Do Culture Negative Periprosthetic Joint Infections Remain Culture Negative?

Timing-specific Debridement, Antibiotics, and Implant Retention and 2-Stage Revision for Megaprosthesis-Related Infection: Optimizing the Window Period for Improved Outcomes

Background

This study aimed to evaluate the outcomes of debridement, antibiotics, and implant retention (DAIR) procedures and 2-stage revision surgeries in patients with periprosthetic joint infection following megaprosthesis, including treatment failure; the patient-reported outcomes; and to determine the survival rates of the revised megaprosthesis.

Methods

A retrospective study of 30 patients diagnosed with periprosthetic joint infection following megaprosthesis between 2018 and 2023, with minimum 1-year follow-up. Patients with previous unsuccessful debridement in other institutions were excluded. Patients presenting within 4 weeks of megaprosthesis implantation underwent the DAIR procedure, while those presenting after this window were taken for a 2-stage revision surgery. The primary outcome was treatment failure, defined as persistent wound complication or the need for subsequent surgical intervention. The secondary outcomes included patient-reported outcomes, assessed with the Oxford Hip Score and Oxford Knee Score, and the survival rates of the revised megaprosthesis.

Results

The mean follow-up duration for all patients was 38 ± 12.6 months. Improvement was found for Oxford Hip Score and Oxford Knee Score with mean 34.22 ± 9.2 and 32.40 ± 8.1, respectively, at the 1-year follow-up. DAIR achieved an 81% success rate (13 out of 16) and 2-stage exchange had a 71.4% success rate (10 out of 14).

Conclusions

Both DAIR and 2-stage exchange procedures yielded favorable functional outcomes with satisfactory 2-year survival function. Careful patient selection and indication management are crucial for optimal results.

Level of evidence

Level IV.

Agreement Analysis Among Hip and Knee Periprosthetic Joint Infections Classifications

Background/Objectives: A missed periprosthetic joint infection (PJI) diagnosis can lead to implant failure. However, to date, no gold standard for PJI diagnosis exists, although several classification scores have been developed in the past years. The primary objective of the study was the evaluation of inter-rater reliability between five PJI classification systems when defining a patient who is infected. Two secondary outcomes were further examined: the inter-rater reliability assessed by comparing the classifications in pairs, and the evaluation of each classification system within the subcategories defined by the World Association against Infection in Orthopaedics and Trauma (WAIOT) definition. Methods: Retrospectively collected data on patients with knee and hip PJIs were used to assess the agreement among five PJI scoring systems: the Musculoskeletal Infection Society (MSIS) 2013 definition, the Infection Consensus Group (ICG) 2018 definition, the European Bones and Joints Infection Society (EBJIS) 2018 definition, the WAIOT definition, and the EBJIS 2021 definition. Results: In total, 203 patients with PJI were included in the study, and the agreement among the examined scores was 0.90 (Krippendorff's alpha = 0.81; p-value < 0.001), with the MSIS 2013 and ICG 2018 classification systems showing the highest agreement (Cohen's Kappa = 0.91; p-value < 0.001). Conclusions: There is a strong agreement between the major PJI classification systems. However, a subset of patients (n = 11, 5.42%) still falls into a diagnostic grey zone, especially in cases of low-grade infections. This highlights the need for enhanced diagnostic criteria that incorporate tools that are available even with limited resources, and the potential of artificial intelligence-based techniques in improving early detection and management of PJIs.

Suction-Powered Intramedullary Bone Debridement Technology Compared to Conventional Curettage in Infected Revision Total Knee Arthroplasty

Background

Revision total knee arthroplasty (TKA) in the United States is an increasingly common procedure, often performed in the setting of prosthetic joint infection. Debridement of the intramedullary canals is traditionally performed with surgical curettes and is technically difficult and time-intensive. A suction-powered bone harvester (SPBH) is designed to improve the quality of debridement in a closed-capture system. This study assesses conventional curettage (CC) versus SPBH in debridement mass and time from intramedullary spaces. We hypothesize that SPBH will increase debridement yield more efficiently than conventional curettes.

Methods

Adult patients undergoing revision TKA were enrolled to participate in the study and were divided into 2 groups. Patients in group 1 received tibial debridement with CC followed by SPBH and femoral canals with SPBH alone. Patients in group 2 received femoral debridement with CC followed by SPBH and tibial canals with SPBH alone.

Results

Data were collected from 30 revision TKA cases in the setting of prosthetic joint infection. In total, 14 femora and 16 tibiae were initially debrided with SPBH, while the opposites were debrided with CC. On average, the intramedullary debridement with SPBH yielded 23.1 g compared to 13.2 g with CC (P = .0017). The intramedullary canal required 1 minute 28 seconds for debridement with SPBH compared to 2 minutes for debridement with CC (P = .0347). Culture data from samples obtained from SPBH were noninferior to CC.

Conclusions

SPBH is an effective tool for debridement of intramedullary canal during revision TKA. SPBH led to a significant increase of debrided mass in significantly less time than CC. There was no difference in positive culture yield between the 2 debridement techniques. This debridement technique merits consideration to reduce bioburden in revision TKA.

Reinfection Patterns Following Two-Stage Exchange for Periprosthetic Joint Infection: A Retrospective Analysis

BACKGROUND

Periprosthetic joint infection (PJI) is a challenging complication following total joint arthroplasty. A two-stage exchange has been the gold standard in the treatment of chronic PJI. However, when this fails, further treatment options become limited. In patients who fail two-stage exchange, the reinfecting organism is different from the original in 50 to 80% of the occurrences. This study aimed to understand reinfection patterns in an attempt to better predict reinfecting organisms to improve the management of PJI.

METHODS

A retrospective query of our institution's PJI registry identified 185 patients (188 procedures, 110 knees, and 78 hips) who underwent a first-time two-stage exchange for culture-positive chronic PJI of total knee and hip arthroplasties from January 2010 to December 2020. Patients who had polymicrobial infections, culture-negative results, or fungal infections were excluded. The primary outcome variable was reoperation for reinfection and comparing the index organism to the reinfecting organisms.

RESULTS

Of the 188 procedures, 31 (16.5%) failed due to reinfection. Among reinfections, 30 (96.8%) were gram-positive, with Staphylococcus aureus species accounting for 22 (71.0%) of the cases. The most common organisms cultured were for methicillin-sensitive S. Aureus, methicillin-resistant S. Aureus, coagulase-negative staphylococcus, and streptococcus. Of reinfections, 19 (61.3%) had a different organism, eight (25.8%) had the same organism, and four (12.9%) were culture-negative. Patients experiencing reinfection were significantly younger (P = 0.012), with no other patterns or predictors identified.

CONCLUSIONS

The majority of reinfections following a two-stage exchange for PJI occur with a different organism than the index infection. We did not find a reliable method to predict the reinfecting organisms based on the initial infecting organism alone. However, the same four gram-positive organisms were the most frequently encountered in both the primary infection and the reinfection. Further research is required to understand factors contributing to reinfection and help guide prevention strategies.

Serum C-Reactive Protein to Hemoglobin Ratio: Novel Biomarkers for the Diagnosis of Chronic Periprosthetic Joint Infection

BACKGROUND

Despite several markers being evaluated and available in recent years, diagnosing periprosthetic joint infection (PJI) remains challenging. There is a pressing need to explore reliable, economical, convenient, highly sensitive, and specific diagnostic biomarkers to diagnose PJI. This study aimed to investigate the diagnostic value of combined serum markers with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in PJI.

METHODS

A total of 841 revision arthroplasty cases, including 435 PJI and 406 non-PJI patients, were enrolled from January 2010 through December 2022. The diagnostic values of CRP, ESR, CRP + ESR, CRP or hemoglobin ratio (CHR), CRP or albumin ratio, CRP or hemoglobin + albumin ratio, ESR or hemoglobin ratio, ESR or albumin ratio, ESR or hemoglobin + albumin ratio, and hemoglobin + albumin were evaluated using sensitivity, specificity, and receiver operating characteristics analysis with area under the curve. The optimal threshold was determined using the Youden index.

RESULTS

The CHR had the highest area under the curve (0.87, 95% CI [confidence interval] 0.85 to 0.90) and sensitivity (0.81, 95% CI: 0.77 to 0.85), compared to other markers. The CHR exhibited reliable diagnostic adequacy for PJIs caused by low-virulent organisms (sensitivity 0.83, 95% CI: 0.76 to 0.89; specificity 0.83, 95% CI: 0.79 to 0.86). However, CHR displayed poor sensitivity (0.77, 95% CI: 0.67 to 0.86) in patients who have diabetes.

CONCLUSIONS

The CHR demonstrated better diagnostic strength in detecting chronic PJI than other classical markers, especially in identifying low-grade infections. Our findings offer new insights into a more accurate and comprehensive picture of pathogens and hosts, thereby improving the accuracy of diagnostic algorithms.

Effects of COVID-19 on short-term outcomes of hip arthroplasty: a multicenter, retrospective, propensity score matched study

PURPOSE

The Coronavirus Disease 2019 (COVID-19) pandemic delayed elective procedures such as total joint arthroplasty. As surgical volumes return to prepandemic levels, understanding the implications of COVID-19 becomes imperative. This study explored the effects of COVID-19 on the short-term outcomes of hip arthroplasty.

METHODS

This multicenter, retrospective, case-control study included patients who had undergone hip arthroplasty between 2020 and 2022. Propensity score matching (PSM) was performed to compare demographic characteristics, primary outcomes, and secondary outcomes between patients with a history of COVID-19 (COVID-19 cohort) and those without it (control cohort). The primary outcomes were surgical site infection, periprosthetic joint infection (PJI), dislocation, prosthesis loosening, deep vein thrombosis, and pulmonary embolism. The secondary outcomes were intraoperative blood loss, nerve injury, renal injury, urinary tract infection (UTI), pneumonia, and acute coronary syndrome.

RESULTS

The COVID-19 and control cohorts comprised 153 and 4925 patients, respectively. After PSM, significant between-cohort differences were observed in the incidence of pneumonia (p < 0.001) and UTI (p = 0.0424). The odds ratio for PJI was 1.62, which is not significant (p = 0.3238) but the culture-negativity rate is higher in the COVID-19 cohort (25%).

CONCLUSION

Our findings suggest that COVID-19 only elevated risks of postoperative pneumonia and UTI after hip arthroplasty. This disease significantly increases the risk of postoperative pneumonia but not of 90-day mortality or any major perioperative complication. On the other hand, PJI still remains a concern because its treatment is challenging owing to its culture-negativity, often necessitating the Girdlestone procedure.

The role of the medial head of the gastrocnemius myocutaneous flap transfer in the management of prosthesis exposure and deep joint infection following total knee arthroplasty

BACKGROUND

There is a lack of effective and innovative treatment for patients with prosthesis exposure and deep joint infection following total knee arthroplasty. This study explores the application of the medial head of the gastrocnemius myocutaneous flap transfer in these conditions, offering new therapeutic strategies for clinical practice.

METHODS

Clinical data of 68 patients with prosthesis exposure and deep joint infection following total knee arthroplasty were included and retrospectively analyzed. Patients were divided into one study group (n = 35, received medial head of the gastrocnemius myocutaneous flap transfer and vacuum sealing drainage) and one control group (n = 33, received vacuum sealing drainage). The total effective rates, visual analogue scale (VAS), Hospital for Special Surgery score (HSS), knee joint function, activity, inflammatory reactions, safety, and recurrence rate were compared between the two groups.

RESULTS

The total effective rate in the study group was higher than that in the control group. VAS scores in the study group were lower at 3 and 7 days after treatment. HSS scores were higher in the study group after treatment. The study group showed lower levels of hs-CRP and IL-6 after treatment. At 1 month and 3 months after treatment, the study group exhibited higher knee joint activity. There was no difference in the incidence of adverse reactions between the two groups, and the study group had a lower recurrence rate.

CONCLUSION

Medial head of the gastrocnemius myocutaneous flap transfer effectively improves knee joint function and activity, reduces pain, alleviates inflammatory reactions, and has fewer adverse reactions and a lower recurrence rate.

The Impact of Culture Negativity on the Outcomes of Revision Total Knee Arthroplasty for Chronic PJI

Culture-positive (CP) and culture-negative (CN) periprosthetic joint infections (PJI) remain a crucial area of research; however, current studies comparing these infections rely on unstandardized outcome reporting tools. Our study aimed to compare the outcomes of two-stage revision of CP and CN PJI using the standardized Musculoskeletal Infection Society (MSIS) outcome reporting tool. We retrospectively reviewed 138 patients who were diagnosed with PJI and indicated for two-stage revision total knee arthroplasty (rTKA). The majority of patients in both CP and CN cohorts achieved infection control without the need for reoperation (54.1% and 62.5%, respectively). There was a significant difference in the overall distribution of MSIS outcomes (p = 0.043), with a significantly greater rate of CN patients falling into Tier 1 (infection control without the use of suppressive antibiotics) (52.5% versus 29.6%, p = 0.011). There was also a significant difference in the distribution of septic versus aseptic reoperations after 2nd stage (p = 0.013), with more CP reoperations being septic and more CN reoperations being aseptic. The duration from first to second stage was significantly shorter in the CN cohort (p = 0.002). While overall infection control was similar between cohorts, these data suggest that the outcomes of two-stage rTKA are favorable in cases of CN PJI.

Optimal selection of specimens for metagenomic next-generation sequencing in diagnosing periprosthetic joint infections

Objective

This study aimed to assess the diagnostic value of metagenomic next-generation sequencing (mNGS) across synovial fluid, prosthetic sonicate fluid, and periprosthetic tissues among patients with periprosthetic joint infection (PJI), intending to optimize specimen selection for mNGS in these patients.

Methods

This prospective study involved 61 patients undergoing revision arthroplasty between September 2021 and September 2022 at the First Affiliated Hospital of Zhengzhou University. Among them, 43 cases were diagnosed as PJI, and 18 as aseptic loosening (AL) based on the American Musculoskeletal Infection Society (MSIS) criteria. Preoperative or intraoperative synovial fluid, periprosthetic tissues, and prosthetic sonicate fluid were collected, each divided into two portions for mNGS and culture. Comparative analyses were conducted between the microbiological results and diagnostic efficacy derived from mNGS and culture tests. Furthermore, the variability in mNGS diagnostic efficacy for PJI across different specimen types was assessed.

Results

The sensitivity and specificity of mNGS diagnosis was 93% and 94.4% for all types of PJI specimens; the sensitivity and specificity of culture diagnosis was 72.1% and 100%, respectively. The diagnostic sensitivity of mNGS was significantly higher than that of culture (X2 = 6.541, P=0.011), with no statistically significant difference in specificity (X2 = 1.029, P=0.310). The sensitivity of the synovial fluid was 83.7% and the specificity was 94.4%; the sensitivity of the prosthetic sonicate fluid was 90.7% and the specificity was 94.4%; and the sensitivity of the periprosthetic tissue was 81.4% and the specificity was 100%. Notably, the mNGS of prosthetic sonicate fluid displayed a superior pathogen detection rate compared to other specimen types.

Conclusion

mNGS can function as a precise diagnostic tool for identifying pathogens in PJI patients using three types of specimens. Due to its superior ability in pathogen identification, prosthetic sonicate fluid can replace synovial fluid and periprosthetic tissue as the optimal sample choice for mNGS.

Outcomes of culture-negative or -positive periprosthetic joint infections: A systematic review and meta-analysis

OBJECTIVES

This study overviewed the current database of studies on periprosthetic joint infections (PJIs) to compare outcomes and antibiotic side effects in culture-negative or culture-positive PJIs and assess treatment options for culture-negative PJIs.

PATIENTS AND METHODS

A systematic review and meta-analysis was undertaken using studies published before July 2022 in MEDLINE, EMBASE, and Cochrane Library. All studies comparing treatment of culture-negative or -positive PJIs were included. Afterward, the infection control rate, periprosthetic or spacer fracture, hip joint or spacer dislocation, and antibiotic side effects in different treatment methods of PJI were analyzed.

RESULTS

Eleven studies involving 1,747 patients were included. Most studies clearly defined the infection control criteria: no pain or swelling, no wound drainage, normal serology, and normal radiographic findings. Patients were followed until treatment failure, death, or until the last clinical visit without evidence of treatment failure. The two types of PJIs did not differ significantly in infection control rates (culture-negative PJI 79.2% vs. culture-positive PJI 76.6%; odds ratio [OR]=1.20, 95% confidence interval [CI]: 0.84 to 1.70), either after all types of surgical treatment or after two-stage revision arthroplasty (OR=1.12, 95% CI: 0.72 to 1.75), single-stage revision arthroplasty (OR=0.51, 95% CI: 0.19 to 1.37), or debridement, antibiotics, and implant retention (OR=0.88, 95% CI: 0.50 to 1.54). Similarly, we did not find differences in periprosthetic or spacer fracture and hip joint or spacer dislocation. For culture-negative PJIs, the infection control rate was 85.2% after two-stage revision arthroplasty, 90.6% after single-stage revision arthroplasty, and 69.7% after debridement, antibiotics, and implant retention. Data pooled from three studies showed higher incidence of antibiotic side effects for culture-negative PJIs.

CONCLUSION

The clinical outcomes of one-stage revision and two-stage revision are comparable. Therefore, both of them can be considered in surgical treatment for culture-negative PJIs. In addition, limited data showed a higher incidence of antibiotic side effects in culture-negative PJIs.

Profiling the Immune Response to Periprosthetic Joint Infection and Non-Infectious Arthroplasty Failure

Arthroplasty failure is a major complication of joint replacement surgery. It can be caused by periprosthetic joint infection (PJI) or non-infectious etiologies, and often requires surgical intervention and (in select scenarios) resection and reimplantation of implanted devices. Fast and accurate diagnosis of PJI and non-infectious arthroplasty failure (NIAF) is critical to direct medical and surgical treatment; differentiation of PJI from NIAF may, however, be unclear in some cases. Traditional culture, nucleic acid amplification tests, metagenomic, and metatranscriptomic techniques for microbial detection have had success in differentiating the two entities, although microbiologically negative apparent PJI remains a challenge. Single host biomarkers or, alternatively, more advanced immune response profiling-based approaches may be applied to differentiate PJI from NIAF, overcoming limitations of microbial-based detection methods and possibly, especially with newer approaches, augmenting them. In this review, current approaches to arthroplasty failure diagnosis are briefly overviewed, followed by a review of host-based approaches for differentiation of PJI from NIAF, including exciting futuristic combinational multi-omics methodologies that may both detect pathogens and assess biological responses, illuminating causes of arthroplasty failure.

Risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for the treatment of periprosthetic joint infection

BACKGROUND

Prosthesis removal and antibiotic bone cement spacer implantation is a very important link in two-stage revision of periprosthetic joint infection (PJI) after artificial joint replacement, which is key to the smooth progress of second-stage revision surgery. There are few reports on the risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for PJI. This study aimed to investigate the risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for the treatment of PJI.

METHODS

Clinical data of 40 patients who underwent prosthesis removal and antibiotic bone cement spacer implantation for PJI after arthroplasty in our hospital from January 2013 to July 2019 were retrospectively analyzed. During the follow-up period of at least 2 years, 21 patients underwent complete two-stage revision after the removal of the antibiotic bone cement spacer, and 19 patients did not receive a new prosthesis due to other factors, such as reinfection or the patient's wishes, record the infection control of patients during the treatment. Reinfection after prosthesis removal and antibiotic bone cement spacer implantation was defined as failure of effective control of infection, symptoms of reinfection, requires increased antibiotic therapy or reoperation. Multivariate Cox proportional hazards model was used to analyze the risk factors associated with reinfection after prosthesis removal and antibiotic bone cement spacer implantation.

RESULTS

Of the 40 patients, nine (22.5%) developed reinfection after prosthesis removal and antibiotic bone cement spacer implantation with a mean follow-up duration of 31 months, and multivariate analysis revealed that history of prior revision surgery (hazard ratio [HR] = 6.317, confidence interval [CI]: 1.495-26.700; p = 0.012) and presence of sinus tract before treatment (HR = 5.117, 95% CI: 1.199-21.828; p = 0.027) were independent risk factors for reinfection after prosthesis removal and antibiotic bone cement spacer implantation.

CONCLUSION

History of prior revision surgery and presence of sinus tract are two independent risk factors for reinfection in patients with PJI treated with prosthesis removal and antibiotic bone cement spacer implantation.

A Comparison of Outcomes of Culture positive and Culture negative Acute Knee Prosthetic Joint Infection following Debridement, Antibiotics and Implant Retention (DAIR)

PURPOSE

We aim to compare the outcome of culture-positive (CP PJI) and culture-negative (CN PJI) acute knee prosthetic joint infection (PJI) following debridement, antibiotics and implant retention (DAIR) with polyethylene insert exchange. We also aim to analyze the factors associated with the successful outcome of DAIR and the influence of failed DAIR on the outcome of subsequent two-stage revision arthroplasty.

METHODS

We performed a retrospective review of 36 consecutive patients who underwent DAIR for acute PJI between January 2013 and January 2018. The patient's demographic data, McPherson grade, surgical details, laboratory and microbiology data were retrieved from the medical records. All the patients have been followed up for a minimum of 3 years or until re-operation, revision or death and any complications, incidence of DAIR failure, revision and mortality were noted.

RESULTS

The mean follow-up was 4.9 ± 2.4 years. Among the 36 patients, 16 had CP PJI and 20 had CN PJI. Among the 16 patients with CP PJI, 8 patients had success with DAIR and 8 patients had a recurrence of infection (50%) at a mean of 21 months (range, 2 weeks to 55 months). Among the 20 patients with CN PJI, 14 patients had success with DAIR and 6 patients had a recurrence of infection [30% (6/20)] at a mean of 69 months (range, 13-221 months) (p < .05). The Kaplan-Meir survival analysis showed survivorship did not vary significantly between both groups (p > .05). Univariate regression analysis showed symptom duration of more than one month found to be significantly associated with the DAIR failure. There was no difference in failure rate after DAIR between age, Charlson comorbidity index, early postoperative versus acute hematogenous group and type of organism grown. Ten out of 14 DAIR failures were successfully managed with two-stage revision surgery with no recurrence of infection till the final follow-up. In the remaining 4 patients, one underwent re-debridement, two underwent arthrodesis and one was left with an antibiotic cement spacer.

CONCLUSION

DAIR with polyethylene exchange will give comparable results irrespective of the culture positivity. Symptom duration of more than 30 days for DAIR is significantly associated with DAIR failure. DAIR failures can be successfully managed with two-stage revision.

An Enhanced Understanding of Culture-Negative Periprosthetic Joint Infection with Next-Generation Sequencing: A Multicenter Study

BACKGROUND

The challenges of culture-negative periprosthetic joint infection (PJI) have led to the emergence of molecular methods of pathogen identification, including next-generation sequencing (NGS). While its increased sensitivity compared with traditional culture techniques is well documented, it is not fully known which organisms could be expected to be detected with use of NGS. The aim of this study was to describe the NGS profile of culture-negative PJI.

METHODS

Patients undergoing revision hip or knee arthroplasty from June 2016 to August 2020 at 14 institutions were prospectively recruited. Patients meeting International Consensus Meeting (ICM) criteria for PJI were included in this study. Intraoperative samples were obtained and concurrently sent for both routine culture and NGS. Patients for whom NGS was positive and standard culture was negative were included in our analysis.

RESULTS

The overall cohort included 301 patients who met the ICM criteria for PJI. Of these patients, 85 (28.2%) were culture-negative. A pathogen could be identified by NGS in 56 (65.9%) of these culture-negative patients. Seventeen species were identified as common based on a study-wide incidence threshold of 5%. NGS revealed a polymicrobial infection in 91.1% of culture-negative PJI cases, with the set of common species contributing to 82.4% of polymicrobial profiles. Escherichia coli, Cutibacterium acnes, Staphylococcus epidermidis, and Staphylococcus aureus ranked highest in terms of incidence and study-wide mean relative abundance and were most frequently the dominant organism when occurring in polymicrobial infections.

CONCLUSIONS

NGS provides a more comprehensive picture of the microbial profile of infection that is often missed by traditional culture. Examining the profile of PJI in a multicenter cohort using NGS, this study demonstrated that approximately two-thirds of culture-negative PJIs had identifiable opportunistically pathogenic organisms, and furthermore, the majority of infections were polymicrobial.

LEVEL OF EVIDENCE

Diagnostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Worse outcome of debridement, antibiotics, and implant retention in acute hematogenous infections than in postsurgical infections after total knee arthroplasty: a multicenter study

Background

We sought to determine (1) the success rate of debridement, antibiotics, and implant retention (DAIR) for acute periprosthetic joint infection (PJI) of the knee in patients with acute postsurgical infection and in those with acute hematogenous infection via a multicenter study, (2) the factors related to the failure of DAIR for overall acute PJI and acute hematogenous PJI via subgroup analysis, and (3) whether the PJI recurrence patterns differed between the two groups over time after DAIR.

Methods

This retrospective multicenter study included 101 acute knee PJI. Acute postsurgical PJI was defined as PJI diagnosed < 3 months following initial knee arthroplasty surgery. DAIR was performed for 34 cases of acute postsurgical PJIs (postsurgical group) and 67 cases of acute hematogenous PJIs (hematogenous group). The success rates between groups were compared, and factors related to DAIR failure were analyzed.

Results

The overall success rate of DAIR was 77%. The success rate tended to be higher in the postsurgical group than in the hematogenous group (p = 0.060). However, there was no significant factor related to DAIR failure in the subgroup analysis of acute hematogenous PJIs. In the postsurgical group, the recurrence of PJI occurred until 3 months, whereas in the hematogenous group, recurrence occurred for up to 2 years.

Conclusions

The failure rate tended to be higher in the acute hematogenous PJI group than in the acute postsurgical PJI group. Since acute hematogenous infections may recur for a longer period than postsurgical infections, careful follow-up is required after DAIR.

Antibiotic Therapy for Prosthetic Joint Infections: An Overview

Prosthetic joint infection (PJI) is a severe complication after arthroplasty. Its management combines surgical intervention, whose type depends on the clinical situation, and prolonged high-dose antibiotics adapted to the responsible microorganism(s) and the patient. Antibiotics are only one part of the therapeutic regimen and are closely related to the surgical strategy. Their efficacy depends to a large extent on the choice and quality of the surgical procedure, and the quality of the microbiological diagnosis. Although guidelines have been published, many aspects of antibiotic therapy remain poorly established. Choosing the optimal agent(s) is one aspect, with others being optimization of drugs' pharmacokinetic/pharmacodynamic parameters, the choice of administration route, use of monotherapy or combination regimens, therapeutic drug-monitoring and patient education to improve compliance and tolerance. Herein, we address PJI management based on recent literature data, guidelines and the experience of our referral center for complex bone-and-joint infections.

Fungal and mycobacterial cultures should not be routinely obtained for diagnostic work-up of patients with suspected periprosthetic joint infections

AIMS

Fungal and mycobacterial periprosthetic joint infections (PJI) are rare events. Clinicians are wary of missing these diagnoses, often leading to the routine ordering of fungal and mycobacterial cultures on periprosthetic specimens. Our goal was to examine the utility of these cultures and explore a modern bacterial culture technique using bacterial blood culture bottles (BCBs) as an alternative.

METHODS

We performed a retrospective review of patients diagnosed with hip or knee PJI between 1 January 2010 and 31 December 2019, at the Mayo Clinic in Rochester, Minnesota, USA. We included patients aged 18 years or older who had fungal, mycobacterial, or both cultures performed together with bacterial cultures. Cases with positive fungal or mycobacterial cultures were reviewed using the electronic medical record to classify the microbiological findings as representing true infection or not.

RESULTS

There were 2,067 episodes of PJI diagnosed within the study period. A total of 3,629 fungal cultures and 2,923 mycobacterial cultures were performed, with at least one of these performed in 56% of episodes (n = 1,157). Test positivity rates of fungal and mycobacterial cultures were 5% (n = 179) and 1.2% (n = 34), respectively. After a comprehensive review, there were 40 true fungal and eight true mycobacterial PJIs. BCB were 90% sensitive in diagnosing true fungal PJI and 100% sensitive in detecting rapidly growing mycobacteria (RGM). Fungal stains were performed in 27 true fungal PJI but were only positive in four episodes (14.8% sensitivity). None of the mycobacterial stains was positive.

CONCLUSION

Routine fungal and mycobacterial stains and cultures should not be performed as they have little clinical utility in the diagnosis of PJI and are associated with significant costs. Candida species and RGM are readily recovered using BCB. More research is needed to predict rare non-Candida fungal and slowly growing mycobacterial PJI that warrant specialized cultures. Cite this article: Bone Joint J 2022;104-B(1):53-58.

Better choice of the type of specimen used for untargeted metagenomic sequencing in the diagnosis of periprosthetic joint infections

AIMS

As a proven and comprehensive molecular technique, metagenomic next-generation sequencing (mNGS) has shown its potential in the diagnosis of pathogens in patients with periprosthetic joint infection (PJI), using a single type of specimen. However, the optimal use of mNGS in the management of PJI has not been explored. In this study, we evaluated the diagnostic value of mNGS using three types of specimen with the aim of achieving a better choice of specimen for mNGS in these patients.

METHODS

In this prospective study, 177 specimens were collected from 59 revision arthroplasties, including periprosthetic tissues, synovial fluid, and prosthetic sonicate fluid. Each specimen was divided into two, one for mNGS and one for culture. The criteria of the Musculoskeletal Infection Society were used to define PJI (40 cases) and aseptic failure (19 cases).

RESULTS

The sensitivity and specificity of mNGS in the diagnosis of PJI were 95% and 94.7%, respectively, for all types of specimen. The sensitivity and specificity were 65% and 100%, respectively, for periprosthetic tissues, 87.5% and 94.7%, respectively, for synovial fluid, and 92.5% and 94.7%, respectively, for prosthetic sonicate fluid. The mNGS of prosthetic sonicate fluid outperformed that for other types of specimen in the rates of detection of pathogens (84.6%), sequencing reads (> ten-fold) and the rate of genome coverage (> five-fold).

CONCLUSION

mNGS could serve as an accurate diagnostic tool in the detection of pathogens in patients with a PJI using three types of specimen. Due to its superior perfomance in identifying a pathogen, mNGS of prosthetic sonicate fluid provides the most value and may partly replace traditional tests such as bacteriological culture in these patients. Cite this article: Bone Joint J 2021;103-B(5):923-930.

Outcome of Debridement, Antibiotics, and Implant Retention With Modular Component Exchange in Acute Culture-Negative Periprosthetic Joint Infections

BACKGROUND

Modular component exchange and culture-directed antibiotic treatment is routinely employed for acute periprosthetic joint infection (PJI). However, as many as 7%-23% of PJIs have been reported to yield negative culture results. The efficacy of debridement, antibiotics, and implant retention (DAIR) with modular component exchange in the setting of acute culture negative PJI remains largely unknown. The aim of our study is to evaluate the outcomes of DAIR with modular component exchange in acute culture-positive and culture-negative PJI.

METHODS

A total of 149 consecutive patients with primary total joint replacements (90 total knee arthroplasties and 59 total hip arthroplasties) who underwent DAIR with modular component exchange for acute PJI with at least 3 years of follow-up were evaluated: (1) 46 culture-negative PJI patients and (2) 103 culture-positive PJI patients. Reinfection and aseptic revision rates along with complication rates were compared.

RESULTS

The reinfection rate for DAIR in acute culture-negative PJI was 13.0% compared to 19.4% in culture-positive PJI (P = .48). Mean survival time from reinfection between culture-negative (7.7 ± 0.4 years) and culture-positive (7.4 ± 0.3 years) PJI groups did not differ significantly (P = .40). Aseptic revision rates were 8.7% and 4.9% (P = .46), respectively, with loosening being the primary reason for implant failure in both cohorts.

CONCLUSIONS

Despite lack of an identifying organism to guide postoperative antibiotic therapy, DAIR with modular component exchange for acute culture-negative PJI was associated with similar reinfection rates compared to acute culture-positive PJI, suggesting that culture negativity may not be a contraindication to DAIR in patients with acute PJI.

Application of leukocyte esterase strip test in the screening of periprosthetic joint infections and prospects of high-precision strips

Periprosthetic joint infection (PJI) represents one of the most challenging complications after total joint arthroplasty (TJA). Despite the availability of a variety of diagnostic techniques, the diagnosis of PJI remains a challenge due to the lack of well-established diagnostic criteria. The leucocyte esterase (LE) strips test has been proved to be a valuable diagnostic tool for PJI, and its weight in PJI diagnostic criteria has gradually increased. Characterized by its convenience, speed and immediacy, leucocyte esterase strips test has a prospect of broad application in PJI diagnosis. Admittedly, the leucocyte esterase strips test has some limitations, such as imprecision and liability to interference. Thanks to the application of new technologies, such as machine reading, quantitative detection and artificial intelligence, the LE strips test is expected to overcome the limitations and improve its accuracy.

New materials for hip and knee joint replacement: What's hip and what's in kneed?

Over the last three decades there have been significant advancements in the knee and hip replacement technology that has been driven by an issue in the past concerning adverse local tissue reactions, aseptic and septic loosening. The implants and the materials we utilize have improved over the last two decades and in knee and hip replacement there has been a decrease in the failures attributed to wear and osteolysis. Despite these advancements there are still issues with patient satisfaction and early revisions due to septic and aseptic loosening in knee replacement patients. This article reviews the state of current implant material technology in hip and knee replacement surgery, discusses some of the unmet needs we have in biomaterials, and reviews some of the current biomaterials and technology that may be able to solve the most common issues in the knee and hip replacement surgery.

Staphylococcus aureus Osteomyelitis: Bone, Bugs, and Surgery

Osteomyelitis, or inflammation of bone, is most commonly caused by invasion of bacterial pathogens into the skeleton. Bacterial osteomyelitis is notoriously difficult to treat, in part because of the widespread antimicrobial resistance in the preeminent etiologic agent, the Gram-positive bacterium Staphylococcus aureus Bacterial osteomyelitis triggers pathological bone remodeling, which in turn leads to sequestration of infectious foci from innate immune effectors and systemically delivered antimicrobials. Treatment of osteomyelitis therefore typically consists of long courses of antibiotics in conjunction with surgical debridement of necrotic infected tissues. Even with these extreme measures, many patients go on to develop chronic infection or sustain disease comorbidities. A better mechanistic understanding of how bacteria invade, survive within, and trigger pathological remodeling of bone could therefore lead to new therapies aimed at prevention or treatment of osteomyelitis as well as amelioration of disease morbidity. In this minireview, we highlight recent developments in our understanding of how pathogens invade and survive within bone, how bacterial infection or resulting innate immune responses trigger changes in bone remodeling, and how model systems can be leveraged to identify new therapeutic targets. We review the current state of osteomyelitis epidemiology, diagnostics, and therapeutic guidelines to help direct future research in bacterial pathogenesis.

Engineered Cationic Antimicrobial Peptides (eCAPs) to Combat Multidrug-Resistant Bacteria

The increasing rate of antibiotic resistance constitutes a global health crisis. Antimicrobial peptides (AMPs) have the property to selectively kill bacteria regardless of resistance to traditional antibiotics. However, several challenges (e.g., reduced activity in the presence of serum and lack of efficacy in vivo) to clinical development need to be overcome. In the last two decades, we have addressed many of those challenges by engineering cationic AMPs de novo for optimization under test conditions that typically inhibit the activities of natural AMPs, including systemic efficacy. We reviewed some of the most promising data of the last two decades in the context of the advancement of the field of helical AMPs toward clinical development.