Quantifying the Burden of Revision Total Joint Arthroplasty for Periprosthetic Infection

Causes of Reoperations after Primary Total Hip Arthroplasty: A Retrospective Cohort Study Over 20 Years

BACKGROUND

Reoperations following total hip arthroplasty (THA) remain a major clinical challenge, with their incidence and socioeconomic burden rising despite advances in surgical techniques and prosthesis design. This study aimed to evaluate the predominant causes of reoperations following THA over two decades at a tertiary referral hospital, comparing trends between 2004 and 2013, and 2014 and 2023.

METHODS

We analyzed all reoperations performed at a tertiary referral hospital between January 2004 and December 2023. A total of 515 hips (483 patients) were included after excluding multiple reoperations on the same hip. The causes of reoperation were stratified into two time periods (2004 to 2013 and 2014 to 2023) to analyze trends. The time interval from primary THA to reoperations was also evaluated.

RESULTS

The main cause of reoperation after primary THA was aseptic loosening, accounting for 52.4% of cases, followed by infection (13.2%), periprosthetic fracture (PPF) (10.7%), wear/osteolysis (8.5%), ceramic fracture (5.8%), and instability/dislocation (5.6%). The proportion of aseptic loosening decreased significantly from 62.5 to 40.4%, while the proportions of infection, PPF, ceramic fracture, and instability/dislocation increased (P < 0.001). The causes of reoperation varied according to the time interval. Instability, PPF, and infection were early causes, and wear/osteolysis and aseptic loosening were relatively later causes of reoperations.

CONCLUSION

Aseptic loosening was the most common cause of reoperation following primary THA. However, the proportion of infection and PPF increased as a cause of reoperations, while the proportion of aseptic loosening decreased with time. Surgeons should consider that the main cause of reoperations differed according to the time interval from primary THA to reoperation.

Is the Effect of Chronological Age on Postoperative Complications Related to Comorbidity Burden? A Population Study of Revision Total Knee Arthroplasty Patients

BACKGROUND

The number of revision total knee arthroplasty (TKA) procedures continues to rise. Both advanced chronological age and comorbidity burden are associated with poor surgical outcomes. However, the question remains whether these two factors have a synergistic effect. Does a patient with advanced age and notable comorbidity burden carry an exponentially increased risk of complications after revision TKA? This study aims to investigate the effect of chronological age on various Charlson-Deyo Comorbidity Index (CDI) categories among revision TKA patients.

METHODS

A total of 144,402 patients who underwent elective revision TKA between 2006 and 2022 were identified from the Premier Healthcare Database. The primary outcome was the effect of chronological age on surgical outcomes following revision TKA, while stratified by the CDI. The analyzed postoperative complications in this study included postoperative cardiac complications, pneumonia, acute kidney injury, infections, central nervous system complications, and intensive care unit admissions. Spearman rank correlation coefficients and logistic regression models were used for analysis. Age was evaluated as both a continuous variable and categorical variable (<80 years versus 80+ years).

RESULTS

Both CDI and chronological age were associated with worse outcomes, with odds ratio (OR) 1.358 to 1.829 and OR 1.015 to 1.070, respectively, across these outcomes of interest. Patients aged 80 years and older had a markedly higher risk of postoperative complications across all CDI categories (OR 1.698 to 3.695) compared with patients younger than 80 years of age. The effect of chronological age on surgical outcomes does not vary under different CDI categories as chronological age presented similar patterns of OR trends on complications.

CONCLUSION

Chronological age and CDI were independent risk factors for postoperative complications in patients after revision TKA. Chronological age and CDI did not exhibit a synergistic effect on outcomes after revision TKA as the trends of impact from chronological age on outcome remained similar across different CDI categories.

Primary total knee arthroplasty in patients under 55 years of age: is the mid-term revision rate worrying?

INTRODUCTION

The indications for total knee arthroplasty (TKA) are expanding to include younger and more active patients. Several recent studies have warned of a higher revision rate and lower patient satisfaction in younger patients. The aim of this study was to assess the survival of TKAs in patients under the age of 55 and to determine the risk factors for revision and complications.

HYPOTHESIS

The hypothesis was that TKA survival in patients under 55 years of age is greater than 90% at 10 years.

MATERIALS AND METHODS

This work was a single-center retrospective study. All patients under 55 years of age with first-line TKA between 2006 and 2016 were included. The survival rate was calculated with TKA failure as the primary outcome, which was defined as revision surgery regardless of cause. The Kaplan‒Meier method was used to meet the primary objective.

RESULTS

A total of 168 patients (median age 52 years) with 193 TKAs were included. The mean follow-up was 7.9 years, and 24 cases of failure were identified. The 10-year survival rate was 86.6% (95% CI [81.1-92.2]). The mean time to failure was 4.1 years. Mechanical loosening and infection were the main causes of failure. Body mass index (BMI) appeared to increase the risk of revision (p < 0.01). TKAs with a third condyle were less strongly associated with the risk of revision and complications (p < 0.05), as was the presence of a tibial keel (p < 0.05). TKAs with posttraumatic gonarthrosis (p = 0.066), osteonecrosis (p < 0.05) and sequelae of septic arthritis (p < 0.05) appeared to be the most at risk of revision.

CONCLUSION

This hypothesis has not been verified, and TKA in patients under 55 years of age appears to have a higher revision rate than in the general population. The indication for TKA in these patients remains a reliable option, but certain risk factors must be considered.

LEVEL OF EVIDENCE

IV; retrospective study.

Trends and Epidemiology in Revision Total Hip Arthroplasty: A Large Database Study

BACKGROUND

The clinical and financial burden of revision total hip arthroplasty (rTHA) continues to grow. Therefore, further investigation is needed to characterize case volume, reason for failure, and postoperative complications. The purpose of this study was to characterize contemporary indications for and complications following rTHA.

METHODS

Patients undergoing rTHA between 2010 and 2021 were identified within the PearlDiver database. Adjusted rTHA incidence was calculated by dividing the annual rTHA volume by the annual primary total hip arthroplasty (THA) and multiplying by 100,000. Mann-Kendall trend tests were utilized to trend revision volume, etiology, and 90-day postoperative complications. A total of 225,958 rTHAs were identified.

RESULTS

The annual volume of rTHA did not change over the study period (18,871 to 15,994; P = 0.064). However, the adjusted incidence of rTHA significantly decreased (20,169.3 to 13,061.2 per 100,000 THAs; P < 0.001). The most common causes of rTHA were aseptic implant loosening (21.5%), instability (19.8%), and infection (19.1%). The adjusted incidences of revision due to infection (4,659.9 to 2,596.1 per 100,000 THAs; P < 0.001) and aseptic implant loosening (4,651.4 to 2,493.2 per 100,000 THAs; P < 0.001) decreased over time. The adjusted rate of instability (3,149.8 to 3,245.3 per 100,000 THAs; P = 0.304) did not change. Rates of post-revision deep vein thrombosis, hematoma, surgical site infection, and transfusion significantly decreased over the study period (P < 0.05), while rates of emergency department visits and readmission did not change.

CONCLUSIONS

In addition to a decreased adjusted incidence of rTHA, our analysis demonstrated a decreased incidence of infection, aseptic loosening, and various postoperative complications. However, no difference in the adjusted incidence of instability and periprosthetic fracture was seen over our study period. Continued study is necessary to further decrease the need for rTHA with a focus on the etiologies and complications that have remained unchanged.

Inflammatory Marker Changes Following Total Knee Arthroplasty for Rheumatoid Arthritis with Vancomycin-Loaded Calcium Sulfate Bone Filling

Rheumatoid arthritis (RA) patients undergoing total knee arthroplasty (TKA) face infection risk. The study evaluates vancomycin-loaded calcium sulfate bone as infection prevention. Patients with RA treated with TKA who had their femoral canal filled using either vancomycin-loaded calcium sulfate bone (experimental group [n = 35]) or the patient's own excised autologous bone (control group [n = 30]) at the Qingdao University Affiliated Hospital, Qingdao, China from January 1, 2017, to March 1, 2023, were retrospectively enrolled in this study. An experienced surgeon used midvastus approach. Surgeries included disinfection, antibiotics, and femoral filling. The age, gender, body mass index (BMI), comorbidities, and intraoperative details were extracted from the patient's medical records. Preoperation and postoperation markers (C-reactive protein [CRP], erythrocyte sedimentation rate [ESR]), pain scale (Visual Analog Scale [VAS]), infection rate, and Knee Society Score (KSS) were collected. Groups matched in age, gender, and BMI. No preoperative inflammatory marker differences were observed. However, compared to the control group, the postoperative inflammatory markers were significantly lower in the experimental group at 1-week postsurgery (CRP: 40.80 ± 23.17 vs. 60.80 ± 43.12 mg/L, p = 0.021; ESR: 72.06 ± 17.52 vs. 83.87 ± 21.52 mm/h, p = 0.012) and at 1-month postsurgery (CRP: 15.63 ± 6.56 vs. 21.17 ± 13.16 mg/L, p = 0.032; ESR: 25.25 ± 20.44 vs. 38.40 ± 25.26 mm/h, p = 0.024). There were no significant differences in the VAS (2.79 ± 0.90 vs. 2.70 ± 0.84 score, p = 0.689) and KSS (64.31 ± 17.88 vs. 66.57 ± 12.36) at 1-month postsurgery. Experimental group: zero infections; control group: only one infection. Administering vancomycin and calcium sulfate during TKA in RA patients reduces postoperative inflammation, but does not significantly affect infection risk; further research may be necessary for validation.

Imaging in Periprosthetic Joint Infection Diagnosis: A Comprehensive Review

Various imaging methods assist in diagnosing periprosthetic joint infection (PJI). These include radiological techniques such as radiography, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US); as well as advanced nuclear medicine techniques including bone scintigraphy (BS), anti-granulocyte antibody imaging (AGS), leukocyte scintigraphy (LS), and fluorodeoxyglucose positron emission tomography (FDG-PET and FDG-PET/CT). Each imaging technique and radiopharmaceutical has been extensively studied, with unique diagnostic accuracy, limitations, and benefits for PJI diagnosis. This review aims to detail and describe the most commonly used imaging techniques and radiopharmaceuticals for evaluating PJI, focusing particularly on knee and hip arthroplasties.

Analysis of systemic serum vancomycin levels following intraarticular application in primary total joint arthroplasty

INTRODUCTION

Periprosthetic joint infection (PJI) is a serious complication following primary total joint arthroplasty (TJA). PJI accounts for 15-25% of revision surgeries, therefore it is associated with PJI is associated with substantial patient morbidity and mortality as well as increased healthcare expenditures due to complex treatment strategies. Recently, intraoperative local application of vancomycin powder is increasingly being used in primary total hip and knee arthroplasty (THA, TKA) as an additive strategy for PJI prevention. Whereas local vancomycin concentrations have already been investigated in prior studies, evidence on systemic vancomycin levels and potential adverse drug reactions (ADR) is limited. Purpose of this study was to investigate systemic vancomycin levels following intraarticular application in primary TJA.

MATERIALS AND METHODS

This pilot study is a prospective analysis of patients undergoing primary THA and TKA between April and July 2023. One gram of vancomycin powder was applied to the prosthesis prior to wound closure. Serum vancomycin levels were measured at two standardised time points, 24 and 48 h postoperatively.

RESULTS

In total, 103 patients were included, and the patient collective was further stratified by surgical procedure into a THA subgroup (n = 52) and a TKA subgroup (n = 51). Mean serum vancomycin levels showed a significant group difference at both time points (24 h: p < 0.001; 48 h: p = 0.044) with higher serum vancomycin concentrations in the THA cohort. Mean serum vancomycin levels in THA patients were 1.25 μg/ml (range 0.00-7.00 μg/ml) after 24 h and 0.34 μg/ml (range 0.00-4.80 μg/ml) 48 h postoperatively. In TKA, no systemic vancomycin levels were detected. Vancomycin concentrations did not reach therapeutic levels in any patient. No ADR was detected in the whole study collective.

CONCLUSION

Following intraarticular administration of vancomycin powder, no systemic vancomycin levels within the therapeutic range were detected, thus it may serve as a safe and cost-effective adjunct to strategies for prevention of PJI.

What Are the Research Highlights of Periprosthetic Joint Infections From the 100 Most Cited Studies?

Background

Periprosthetic joint infections (PJIs) are a serious complication after total joint arthroplasty. Our study aimed to analyze the characteristics and research highlights of the top 100 most cited studies on PJI from an orthopaedic standpoint. Moreover, we sought to assess whether there has been a change in the level of evidence (LOE) throughout time.

Methods

We conducted a search of the PubMed, Embase, and Web of Science databases to identify the top 100 studies primarily focusing on PJI. Study characteristics assessed included publication year, LOE, journal of publication, and type of study. Research highlights of the included studies were classified into 6 sections. Linear regression was employed to assess correlation between LOE and publication year.

Results

The aggregated citation count of all studies was 19,558 and the median citation number was 129.5. While cohort studies were the most prevalent, articles focusing on analysis of costs associated with PJI care or PJI definition garnered the highest yearly citation counts. The bulk of included studies were concentrated in 3 orthopaedic journals and published in the 2010s. The majority of studies had a LOE II (30%) or III (34%). On regression analysis, LOE was not correlated with publication year (Pearson's r = 0.013, P = .61).

Conclusions

The most cited PJI articles assessed the definition of PJI and PJI cost. Despite growing interest in PJI, the majority of studies had LOE II or III, highlighting the difficulty of conducting prospective randomized controlled trials in PJI patients.

Level of evidence

IV.

Unexpected positive cultures in conversion hip and knee arthroplasty

PURPOSE

Total hip and knee arthroplasty in patients with previous history of periarticular surgery, such as osteosynthesis, can be surprisingly complex. This type of procedure is known as conversion arthroplasty (cTHA or cTKA) and has a higher risk of complications. The rates of unexpected positive cultures (UPC) and the risk of periprosthetic joint infection (PJI) compared to primary arthroplasty is unclear. The main purpose of this study was to evaluate rates of Unexpected Positive Cultures (UPC) in a series of conversion arthroplasty patients. The main questions to answer are: 1. Are the patients with conversion arthroplasties more susceptible to UPC than other causes of revision arthroplasties? 2. Are the conversion patients with UPC more susceptible to developing PJI?

METHODS

This was a retrospective review of patients submitted to cTHA and cTKA from January 2012 to September 2018. Patients with history of previous infection or with missing intraoperative cultures were excluded. The UPC was defined as a single positive culture obtained during a procedure previously considered aseptic and PJI was defined according to the 2018 ICM criteria. After excluding 141 cases, 205 patients were analyzed, 160 hips and 45 knees.

RESULTS

Nine (4.4%) UPC were identified, five (3.1%) in the hip group and four (8,9%) in the knee group. Staphylococcal species were the most common isolated bacteria (n = 7, 77.7%). During the study period, four (1,9%) patients were diagnosed with PJI. Only one case had an UPC and a different germ was identified during revision arthroplasty workup.

CONCLUSIONS

While UPC are more prevalent in conversion knee arthroplasties compared to conversion hip arthroplasties, the rates are similar to those observed in revision arthroplasty for other indications. Importantly, the presence of a UPC in conversion arthroplasty does not appear to elevate the risk of subsequent periprosthetic joint infection, provided a thorough PJI workup has been conducted preoperatively. Therefore, in such cases, UPCs may be safely disregarded.

Initiating chemotherapy in joint arthroplasty patients increases the risk of periprosthetic joint infections

BACKGROUND

Total Joint Arthroplasties (TJAs) are becoming more popular, resulting in a growing economic burden due to potential postoperative complications, with periprosthetic joint infections (PJIs) playing a significant role. The effect of immunosuppression on PJI risk, particularly in cancer patients following chemotherapy, is unknown. The hypothesis of this study investigated whether chemotherapy increases PJI rates in patients who received post-arthroplasty chemotherapy within one year of surgery.

METHODS

Data from the M161Ortho dataset of PearlDiver patient records database were utilized using ICD-9, ICD-10, and CPT codes. The cohort includes Total Knee Arthroplasty (TKA), Total Hip Arthroplasty (THA), and Total Shoulder Arthroplasty (TSA) patients who underwent post-arthroplasty chemotherapy within one year after surgery between 2010 and 2022. Patients in the matched control group did not receive post-arthroplasty chemotherapy. Pre-arthroplasty chemotherapy recipients, PJI, and post-op first year revisions were excluded. Analyses including the linear logistic regression were performed via R statistical software.

RESULTS

Totally, 17,026 patients (8,558 TKAs, 6,707 THAs, and 1,761 TSAs) were included. At two (OR = 1.59, p = 0.034), three (OR = 1.57, p = 0.009), and four (OR = 1.40, p = 0.032) years for TKA, and two (OR = 2.27, p = 0.008), three (OR = 2.32, p < 0.001), and four (OR = 2.25, p0.001) years for THA, PJI rates were significantly higher in the chemotherapy group. TSA patients had a significant rise in PJI after four years (OR = 2.20, p = 0.031).

CONCLUSIONS

This study reveals a possible relationship between postoperative chemotherapy and an increased incidence of PJI in patients with arthroplasty. Chemotherapy suppresses the immune system, rendering patients more vulnerable to infections. Additional research is required to confirm these findings.

Latent infections in conversion total hip arthroplasty following internal fixation of femoral neck fractures: a systematic review and meta-analysis of diagnostic methods

BACKGROUND

Accurate diagnosis of latent infections prior to conversion total hip arthroplasty (THA) following internal fixation of femoral neck fractures is crucial for successful surgical outcomes. This systematic review aimed to provide a comprehensive evaluation of the current literature regarding the diagnosis of latent infections before conversion THA.

METHODS

Systematic search of PubMed, EMBASE, and Cochrane (CENTRAL) databases was conducted, and the diagnostic accuracy of various markers and techniques was assessed. The quality of the included studies was evaluated using the QUADAS-2 instrument.

RESULTS

Five studies comprising 661 patients were included in the review. Pooled analysis using C-reactive protein (CRP) as a diagnostic marker resulted in a sensitivity and specificity of 72% and 76%, respectively, while using erythrocyte sedimentation rate (ESR) yielded a sensitivity and specificity of 75% and 78%, respectively. Fibrinogen and platelet count showed lower sensitivity and specificity compared to CRP and ESR. The best combined markers were CRP and serum platelet count, with a sensitivity of 76% and specificity of 86% based on one study.

CONCLUSION

Our review underscored the limitations and inconsistencies present in current diagnostic methods for latent infections in conversion surgery. Future research needs to focus on standardizing threshold values, exploring the potential of synovial fluid analysis, imaging techniques, and molecular methods, as well as developing tailored diagnostic algorithms.

PROSPERO

CRD42023394757.

Preoperative MRSA screening using a simple questionnaire prior elective total joint replacement

INTRODUCTION

The purpose of this study was to evaluate the management and results of our standarized protocol for preoperative identification of MRSA colonisation in patients undergoing primary total hip and knee replacement procedures.

METHODS

Following hospital protocol, between January 2016 and June 2019 37,745 patients awaiting elective joint replacement underwent a standardized questionnaire to assess the risk of MRSA infection, identifying patients requiring preoperative MRSA screening. An evaluation of the questionnaire identified effective questions for identifying infected patients. Furthermore, an analysis evaluated the impact of comorbidities or Charlson Comorbidity Index scores on positive MRSA colonization. Additionally, we evaluated the cost savings of targeted testing compared to testing all surgery patients.

RESULTS

Of the 37,745 patients, 8.057 (21.3%) were swabbed, with a total of 65 (0.81%) positive tests. From this group 27 (36.48%) who were treated were negative before surgery. Some of the questionnaire results were consistently associated with a higher chance of colonization, including hospitalization during the past year (47,7%), previous history of MRSA (44,6%), and agriculture or cattle farming related work (15,4%). By selectively testing high-risk patients identified through the questionnaire, we achieved a 79% reduction in costs compared to universal MRSA screening.

CONCLUSION

Our results suggest that the simple and standardized questionnaire is a valuable tool for preoperative screening, effectively identifying high-risk patients prone to MRSA colonisation. The risk of periprosthetic joint infection (PJI) and its associated sequelae may be reduced by this approach.

Bacteriophage therapy as an innovative strategy for the treatment of Periprosthetic Joint Infection: a systematic review

BACKGROUND

Periprosthetic Joint Infection (PJI) following hip and knee arthroplasty is a catastrophic complication in orthopaedic surgery. It has long been a key focus for orthopaedic surgeons in terms of prevention and management. With the increasing incidence of antibiotic resistance in recent years, finding more targeted treatment methods has become an increasingly urgent issue. Bacteriophage Therapy (BT) has emerged as a promising adjunctive treatment for bone and joint infections in recent years. It not only effectively kills bacteria but also demonstrates significant anti-biofilm activity, garnering substantial clinical interest due to its demonstrated efficacy and relatively low incidence of adverse effects.

PURPOSE

This review aims to systematically evaluate the efficacy and safety of bacteriophage therapy in treating PJI following hip and knee arthroplasty, providing additional reference for its future clinical application.

METHODS

Following predefined inclusion and exclusion criteria, our team conducted a systematic literature search across seven databases (PubMed, Embase, Web of Science, Cochrane Library, ClinicalTrials.gov, CNKI, and WanFang Database). The search was conducted up to May 2024 and included multiple clinical studies on the use of bacteriophage therapy for treating PJI after hip and knee arthroplasty to assess its efficacy and safety.

RESULTS

This systematic review included 16 clinical studies after screening, consisting of 15 case reports and one prospective controlled clinical trial, involving a total of 42 patients with PJI treated with bacteriophage therapy. The average patient age was 62.86 years, and 43 joints were treated, with patients undergoing an average of 5.25 surgeries. The most common pathogen in these infections was Staphylococcus aureus, accounting for 18 cases. 33 patients received cocktail therapy, while nine were treated with a single bacteriophage preparation. Additionally, all patients underwent suppressive antibiotic therapy (SAT) postoperatively. All patients were followed up for an average of 13.55 months. There were two cases of recurrence, one of which resulted in amputation one year postoperatively. The remaining patients showed good recovery outcomes. Overall, the results from the included studies indicate that bacteriophage therapy effectively eradicates infectious strains in various cases of PJI, with minimal side effects, demonstrating promising clinical efficacy.

CONCLUSION

In the treatment of PJI following hip and knee arthroplasty, bacteriophages, whether used alone or in combination as cocktail therapy, have shown therapeutic potential. However, thorough preoperative evaluation is essential, and appropriate bacteriophage types and treatment regimens must be selected based on bacteriological evidence. Future large-scale, randomized controlled, and prospective trials are necessary to validate the efficacy and safety of this therapy.

Evaluating the impact of surgery sequence on infection rates in hip or knee arthroplasty: does sequence matter?

PURPOSE

The potential influence of surgical sequence of elective hip-and-knee reconstructive surgery in relation to an infection-related procedure on postoperative infection rates is not clearly understood. Therefore, we aimed to examine the impact of surgical sequence on the incidence of postoperative infections within one-year and the longest available follow-up period in patients undergoing hip-and-knee reconstructive surgery.

METHODS

A case-control study with propensity matching was utilized to examine elective surgeries conducted at Sunnybrook Holland Orthopaedic & Arthritic centre, Toronto, Canada between 2015 and 2018. We determined and categorized them based on their operating room (OR) sequence in relation to an infected case; the cases were those performed right after (post-infection cohort), and the controls were those performed before an infection-related procedure in the same OR (pre-infection cohort). We employed survival analysis to compare the infection incidence within one year and at the longest available follow-up among the propensity-matched cohort.

RESULTS

A total of 13,651 cases were identified during the four year period. We successfully matched 153 cases (21 post-infection and 132 pre-infection) using propensity scores. Demographic and clinical characteristics were balanced through matching. Kaplan-Meier survival analysis showed no significant difference in infection-free survival within one year and at a median follow-up of 2.2 years [interquartile range 0.9-5.0] between surgeries conducted before and after infected cases (both log-rank p-values = 0.4). The hazard ratios for infection within one year and the longest follow-up period were both 0.37 [95%Confidence Interval 0.03-4.09, p = 0.418], as no more events occurred after one year.

CONCLUSION

The sequence of surgical procedures, whether or not an elective arthroplasty or lower limb reconstructive procedure occurs before or after an infection-related case in the same OR, does not significantly affect postoperative infection rates. This finding supports the efficacy of the current infection control measures and suggests a reconsideration of surgical scheduling standards.

Systemic iodine levels increase with povidone-iodine irrigation, but does this affect thyroid functions? A case-control study

BACKGROUND

Intraoperative irrigation with diluted povidone iodine (PI) can be used to reduce the incidence of infection-related complications in arthroplasty surgeries. Since PI is associated with many interventions, especially skin antisepsis, its systemic effects are being studied. The aim of our study is to evaluate the systemic effects of PI, which we use as an irrigation solution, by means of urine iodine and thyroid function tests.

METHODS

In this case-control study, 96 patients who underwent knee or hip arthroplasty were included and divided into two groups according to the irrigation solution. In the first group, PI was added to the standard irrigation. The second group was considered as the control group and only standard irrigation was applied. Urine iodine, thyroid stimulating hormone, free T3 and free T4 values were compared in the preoperative and postoperative periods of these two groups. In this way, the effect of absorbed iodine on thyroid functions was investigated.

RESULTS

In the diluted PI group, urinary iodine levels were measured at maximum levels (450 µg/L) in the early postoperative period in most of the patients. The statistically significant difference in urinary iodine levels between the PI group and the control group, which started in the early postoperative period, continued until the last follow-up on the 14th postoperative day. In terms of thyroid functions, the observed differences were not statistically significant.

CONCLUSION

Studies to reduce periprosthetic infection show that PI can be preferred for irrigation before the closure of the joint area in total joint arthroplasty. Although the success of this treatment in periprosthetic infection has been investigated, its systemic examination has not been demonstrated. It was determined that PI treatment, which was seen to decrease in the systemic circulation within 14 days, did not show a statistically significant change in terms of thyroid functions when used at the determined concentration and duration. These results should be evaluated with larger and longer-term studies.

TRIAL REGISTRATION

Clinical trials ID no. NCT05599841.

Estimation of two-year hospital costs of hip and knee periprosthetic joint infection treatments using activity-based costing

Aims

Our aim was to estimate the total costs of all hospitalizations for treating periprosthetic joint infection (PJI) by main management strategy within 24 months post-diagnosis using activity-based costing. Additionally, we investigated the influence of individual PJI treatment pathways on hospital costs within the first 24 months.

Methods

Using admission and procedure data from a prospective observational cohort in Australia and New Zealand, Australian Refined Diagnosis Related Groups were assigned to each admitted patient episode of care for activity-based costing estimates of 273 hip PJI patients and 377 knee PJI patients. Costs were aggregated at 24 months post-diagnosis, and are presented in Australian dollars.

Results

The mean cost per hip and knee PJI patient was $64,585 (SD $53,550). Single-stage revision mean costs were $67,029 (SD $47,116) and $80,063 (SD $42,438) for hip and knee, respectively. Two-stage revision costs were $113,226 (SD $66,724) and $122,425 (SD $60,874) for hip and knee, respectively. Debridement, antibiotics, and implant retention in hips and knees mean costs were $53,537 (SD$ 39,342) and $48,463 (SD $33,179), respectively. Suppressive antibiotic therapy without surgical management mean costs were $20,296 (SD $8,875) for hip patients and $16,481 (SD $6,712) for knee patients. Hip patients had 16 different treatment pathways and knee patients had 18 treatment pathways. Additional treatment, episodes of care, and length of stay contributed to substantially increased costs up to a maximum of $369,948.

Conclusion

Treating PJI incurs a substantial cost burden, which is substantially influenced by management strategy. With an annual PJI incidence of 3,900, the cost burden would be in excess of $250 million to the Australian healthcare system. Treatment pathways with additional surgery, more episodes of care, and a longer length of stay substantially increase the associated hospital costs. Prospectively monitoring individual patient treatment pathways beyond initial management is important when quantifying PJI treatment cost. Our study highlights the importance of optimizing initial surgical treatment, and informs treating hospitals of the resources required to provide care for PJI patients.

Causes of Revision of Total Knee Arthroplasties in a Tertiary Hospital in Brazil

Objective  To identify the causes of revision of total knee arthroplasty in a referral center in Brazil. Methods  This is a case series, with 80 patients undergoing revision surgery for total knee arthroplasty (RTKA) at a referral center for knee surgery, between August 2019 and November 2021, with a mean age of 69.6 years. Of these patients, 60.23% were female and 39.77% were male. The average body mass index (BMI) was 30.23 kg/m 2 . The causes of TKA failure were defined as: periprosthetic infection according to the 2018 International Consensus Meeting criteria, ligament instability, range of motion limitation, periprosthetic fracture, malalignment, aseptic loosening, pain due to non-replacement of the patellar cartilage, polyethylene wear, fracture of implants, insufficiency of the extensor mechanism. Results  Periprosthetic joint infection (PJI) was the main cause of revision total knee arthroplasty (TKA), corresponding to 47.73% of cases. Aseptic loosening of one or more components represented the second most frequent reason for TKA failure, accounting for 35.23% of revisions. Range of motion limitation represented the third most frequent cause, accounting for 5.68% of surgeries. Instability was the fourth most frequent reason for RTKA, occurring in 4.55% of patients. The other causes of revision were: periprosthetic fracture (3.41%), failure due to rupture of the extensor mechanism (2.27%), and pain attributed to non-replacement of the patellar cartilage (1.14%). Conclusions  Periprosthetic joint infection was the most frequent cause of TKA revision in our series. Other reasons for TKA failures were, in descending order: aseptic loosening, limited range of motion, and instability.

Mapping Staphylococcus aureus at Early and Late Stages of Infection in a Clinically Representative Hip Prosthetic Joint Infection Rat Model

Prosthetic joint infection (PJI) continues to be a devastating complication following total joint replacement surgeries where Staphylococcus aureus is the main offending organism. To improve our understanding of the disease pathogenesis, a histological analysis of infected peri-implant tissue in a hip PJI rat model was utilized to assess S. aureus spread and tissue reaction at early and late stages of infection. Sprague-Dawley rats were used and received a left cemented hip hemiarthroplasty using a 3D-printed titanium femoral stem. The rats received an intra-articular injection of S. aureus Xen36. These infected rats were sacrificed either at 3 days post-infection (early-stage infection) or at 13-days post-infection (late-stage infection). The femoral and acetabular tissues of all animals were harvested at euthanasia. Histological analysis for the harvested tissue was performed using immunohistochemistry, hematoxylin and eosin, as well as Masson's trichrome stains. Histological examination revealed significant quantitative and qualitative differences in peri-implant tissue response to infection at early and late stages. This hip PJI rat model identified clear histologic differences between early and late stages of S. aureus infection and how quickly bacterial infiltration could occur. These findings can provide insight into why certain surgical strategies like debridement and antibiotics may be associated with high failure rates.

Clinic of Hope: bridging infectious disease and orthopaedic surgery in prosthetic joint infection management

Prosthetic joint infections (PJIs) following total joint arthroplasty are a significant and costly complication. To address fragmented care typically seen with separate management, we established a combined infectious disease and orthopaedic surgery clinic at Duke Health in July 2020. This clinic focuses on patients experiencing acute deterioration or multiple PJI episodes, often at the stage where amputation is the only option offered. From July 2021 to March 2024, the clinic completed 974 visits with 319 unique patients. The clinic maintained a low no-show rate of 5.0%. Treatment plans included procedures such as debridement, antibiotics and implant retention (38%), as well as implant explantation and one-stage exchange (32% each), with amputation required in only 4% of cases. The integrated clinic model facilitated real-time, multidisciplinary care, improving patient outcomes and operational efficiency. This approach offers a promising model for managing complex infections.

Effects of Vancomycin/Tobramycin-Doped Ceramic Composite (Polyvinyl Alcohol Composite-Vancomycin/Tobramycin-Polymeric Dicalcium Phosphate Dihydrate) in a Rat Femur Model Implanted With Contaminated Porous Titanium Cylinders

BACKGROUND

Periprosthetic joint infection (PJI) remains common and problematic. We hypothesized that using a bioceramic that provided rapid release of the antibiotics (vancomycin [VAN] or VAN and tobramycin [VAN and TOB]) from a polyvinyl-alcohol-composite (PVA) combined with a delayed and sustained antibiotic release from polymeric-dicalcium-phosphate-dihydrate (PDCPD) ceramic would inhibit S. aureus-associated implant infections.

METHODS

A total of 50 male Sprague Dawley rats were randomly divided into 5 groups-I: negative control; II: bacteria only; III: bacteria + saline wash; IV: bacteria + PVA-VAN-PDCPD, and V: bacteria + PVA-VAN-TOB-PDCPD. A porous titanium (Ti) implant was press-fit into the rat knee. S. aureus-containing broth was added into the joint space creating a PJI. After 1 week, the joints from groups III to V were washed with saline and the fluid collected for bacterial quantification. This was followed by saline irrigation treatment (groups III to V) and application of the antibiotic-loaded PVA-PDCPD bioceramic (groups IV and V). On day 21, joint fluid was collected, and the implants harvested for bacterial quantification.

RESULTS

No bacteria were isolated from the negative control (group I). The positive control (group II) was positive on both days 7 and 21. Bacteria were still present on day 21 in the fluid and implant in group III. Groups (IV and V) showed a decrease in the bacterial burden in the fluid and implant on day 21. There were significant differences in bacteria levels in the collected wash fluid and on the implant at day 21 between the saline wash (group III) and treatment groups (IV and V).

CONCLUSIONS

In this animal model of acute periprosthetic infection, treatment with PVA-VAN-PDCPD and PVA-VAN/TOB-PDCPD reduced bacterial load in the infected joint and the infected Ti implant. Application of PVA-VAN-PDCPD and/or PVA-VAN/TOB-PDCPD after saline irrigation could be used as an addition to the treatment of PJI.

Advanced Multi-Layer Watertight Closure versus Conventional Closure in Total Hip and Knee Replacement Surgery

Background

In total joint replacement procedures, surgeons have increasingly adopted advanced multi-layer, watertight closure. The objective of the study was to compare the clinical and economic outcomes for advanced multi-layer, watertight closure patients to those with conventional closure with sutures and skin staples.

Methods

Patients aged ≥18 years were included in the study if they underwent total joint arthroplasty of the hip or knee as an elective, primary, inpatient procedure between January 2014 and March 2019. Cohorts having advanced multi-layer, watertight closure or conventional closure were compared using multivariable regression analysis of surgical site infections, length of stay, operating room time, procedure time, discharge status, readmissions, reoperations, and hospital emergency department visits.

Results

A total of 1828 patients received at least one total hip or knee replacement, of which 434 (23.7%) had advanced multi-layer, watertight closure and 1394 (76.3%) had conventional closure. Unadjusted time to readmission, when occurring, was considerably longer following advanced multi-layer, watertight closure (89.9 vs 51.1 days, p < 0.0001), and a lower proportion of the advanced multi-layer, watertight closure cohort required reoperation within 90 days (0.0% vs 2.6%, p < 0.0001). Adjusted mean hospital length of stay was approximately half of a day shorter for advanced multi-layer, watertight closure patients (1.10 vs 1.65 days; p < 0.001), and they were also more likely to be discharged to home (Odds Ratio: 4.61; p = 0.002).

Conclusion

Among patients undergoing total hip and knee arthroplasty in a highly optimized real-world clinical practice, advanced multi-layer, watertight closure was associated with significantly shorter inpatient length of stay and increased likelihood of being discharged to home compared with conventional closure. These findings suggest that advanced multi-layer, watertight closure is a valuable component of an optimal workflow for total hip or knee replacement, and may be especially valuable for high-risk patients.

Biomedical Applications of Electro-Initiated Polymerisation on Ti6Al4 V Titanium Alloy using Silk Fibroin Coatings for Antibiotic Delivery and Improved Cell Metabolism

Silk fibroin interactions with metallic surfaces can provide utility for medical materials and devices. Toward this goal, titanium alloy (Ti6Al4 V) was covalently grafted with polyacrylamide via electrochemically reducing 4-nitrobenzene diazonium salt in the presence of acrylamide. Analysis of the modified surfaces with FT-IR spectra, SEM and AFM were consistent with surface grafting. Functionalised titanium samples with a silk fibroin membrane, with and without impregnated therapeutics, were used to assess cytocompatibility and drug delivery. Initial cytocompatibility experiments using fibroblasts showed that the functionalised samples, both with and without silk fibroin coatings, supported significant increases between 72-136 % in cell metabolism, compared to the controls after 7 days. A 7-days release profiling showed consistent bacterial inhibition through gentamicin release with average inhibition zones of 239 mm2. Over a 5-week period, silk fibroin coated samples, both with and without growth factors, supported better human mesenchymal stem cell metabolism with increases reaching 1031 % and 388 %, respectively, compared to samples without the silk fibroin coating with.

Complications of periprosthetic fracture revision vs aseptic revision of total knee arthroplasty

Background

Periprosthetic fractures after total knee arthroplasty (TKA) are a challenging problem due to complex fracture patterns, poor bone quality, and a high-risk patient population. Treatment of both periprosthetic fractures and aseptic complications can include revision TKA. In this study, we compared systemic and orthopaedic complications following periprosthetic fracture associated revision TKA to aseptic revision TKA.

Methods

This is a retrospective cohort study using data from the years 2010-2020 from a national administrative claims database. Billing codes were used to identify revision TKAs with a diagnosis of periprosthetic fracture or aseptic complications (loosening, dislocation, arthrofibrosis, osteolysis, or prosthetic wear) within one year prior to revision. Pertinent systemic complications and rates of repeat revision TKA, periprosthetic infection, and repeat fractures were compared between the two groups.

Results

We identified 9891 periprosthetic fracture associated revision TKAs and 47,071 aseptic revision TKAs. Our study found higher rate of systemic complications including AKI, DVT, wound disruption, hematoma, and surgical site infections in periprosthetic fracture associated revision TKA compared to aseptic revision TKA. Furthermore, we found higher rates of repeat revision TKA, periprosthetic infections, and repeat periprosthetic fractures in fracture associated revision TKA group compared to aseptic revision group.

Conclusions

Our work highlights the significant short- and long-term complications associated with periprosthetic fracture associated revision TKA. Future working comparing functional outcomes and optimal surgical techniques are needed.

The cost-effectiveness of osteoporosis medications for preventing periprosthetic fractures following femoral neck fracture indicated hip arthroplasty: a break-even analysis

Osteoporosis treatment following arthroplasty for femoral neck fracture (FNF) is associated with lower rates of periprosthetic fracture (PPF). Our study evaluated the economic viability of treatment in patients following arthroplasty and demonstrates that treatment with oral bisphosphonates can be cost-effective in preventing PPF.

INTRODUCTION

Osteoporosis treatment following arthroplasty for femoral neck fracture (FNF) is associated with lower rates of periprosthetic fracture (PPF). Although cost-effective in reducing the rate of secondary fragility fracture, the economic viability of osteoporosis treatment in preventing PPF has not been evaluated. Therefore, the purpose of this study is to use a break-even analysis to determine whether and which current osteoporosis medications are cost-effective in preventing PPF following arthroplasty for FNFs.

METHODS

Three-year average cost of osteoporosis medication (oral bisphosphonates, estrogen hormonal therapy, intravenous (IV) bisphosphonates, denosumab, teriparatide, and abaloparatide), costs of PPF care, and PPF rates in patients who underwent hip arthroplasty for FNFs without osteoporosis treatment were used to perform a break-even analysis. The absolute risk reduction (ARR) related to osteoporosis treatment and sensitivity analyses were used to evaluate the cost-effectiveness of this intervention and break-even PPF rates.

RESULTS

Oral bisphosphonate therapy following arthroplasty for hip fractures would be economically justified if it prevents one out of 56 PPFs (ARR, 1.8%). Given the current cost and incidence of PPF, overall treatment can only be economically viable for PPF prophylaxis if the 3-year costs of these agents are less than $1500.

CONCLUSION

The utilization of lower cost osteoporosis medications such as oral bisphosphonates and estrogen hormonal therapy as PPF prophylaxis in this patient population would be economically viable if they reduce the PPF rate by 1.8% and 1.5%, respectively. For IV bisphosphonates and newer agents to be economically viable as PPF prophylaxis in the USA, their costs need to be significantly reduced.

3DFRINet: A Framework for the Detection and Diagnosis of Fracture Related Infection in Low Extremities Based on 18F-FDG PET/CT 3D Images

Fracture related infection (FRI) is one of the most devastating complications after fracture surgery in the lower extremities, which can lead to extremely high morbidity and medical costs. Therefore, early comprehensive evaluation and accurate diagnosis of patients are critical for appropriate treatment, prevention of complications, and good prognosis. 18Fluoro-deoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is one of the most commonly used medical imaging modalities for diagnosing FRI. With the development of deep learning, more neural networks have been proposed and become powerful computer-aided diagnosis tools in medical imaging. Therefore, a fully automated two-stage framework for FRI detection and diagnosis, 3DFRINet (Three Dimension FRI Network), is proposed for 18F-FDG PET/CT 3D imaging. The first stage can effectively extract and fuse the features of both modalities to accurately locate the lesion by the dual-branch design and attention module. The second stage reduces the dimensionality of the image by using the maximum intensity projection, which retains the effective features while reducing the computational effort and achieving excellent diagnostic performance. The diagnostic performance of lesions reached 91.55% accuracy, 0.9331 AUC, and 0.9250 F1 score. 3DFRINet has an advantage over six nuclear medicine experts in each classification metric. The statistical analysis shows that 3DFRINet is equivalent or superior to the primary nuclear medicine physicians and comparable to the senior nuclear medicine physicians. In conclusion, this study first proposed a method based on 18F-FDG PET/CT three-dimensional imaging for FRI location and diagnosis. This method shows superior lesion detection rate and diagnostic efficiency and therefore has good prospects for clinical application.

MicroRNA expression analysis in peripheral blood and soft-tissue of patients with periprosthetic hip infection

Aims

Current diagnostic tools are not always able to effectively identify periprosthetic joint infections (PJIs). Recent studies suggest that circulating microRNAs (miRNAs) undergo changes under pathological conditions such as infection. The aim of this study was to analyze miRNA expression in hip arthroplasty PJI patients.

Methods

This was a prospective pilot study, including 24 patients divided into three groups, with eight patients each undergoing revision of their hip arthroplasty due to aseptic reasons, and low- and high-grade PJI, respectively. The number of intraoperative samples and the incidence of positive cultures were recorded for each patient. Additionally, venous blood samples and periarticular tissue samples were collected from each patient to determine miRNA expressions between the groups. MiRNA screening was performed by small RNA-sequencing using the miRNA next generation sequencing (NGS) discovery (miND) pipeline.

Results

Overall, several miRNAs in plasma and tissue were identified to be progressively deregulated according to ongoing PJI. When comparing the plasma samples, patients with a high-grade infection showed significantly higher expression levels for hsa-miR-21-3p, hsa-miR-1290, and hsa-miR-4488, and lower expression levels for hsa-miR-130a-3p and hsa-miR-451a compared to the aseptic group. Furthermore, the high-grade group showed a significantly higher regulated expression level of hsa-miR-1260a and lower expression levels for hsa-miR-26a-5p, hsa-miR-26b-5p, hsa-miR-148b-5p, hsa-miR-301a-3p, hsa-miR-451a, and hsa-miR-454-3p compared to the low-grade group. No significant differences were found between the low-grade and aseptic groups. When comparing the tissue samples, the high-grade group showed significantly higher expression levels for 23 different miRNAs and lower expression levels for hsa-miR-2110 and hsa-miR-3200-3p compared to the aseptic group. No significant differences were found in miRNA expression between the high- and low-grade groups, as well as between the low-grade and aseptic groups.

Conclusion

With this prospective pilot study, we were able to identify a circulating miRNA signature correlating with high-grade PJI compared to aseptic patients undergoing hip arthroplasty revision. Our data contribute to establishing miRNA signatures as potential novel diagnostic and prognostic biomarkers for PJI.

Update on Focal Infection Management: A Czech Interdisciplinary Consensus

BACKGROUND

The focal infection theory has been used to explain several chronic systemic diseases in the past. Systemic diseases were thought to be caused by focal infections, such as caries and periodontal diseases, and dentists were held responsible for these diseases due to the spread of oral infections. As knowledge of the interrelationship between oral microorganisms and the host immune response has evolved over the last few decades, the focal infection theory has been modified in various ways. The relationship between oral and systemic health appears to be more complex than that suggested by the classical theory of focal infections. Indeed, the contribution of the oral microbiota to some systemic diseases is gaining acceptance, as there are strong associations between periodontal disease and atherosclerotic vascular disease, diabetes, and hospital-associated pneumonia, amongst others. As many jurisdictions have various protocols for managing this oral-systemic axis of disease, we sought to provide a consensus on this notion with the help of a multidisciplinary team from the Czech Republic.

METHODS

A multidisciplinary team comprising physicians/surgeons in the specialities of dentistry, ear-nose and throat (ENT), cardiology, orthopaedics, oncology, and diabetology were quetioned with regard to their conceptual understanding of the focal infection theory particularly in relation to the oral-systemic axis. The team also established a protocol to determine the strength of these associations and to plan the therapeutic steps needed to treat focal odontogenic infections whenever possible.

RESULTS

Scoring algorithms were devised for odontogenic inflammatory diseases and systemic risks, and standardised procedures were developed for general use.

CONCLUSIONS

The designed algorithm of the oral-systemic axis will be helpful for all health care workers in guiding their patient management protocol.

Is Penicillin Allergy a Clinical Problem? A Systematic Review of Total Joint Arthroplasty Procedures With Implications for Patient Safety and Antibiotic Stewardship

BACKGROUND

Patients undergoing total joint arthroplasty (TJA) who report penicillin allergy (PA) are frequently administered second-line antibiotics, although recent evidence suggests that this may be unnecessary and could increase infection risk. Many institutions have aimed to improve antibiotic deployment via allergy testing and screening; however, there is little standardization to this process. This review aimed to evaluate (1) antibiotic selection in patients who report PA and assess the impact of screening and testing interventions, (2) rates of allergic reactions in patients who report PA, and (3) the association between reported PA and screening or testing programs and odds of surgical site infection or periprosthetic joint infection.

METHODS

PubMed, EBSCOhost, and Google Scholar electronic databases were searched on February 4, 2023 to identify all studies published since January 1, 2000 that evaluated the impact of PA on patients undergoing TJA (PROSPERO study protocol registration: CRD42023394031). Articles were included if full-text manuscripts in English were available, and the study analyzed the impact of PA and related interventions on TJA patients. There were 11 studies evaluating 1,276,663 patients included. Interventions were compared via presentation of key findings regarding rates of clinically relevant or high-risk PA reported upon screenings or testings, cephalosporin utilizations, allergic reactions, and postoperative infections (surgical site infection and periprosthetic joint infection).

RESULTS

All 6 studies found that PA screening and testing markedly increase the use of first-line antibiotics. Testing showed low rates of true allergy (0.7 to 3%) and allergic reaction frequency for patients who have reported PA receiving cephalosporins was between 0% and 2%. Although there were mixed findings across studies, there was a trend toward second-line antibiotic prophylaxis being associated with a slightly higher rate of infection in PA patients.

CONCLUSIONS

Using PA screening and testing can promote antibiotic stewardship by safely increasing the use of first-line antibiotics in patients who have a reported PA.

LEVEL OF EVIDENCE

Level III, Therapeutic Study.

Systemic Inflammation Response Index (SIRI) and Monocyte-to-Lymphocyte Ratio (MLR) Are Predictors of Good Outcomes in Surgical Treatment of Periprosthetic Joint Infections of Lower Limbs: A Single-Center Retrospective Analysis

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication that develops after total joint arthroplasty (TJA), whose incidence is expected to increase over the years. Traditionally, surgical treatment of PJI has been based on algorithms, where early infections are preferably treated with debridement, antibiotics, and implant retention (DAIR) and late infections with two-stage revision surgery. Two-stage revision is considered the "gold standard" for treatment of chronic prosthetic joint infection (PJI) as it enables local delivery of antibiotics, maintenance of limb-length and mobility, and easier reimplantation. Many studies have attempted to identify potential predicting factors for early diagnosis of PJI, but its management remains challenging. In this observational retrospective study, we investigated the potential role of inflammatory blood markers (neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), platelet-to-lymphocyte ratio (PLR), systemic inflammatory index (SII), systemic inflammatory response index (SIRI), and aggregate index of systemic inflammation (AISI)) as prognostic factors in two-stage exchange arthroplasty for PJI.

METHODS

A single-center retrospective analysis was conducted, collecting clinical data and laboratory parameters from patients submitted to prosthetic explantation (EP) for chronic PJI. Laboratory parameters (PCR, NLR, MLR, PLR, SIRI, SII, and AISI) were evaluated at the explantation time; at 4, 6, and 8 weeks after surgery; and at reimplantation time. The correlation between laboratory parameters and surgery success was evaluated and defined as infection absence/resolution at the last follow-up.

RESULTS

A total of 57 patients with PJI were evaluated (62% males; average age 70 years, SD 12.14). Fifty-three patients with chronic PJI were included. Nine patients underwent DAIR revision surgery and chronic suppressive therapy; two patients died. Nineteen patients completed the two-stage revision process (prosthetic removal, spacer placement, and subsequent replanting). Among them, none showed signs of reinfection or persistence of infection at the last available follow-up. The other twenty-three patients did not replant due to persistent infection: among them, some (the most) underwent spacer retention; others (fewer in number) were submitted to resection arthroplasty and arthrodesis (Girdlestone technique) or chronic suppressive antibiotic therapy; the remaining were, over time, lost to follow-up. Of the patients who concluded the two-stage revision, the ones with high SIRI values (mean 3.08 SD 1.7 and p-value 0.04) and MLR values (mean 0.4 SD 0.2 and p-value 0.02) at the explantation time were associated with a higher probability of infection resolution. Moreover, higher variation in the SIRI and PCR, also defined, respectively, as delta-SIRI (mean -2.3 SD 1.8 and p-value 0.03) and delta-PCR (mean -46 SD 35.7 and p-value 0.03), were associated with favorable outcomes.

CONCLUSIONS

The results of our study suggest that, in patients with PJI undergoing EP, the SIRI and MLR values and delta-SIRI and delta-PCR values could be predictive of a favorable outcome. The evaluation of these laboratory indices, especially their determination at 4 weeks after removal, could therefore help to determine which patients could be successfully replanted and to identify the best time to replant. More studies analyzing a wider cohort of patients with chronic PJI are needed to validate the promising results of this study.

Evaluation of time to reimplantation as a risk factor in two-stage revision with static spacers for periprosthetic knee joint infection

INTRODUCTION

We investigated the time to reimplantation (TTR) during two-stage revision using static spacers with regard to treatment success and function in patients with chronic periprosthetic joint infection (PJI) of the knee.

METHODS

163 patients (median age 72 years, 72 women) who underwent two-stage exchange for chronic knee PJI between 2012 and 2020 were retrospectively analyzed (based on the 2011 Musculoskeletal Infection Society criteria). A cutoff TTR for increased risk of reinfection was identified using the maximally selected log-rank statistic. Infection control, aseptic revisions and overall survival were analyzed using Kaplan-Meier survival estimates. Adjustment for confounding factors-the Charlson Comorbidity Index (CCI) and C-reactive protein (CRP)-was done with a Cox proportional hazards model.

RESULTS

When TTR exceeded 94 days, the adjusted hazard of reinfection was increased 2.8-fold (95% CI 1.4-5.7; p = 0.0036). The reinfection-free rate was 67% (95% CI 52-79%) after 2 years and 33% (95% CI 11-57%) after 5 years for a longer TTR compared to 89% (95% CI 81-94%) and 80% (95% CI 69-87%) at 2 and 5 years, respectively, for a shorter TTR. Adjusted overall survival and number of aseptic revisions did not differ between the longer TTR and shorter TTR groups. Maximum knee flexion was 90° (IQR 84-100) for a longer TTR and 95° (IQR 90-100) for a shorter TTR (p = 0.0431), with no difference between the groups in Oxford Knee Score. Baseline characteristics were similar (body mass index, age, previous surgeries, microorganisms) for the two groups, except that there was a higher CCI (median 4 vs. 3) and higher CRP (median 3.7 vs 2.6 mg/dl) in the longer TTR group.

CONCLUSION

A long TTR is sometimes unavoidable in clinical practice, but surgeons should be aware of a potentially higher risk of reinfection.

LEVEL OF EVIDENCE

III, retrospective comparative study.

Neutrophil to Lymphocyte Ratio as an Indicator of Periprosthetic Joint Infection: A Retrospective Cohort Study

INTRODUCTION

Periprosthetic joint infection (PJI) after total joint arthroplasty (TJA) is a serious complication posing notable clinical implications for patients and substantial economic burdens. Neutrophil to lymphocyte ratio (NLR) is an emerging biomarker of inflammation, which may better predict PJI. The objective of this review was to evaluate NLR changes in patients with confirmed PJI, to compare NLR between an aseptic revision and a revision for PJI, and to establish whether an NLR of 2.45 is an appropriate cutoff for predicting infection.

METHODS

A retrospective review of patients who underwent revision TJA for PJI at a single center between January 1, 2005, and December 31, 2018, was performed and compared with an aseptic cohort who underwent aseptic revision TJA. NLR was calculated from complete blood counts performed at index surgery and at the time of revision surgery. Receiver operating characteristic curves were analyzed, along with sensitivity, specificity, and positive and negative likelihood ratios.

RESULTS

There were 89 patients included in each cohort. Mean NLR in patients who underwent revision for PJI was 2.85 (± 1.27) at the time of index surgery and 6.89 (± 6.64) at the time of revision surgery ( P = 0.017). Mean NLR in patients undergoing revision for PJI (6.89) was significantly higher than aseptic revisions (3.17; P < 0.001).

DISCUSSION

In patients who underwent revision surgery for PJI, NLR was markedly elevated at time of revision compared with the time of index surgery. Because it is a cost-effective and readily available test, these findings suggest that NLR may be a useful triage test in the diagnosis of PJI.

LEVEL OF EVIDENCE

Level III Diagnostic Study.

A meta-analysis on the role of sonication in the diagnosis of cardiac implantable electronic device-related infections

Introduction

One of the biggest obstacles in diagnosing Implant-Associated Infections is the lack of infection criteria and standardized diagnostic methods. These infections present a wide range of symptoms, and their diagnosis can be hampered by the formation of microbial biofilms on the surface of implants. This study aimed to provide insight into the performance of sonication in the diagnosis of infections associated with Cardiac Implantable Electronic Devices, to help define a consensus on the algorithm for the microbial diagnosis of these infections.

Methods

We carried out a systematic review with meta-analysis. The PRISMA methodology guidelines were followed, and an advanced search was carried out in PubMed and Web of Science, which enabled 8 articles to be included in the review, in which a meta-analysis was also carried out. QUADAS-2 was used to assess the risk of bias and effect measures were calculated to assess publication bias.

Results

The overall sensitivity of the method was 0.823 (95% CI: 0.682-0.910) and the specificity was 0.632 (95% CI: 0.506-0.743).

Discussion

These results suggest that sonication may offer advantages in diagnosing these infections. However, it is essential to approach these findings carefully and take into account the recommendations provided in the EHRA 2019 guidelines. This study highlights the importance of more effective diagnostic approaches for implantable medical device-associated infections to improve the quality of treatment and minimize the risks associated with these challenging medical conditions.

Effect of tobacco usage on surgical site wound problems after primary total hip and total knee arthroplasty: A meta-analysis

The meta-analysis aims to assess and compare the effect of tobacco usage on surgical site wound problems (SSWPs) after primary total hip and total knee arthroplasty (PTH&TKA). Using dichotomous random- or fixed-effects models, the outcomes of this meta-analysis were examined, and the odds ratio (OR) with 95% confidence intervals (CIs) was computed. Fifteen studies from 2001 to 2023 were enrolled for the present meta-analysis including 560 819 personals with PTH&TKA. Smokers had significantly higher SSWPs (OR, 1.53; 95% CI, 1.21-1.94, p < 0.001) compared with non-smokers in personals with PTH&TKA. Current smokers had significantly higher SSWPs (OR, 1.59; 95% CI, 1.40-1.80, p < 0.001) compared with non-smokers in personals with PTH&TKA. Current smokers had significantly higher SSWPs (OR, 1.42; 95% CI, 1.19-1.70, p < 0.001) compared with former smokers in personals with PTH&TKA. However, former smokers and non-smokers had no significant difference in SSWPs (OR, 1.11; 95% CI, 0.95-1.30, p = 19) in personals with PTH&TKA. The examined data revealed that in personals with PTH&TKA smokers had significantly higher SSWPs compared with non-smokers, and current smokers had significantly higher SSWPs compared with non-smokers and former smokers; however, former smokers and non-smokers had no significant difference in SSWPs. Yet, attention should be implemented while relating to its values since some of the comparisons were made using a low number of selected studies.

Symptomatic Benign Prostatic Hyperplasia Is Not Associated With a Higher Risk of Periprosthetic Joint Infections and Periprosthetic Joint Infection-related Revisions After Primary THA

BACKGROUND

Symptomatic benign prostatic hyperplasia (sBPH) is a potential risk factor for periprosthetic joint infection (PJI), a leading cause of implant failure and revision THA. However, the available evidence is mixed on whether this is the case.

QUESTIONS/PURPOSES

(1) What is the prevalence of sBPH in male recipients of primary THA by age group? (2) Do patients with sBPH compared with those without sBPH have higher 30-day, 90-day, and 2-year odds of PJI and higher 30-day and 90-day odds of urinary catheterization, urinary tract infection (UTI), and sepsis after primary THA? (3) Do patients with sBPH compared with those without sBPH have lower survivorship free from PJI-related revision at 5 years after THA?

METHODS

The PearlDiver database was used as it provided the largest sample of patients across all payer types to perform longitudinal research. Between January 2010 and April 2021, 1,056,119 patients who underwent primary THA were identified. After applying the inclusion criteria (that is, male sex, minimum age of 18, and diagnosis of hip osteoarthritis) and exclusion criteria (that is, history of asymptomatic BPH or any other joint arthroplasty), 16% (172,866) of patients remained. A further 6% (59,500) of patients were excluded as they did not meet the minimum study follow-up of 2 years, leaving 11% (113,366) for analysis. Of those, patients with sBPH were matched to those without in a 1:4 ratio by age and comorbidities, including alcohol abuse, anemia, cardiovascular disorders, chronic pulmonary disease, diabetes mellitus, depression, obesity, peripheral vascular disorders, renal failure, and rheumatoid arthritis. Age and comorbidities of the two groups postmatch were balanced. Logistic regression was performed to analyze the odds for 30-day, 90-day, and 2-year postoperative complications. Survivorship free from PJI-related revision at 5 years after THA was estimated using the Kaplan-Meier method and compared with the log-rank test.

RESULTS

Among male recipients of primary THA ages 65 or older, 24% (11,319 of 47,426) had a medical history of sBPH. We found no difference in the odds of PJI at 30 days, 90 days, and 2 years after primary THA between the two groups. PJI occurred in 0.5% (62 of 11,819), 0.8% (97 of 11,819), and 1.3% (150 of 11,819) of patients with sBPH versus in 0.5% (227 of 47,103), 0.8% (360 of 47,103), and 1.2% (570 of 47,103) of those without sBPH within 30 days (OR 1.09 [95% CI 0.82 to 1.43]), 90 days (OR 1.07 [95% CI 0.85 to 1.34]), and 2 years (OR 1.05 [95% CI 0.87 to 1.25]) after THA, respectively. Patients with sBPH compared with those without had higher odds of 30-day and 90-day urinary catheterization (OR 5.00 [95% CI 3.64 to 6.88] and OR 5.36 [95% CI 4.04 to 7.13], respectively), 30-day and 90-day UTI (OR 2.18 [95% CI 1.88 to 2.54] and OR 2.55 [95% CI 2.26 to 2.87], respectively), and 30-day and 90-day sepsis (OR 1.55 [95% CI 1.11 to 2.13] and OR 1.43 [95% CI 1.10 to 1.83], respectively). We found no difference in survival free from PJI-related revision at 5 years after THA between patients with and without sBPH (98.3% [95% CI 98.1% to 98.6%] versus 98.1% [95% CI 98.1% to 98.2%]; p = 0.10).

CONCLUSION

sBPH is common among THA recipients, and surgeons should be aware of the added risk of postoperative urinary complications and sepsis in this subset that could lead to additional postoperative care requirements. Surgeons may consider perioperative measures such as preoperative use of short-form questionnaires to assess urinary symptoms, urology clearance or referral, and closer follow-up to improve care of sBPH patients undergoing THA. As currently available tools for assessing sBPH are limited and lack sensitivity as well as specificity, future studies may develop validated tools that can be used to quickly assess risk in sBPH patients before surgery.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Decreasing trend of inpatient mortality rates of aseptic versus septic revision total hip arthroplasty: an analysis of 681,034 cases

BACKGROUND

While most revision total hip arthroplasties (rTHAs) are for aseptic loosening/instability, infection accounts for approximately 16%. The purpose of this study was to: (1) quantify mortality rates of aseptic versus septic rTHA; (2) determine if mortality rates have changed over the past 20 years; and (3) identify associated preoperative risk factors, focusing on the utility/validity of the Elixhauser comorbidity index (ECI).

METHODS

ICD-9/ICD-10 codes were used to identify patients undergoing rTHA in the National Inpatient Sample database between 1998 and 2017. A total of 681,034 cases (576,143 aseptic THA and 104,891 septic THA) were identified. For each patient, demographic variables including age, sex, race, insurance type, ECI, and inhospital mortality were gathered. A logistic regression model was constructed to assess risk of inhospital mortality.

RESULTS

From 1998 to 2017, inpatient mortality rates of aseptic and septic rTHA decreased from 0.83 to 0.45%, and from 2.58 to 1.24%, respectively. Septic rTHA was independently associated with higher odds of mortality relative to aseptic (odds ratio (OR): 2.305, 95% confidence interval (CI): (2.014, 2.638), p < 0.0001). Increased ECI was associated with higher odds of mortality at both medium (OR: 5.147, 95% CI: (4.433,5.977), p < 0.0001) and high index scores (OR: 13.714, 95% CI: (11.519,16.326), p < 0.0001).

CONCLUSIONS

Mortality rates for both aseptic and septic rTHA have been declining over the past 20 years, potentially due to patient selection guidelines and advances in medical management. Our study confirms that the ECI is independently associated with increased inpatient mortality.

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

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

Incidence, Microbiological Studies, and Factors Associated With Prosthetic Joint Infection After Total Knee Arthroplasty

Importance

Despite the frequency of total knee arthroplasty (TKA) and clinical implications of prosthetic joint infections (PJIs), knowledge gaps remain concerning the incidence, microbiological study results, and factors associated with these infections.

Objectives

To identify the incidence rates, organisms isolated from microbiological studies, and patient and surgical factors of PJI occurring early, delayed, and late after primary TKA.

Design, Setting, and Participants

This cohort study obtained data from the US Department of Veterans Affairs (VA) Corporate Data Warehouse on patients who underwent elective primary TKA in the VA system between October 1, 1999, and September 30, 2019, and had at least 1 year of care in the VA prior to TKA. Patients who met these criteria were included in the overall cohort, and patients with linked Veterans Affairs Surgical Quality Improvement Program (VASQIP) data composed the VASQIP cohort. Data were analyzed between December 9, 2021, and September 18, 2023.

Exposures

Primary TKA as well as demographic, clinical, and perioperative factors.

Main Outcomes and Measures

Incident hospitalization with early, delayed, or late PJI. Incidence rate (events per 10 000 person-months) was measured in 3 postoperative periods: early (≤3 months), delayed (between >3 and ≤12 months), and late (>12 months). Unadjusted Poisson regression was used to estimate incidence rate ratios (IRRs) with 95% CIs of early and delayed PJI compared with late PJI. The frequency of organisms isolated from synovial or operative tissue culture results of PJIs during each postoperative period was identified. A piecewise exponential parametric survival model was used to estimate IRRs with 95% CIs associated with demographic and clinical factors in each postoperative period.

Results

The 79 367 patients (median (IQR) age of 65 (60-71) years) in the overall cohort who underwent primary TKA included 75 274 males (94.8%). A total of 1599 PJIs (2.0%) were identified. The incidence rate of PJI was higher in the early (26.8 [95% CI, 24.8-29.0] events per 10 000 person-months; IRR, 20.7 [95% CI, 18.5-23.1]) and delayed periods (5.4 [95% CI, 4.9-6.0] events per 10 000 person-months; IRR, 4.2 [95% CI, 3.7-4.8]) vs the late postoperative period (1.3 events per 10 000 person-months). Staphylococcus aureus was the most common organism isolated overall (489 [33.2%]); however, gram-negative infections were isolated in 15.4% (86) of early PJIs. In multivariable analyses, hepatitis C virus infection, peripheral artery disease, and autoimmune inflammatory arthritis were associated with PJI across all postoperative periods. Diabetes, chronic kidney disease, and obesity (body mass index of ≥30) were not associated factors. Other period-specific factors were identified.

Conclusions and Relevance

This cohort study found that incidence rates of PJIs were higher in the early and delayed vs late post-TKA period; there were differences in microbiological cultures and factors associated with each postoperative period. These findings have implications for postoperative antibiotic use, stratification of PJI risk according to postoperative time, and PJI risk factor modification.

Two-Stage Exchange Using a Total Femur Spacer in the Management of Periprosthetic Joint Infection - Spacer Complications and Implant Survivorships

BACKGROUND

Chronic periprosthetic joint infection after revision hip and knee arthroplasties can lead to subsequent massive femoral bone loss. In these cases, resection of the residual femur and placement of an antibiotic total femoral spacer can be an option to salvage the limb.

METHODS

This is a single-center retrospective analysis of 32 patients (median age 67 years; range 15-93; 18 women) who underwent placement of a total femur spacer for chronic periprosthetic joint infection with massive femoral bone loss between 2010 and 2019 as part of a planned two-stage exchange. The median follow-up period amounted to 46 months (range, 1-149). Implant and limb survival were analyzed using Kaplan-Meier survival estimates. Potential risk factors for failure were analyzed.

RESULTS

There were 34% (11 of 32) of patients having a spacer-associated complication, and 25% underwent revision for this reason. After the first stage, 92% were considered infection-free. There were 84% of patients who underwent second-stage reimplantation of a total femoral arthroplasty using a modular megaprosthetic implant. Infection-free implant survival was 85% after 2 years and 53% after 5 years. There were 44% of patients who underwent amputation after a median time of 40 months (range, 2-110). Most commonly, coagulase-negative staphylococci were cultured at first-stage surgery, while polymicrobial growth was most common at reinfection.

CONCLUSION

Total femur spacers can lead to infection control in over 90% of cases with a reasonable complication rate for the spacer itself. However, the reinfection and subsequent amputation rate after second-stage megaprosthetic total femoral arthroplasty is around 50%.

An artificial intelligence framework for the diagnosis of prosthetic joint infection based on 99mTc-MDP dynamic bone scintigraphy

OBJECTIVES

Dynamic bone scintigraphy (DBS) is the first widely reliable and simple imaging modality in nuclear medicine that can be used to diagnose prosthetic joint infection (PJI). We aimed to apply artificial intelligence to diagnose PJI in patients after total hip or knee arthroplasty (THA or TKA) based on 99mTc-methylene diphosphonate (99mTc-MDP) DBS.

METHODS

A total of 449 patients (255 THAs and 194 TKAs) with a final diagnosis were retrospectively enrolled and analyzed. The dataset was divided into a training and validation set and an independent test set. A customized framework composed of two data preprocessing algorithms and a diagnosis model (dynamic bone scintigraphy effective neural network, DBS-eNet) was compared with mainstream modified classification models and experienced nuclear medicine specialists on corresponding datasets.

RESULTS

In the fivefold cross-validation test, diagnostic accuracies of 86.48% for prosthetic knee infection (PKI) and 86.33% for prosthetic hip infection (PHI) were obtained using the proposed framework. On the independent test set, the diagnostic accuracies and AUC values were 87.74% and 0.957 for PKI and 86.36% and 0.906 for PHI, respectively. The customized framework demonstrated better overall diagnostic performance compared to other classification models and showed superiority in diagnosing PKI and consistency in diagnosing PHI compared to specialists.

CONCLUSION

The customized framework can be used to effectively and accurately diagnose PJI based on 99mTc-MDP DBS. The excellent diagnostic performance of this method indicates its potential clinical practical value in the future.

KEY POINTS

• The proposed framework in the current study achieved high diagnostic performance for prosthetic knee infection (PKI) and prosthetic hip infection (PHI) with AUC values of 0.957 and 0.906, respectively. • The customized framework demonstrated better overall diagnostic performance compared to other classification models. • Compared to experienced nuclear medicine physicians, the customized framework showed superiority in diagnosing PKI and consistency in diagnosing PHI.

Utility of Diagnostic Markers in Late Periprosthetic Joint Infection Workup for Total Knee Arthroplasty Patients Who Received Antibiotics 48 Hours Before Aspiration

BACKGROUND

Diagnosing periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) remains challenging despite recent advancements in testing and evolving criteria over the last decade. Moreover, the effects of antibiotic use on diagnostic markers are not fully understood. Thus, this study sought to determine the influence of antibiotic use within 48 hours before knee aspiration on synovial and serum laboratory values for suspected late PJI.

METHODS

Patients who underwent a TKA and subsequent knee arthrocentesis for PJI workup at least 6 weeks after their index arthroplasty were reviewed across a single healthcare system from 2013 to 2020. Median synovial white blood cell (WBC) count, synovial polymorphonuclear (PMN) percentage, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), and serum WBC count were compared between immediate antibiotic and nonantibiotic PJI groups. Receiver operating characteristic (ROC) curves and Youden's index were used to determine test performance and diagnostic cutoffs for the immediate antibiotics group.

RESULTS

The immediate antibiotics group had significantly more culture-negative PJIs than the no antibiotics group (38.1 versus 16.2%, P = .0124). Synovial WBC count demonstrated excellent discriminatory ability for late PJI in the immediate antibiotics group (area under curve, AUC = 0.97), followed by synovial PMN percentage (AUC = 0.88), serum CRP (AUC = 0.86), and serum ESR (AUC = 0.82).

CONCLUSION

Antibiotic use immediately preceding knee aspiration should not preclude the utility of synovial and serum lab values for the diagnosis of late PJI. Instead, these markers should be considered thoroughly during infection workup considering the high rate of culture-negative PJI in these patients.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Induction Heating Triggers Antibiotic Release and Synergistic Bacterial Killing on Polymer-Coated Titanium Surfaces

Infection is a major complication associated with orthopedic implants. It often involves the development of biofilms on metal substrates, which act as barriers to the host's immune system and systemic antibiotic treatment. The current standard of treatment is revision surgery, often involving the delivery of antibiotics through incorporation into bone cements. However, these materials exhibit sub-optimal antibiotic release kinetics and revision surgeries have drawbacks of high cost and recovery time. Herein, a new approach is presented using induction heating of a metal substrate, combined with an antibiotic-loaded poly(ester amide) coating undergoing a glass transition just above physiological temperature to enable thermally triggered antibiotic release. At normal physiological temperature, the coating provides a rifampicin depot for >100 days, while heating of the coating accelerates drug release, with >20% release over a 1-h induction heating cycle. Induction heating or antibiotic-loaded coating alone each reduce Staphylococcus aureus (S. aureus) viability and biofilm formation on Ti, but the combination causes synergistic killing of S. aureus as measured by crystal violet staining, determination of bacterial viability (>99.9% reduction), and fluorescence microscopy of bacteria on surfaces. Overall, these materials provide a promising platform enabling externally triggered antibiotic release to prevent and/or treat bacterial colonization of implants.

Cost-effectiveness and clinical utility of universal pre-admission MRSA screening in total joint arthroplasty patients

BACKGROUND

For patients undergoing total joint arthroplasty (TJA), pre-admission meticillin-resistant Staphylococcus aureus (MRSA) nasal screening has been widely adopted to prevent postoperative joint infection. However, screening cost-effectiveness and clinical utility have not been adequately evaluated.

AIM

To assess the MRSA infection rate, associated costs, and costs of screening at our institution, before and after screening implementation.

METHODS

This was a retrospective cohort study examining patients who underwent TJA at a health system in New York State, between 2005 and 2016. Patients were divided into the 'no-screening' group if the operation occurred prior to adoption of the MRSA screening protocol in 2011 and the 'screening' group if afterwards. The number of MRSA joint infections, cost of each infection, and costs associated with preoperative screening were recorded. Fisher's exact test and cost comparison analysis were performed.

FINDINGS

The no-screening group had four MRSA infections in 6088 patients over a seven-year period, whereas the screening group had two in 5177 patients over five years. Fisher's exact test showed no significant association between screening and MRSA infection rate (P = 0.694). The cost of postoperative MRSA joint infection treatment was US$40,919.13 per patient, whereas annual nasal screening was US$103,999.97.

CONCLUSION

At our institution, MRSA screening had little impact on infection rates and led to increased costs, with 2.5 MRSA infections required annually to meet the costs of screening. Therefore, the screening protocol may be best suited for high-risk populations, rather than the average TJA patient. The authors recommend a similar clinical utility and cost-effectiveness analysis at other institutions implementing MRSA screening programmes.

Current relevance of biomarkers in diagnosis of periprosthetic joint infection: an update

With a significant rise in the number of arthroplasty procedures performed worldwide, the increasing revision burden posed by periprosthetic joint infection (PJI) is a matter of growing concern. In spite of various attempts to diagnose PJI, there are no defined tests that can be called a gold standard. Given the importance of early diagnosis in PJI, newer tests and biomarkers have been introduced to improve cumulative diagnostic accuracy. Novel biomarkers like calprotectin, lipocalcin, monocyte-to-lymphocyte ratio, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and platelet-to-mean platelet volume ratio have demonstrated a potential as diagnostic biomarkers for PJI. This article discusses the relevance of available and newly described diagnostic biomarkers to provide a perspective on the practical applicability in current medical practice, as well as highlights some recent advances in biomarkers for the diagnosis of PJI.

Selecting a high-dose antibiotic-laden cement knee spacer

Prosthetic joint infection [PJI] after total knee arthroplasty (TKA) remains a common and challenging problem for joint replacement surgeons and patients. Once the diagnosis of PJI has been made, patient goals and characteristics as well as the infection timeline dictate treatment. Most commonly, this involves a two-stage procedure with the removal of all implants, debridement, and placement of a static or dynamic antibiotic spacer. Static spacers are commonly indicated for older, less healthy patients that would benefit from soft tissue rest after initial debridement. Mobile spacers are typically used in younger, healthier patients to improve quality of life and reduce soft-tissue contractures during antibiotic spacer treatment. Spacers are highly customizable with regard to antibiotic choice, cement variety, and spacer design, each with reported advantages, drawbacks, and indications that will be covered in this article. While no spacer is superior to any other, the modern arthroplasty surgeon must be familiar with the available modalities to optimize treatment for each patient. Here we propose a treatment algorithm to assist surgeons in deciding on treatment for PJI after TKA.

Projections and Epidemiology of Revision Hip and Knee Arthroplasty in the United States to 2040-2060

Background

National projections of future joint arthroplasties are useful in understanding the changing burden of surgery and related outcomes on the health system. The aim of this study is to update the literature by producing Medicare projections for revision total joint arthroplasty procedures from 2040 through 2060.

Methods

The study uses 2000-2019 data from the CMS Medicare Part-B National Summary and combines procedure counts using CPT codes for revision total joint arthroplasty procedures. In 2019, revision total knee arthroplasty (rTKA) and revision total hip arthroplasty (rTHA) procedures totaled 53,217 and 30,541, respectively, forming a baseline from which we generated point forecasts between 2020 and 2060 and 95% forecast intervals (FI).

Results

On average, the model projects an annual growth rate of 1.77% for rTHAs and 4.67% for rTKAs. By 2040, rTHAs were projected to be 43,514 (95% FI = 37,429-50,589) and rTKAs were projected to be 115,147 (95% FI = 105,640-125,510). By 2060, rTHAs was projected to be 61,764 (95% FI = 49,927-76,408) and rTKAs were projected to be 286,740 (95% FI = 253,882-323,852).

Conclusions

Based on 2019 total volume counts, the log-linear exponential model forecasts an increase in rTHA procedures of 42% by 2040 and 101% by 2060. Similarly, the estimated increase for rTKA is projected to be 149% by 2040 and 520% by 2060. An accurate projection of future revision procedure demands is important to understand future healthcare utilization and surgeon demand. This finding is only applicable to the Medicare population and demands further analysis for other population groups.

Epidemiology of primary and revision total knee arthroplasty: analysis of demographics, comorbidities and outcomes from the national inpatient sample

INTRODUCTION

Primary total knee arthroplasty (TKA) is a preferred treatment for end-stage knee osteoarthritis. In the setting of a failed TKA, revision total knee arthroplasty (rTKA) acts as a salvage procedure and carries a higher risk compared to primary TKA. Given increased interest in postoperative outcomes from these procedures, a thorough understanding of the demographics, comorbidities, and inpatient outcomes is warranted. This study aimed to report the epidemiological data of demographics, comorbidity profiles and outcomes of patients undergoing TKA and rTKA.

METHODS

A retrospective review of NIS registry discharge data from 2006 to 2015 third quarter was performed. This study included adults aged 40 and older who underwent TKA or rTKA. A total of 5,901,057 TKA patients and 465,968 rTKA patients were included in this study. Simple descriptive statistics were used to present variables on demographics, medical comorbidities, and postoperative complications.

RESULTS

A total of 5,901,057 TKA and 465,968 rTKA discharges were included in this study, with an average age of 66.30 and 66.56 years, and the major payor being Medicare, accounting for 55.34% and 59.88% of TKA and rTKA cases, respectively. Infection (24.62%) was the most frequent reason for rTKA, and was followed by mechanical complications (18.62%) and dislocation (7.67%). The most common medical comorbidities for both groups were hypertension, obesity, and diabetes. All types of inpatient complications were reported in 22.21% TKA and 28.78% of rTKA cases. Postoperative anemia was the most common complication in both groups (20.34% vs. 25.05%).

CONCLUSIONS

Our data demonstrated a 41.9% increase in patients receiving TKA and 28.8% increase in rTKA from the years 2006 to 2014. The data showed a 22.21% and a 28.78% "complication" rate with TKA and rTKA, with postoperative anemia being the most common complication. The top 3 medical comorbidities were hypertension, obesity, and diabetes for both groups and with increased focus on perioperative optimization, future analyses into preoperative medical optimization, and improved primary arthroplasty protocol may result in improved postoperative outcomes.

Mapping bacterial biofilm on explanted orthopedic hardware: An analysis of 14 consecutive cases

Hardware implanted during primary total joint arthroplasty carries a serious risk for periprosthetic joint infection (PJI). The formation of bacterial biofilms, which are highly tolerant of antibiotics and host immunity, is recognized as being a major barrier to treatment. It is not known whether some components and their surface features are more prone to biofilm than others. This study attempted to map biofilm on different components and features of orthopedic hardware recovered during revision. Implant surface culture (ISC) was used on 53 components from 14 hip and knee revisions. ISC achieves a thin agar coating over components, followed by incubation and observation for colony outgrowth over 9 days. Recovered organisms were identified by selective culture and 16s rRNA sequencing. Outcomes were compared with clinical culturing and PJI diagnosis based on 2013 Musculoskeletal Infection Society criteria. ISC paralleled clinical culturing with a sensitivity of 100% and a specificity of 57.1%. When compared to Musculoskeletal Infection Society criteria, sensitivity remained at 100% while specificity was 80%. Biofilm accumulation was patchy and heterogeneous throughout different prostheses, though notably the non-articulating surfaces between the tibial tray and polyethylene insert showed consistent growth. On individual components, ridges and edges consistently harbored biofilm, while growth elsewhere was case dependent. ISC successfully identified microbial growth with high sensitivity while also revealing that biofilm growth was commonly localized to particular locations. Understanding where biofilm formation occurs most often on implanted hardware will help guide debridement, retention choices, and implant design.

Absolute synovial polymorphonuclear neutrophil cell count as a biomarker of periprosthetic joint infection

The aim of this study was to evaluate the diagnostic accuracy of the absolute synovial polymorphonuclear neutrophil cell (PMN) count for the diagnosis or exclusion of periprosthetic joint infection (PJI) after total hip (THA) or knee arthroplasty (TKA). In this retrospective cohort study, 147 consecutive patients with acute or chronic complaints following THA and TKA were included. Diagnosis of PJI was established based on the 2018 International Consensus Meeting criteria. A total of 39 patients diagnosed with PJI (32 chronic and seven acute) and 108 patients with aseptic complications were surgically revised. Using receiver operating characteristic curves and calculating the area under the curve (AUC), an optimal synovial cut-off value of 2,000 PMN/µl was determined (AUC 0.978 (95% confidence interval (CI) 0.946 to 1)). Using this cut-off, sensitivity and specificity of absolute synovial PMN count for PJI were 97.4% (95% CI 91.2 to 100) and 93.5% (95% CI 88.9 to 98.1), respectively. Positive and negative predictive value were 84.4% (95% CI 72.7 to 93.9) and 99.0% (95% CI 96.7 to 100), respectively. Exclusion of 20 patients with acute complications improved specificity to 97.9% (95% CI 94.6 to 100). Different cut-off values for THA (< 3,600 PMN/µl) and TKA (< 2,000 PMN/µl) were identified. Absolute synovial PMN count correlated strongly with synovial alpha-defensin (AD) (r = 0.759; p < 0.001). With a positive AD result, no additional PJI could be identified in any case. Absolute synovial PMN count is a widely available, rapid, cost-effective, and accurate marker in PJI diagnostics, whereas synovial AD appears to be a surrogate parameter of absolute synovial PMN count. Despite limitations in the early postoperative phase, wear, and rheumatic diseases in confirming PJI, an absolute synovial PMN count below 2,000/µl is highly suitable for ruling out PJI, with specific cut-off values for THA and TKA.

Promoting Silk Fibroin Adhesion to Stainless Steel Surfaces by Interface Tailoring

Bonding dissimilar materials has been a persistent challenge for decades. This paper presents a method to modify a stainless steel surface (316 L), routinely used in medical applications to enable the significant adhesion of a biopolymer (silk fibroin). The metallic surface was first covalently grafting with polyacrylamide, to enable a hydrogen bonding compatible surface. The polymerisation was initiated via the irreversible electrochemical reduction of a 4-nitrobenzene diazonium salt (20 mM), in the presence of an acrylamide monomer (1 M) at progressively faster scan rates (0.01 V/s to 1 V/s). Examination of the modified samples by FT-IR was consistent with successful surface modification, via observations of the acrylamide carbonyl (1600-1650 cm^-1 ) was observed, with more intense peaks correlating to slower scan rates. Similar observations were made with respect to increasing surface polarity, assessed by water contact angle. Reductions of >60° were observed for the grafted surfaces, relative to the unmodified control materials, indicating a surface able to undergo significant hydrogen bonding. The adhesion of silk to the metallic surface was quantified using a lap shear test, effectively using silk fibroin as an adhesive. Adhesion improvements of 5-7-fold, from 4.1 MPa to 29.3 MPa per gram of silk fibroin, were observed for the treated samples, highlighting the beneficial effect of this surface treatment. The methods developed in this work can be transferred to any metallic (or conductive) surface and can be tailored to complement any desired interface.