PJIs were assessed.

METHODS

Revisions (n = 423, 418 patients) due to PJI of the hip performed at our institution between 2008 and September 2021 were identified. All included PJIs fulfilled the 2013 International Consensus Meeting diagnostic criteria. The surgeries were categorized into one of the following categories: debridement, antibiotics, and implant retention, 1-stage revision, and 2-stage revision. Infections were classified as early, acute hematogenous, and chronic infections.

RESULTS

There was no change in the median age of the patients, but the proportion of ASA-class 4 patients increased from 10.5% to 20%. The incidence of early infections increased from 0.11 per 100 primary THAs in 2008 to 1.09 in 2021. The incidence of 1-stage revisions increased the most, rising from 0.10 per 100 primary THAs in 2010 to 0.91 per 100 primary THAs in 2021. Furthermore, the proportion of infections caused by Staphylococcus aureus increased from 26.3% in 2008 to 2009 to 40% in 2020 to 2021.

CONCLUSION

The comorbidity burden of PJI patients increased during the study period. This increase may present a treatment challenge, as comorbidities are known to have a negative effect on PJI treatment outcomes.

Is the routine use of local antibiotics in the management of periprosthetic joint infections justified?

Periprosthetic joint infection (PJI) following total hip and total knee arthroplasty continues to be a leading cause of re-operation and revision arthroplasty. Not only is the treatment of PJI notoriously challenging, but success rates are variable. Regardless of the surgical strategy used, successful management of PJI requires a comprehensive surgical debridement focused at eradicating the underlying biofilm followed by appropriate antimicrobial therapy. Although systemic antimicrobial delivery continues to be a cornerstone in the treatment of PJI, many surgeons have started using local antibiotics to deliver higher concentrations of antibiotics directly into the vulnerable joint and adjacent soft tissues, which often have compromised vascularity. Available evidence on the use of topical powder, bone cement, and calcium sulphate carriers for local delivery of antibiotics during the initial treatment of PJI is limited to studies that are extremely heterogeneous. There is currently no level-1 evidence to support routinely using these products. Further, appropriately powered, prospective studies are needed to quantify the safety and efficacy of antibiotic-located calcium-sulphate carriers to justify their added costs. These products should not encourage surgeons to deviate from best practice guidelines, such as those recommended during the International Consensus Meeting on Musculoskeletal Infections.

A retrospective study of risk factors, causative micro-organisms and healthcare resources consumption associated with prosthetic joint infections (PJI) using the Clinical Practice Research Datalink (CPRD) Aurum database

BACKGROUND

Prosthetic joint infection (PJI) is a serious complication after joint replacement surgery and it is associated with risk of mortality and morbidity along with high direct costs.

METHODS

The Clinical Practice Research Datalink (CPRD) data were utilized to quantify PJI incidence after hip or knee replacement up to 5 years after implant and a variety of risk factors related to patient characteristics, medical and treatment history along with characteristics of the original surgery were analyzed through Cox proportional hazard.

RESULTS

221,826 patients (individual joints 283,789) met all the inclusion and exclusion criteria of the study; during the study follow-up period (5 years), 707 and 695 PJIs were diagnosed in hip and knee, respectively. Patients undergoing joint replacement surgery during an unscheduled hospitalization had greater risk of PJI than patients whose surgery was elective; similarly, the risk of developing PJI after a secondary hip or knee replacement was about 4 times greater than after primary arthroplasty when adjusted for all other variables considered. A previous diagnosis of PJI, even in a different joint, increased the risk of a further PJI. Distribution of average LoS per each hospitalization caused by PJI exhibited a right skewed profile with median duration [IQR] duration of 16 days [8-32] and 13 days [7.25-32] for hip and knee, respectively. PJIs causative micro-organisms were dependent on the time between initial surgery and infection offset; early PJI were more likely to be multispecies than later (years after surgery); the identification of Gram- pathogens decreased with increasing post-surgery follow-up.

CONCLUSIONS

This study offers a contemporary assessment of the budgetary and capacity (number and duration of hospitalizations along with the number of Accident and Emergency (A&E) visits) posed by PJIs in UK for the national healthcare system (NHS). The results to provide risk management and planning tools to health providers and policy makers in order to fully assess technologies aimed at controlling and preventing PJI. The findings add to the existing evidence-based knowledge surrounding the epidemiology and burden of PJI by quantifying patterns of PJI in patients with a relatively broad set of prevalent comorbidities.

Epidemiology and outcomes of bone and joint infections in solid organ transplant recipients

Bone and joint infection (BJI) epidemiology and outcomes in solid organ transplant recipients (SOTr) remain largely unknown. We aim to describe BJI in a multi-center cohort of SOTr (Swiss Transplant Cohort Study). All consecutive SOTr with BJI (01.05.2008-31.12.2019) were included. A nested case-control study to identify risk factors for BJI was performed. Among 4482 patients, 61 SOTr with 82 BJI were included, at an incidence of 1.4% (95% CI 1.1-1.7), higher in heart and kidney-pancreas SOTr (Gray's test p < .01). Although BJI were predominately late events (median of 18.5 months post-SOT), most infections occurred during the first year post-transplant in thoracic SOTr. Diabetic foot osteomyelitis was the most frequent infection (38/82, 46.3%), followed by non-vertebral osteomyelitis (26/82, 31.7%). Pathogens included Gram-positive cocci (70/131, 53.4%), Gram-negative bacilli (34/131, 26.0%), and fungi (9/131, 6.9%). BJI predictors included male gender (OR 2.94, 95% CI 1.26-6.89) and diabetes (OR 2.97, 95% CI 1.34-6.56). Treatment failure was observed in 25.9% (21/81) patients and 1-year mortality post-BJI diagnosis was 14.8% (9/61). BJI remain a rare event in SOTr, associated with subtle clinical presentations, high morbidity and relapses, requiring additional studies in the future.

Temporal Trends in Deep Surgical Site Infections After Six Orthopaedic Procedures Over a 12-year Period Within a US-based Healthcare System

INTRODUCTION

Centers of excellence and bundled payment models have driven perioperative optimization and surgical site infection (SSI) prevention with decolonization protocols and antibiotic prophylaxis strategies. We sought to evaluate time trends in the incidence of deep SSI and its causative organisms after six orthopaedic procedures in a US-based integrated healthcare system.

METHODS

We conducted a population-level time-trend study using data from Kaiser Permanente's orthopaedic registries. All patients who underwent primary anterior cruciate ligament reconstruction (ACLR), total knee arthroplasty (TKA), elective total hip arthroplasty (THA), hip fracture repair, shoulder arthroplasty, and spine surgery were identified (2009 to 2020). The annual incidence of 90-day deep SSI was identified according to the National Healthcare Safety Network/Centers for Disease Control and Prevention guidelines with manual chart validation for identified infections. Poisson regression was used to evaluate annual trends in SSI incidence with surgical year as the exposure of interest. Annual trends in overall incidence and organism-specific incidence were considered.

RESULTS

The final study sample was composed of 465,797 primary orthopaedic procedures. Over the 12-year study period, a decreasing trend in deep SSI was observed for ACLR and hip fracture repair. Although there was variation in incidence rates for specific operative years for TKA, elective THA, shoulder arthroplasty, and spine surgery, no consistent decreasing trends over time were found. Decreasing rates of Staphylococcus aureus infections over time after hip fracture repair, shoulder arthroplasty, and spine surgery and decreasing trends in antibiotic resistance after elective THA and spine surgery were also observed. Increasing trends of polymicrobial infections were observed after TKA and Cutibacterium acnes after elective THA.

CONCLUSIONS

The overall incidence of deep SSI after six orthopaedic procedures was rare. Decreasing SSI rates were observed for ACLR and hip fracture repair within our US-based healthcare system. Polymicrobial infections after TKA and Cutibacterium acnes after elective THA warrant closer surveillance.

LEVEL OF EVIDENCE

IV.

Preoperative and postoperative risk factors for periprosthetic joint infection in primary total hip arthroplasty: A 1-year experience

BACKGROUND

Periprosthetic joint infection (PJI) in primary total hip replacement (THR) is one of the most important threats in orthopedic surgery, so one important surgeon’s target is to avoid or early diagnose a PJI. Although the incidence of PJI is very low (0.69%) in our department, with an average follow-up of 595 d, this infection poses a serious threat due to the difficulties of treatment and the lower functional outcomes after healing.

AIM

To study the incidence of PJI in all operations occurring in the year 2016 in our department to look for predictive signs of potential infection.

METHODS

We counted 583 THR for 578 patients and observed only 4 cases of infection (0.69%) with a mean follow-up of 596 d (min 30, max 1451). We reviewed all medical records to collect the data: duration and time of the surgery, presence, type and duration of the antibiotic therapy, preoperative diagnosis, blood values before and after surgery, transfusions, presence of preoperative drugs (in particularly anticoagulants and antiaggregant, corticosteroids and immunosuppressants), presence of some comorbidities (high body mass index, blood hypertension, chronic obstructive pulmonary disease, cardiac ischemia, diabetes, rheumatological conditions, previous local infections).

RESULTS

No preoperative, intraoperative, or postoperative analysis showed a higher incidence of PJI. We did not find any class with evident major odds of PJI. In our study, we did not find any border value to predict PJI and all patients had similar values in both groups (non-PJI and PJI). Only some categories, such as female patients, showed more frequency of PJI, but this difference related to sex was not statistically significant.

CONCLUSION

We did not find any category with a higher risk of PJI in THR, probably due to the lack of few cases of infection.

Periprosthetic joint infection rates across primary total hip arthroplasty surgical approaches: a systematic review and meta-analysis of 653,633 procedures

INTRODUCTION

Evidence demonstrates comparable clinical outcomes across the various surgical approaches to primary total hip arthroplasty (THA). However, high-quality contemporary data regarding periprosthetic joint infection (PJI) risk between direct anterior approach (DAA) and other (THA) approaches is lacking. This systematic review and meta-analysis evaluated PJI rates reported in the literature between the DAA and other approaches.

MATERIALS AND METHODS

Five online databases were queried for all studies published from January 1st, 2000 through February 17th, 2021 that reported PJI rates between DAA and other surgical approaches. Studies reporting on primary THAs for osteoarthritis (OA) and that included PJI rates segregated by surgical approach were included. Articles reporting on revision THA, alternative THA etiologies, or minimally invasive techniques were excluded. Mantel-Haenszel (M-H) models were utilized to evaluate the pooled effect of surgical approach on infection rates. Validated risk of bias and methodological quality assessment tools were applied to each study. Multiple sensitivity analyses were conducted to evaluate the robustness of analyses.

RESULTS

28 articles reporting on 653,633 primary THAs were included. No differences were found between DAA cohorts and combined other approaches (OR: 0.95; 95% CI 0.74-1.21; p = 0.67) as well as segregated anterolateral approach cohorts (OR: 0.82, 95% CI 0.64-1.06; p = 0.13). However, DAA patients had a significantly reduced risk of infection compared to those undergoing posterior (OR: 0.66, 95% CI 0.58-0.74; p < 0.0001) and direct lateral (OR: 0.56, 95% CI 0.48-0.65; p < 0.00001) approaches.

CONCLUSION

The DAA to primary THA had comparable or lower PJI risk when compared to other contemporary approaches. The results of the most up-to-date evidence available serve to encourage adult reconstruction surgeons who have already adopted the DAA. Additionally, orthopaedic surgeons considering adoption or use of the direct anterior approach for other reasons should not be dissuaded over theoretical concern for a general increase in the risk of PJI.

LEVEL OF EVIDENCE

Level III.

Treatment outcomes of patients with Cutibacterium acnes-positive cultures during total joint replacement revision surgery: a minimum 2-year follow-up

INTRODUCTION

Periprosthetic joint infection (PJI) is a devastating complication following total joint replacement (TJR). Cutibacterium acnes (C. acnes) is a low virulent skin commensal, commonly found during TJR revision surgery for "aseptic" causes. The purpose of the present study was to report the treatment outcomes of patients with C. acnes contamination or infection in the presence of a TJR treated with a revision surgery ± implant exchange ± prolonged (≥ 8 weeks) postoperative antibiotics.

METHODS

Medical records of patients with at least one positive C. acnes culture in intraoperative tissue samples or sonication fluid from a TJR revision surgery between January 2005 and December 2014 were retrospectively evaluated. The primary endpoint was infection eradication according to Delphi criteria. The diagnostic accuracy of preoperative TJR aspiration regarding the diagnosis of C. acnes PJI was also investigated.

RESULTS

A total of 52 TJR (28 shoulders, 17 hips, 7 knees) in 52 patients (35 males, 17 females) with an average age of 63 ± 11 (33-86) years were included. At an average follow-up of 67 ± 33 (24-127) months, the infection eradication of C. acnes PJI was 97% regardless of the surgical treatment or administration of prolonged postoperative antibiotics. The incidence of unsuspected C. acnes PJI was 28.8%. The sensitivity and specificity of preoperative joint aspiration in detecting C. acnes PJI were 59% and 88%, whereas the PPV and NNV were 83% and 67%, respectively.

CONCLUSION

Infection eradication of C. acnes PJI was very high at a minimum follow-up of 24 months, suggesting that C. acnes PJI could be adequately treated with a combination of revision surgery and prolonged postoperative antibiotics. The preoperative diagnosis of C. acnes PJI might be challenging with more than one-quarter of patients presenting without suspicion of C. acnes PJI. The appropriate treatment of patients with a single positive culture remains still unclear. A negative TJR aspiration should not rule out a C. acnes PJI, especially in the presence of clinical correlates of infection.

LEVEL OF EVIDENCE

Retrospective case-control study, Level III.

IRB APPROVAL

Kantonale Ethikkommission Zürich, BASEC Nr.:2017-00567.

Pharmacological thromboprophylaxis as a risk factor for early periprosthetic joint infection following primary total joint arthroplasty

Venous thromboembolism (VTE) prophylaxis has been suggested for patients who underwent total join arthroplasty (TJA). However, the morbidity of surgical site complications (SSC) and periprosthetic joint infection (PJI) has not been well evaluated. We aimed to evaluate the impact of VTE prophylaxis on the risk of early postoperative SSC and PJI in a Taiwanese population. We retrospectively reviewed 7511 patients who underwent primary TJA performed by a single surgeon from 2010 through 2019. We evaluated the rates of SSC and PJI in the early postoperative period (30-day, 90-day) as well as 1-year reoperations. Multivariate regression analysis was used to identify possible risk factors associated with SSC and PJI, including age, sex, WHO classification of weight status, smoking, diabetes mellitus (DM), rheumatoid arthritis(RA), Charlson comorbidity index (CCI), history of VTE, presence of varicose veins, total knee or hip arthroplasty procedure, unilateral or bilateral procedure, or receiving VTE prophylaxis or blood transfusion. The overall 90-day rates of SSC and PJI were 1.1% (N = 80) and 0.2% (N = 16). VTE prophylaxis was a risk factor for 90-day readmission for SSC (aOR: 1.753, 95% CI 1.081-2.842), 90-day readmission for PJI (aOR: 3.267, 95% CI 1.026-10.402) and all 90-day PJI events (aOR: 3.222, 95% CI 1.200-8.656). Other risk factors included DM, underweight, obesity, bilateral TJA procedure, younger age, male sex and RA. Pharmacological thromboprophylaxis appears to be a modifiable risk factor for SSC and PJI in the early postoperative period. The increased infection risk should be carefully weighed in patients who received pharmacological VTE prophylaxis.

Application of a novel osteotomy instrumentation as a substitute tool in total hip arthroplasty

BACKGROUND

Mechanical failure, power shortage, and inadvertent contamination of the oscillating saw occasionally occurs in actualizing femoral neck osteotomy during total hip arthroplasty (THA); however, no appropriate alternative solution is currently available. This study aimed to introduce a novel osteotomy instrumentation (fretsaw, jig, cable passer hook) as a substitute tool while the oscillating saw was unavailable during THA.

METHODS

This study included 40 patients (40 hips) who underwent femoral neck osteotomy during primary THA using the new osteotomy instrumentation (n = 20) and the oscillating saw (n = 20). Clinical data and intraoperative findings of all patients were evaluated.

RESULTS

The mean osteotomy time was 22.3 ± 3.1 s (range, 17-30 s) and 29.4 ± 3.7 s (range, 25-39 s) in the oscillating saw group and in the new osteotomy instrumentation group, respectively (P < 0.001). The Harris Hip Score (HHS) improved in both groups; the mean HSS was 82.3 ± 2.5 and 83.3 ± 3.5 in the oscillating saw group and new osteotomy instrumentation group at 6 months after surgery, respectively (P = 0.297).

CONCLUSIONS

The original osteotomy instrumentation can be an ideal substitute tool for femoral neck osteotomy in THA, especially when the oscillating saw is unavailable or malfunctioning.

Risk factors for reoperation due to periprosthetic joint infection after elective total hip arthroplasty: a study of 35,056 patients using linked data of the Swedish Hip Arthroplasty Registry (SHAR) and Swedish Perioperative Registry (SPOR)

Background

In Sweden, the incidence of a prosthetic joint infection (PJI) after a planned Total Hip Arthroplasty (THA) is 1.3%, but the worldwide incidence of PJI after THA is unknown. This study explores associations between reoperation due to PJI and potential risk factors.

Methods

Primary elective THA surgery registered in both the Swedish Hip Arthroplasty Registry (SHAR) and the Swedish Perioperative Registry (SPOR) between 1 January 2015 and 31 December 2019 were included in this registry study, resulting in a total study population of 35,056 cases. The outcome variable was reoperation as the result of PJI within a year after surgery. Data were analysed using a multivariable Cox regression model.

Results

Reoperation due to PJI occurred in 460 cases (i.e., 1.3% of the study population). Each year of age increased the risk with 2% (HR 1.02 Cl 1.01, 1.03 P = < 0.001). Compared to men, women had significantly less risk for reoperation (HR 2.17 Cl 1.79, 2.53 P = < 0.001). For patients with obesity (BMI > 30), the risk increased considerably compared to underweight, normal weight, or overweight patients (HR 1.89 Cl 1.43, 2.51 P = < 0.001). The risk also increased by 6% for every 10 min of operative time (HR 1.06 Cl 1.02, 1.09 P = < 0.001). Patients having general anaesthesia had greater risk compared to those with spinal anaesthesia (HR 1.34 Cl 1.04, 1.73 P = 0.024). Finally, a lateral approach showed higher risk of reoperation than a posterior approach (HR 1.43 Cl 1.18, 1.73 P = < 0.001).

Conclusion

Recognition of the several risk factors identified in this study will be important for the perioperative management of patients undergoing THA.

Incidence and Predictors of Prosthetic Joint Infection Following Primary Total Knee Arthroplasty: A 15-Year Population-Based Cohort Study

BACKGROUND

One of the most devastating complications of total knee arthroplasty (TKA) is periprosthetic joint infection (PJI). Although many complications associated with TKA have decreased over time, the trends associated with PJI are less clear. Thus, the purpose of this study is to determine the incidence and risk factors for PJI after primary TKA.

METHODS

We performed a population-based cohort study using linked administrative databases in Ontario, Canada. We used a Cox proportional hazards model to analyze the effect of surgical factors and patient factors on the risk of developing PJI.

RESULTS

In total, 129,613 patients aged 50+ received a primary TKA for osteoarthritis from 2002 to 2016 in Ontario, Canada. In total, 1.41% of patients underwent revision surgery for PJI. When accounting for censoring, the cumulative incidence for PJI was 0.51% (95% confidence interval 0.46-0.55) at 1 year, 1.12% (1.05-1.18) at 5 years, 1.49% (1.41-1.57) at 10 years, and 1.65% (1.55-1.75) at 15 years. The multivariable model revealed that male gender, younger age, type II diabetes, post-traumatic arthritis, patellar resurfacing, and discharge to convalescent care were associated with increased risk of PJI.

CONCLUSION

The risk of PJI following TKA has decreased in small but steady increments over the past 15 years. Most PJIs are diagnosed within the first 2 years postoperatively, though a small group do continue to occur after 10 years. Overall, while the incidence of PJI has decreased slightly over the past 15 years, it remains among the most concerning complications of TKA and continued efforts aimed at further reducing its occurrence are needed.

Assessment of risk factors for early-onset deep surgical site infection following primary total hip arthroplasty for osteoarthritis

The aim of this study was to determine the incidence, annual trend, and perioperative outcomes and identify risk factors of early-onset (≤90 d) deep surgical site infection (SSI) following primary total hip arthroplasty (THA) for osteoarthritis. We performed a retrospective study using prospectively collected patient-level data from January 2013 to March 2020. The diagnosis of deep SSI was based on the published Centre for Disease Control/National Healthcare Safety Network (CDC/NHSN) definition. The Mann–Kendall trend test was used to detect monotonic trends. Secondary outcomes were 90 d mortality and 90 d readmission. A total of 22 685 patients underwent primary THA for osteoarthritis. A total of 46 patients had a confirmed deep SSI within 90 d of surgery representing a cumulative incidence of 0.2 %. The annual infection rate decreased over the 7-year study period (p=0.026). Risk analysis was performed on 15 466 patients. Risk factors associated with early-onset deep SSI included a BMI > 30 kg m-2 (odds ratio (OR) 3.42 [95 % CI 1.75–7.20]; p<0.001), chronic renal disease (OR, 3.52 [95 % CI 1.17–8.59]; p=0.011), and cardiac illness (OR, 2.47 [1.30–4.69]; p=0.005), as classified by the Canadian Institute for Health Information. Early-onset deep SSI was not associated with 90 d mortality (p=0.167) but was associated with an increased chance of 90 d readmission (p<0.001). This study establishes a reliable baseline infection rate for early-onset deep SSI after THA for osteoarthritis through the use of a robust methodological process. Several risk factors for early-onset deep SSI are potentially modifiable, and therefore targeted preoperative interventions of patients with these risk factors is encouraged.

The risk of revision following total hip arthroplasty in patients with inflammatory bowel disease, a registry based study

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the intestinal tract and is associated with decreased bone mineral density. IBD patients are at higher risk of osteopenia, osteoporosis and fracture compared to non-IBD patients. The impact of IBD on the performance of orthopedic implants has not been well studied. We hypothesized that a history of IBD at the time of primary total hip arthroplasty (THA) would increase the risk of subsequent failure as assessed by revision surgery. A retrospective implant survival analysis was completed using the Swedish Hip Arthroplasty Registry and the Sweden National Patient Register. A total of 150,073 patients undergoing THA for osteoarthritis within an 18-year period were included in the study. THA patients with (n = 2,604) and without (n = 147,469) a history of IBD at the time of THA were compared with primary revision as the main endpoint and adjusted using sex, age category and comorbidity (Elixhauser scores) as covariates. We found that patients with a history of IBD had a relatively higher risk of revision surgery for septic causes while the non-IBD patients had a relatively higher risk of revision for aseptic causes (p = 0.004). Our findings suggest there may be an association between gut health and THA performance.

Orthopedic Surgical Helmet Systems Significantly Impair Speech Intelligibility

Surgical suits provide protection to orthopedic surgeons, but the suits and fan noise may interfere with communication between operative team members. The goal of this study was to quantify the fan sound and effect of the suit, fan, and N95 mask. Sound levels were measured using a specialized manikin and evaluated using preferred speech interference levels (PSILs), noise criterion (NC) ratings, and comparison with speech sound levels from the literature. Additionally, sound blocking due to the surgical suit was measured and combined effects of the fan and suit were described using a signal to noise ratio (SNR). The noise with the fan at medium and high speed was louder than average speech and the PSILs at these speeds were significantly higher than with the fan off. The fan NC rating of 50 to 60 exceeded the recommended range of 25 to 30 for operating rooms. The N95 mask, space suit, and distance between speaker and receiver all reduced the sound signal at the receiver's ear, with the worst case being full personal protective equipment on both and speaker distanced from receiver. The estimated SNR for the suit and fan system was negative for many frequency bands used in speech, indicating more noise than signal. Multiple measures indicated that the fan noises were at levels associated with speech interference. This noise combined with sound blocking provided by the suit produced SNRs commonly associated with noisy to very noisy environments. This study suggests the combined effects of the suit, fan, and distance may negatively impact operating room communication. [Orthopedics. 2021;44(4):208-214.].

The AAHKS Clinical Research Award: Extended Oral Antibiotics Prevent Periprosthetic Joint Infection in High-Risk Cases: 3855 Patients With 1-Year Follow-Up

BACKGROUND

Surgical and host factors predispose patients to periprosthetic joint infection (PJI) after primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). While surgical factors are modifiable, host factors can be challenging, and there are limited data demonstrating that preoperative patient optimization decreases risk of PJI. The goal of this study was to evaluate whether extended oral antibiotic prophylaxis reduces the one-year infection rate in high-risk patients.

METHODS

A total of 3855 consecutive primary THAs and TKAs performed between 2011 and 2019 at a suburban academic hospital with modern perioperative and infection-prevention protocols were retrospectively reviewed. Beginning in January 2015, a 7-day oral antibiotic prophylaxis protocol was implemented after discharge for patients at high risk for PJI. The percentage of high-risk patients diagnosed with PJI within 1 year was compared between groups that did and did not receive extended antibiotic prophylaxis. Univariate and logistic regression analyses were performed, with P ≤ .05 denoting statistical significance.

RESULTS

Overall 1-year infection rates were 2.26% and 0.85% after THA and TKA, respectively. High-risk patients with extended antibiotic prophylaxis had a significantly lower rate of PJI than high-risk patients without extended antibiotic prophylaxis (0.89% vs 2.64%, respectively; P < .001). There was no difference in the infection rate between high-risk patients who received antibiotics and low-risk patients (0.89% vs 1.29%, respectively; P = .348) with numbers available.

CONCLUSION

Extended postoperative oral antibiotic prophylaxis for 7 days led to a statistically significant and clinically meaningful reduction in 1-year infection rates of patients at high risk for infection. In fact, the PJI rate in high-risk patients who received antibiotics was less than the rate seen in low-risk patients. Thus, extended oral antibiotic prophylaxis may be a simple measure to effectively counteract poor host factors. Moreover, the findings of this study may mitigate the incentive to select healthier patients in outcome-based reimbursement models. Further study with a multicenter randomized control trial is needed to further validate this protocol.

LEVEL OF EVIDENCE

Therapeutic level III.

International Organism Profile of Periprosthetic Total Hip and Knee Infections

BACKGROUND

There is scarce literature describing pathogens responsible for periprosthetic joint infections (PJIs) around the world. Therefore, we sought to describe periprosthetic joint infection causative organisms, rates of resistant organisms, and polymicrobial infections at 7 large institutions located in North/South America and Europe.

METHODS

We performed a retrospective study of 654 periprosthetic hip (n = 361) and knee (n = 293) infections (January 2006 to October 2019) identified at Cleveland Clinic Ohio/Florida in the United States (US) (n = 159), Hospital Italiano de Buenos Aires in Argentina (n = 99), Hospital Asociación Española in Uruguay (n = 130), Guy's and St Thomas' Hospital in the United Kingdom (UK) (n = 103), HELIOS Klinikum in Germany (n = 59), and Vreden Institute for Orthopedics in St. Petersburg, Russia (n = 104). Analyses were performed for the entire cohort, knees, and hips. Alpha was set at 0.05.

RESULTS

Overall, the most frequent organisms identified were Staphylococcus aureus (24.8%) and Staphylococcus epidermidis (21.7%). The incidence of organisms resistant to at least one antibiotic was 58% and there was a significant difference between hips (62.3%) and knees (52.6%) (P = .014). Rates of resistant organisms among countries were 37.7% (US), 66.7% (Argentina), 71.5% (Uruguay), 40.8% (UK), 62.7% (Germany), and 77.9% (Russia) (P < .001). The overall incidence of polymicrobial infections was 9.3% and the rates across nations were 9.4% in the US, 11.1% in Argentina, 4.6% in Uruguay, 4.9% in UK, 11.9% in Germany, and 16.3% in Russia (P = .026).

CONCLUSION

In the evaluated institutions, S aureus and S epidermidis accounted for almost 50% of all infections. The US and the UK had the lowest incidence of resistant organisms while Germany and Russia had the highest. The UK and Uruguay had the lowest rates of polymicrobial infections.