Diagnostic and Predictive Efficacy of Synovial Fluid Versus Serum C-Reactive Protein Levels for Periprosthetic Joint Infection and Reimplantation Success

INTRODUCTION

A two-stage exchange revision for periprosthetic joint infection (PJI) is associated with major risks for reinfection. Although serum markers are frequently used for diagnosis, their effectiveness remains debatable. Synovial fluid markers may offer a more accurate diagnosis of PJI; however, the importance of these biomarkers, notably synovial fluid C-reactive protein (syCRP), remains controversial, particularly in the context of reimplantation. The present study aimed to clarify these diagnostic uncertainties by evaluating the diagnostic efficacy of syCRP versus serum CRP (seCRP) levels in the context of PJI and recurring or persisting infections before reimplantation.

METHODS

A total of 186 patients were enrolled and divided into two groups: aseptic revision (n = 112) and PJI revision (n = 74). Of the PJI group, 65 were categorized as success and 9 as failure, based on the presence of recurrent or persistent infection before reimplantation. The syCRP and seCRP levels and their changes were assessed preoperatively and in the first- and second-stage revisions. Additionally, receiver operating characteristic (ROC) curves and area under the ROC curves (AUC) were analyzed.

RESULTS

Both seCRP and syCRP levels were significantly elevated in the PJI group compared with the aseptic group (P < 0.001). The ROC curve analysis highlighted the enhanced diagnostic accuracy of syCRP for PJI, with an AUC of 0.93 versus 0.80 for seCRP. Furthermore, syCRP proved to be more reliable in predicting reimplantation success, exhibiting an AUC of 0.86 versus 0.63 for seCRP. In evaluating trends in CRP levels to determine reimplantation timing, changes in syCRP levels demonstrated superior diagnostic utility, exhibiting an AUC of 0.79 versus 0.63 for changes in seCRP levels.

CONCLUSION

In assessing PJI and infections before reimplantation, syCRP may offer enhanced accuracy compared with seCRP. Nevertheless, variations in both syCRP and seCRP levels did not consistently predict the outcome of reimplantation.

Smoking is not closely related to revision for periprosthetic joint infection after primary total knee and hip arthroplasty

BACKGROUND

The influence of smoking on the risk of periprosthetic joint infection (PJI) remains unclear. The objective was to explore the impact of smoking on PJI after primary total knee (TKA) and hip (THA) arthroplasty.

HYPOTHESIS

Current smoking patients should have an increased risk of PIJ compared with nonsmoking patients.

PATIENTS AND METHODS

A prospective registry-based observational cohort study was performed. A total of 4591 patients who underwent primary TKA (3076 patients) or THA (1515) were included. According to the smoking status at the time of arthroplasty, patients were classified as nonsmokers (3031 patients), ex-smokers (688), and smokers (872). Multivariate analysis included smoking status, age, gender, education level, body mass index, American Society of Anesthesiologists class, diagnosis (osteoarthritis, rheumatism), diabetes, chronic obstructive pulmonary disease, perioperative blood transfusion, site of arthroplasty (knee, hip), length of operation, and length of stay.

RESULTS

There were PJI after 59 (1.9%) TKA and 27 (1.8%) THA (p=0.840). There were PJI in 47 (1.6%) nonsmokers, 12 (1.7%) ex-smokers, and 17 (1.9%) smokers (p=0.413). There were wound complications (delayed wound healing and superficial wound infection) in 34 (0.7%) nonsmokers, 9 (1.3%) in ex-smokers, and 17 (1.9%) in smokers (p=0.045). In multivariate analysis, only the female gender was a significant predictor of PJI (OR 1.3, 95% CI 1.1-2.4 [p=0.039]). Specifically, the categories of ex-smokers (OR 0.8, 95% CI 0.2-1.7 [p=0.241]) and smokers (OR 1.1, 95% CI 0.6-1.5 [p=0.052]) were not significant predictors. The 4-year arthroplasty survival with PJI as the endpoint was 99.1% (95% CI: 99.0-99.7) for nonsmokers, 99.0% (95% CI: 98.8-99.2) for ex-smokers, and 98.7% (95% CI: 98.2-99.0) for smokers was not significantly different between smoking status groups (p=0.318).

DISCUSSION

Smoking was not identified as a significant predictor for PJI following primary TKA or THA.

LEVEL OF EVIDENCE

III, prospective cohort study.

Self-controllable proteinic antibacterial coating with bacteria-triggered antibiotic release for prevention of periprosthetic infection

Periprosthetic infection is a devastating postimplantation complication in which a biofilm layer harboring invasive microorganisms forms around orthopedic implants, leading to severe implant failure and patient morbidity. Despite the development of several infection-triggered antibiotic release approaches, most current antibacterial coatings are susceptible to undesired antibiotic leakage or mechanical disintegration during prosthesis installation. Herein, we propose a self-controllable proteinic antibacterial coating capable of both long-lasting adherence onto titanium implant substrates over the implant fixation period and instantaneous bacterial eradication. Importantly, the pH-dependent reversible metal coordination of mussel adhesive protein (MAP) enabled bacterial concentration-dependent antibiotic delivery in response to infection-induced acidification. In addition, the MAP coating exhibited superior self-healable adhesive properties and scratch resistance, which enabled to avert issues associated with mechanical damages, including peeling and cracking, often occurring in conventional implant coating systems. The gentamicin-loaded MAP coating exhibited complete inhibition of bacterial growth in vivo against Staphylococcus aureus penetrations during implantation surgery (immediate infection) and even 4 weeks after implantation (delayed infection). Thus, our antibiotic-loaded MAP hydrogel coating can open new avenues for self-defensive antibiotic prophylaxis to achieve instant and sustainable bacteriocidal activity in orthopedic prostheses. © 2017 Elsevier Inc. All rights reserved.

Adjuvant intra-articular vancomycin for recalcitrant Staphylococcal prosthetic joint infections of the knee

OBJECTIVE

Chronic prosthetic joint infection patients who fail conventional two-stage revision surgery are an especially difficult to treat patient population. Consequently, the objective of this study was to investigate the safety and long-term effectiveness of adjuvant intra-articular vancomycin therapy in conjunction with two-stage revision knee arthroplasties for recalcitrant Staphylococcal prosthetic joint infections.

METHODS

This was an observational cohort study of twelve patients with recalcitrant Staphylococcal prosthetic joint infections of the knee which had failed previous revision surgeries. Each patient subsequently underwent two-stage revision with placement of Hickman catheters to deliver intra-articular vancomycin therapy. In addition, systemic antibiotic therapy was administered for 6 weeks, and long-term follow-up was evaluated then for 5 years.

RESULTS

Seventy-five percent of the cohort have had no recurrence of their infections at 5 years. Two patients formed fistulas requiring above the knee amputations, and three patients had acute kidney injury. All patients had maximum measurable serum vancomycin trough levels that ranged from 6.1 to 93.6 mcg/mL.

CONCLUSION

The aggressive protocol used in this cohort with repeat two-stage revision surgery, intra-articular vancomycin and systemic antibiotics was able to prevent recurrence of infection in most patients, but higher than expected rates of acute kidney injury were observed in this study. Therefore, while intra-articular vancomycin therapy may have some effectiveness in treating recalcitrant prosthetic joint infections, its ability to eradicate all bacterial niduses is unproven, and clinicians should be cognizant of potential adverse events that can occur with this therapy.

Update on the role of pathology and laboratory medicine in diagnosing periprosthetic infection

Technological and implant design advances have helped reduce the frequency of aseptic total joint arthroplasty failure, but periprosthetic joint infections (PJI) remain a clinical important problem with high patient morbidity. Misinterpreting PJI as aseptic mechanical loosening commonly leads to unsatisfactory revision arthroplasty, persistent infection, and poor long-term results. While there is no single "gold standard" diagnostic test for PJI, recent collaborative efforts by Orthopaedic and Infectious Disease Societies have developed algorithms for diagnosing PJI. However, the efficacy of individual tests as well as diagnostic thresholds are controversial. We review the recommended thresholds for commonly used screening tests as well as tissue histopathology and confirmatory tests to diagnose periprosthetic infection. We also update lesser-known laboratory tests, and we briefly summarize rapidly evolving molecular tests to diagnose periprosthetic infection. Pathologists hold a critical role in assisting with PJI diagnosis, maintaining laboratory test quality and interpreting test results. Collaboration between clinicians and pathologists is essential to provide optimal patient care and reduce the burden of PJI.

One-stage revision for infected shoulder arthroplasty: prospective, observational study of 37 patients

Background

Periprosthetic joint infection is a severe complication of joint replacement surgery. Thus two-stage exchange remains the gold standard, one-stage exchange is now widely recommended. We hypothesized that, for patients with chronic periprosthetic shoulder infection (PSI), treatment with a one-stage exchange would be an effective approach to eradicate infection, relieve pain, and restore function to the involved shoulder.

Materials and methods

This monocenter cohort study in a Bone and Joint Infection Referral Center (11/2003-05/2020) included all patients with confirmed PSI treated by one-stage revision. Data were extracted from the prospective database, including demographics, infection characteristics, and functional evaluations (range of motion and Constant Score at admission and last follow-up). The primary outcome was the 2-year reinfection-free rate.

Results

We included 37 patients. The refection-free rate was 5%. The most commonly isolated pathogen was Cutibacterium acnes (68%), isolated alone (15 patients, 41%) or as polymicrobial infections (10 patients, 27%). The Constant Score increased significantly from 24 to 53 (P = .001). Range of motion (forward elevation, abduction) was also significantly improved after surgery. Mean active forward elevation increased significantly by 45° from 60° to 105° postoperatively (P < .001), mean abduction increased by 42° from 55° to 97° (P < .001).

Discussion

Results from our prospective cohort-extracted series suggest that one-stage revision is a reliable treatment with a low infection recurrence rate. Improved functional outcomes can be achieved with one-stage exchange. Our patients' overall functional results were similar to those previously reported for one-stage revision and better than those reported after two-stage exchange. Patients with multiple previous surgeries seem to have worse functional outcomes than the subgroup without surgery before the index arthroplasty.

Conclusions

Our results and literature search findings suggest that one-stage revisions effectively eradicate PSIs, with good functional outcomes.

Functional outcomes and complications of patients contaminated with Cutibacterium acnes during primary reverse shoulder arthroplasty: study at two- and five-years of follow-up

PURPOSE

The objective of the study was to compare the functional outcomes and the complication rate of the patients with C. acnes contamination at the end of the primary reverse shoulder arthroplasty (RSA) surgery to those patients without C. acnes contamination.

METHOD

A total of 162 patients were included. In all cases, skin and deep tissue cultures were obtained. A molecular typing characterization of the C. acnes strains was performed. Functional outcomes were assessed with the Constant score at the two and five year follow-up and all complications were also recorded.

RESULTS

A total of 1380 cultures were obtained from the 162 primary RSA surgeries. Of those, 96 turned out to be positive for C. acnes. There were 25 patients with positive cultures for C. acnes. The overall postoperative Constant score was not significantly different between those patients having C. acnes-positive cultures and those with negative cultures at the two and five year follow-up (59.2 vs. 59.6 at two years, p 0.870, and 59.5 vs. 62.4 at five years, p 0.360). Patients with positive cultures presented a higher complication rate (p 0.001) with two infections, one revision surgery, and one dislocation.

CONCLUSION

Patients ending up with C. acnes-positive cultures after primary shoulder arthroplasty surgery do not have worse clinical outcomes when compared to patients having negative cultures, but a greater number of complications were found in those patients with C. acnes-positive cultures.

Diagnostic arthroscopy for periprosthetic shoulder arthroplasty infections: a systematic review and meta-analysis

Background

Periprosthetic joint infection of the shoulder (PJI) is a devastating complication with a reported incidence of 1%-15.4% and is often difficult to diagnose with current diagnostic tools including serologic tests and arthrocentesis. This systematic review evaluates the reliability and validity of arthroscopic biopsy in the current literature for the diagnosis of shoulder PJI.

Methods

MEDLINE, Scopus, Web of Sciences, Google Scholar, and Cochrane databases were queried electronically from inception to June 2022 for publications reporting diagnostic accuracy of shoulder arthroscopic biopsy for detecting infection after anatomic total shoulder arthroplasty, shoulder hemiarthroplasty, or reverse total shoulder arthroplasty. This systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Results

After exclusion, our meta-analysis consisted of 7 articles with a total of 112 patients. The estimated pooled sensitivity and specificity of arthroscopic biopsy for confirmation of shoulder periprosthetic infection were 0.87 (95% confidence interval [CI]: 0.73-0.95) and 0.79 (95% CI: 0.67-0.88), respectively. The pooled positive likelihood ratio and negative likelihood ratio were 4.15 (95% CI: 2.57, 6.70) and 0.17 (95% CI: 0.08, 0.36), respectively. The aggregate positive predictive value was 73.58% (95% CI: 63.29%-81.82%), and aggregate negative predictive value was 89.83% (95% CI: 80.59%-94.95%). The diagnostic odds ratio of arthroscopic biopsy was 19.92 (95% CI: 4.96-79.99).

Conclusion

Arthroscopic biopsy in patients suspected of shoulder PJI has good diagnostic accuracy, with high sensitivity and specificity. Given the various biopsy protocols (such as devices, numbers, locations, etc.), further prospective studies are necessary to define the future role of arthroscopic biopsy in diagnosis and treatment.

Functional Outcome of Above-Knee Amputation After Infected Total Knee Arthroplasty

Background

Periprosthetic joint infection is a serious complication of total knee arthroplasty (TKA). Management usually involves irrigation and debridement, polyethylene liner exchange, one-stage revision, two-stage revision, knee arthrodesis, or ultimately above-knee amputation (AKA). We present our experience with 21 patients who underwent AKA as a sequela of unresolved infected TKA, highlighting their etiology and functional outcomes.

Methods

A retrospective chart review was performed for all cases of infected TKA treated with AKA at 1 institute from January 2007 to December 2020, with a minimum follow-up of 1 year. Patient demographics, Charlson comorbidity index, culture results, ambulation status, prosthesis fitting, and functional outcomes were collected. Short Form-36 and activities of daily living questionnaires were used for functional outcome assessment.

Results

Twenty-one patients were identified, 7 of whom were male (33.3%). Mean ± standard deviation follow-up was 5.7 ± 3.1 years (range, 1-11 years). Mean ± standard deviation age was 57.9 ± 10.7 years (range, 38-87 years), and the mean body mass index was 33.5 ± 6.4 kg/m2 (range, 25.4-46 kg/m2). Gram-positive organisms were identified in 15 cases (66.7%). Prosthesis fitting was successful in 17 patients (81%). Post-AKA ambulation was achieved in 12 patients (57.1%). The ambulating group showed higher Short Form-36 and activities of daily living scores when compared with patients who did not ambulate (60.2 vs 43.3, P = .041, and 67.2 vs 52.7, P = .029, respectively).

Conclusions

AKA should be considered solely as the final recourse for infected TKA. Despite the low-to-moderate patient-reported postoperative outcomes, prosthesis fitting and maintaining ambulation can improve postoperative functional outcomes.

Joint fluid interleukin-6 combined with the neutral polymorphonuclear leukocyte ratio (PMN%) as a diagnostic index for chronic periprosthesis infection after arthroplasty

BACKGROUND

The diagnosis of periprosthetic joint infection (PJI) remains a challenge in clinical practice. Many novel serum and joint fluid biomarkers have important implications for the diagnosis of PJI. The presented study evaluated the value of joint fluid interleukin-6 (IL-6) combined with the neutral polymorphonuclear leukocyte (PMN%) ratio for chronic PJI diagnosis after arthroplasty.

MATERIALS AND METHODS

Sixty patients with chronic PJI or aseptic failure who underwent hip or knee revision from January 2018 to January 2020 in our department were included in this retrospective study. According to the 2013 MSIS diagnostic criteria, the 60 patients were divided into a PJI group and a non-PJI group (30 patients per group). We collected the joint fluid before surgery and determined the level of IL-6 and the PMN% by ELISA, and the differences between the two groups were compared. The diagnostic efficacy of joint fluid IL-6 combined with PMN% in chronic PJI was analyzed using a receiver operating characteristic curve (ROC curve).

RESULTS

The diagnosis of PJI using joint fluid IL-6 combined with PMN% presented an area under the curve of 0.983, which was more accurate than the areas under the curve for diagnosis using IL-6 and PMN% individually (0.901 and 0.914, respectively). The optimal threshold values for IL-6 and PMN% were 662.50 pg/ml and 51.09%, respectively. Their sensitivity and specificity were 96.67% and 93.33%, respectively. The accuracy of the diagnosis of PJI was 95.00%.

CONCLUSIONS

Joint fluid IL-6 combined with PMN% can be used as an auxiliary method to detect chronic infection around the prosthesis after hip/knee arthroplasty.

LEVEL OF EVIDENCE

Patients who underwent hip/knee revision at the First Hospital of Chongqing Medical University for periprosthetic infection or aseptic failure of the prosthesis after hip/knee arthroplasty from January 2018 to January 2020 were included. Trial registration This study was approved by the ethics committee of the First Hospital of Chongqing Medical University on September 26, 2018 (local ethics committee number: 20187101) and registered with the China Clinical Trials Registry (registration number: ChiCTR1800020440) with an approval date of December 29, 2018.

Two-stage revision for periprosthetic joint infection in cemented total hip arthroplasty: an increased risk for failure?

BACKGROUND

The impact of the prior fixation mode on the treatment outcome of chronic periprosthetic joint infection (PJI) of the hip is unclear. Removal of cemented total hip arthroplasty (THA) is particularly challenging and residual cement might be associated with reinfection. This study seeks to compare the results of two-stage revision for PJI in cemented and cementless THA.

METHODS

We reviewed 143 consecutive patients undergoing two-stage revision THA for PJI between 2013 and 2018. Thirty-six patients with a fully cemented (n = 6), hybrid femur (n = 26) or hybrid acetabulum (n = 4) THA (cemented group) were matched 1:2 with a cohort of 72 patients who underwent removal of a cementless THA (cementless group). Groups were matched by sex, age, number of prior surgeries and history of infection treatment. Outcomes included microbiological results, interim re-debridement, reinfection, all-cause revision, and modified Harris hip scores (mHHS). Minimum follow-up was 2 years.

RESULTS

Compared with PJI in cementless THA, patients undergoing removal of cemented THA had increasingly severe femoral bone loss (p = 0.004). Patients in the cemented group had an increased risk for positive cultures during second-stage reimplantation (22% compared to 8%, p = 0.043), higher rates of reinfection (22% compared to 7%, p = 0.021) and all-cause revision (31% compared to 14%, p = 0.039) compared to patients undergoing two-stage revision of cementless THA. Periprosthetic femoral fractures were more frequent in the group of patients with prior cementation (p = .004). Mean mHHS had been 37.5 in the cemented group and 39.1 in the cementless group, and these scores improved significantly in both groups (p < 0.01).

CONCLUSION

This study shows that chronic infection in cemented THA might be associated with increased bone loss, higher rates of reinfection and all-cause revision following two-stage revision. This should be useful to clinicians counselling patients with hip PJI and can guide treatment and estimated outcomes.

[Periprosthetic gout flare after total knee arthroplasty: A misdiagnostic case report]

Periprosthetic gout flare is a rare arthritic condition after total knee arthroplasty, but the symptoms of gout may have often been mistaken as acute periprosthetic infection given their similarity. Misdiagnosis as periprosthetic infection can lead to unnecessary surgery, long-term dependence on anti-biotics, and even malfunction of the involved knee joint. Here, we report a case study of a patient with immunodeficiency condition of long-term oral glucocorticoid and diabetes mellitus, who had undergone a knee replacement 8 weeks before. The initial symptoms of fever and joint pain together with the dysfunction of her right knee with elevated inflammatory markers, such as increased serum leukocytes, erythrocyte sedimentation rate, C-reactive protein, and synovial cell counts led to a diagnosis of acute periprosthetic infection. Arthrocentesis and bacterial culture were performed preoperatively. According to the current Musculoskeletal Infection Society (MSIS) criteria for diagnosis of periprosthetic infection, the case was classified as periprosthetic infection and a prosthesis retained debridement surgery was performed. However we got negative culture results in all the pre-operative and intro-operative samples. The symptoms as well as the laboratory inflammatory markers improved shortly after the debridement surgery until the 11th day when all the similar systemic and local symptoms recurred. With a remedial crystal analysis of synovial fluid from the patient, gouty flare was found to be the cause of acute arthritis finally. Accor-dingly, after anti-gout medications were administrated, the symptoms associated with acute arthritis gra- dually subsided, and there was no recurrence during a 24-month follow-up. This article described the cli-nical manifestation, diagnosis and differential diagnosis, treatment of a case of periprosthetic gout. Although relatively rare, gout should be considered as a differential diagnosis in suspected periprosthetic infection. Current criteria for periprosthetic infection can not exclude the diagnosis of periprosthetic gout flare, it is therefore imperative that the analysis of joint aspirate for crystals be conducted to determine the correct course of treatment, or unnecessary surgical procedure may be performed in periprosthetic gout case.

Povidone-iodine irrigation reduces infection after total hip and knee arthroplasty

INTRODUCTION

One of the most important challenges faced by orthopedic surgeons is periprosthetic joint infection (PJI). PJI is a common cause for total joint arthroplasty failure with an incidence of 0.3-1.9%. PJI can be devastating for the patient and extremely costly for the healthcare system. There is concern that a major cause of PJI is intra-operative colonization and recent studies have shown a decrease in PJI with the use of dilute povidone-iodine (Betadine^®, Avrio Health L.P, Stamford, CT) irrigation prior to wound closure. This study presents our experience with the use of dilute Betadine^® irrigation prior to wound closure and its effect on our post-operative hip and knee arthroplasty acute infection rate.

MATERIALS AND METHODS

Retrospective chart review performed at our hospital looking at PJI amongst patients who underwent primary total hip arthroplasty (THA) or total knee arthroplasty (TKA) between 2013 and 2017 comparing different irrigation methods (n = 3232). The study group (n = 1207) underwent irrigation prior to wound closure with dilute Betadine for 3 min and the control group (n = 1511) underwent irrigation using normal saline (NS).

RESULTS

Using a logistic regression model where the following variables were adjusted for; ASA, age, sex, foley insertion, surgical duration and diabetes mellitus status a statistical significant reduction was seen in any infection (OR 0.45 [0.22; 0.89], p value < 0.05) and SSI (OR 0.30 [0.13; 0.70], p value 0.01) with the Betadine group. No significant reduction was seen with deep infections with the Betadine group compared to the NS group.

CONCLUSION

PJI is a devastating complication following total joint arthroplasty and we found Betadine compared to NS irrigation provides an inexpensive and simple method to lower any PJI and more specifically SSI in THA and TKA.

LEVEL OF EVIDENCE

III.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Survival analysis of one-stage exchange of infected unicompartmental knee arthroplasty: a single-center study with minimum 3 years follow-up

PURPOSE

The rates of unicompartmental knee arthroplasty (UKA) are increasing yet little data exists regarding management of periprosthetic joint infections (PJI) after UKA, particularly utilizing one-stage revision. The aim of this study was to determine the septic and all-cause revision-free survival of UKA PJIs treated with one-stage revision, as well as functional outcomes and risk factors for failure.

METHODS

A retrospective review of one-stage septic revisions with a hinged or rotating hinged implant between 2000 and 2015 at a single institution was performed. Results of 15 patients with a minimum of 3-year follow-up (mean = 93 months; range 37-217) were evaluated by means of infection control, survivorship, patient reported functional score and possible causal factors for a re-revision. Kaplan-Meier curves and Cox regression analysis were used.

RESULTS

After a mean of 8 years of follow-up infection control rate was 93.3%, the survivorship free of any reoperation, including both septic and aseptic causes, was 80% at 5 years and 64.2% at ten years and average Lysholm score was 72.7 ± 21.3 (33-100).

CONCLUSION

One-stage revision for PJI of UKA using a hinged knee design has excellent infection-free survival at mid to long-term follow-up. Likewise, patient reported functional outcomes are promising. However, one-third of patients required aseptic reoperation and aseptic loosening was the dominant etiology.

Total hip arthroplasty for destructive septic arthritis of the hip using a two-stage protocol without spacer placement

INTRODUCTION

The optimal treatment of patients with a degenerative joint disease secondary to an active or chronic septic arthritis of the hip is unclear. The aim of the present study was to report on our experience with two-stage total hip arthroplasty (THA) using a contemporary treatment protocol without spacer insertion.

MATERIALS AND METHODS

Our prospective institutional database was used to identify all patients with degenerative septic arthritis treated with a non-spacer two-stage protocol between 2011 and 2017. Clinical outcomes included interim revision, periprosthetic infection (PJI) and aseptic revision rates. Restoration of leg-length and offset were assessed radiographically. Modified Harris hip score (mHHS) were obtained. Treatment success was defined using the modified Delphi consensus criteria. Mean follow-up was 62 months (13-110).

RESULTS

A total of 33 patients with a mean age of 60 years (13-85) were included. 55% of the cohort was male and average Charlson Comorbidity Index (CCI) was 3.7 (0-12). 21 patients (64%) had an active/acute infection and 12 patients (36%) were treated for chronic/quiescent septic arthritis. Overall, 11 patients (33%) had treatment failure, including 5 patients who failed to undergo THA, 2 interim re-debridement for persistent infection, and 4 patients who developed PJI after an average of 7 months (0.3-13) following THA. The most common identified pathogen was Staphylococcus aureus (42.4%). No aseptic revision was recorded following THA. Leg-length and offset were successfully restored. Mean mHHS improved from 35.2 points to 73.4 points.

CONCLUSION

Two-stage THA without spacer placement is a viable treatment option for destructive septic arthritis of the hip, demonstrating comparable rates of infection control and functional outcome. However, definitive resection arthroplasty is not uncommon in these often critically ill patients.

Palmitic acid coating of allogeneic cancellous bone for local antibiotic treatment: A porcine impaction bone grafting model

Introduction

The worldwide rising number of joint replacements results in increasing revision surgery including a relevant portion of septic loosening accompanied by bone deficiencies. Loading of allogeneic bone with antibiotics provides high local antibiotic concentrations and might eradicate bacteria which appear resistant to systemic antibiotic application. Hydrophobic palmitic acid was shown to be a suitable carrier for antibiotics and prevents biofilm.

Methods

Cancellous bone derived from 6 to 7 months old piglets was used for a standardized in vitro impaction bone grafting model according to previous studies. The specimens were either thermodisinfected or remained native and palmitic acid with one third and two third partial weight were added and compared with control. Shear force at the interface prosthesis to cement and between cement and bone was measured. The relative micromovements were measured with 6 inductive sensors with a resolution of 0.1 μm at three different measuring heights up to a maximum movement of 150 μm between cement and bone. Taking into account the corresponding applied torque the measured values were normalized in μm/Nm. Statistical analysis was done with SPSS Statistics® Version 26.0 IBM.

Results

Smallest movement was measured for thermodisinfected cancellous bone and a not significant decrease of shear force resistance with addition of palmitic acid was found since supplementing native cancellous bone reduced shear force resistance significantly depending on the weight percentage of palmitic acid.

Conclusion

Supplementation of porcine cancellous bone with palmitic acid did not significantly reduce shear force resistance of thermodisinfected bone since adding palmitic acid to native bone decreased it significantly depending on the volume added. Palmitic acid seems to be a suitable coating for allogeneic cancellous bone to deliver high local antibiotic concentrations and thermodisinfected cancellous bone might be able to store larger volumes of palmitic acid than native bone without relevant influence on shear force resistance.

Sonication of revised hip and knee prostheses detects occult infections, improves clinical outcomes and prevents re - revisions. A case series study

Introduction

Periprosthetic joint infection (PJI) is a devastating complication occurring in 1–2% of primary and up to 10% of revised total hip and knee arthroplasties (THA and TKA) impairing patient's quality of life. Occult infections are underdiagnosed, sub-treated and sub-clinically experienced by patients. This study aimed to correlate patients' clinical outcomes with early antibiotic treatment based on use or non-use of a sonication technique on explanted prostheses.

Methods

33 patients with revised THA or TKA were retrospectively evaluated. Clinical outcomes were assessed via Oxford hip or knee scores, and correlated with administration or not of antibiotic treatment based on sonication results.

Results

According to laboratory findings the patients were divided in the following three groups: 1. Septic loosening (conventional cultures and/or sonication positive), 2. Aseptic loosening (conventional cultures and sonication negative) and 3. Occult loosening (conventional cultures negative, sonication not performed). The average Oxford score was poor (27.9/60) for the septic, excellent (43.8/60) for the aseptic and intermediate (37.7/60) for the occult group. Additionally, conventional cultures were negative, but sonication-positive, in 6 individuals with patient-related risk factors (male gender, BMI > 30 kg/m², diabetes, hypertension, steroids and rheumatoid arthritis).

Conclusions

Sonication represents a valuable diagnostic technique to guide administration of effective antibiotic treatment for patients, especially for detection of persistent post-revision occult infections. We recommend the systematic investigation of revised prostheses with a sonication technique, but especially in cases with risk factors for infection who it is suspected may have occult loosening.

C-reactive protein during the first 6 postoperative days after total hip arthroplasty cannot predict early periprosthetic infection

INTRODUCTION

Periprosthetic joint infection (PJI) after total hip arthroplasty (THA) remains a serious complication in orthopaedic surgery. C-reactive protein (CRP) is widely used as a marker to screen for inflammatory complications. The early postoperative course is well known, but knowledge about the predictive value of CRP in the first 6 postoperative days for detecting an acute postoperative PJI is lacking.

METHODS

We retrospectively analyzed the inpatient course of CRP of all primary THA and THA with acute PJI within 28 days in our hospital from 2013 to 2021. A receiver-operating curve (ROC) analysis was performed and the best CRP threshold for detecting an acute PJI based on Youden's-index was calculated and an area-under-the curve (AUC) analysis of the threshold was performed.

RESULTS

33 of 7042 patients included had an acute PJI within 28 days. Patients with acute PJI were older, had a higher BMI and longer operation time and suffered more often from diabetes mellitus. A preoperatively elevated CRP was a risk factor for PJI. CRP was significantly higher in the PJI group on postoperative days 3 and 5. Threshold values were calculated to be 152 mg/l on day 3 and 73 mg/l on day 5. However, these values had a low sensitivity (75%, 76%) and specificity (67%, 61%).

CONCLUSION

Especially considering the decreasing length of stay after THA, the question of the usefulness of regular inpatient CRP checks arises. AUC analysis of the ROC showed a poor diagnostic accuracy in almost all cases. Only the dynamic analysis of the maximum CRP value to the lowest CRP value with a decrease of 102.7 mg/l showed a fair accuracy. This calls into question the clinical relevance of CRP in the first postoperative week for detection of acute postoperative PJI.

Efficacy of antimicrobial washes before shoulder surgery against Cutibacterium: a systematic review and meta-analysis

Background

Cutibacterium acnes is a commensal intradermal microorganism that is commonly isolated at revision shoulder arthroplasty. Standard practice chlorhexidine gluconate (CHG) skin preparation agents have limited effectiveness at eradicating C. acnes in the dermis. Benzoyl peroxide (BPO) has demonstrated effectiveness against C. acnes. This meta-analysis compares the efficacy of at-home shoulder decolonization before surgery using CHG vs. BPO to reduce shoulder C. acnes burden.

Methods

This was a Preferred Reporting Items for Systematic Reviews and Meta-Analyses systematic review. PubMed and MEDLINE databases were searched for studies evaluating the effects of CHG and BPO in reducing C. acnes at the shoulder. Trial results were extracted and pooled using a random effects model, separating data from randomized controlled trials (RCTs) and non-RCTs. Methodologic quality of studies was assessed using the Cochrane Risk of Bias Assessment Tools.

Results

Ten studies (589 patients) were included. RCTs showed that both BPO and CHG led to significant reductions in culture positivity compared with negative controls (risk ratio [RR] with 95% confidence interval [CI] = 0.20 [0.13, 0.30], P < .0001 and 0.46 [0.37, 0.57], P < .0001, respectively). Non-RCT data demonstrated similar results comparing BPO and CHG to the control (RR with 95% CI = 0.34 [0.21, 0.57], P < .0001 and 0.31 [0.20, 0.49], P < .0001, respectively). Comparing BPO and CHG, RCT data showed a significant reduction in culture positivity with BPO (RR with 95% CI = 0.46 [0.27, 0.77], P < .009). Of RCTs, 5 were low and one was of moderate risk of bias. Of non-RCTs, 3 had low risk of bias, whereas one had moderate risk of bias.

Conclusion

This review demonstrated that preoperative CHG and BPO can reduce C. acnes at the shoulder. However, BPO exhibits greater efficacy than CHG, potentially because of the compound's ability to penetrate the dermis. BPO is a simple and economical agent that may reduce joint exposure to C. acnes in shoulder surgery.

Use of antibiotic-cement coated locking plates in the setting of periprosthetic infection and infected nonunion

INTRODUCTION

In the setting of periprosthetic total hip and knee arthroplasty (THA/TKA) infection, plating of the femur may be necessary for fracture fixation, prophylactic fixation of the femur, poor bone quality, or infected femoral shaft nonunion. The purpose of this study was to investigate infection control rates and fracture healing in patients receiving antibiotic cement coated plates in the setting of infected nonunion and periprosthetic infections.

METHODS

We retrospectively reviewed a series of ten patients who had an antibiotic coated plate placed in the setting of periprosthetic infection or infected nonunion with a minimum follow-up of six months. 80 g of Simplex bone cement (Stryker, Mahwah, NJ) were mixed with 4 g of powdered vancomycin and 4.8 g of powdered tobramycin and applied to a dynamic compression plate with locking screw guides in every hole. The antibiotic loaded cement was allowed to harden before implantation. Outcome measures were designed to assess for fracture healing defined as three out of four cortices united on radiographs along with bearing full weight without pain and evidence of infection control defined as normalized erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in the absence of antibiotic treatment with no clinical signs of infection.

RESULTS

Ten patients were treated with an antibiotic cement coated plate in the settings of infectious nonunion and periprosthetic infection and followed for an average of three years (mean 21.4 months, seven months to 61 months). Eight patients (80%) went on to successful control of infection after initial procedure. Two patients developed chronic drainage and had a second antibiotic spacer with antibiotic cement coated plate placed before the infection was controlled. All patients obtained successful control of infection at latest follow-up showing no clinical signs of infection, normalized laboratory markers, and negative culture results. There were no reported mechanical failures of the implant, fractures of the femur, or soft tissue complications.

CONCLUSION

An antibiotic cement coated plating technique is a viable option for periprosthetic THA and TKA infections requiring plating of the femur or in patients with an infected nonunion.

The Performances of Conventional Titanium and Silver-Coated Megaprostheses in Non-oncological and Post-oncological Patients: An Analysis of Infection Failures in 142 Patients

BACKGROUND

Megaprostheses are one of the preferred choices of reconstruction after tumor resection. Periprosthetic joint infections are one of the most serious complications of joint prostheses surgeries. In this study, our aim was to analyze the efficacy of silver-coated megaprostheses in reducing the risk of prosthesis-related infection.

METHODS

One hundred forty-two patients who had undergone implantation of a mega-endoprosthesis for non-neoplastic or post-neoplastic conditions were included in this retrospective study. The end-point of the survival analysis was the prosthesis failure due to infection.

RESULTS

Thirty-eight patients had undergone implantation of a silver-coated megaprosthesis and 104 patients a megaprosthesis without silver coating. The survival analysis showed an overall infection-free survival rate of 82.3% at five years and 61.9% at 10 years. Silver-coated prostheses had an HR of 0.72 (95% CI: 0.26-2.05; P=0.54).

CONCLUSION

Implantation of a silver-coated mega-prosthesis in non-oncological patients did not significantly reduce the risk of prosthesis-related infection.

Can "domino" therapy effectively treat the infection around the prosthesis after the limb salvage surgery of bone tumor? - A study of sequential therapy

BACKGROUND

Tumor resection and prosthetic replacement have become the treatments of choice for malignant bone tumors. Infections are the leading cause of failure of limb salvage surgeries. Therefore, treating infections around prostheses after limb salvage is essential and challenging. Our research team designed a "domino" sequential treatment plan to treat postoperative infections around tumor prostheses and evaluated its efficacy.

PURPOSE

To introduce the new domino sequential treatment plan for postoperative infections of tumor prostheses, and evaluate the technical points of the plan and prognosis in medium- and long-term follow-ups.

METHODS

Between January 2015 and August 2021, 14 patients were treated with prosthesis-preserving domino sequential therapy for peripheral prosthesis infections after bone-tumor limb salvage. The sample included eight cases of distal femur tumor, two of proximal tibia tumor, three of pelvic tumor, and one of middle femur tumor. We evaluated routine blood test results, C-reactive protein level, the erythrocyte sedimentation rate, and other indicators. X-rays and CT scans of the surgical site were obtained and the Musculoskeletal Tumor Society (MSTS) score was calculated. Treatment involved debridement and lavage of the prosthesis, and systemic and local antibiotics.

RESULTS

The positivity rate of microbial culture was 78.6%. There were three cases of Staphylococcus aureus, one of Staphylococcus epidermidis, two of methicillin-resistant Staphylococcus epidermidis, one of methicillin-resistant Staphylococcus aureus, two of Acinetobacter baumannii, one of Streptococcus lactis (group C), one of Streptococcus mitis, and three with negative cultures. In three cases, sequential treatment failed to control the infection. The operation success rate was 78.6% (11/14). One case eventually required amputation, and another required long-term wound dressings. To control the infection, a third had to be treated using antibiotic bone cement combined with the "intramedullary nail reverse double insertion" technique. The MSTS scores of patients before infection debridement and at the last follow-up showed statistically significant differences (t = 5.312, p = 0.02).

CONCLUSIONS

The prosthesis-preserving domino sequential method has certain advantages for treating bone-tumor limb salvage infections around the prosthesis.

LEVEL OF EVIDENCE

Level IV, therapeutic.

Debridement, antibiotics, and implant retention in non-oncological femoral megaprosthesis infections: minimum 5 year follow-up

Purpose

Megaprostheses are increasingly utilised outside of the oncological setting, and remain at significant risk of periprosthetic joint infection (PJI). Debridement, antibiotic, and implant retention (DAIR) is an established treatment for PJI, however its use in non-oncological patients with femoral megaprostheses has not been widely reported. There are significant differences in patient physiology, treatment goals, and associated risks between these patient cohorts.

Methods

We identified 14 patients who underwent DAIR for a PJI of their femoral megaprostheses, between 2000 and 2014, whom had their index procedure secondary to non-oncological indications. Patients were managed as part of a multidisciplinary team, with our standardised surgical technique including exchange of all mobile parts, and subsequent antibiotic therapy for a minimum of 3 months. Patients were followed up for a minimum of 5 years.

Results

Patients included six proximal femoral replacements, five distal femoral replacements, and three total femoral replacements. No patients were lost to follow-up. There were six males and eight females, with a mean age of 67.2 years, and mean ASA of 2.3.

Nine patients (64.3%) successfully cleared their infection following DAIR at a minimum of 5 year follow-up. Five patients (35.7%) required further revision surgery, with four patients cleared of infection. No patients who underwent DAIR alone suffered complications as a result of the procedure.

Conclusions

The use of DAIR in these complex patients can lead to successful outcomes, but the risk of further revision remains high. The success rate (64.3%) remains on par with other studies evaluating DAIR in megaprostheses and in primary arthroplasty. This study indicates judicious use of DAIR can be an appropriate part of the treatment algorithm.

Level of evidence

II

Optimal time period for blood glucose level evaluation after total knee arthroplasty in patients without diabetes: a prospective, observational study

Background

Postoperative hyperglycemia has been reported to be a risk factor for postoperative infection even in patients without diabetes mellitus (DM). However, there is no standard for how long blood glucose level (BGL) monitoring should be performed after total knee arthroplasty (TKA). The purpose of this study was to determine the optimal time period for BGL evaluation after TKA in patients without DM.

Methods

This prospective study included 132 knees of 110 patients who underwent TKA between March 2018 and July 2021 in our hospital. Fasting BGLs were measured preoperatively, at 9:00 PM on the day of surgery (DOS), and at 7:00 AM on postoperative days (PODs) 1, 2, and 3. Patients were divided into two groups with a preoperative hemoglobin A1c (HbA1c) cut-off value of 5.9%, and the BGLs on POD 1 were compared between the two groups.

Results

The BGLs were significantly higher on the DOS, POD 1, and POD 2 than preoperative levels. The BGL was significantly higher on POD 1 than at any other time point. Patients with an HbA1c ≥ 5.9% had significantly higher BGLs than those with an HbA1c < 5.9% on POD 1.

Conclusions

The optimal time period for BGL evaluation after TKA in patients without DM was considered to be from postoperative to POD 2. Patients with an HbA1c ≥ 5.9% may require careful perioperative glycemic control.

The accuracy of D-dimer in the diagnosis of periprosthetic infections: a systematic review and meta-analysis

Background

Periprosthetic joint infection (PJI) is a devastating complication after total hip arthroplasty (THA) or total knee arthroplasty (TKA). It is scarce and contradicting evidence supporting the use of serum D-dimer to diagnose PJI in revision THA and TKA. This systematic review and meta-analysis aimed to investigate the accuracy of D-dimer in the diagnosis of periprosthetic infections.

Methods

The PubMed, Embase, Web of Science were systematically searched from the inception dates to August 15, 2020. We included all diagnostic studies of D-dimer in the diagnosis of periprosthetic infections. The literature's quality was evaluated by the QUADAS-2 tool, and Stata16 and Revman5.3 software carried out the meta-analysis.

Results

Of 115 citations identified by the search strategy, 10 studies (comprising 1756 participants) met the inclusion criteria. The literature quality assessment results show that most of the literature is low-risk bias literature. The combined sensitivity of D-dimer in diagnosing periprosthetic infections was 0.81 (95% confidence interval [CI] 0.71–0.88), combined specificity was 0.74 (95% CI 0.61–0.84), combined positive likelihood ratio was 3.1 (95% CI 2.0–5.0), combined negative likelihood ratio 0.26 (95% CI 0.16–0.41), combined diagnosis odds ratio 12 (95% CI 5–27), area under the Summary Receiver Operator Characteristic Curve (SROC) is 0.85 (95% CI 0.81–0.88). The data are statistically significant.

Conclusion

D-dimer has a high diagnostic value in diagnosing PJI and has clinical significance in diagnosing periprosthetic infection. In addition, there are relatively few studies on the threshold of D-dimer, different sampling types, different laboratory detection methods, and different races, so more prospective trials with large samples, multi-centers, and scientific design should be carried out in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03001-y.

Factors associated with failure of surgical revision and IV antibiotics to resolve Cutibacterium periprosthetic infection of the shoulder

PURPOSE

Cutibacterium is the most common organism causing shoulder periprosthetic infection (PJI). While most shoulder PJIs are well treated by prosthesis exchange and antibiotics, in some cases this treatment fails to resolve the infection. The factors associated with these failures have not been previously identified. The aim of this study was to identify the characteristics of patients with failure of treatment for PJI.

METHODS

Thirty-five patients suspected of having Cutibacterium PJI had revision arthroplasty with single-stage implant exchange followed by intravenous antibiotics. The characteristics of those with ≥ two positive cultures at revision surgery were compared to those who did not. The characteristics of those patients having a re-revision with ≥ two positive deep cultures (documented treatment failures) were compared to those who did not.

RESULTS

The 17 patients that had ≥ two positive cultures at their index revision were more likely to be male, to have had ream and run procedures, and to have higher loads of Cutibacterium on pre-operative cultures of their unprepared skin. The five patients that had documented treatment failure had higher loads of Cutibacterium on their skin and in deep cultures obtained at their index revision.

CONCLUSION

Patients harboring high loads of Cutibacterium on their unprepared skin prior to revision and high loads of Cutibacterium on deep cultures at the time of their index revision are at increased risk for failure of implant exchange and antibiotics to resolve a Cutibacterium PJI.

Applications of thermal imaging with infrared thermography in Orthopaedics

BACKGROUND

Pathological conditions with ongoing inflammatory processes result in specific heat signatures at the affected body parts; infrared thermography (IRT) detects these changes and can be utilied in screening such conditions. The modern devices are advanced and their non contact, convenient and precise readings can aid in multiple medical sub fields. Orthopaedics as a broad entity has witnessed utilisation of this technology for different indications and the present scoping review was done to assess these established indications and further scope of its utility.

METHOD

ology: A Medline search was done on April 26, 2021 with specific keywords for studies of any design in English language discussing the usage of thermography in Orthopaedics. Animal studies, conference abstracts, systematic reviews, e-posters, case reports, book chapters, and studies describing the use of thermography in non-Orthopaedic patients were excluded.

RESULTS

Total number of hits were 1380. 43 studies including case series and case control studies were included in the review. The subfields or indications described were pain/arthritis, Charcot's foot/neuropathic ulcers, infections associated with diabetic feet and arthroplasties, reflex sympathetic dystrophy, carpal tunnel syndrome, sports medicine, paediatric orthopaedics, spine, ergonomics and compartment syndrome.

CONCLUSION

IRT has been described to be effective in orthopaedic conditions with specific heat signatures and this can assess the trend of the ongoing inflammatory process as well as response to a particular treatment. Additionally, it can specifically determine the exact loci of the pathology for targeted interventions.

Use of PET-CT in diagnostic workup of periprosthetic infection of hip and knee joints: significance in detecting additional infectious focus

Introduction

The diagnosis and management of periprosthetic knee and hip infections as well as the identification and management of possible additional infectious foci is of great importance for successful therapy. This study analyses the importance of ¹⁸F deoxyglucose PET-CT (PET-CT) in the identification of additional infectious focus and subsequent impact on management of periprosthetic infection (PPI).

Material and methods

A retrospective analysis of the clinical data and findings in the period from January 2008 to December 2018 was carried out. One hundred and four patients with in-hospital treatment due to PPI of a hip or knee joint were identified and included in this study. All patients underwent a standardized clinical examination and further surgical and antibiotic therapy. The reevaluation of performed PET-CTs was specifically carried out with regard to the local PPI or detection of secondary foci.

Results

PET-CT successfully verified the PPI in 84.2% of the patients. A total of 78 possible additional foci were detected in PET-CT in 56 (53.8%) of the examined patients. Predilection sites for possible secondary foci were joints (42.3%), pulmonary (15.4%), ear-nose-throat (15.4%), spine (11.5%), and the musculocutaneous tissues (11.5%). Fifty-four positive PET-CT findings were confirmed clinically with need of additional adequate treatment.

Conclusion

PET-CT is a valuable diagnostic tool to confirm periprosthetic joint infection. At the same time, the whole-body PET/CT may detect additional foci of infection with impact on subsequent treatment strategy. PET was of special value in detecting infections at distant locations far from the primary infected joint in significant number. These distant infection locations can be potential cause of a re-infection. This clearly reflects the need of their diagnosis.

[Treatment of bone and periprosthetic infections with bacteriophages : A systematic review]

Hintergrund

Die Behandlung von Knochen- und Protheseninfektionen bleibt trotz moderner Behandlungskonzepte mit interdisziplinärem Therapieansatz schwierig und weitere Maßnahmen zur Verbesserung des Behandlungsergebnisses sind wünschenswert. Präklinischen Studien liefern ein vielversprechendes Bild der Wirksamkeit von Bakteriophagen zur Behandlung von Knochen- und Protheseninfektionen.

Ziel der Arbeit

Die vorliegende Arbeit gibt eine systematische Übersicht über die klinische Anwendung von Bakteriophagen zur Behandlung von Knochen- und Protheseninfektionen.

Material und Methoden

Eine systematische Suche wurde in PubMed zur Identifikation von primären klinischen Daten zur Anwendung der Phagentherapie bei Patienten mit Knochen- und Protheseninfektion durchgeführt.

Ergebnisse

Elf Studien wurden eingeschlossen, bestehend aus 8 Fallberichten und 3 Fallserien. Indikationen der Phagentherapie waren periprothetische Infektionen (n = 12, 52,2 %), frakturassoziierte Infektionen (n = 9, 39,1 %), Osteomyelitis (n = 1, 4,4 %) und eine Iliosakralgelenkinfektion nach Zementaugmentation einer Metastase (n = 1, 4,4 %). Die Interventionen waren heterogen, Phagen wurden intravenös verabreicht, intraoperativ ins Gelenk injiziert, intraoperativ lokal angewendet oder über Drainagen appliziert. In Kombination mit Antibiotikatherapie konnte eine vollständige Infekteradikation bei 18 Patienten (78,3 %) erreicht werden. Bei 91,3 % der Patienten wurden keine Nebenwirkungen berichtet.

Schlussfolgerung

Bakteriophagen sind eine vielversprechende Behandlungsmethode von Knochen- und Protheseninfektionen in Kombination mit einer Antibiotikatherapie. Zukünftige klinische Studien mit höherem Evidenzgrad werden benötigt, um eine erfolgreiche Translation der Bakteriophagentherapie in die klinische Praxis weiter zu etablieren.

Partial two-stage exchange: an alternative method for infected total hip arthroplasty

Background

Total two-stage exchange is commonly used in clinical practice as a treatment for infected total hip arthroplasty (THA); however, this approach involves considerable limitations, including significant bone loss and severe trauma. This retrospective cohort study was conducted to evaluate clinical outcomes following the use of partial two-stage exchange (PTE) for infected THA.

Methods

We performed a retrospective analysis of 28 patients with infected THA who were treated by PTE between September 2000 and June 2019. Eligibility for PTE was limited to patients with a well-fixed femoral stem prosthesis. In the first stage of the operation, the femoral stem prosthesis was preserved; subsequently, the acetabular prosthesis, liner, and head were replaced with an antibiotic-loaded spacer. The new prosthesis was then implanted into patients and monitored for at least 3 months to ensure freedom from infection.

Results

Patients were followed for an average of 4 years (range, 2–11 years), with an overall success rate of 85.7% (24/28). The mean Harris hip score at the final follow-up was 76.2 ± 11.7 points.

Conclusions

The findings of this study suggest that PTE could be an acceptable option for a subset of patients with infected THA, offering a satisfactory infection control rate and clinical outcomes comparable to those of total two-stage exchange, but with less harm.

Diagnosing a periprosthetic shoulder infection: A systematic review

Introduction

The aim of this study was to systematically review the literature regarding accurate shoulder prosthetic joint infection (PJI) diagnosis.

Methods

Using PRISMA guidelines, we analyzed 25 studies reporting on 5535 patients and 646 infections.

Results

Cutibacterium acnes (C. acnes) cultures were positive in 60% of patients. Serum markers WBC, CRP, ESR, and IL-6 appear to lack diagnostic reliability. Synovial IL-6 and alpha-defensin may be more accurate in detecting infections.

Conclusion

Synovial IL-6 and alpha-defensin appear to have greater utility than serum markers. These may be incorporated into new criteria to accurately diagnose shoulder PJI.

Level of evidence

IV.

Unexpected low-grade infections in revision hip arthroplasty for aseptic loosening : a single-institution experience of 274 hips

AIMS

The purpose of this study was to evaluate unexpected positive cultures in total hip arthroplasty (THA) revisions for presumed aseptic loosening, to assess the prevalence of low-grade infection using two definition criteria, and to analyze its impact on implant survival after revision.

METHODS

A total of 274 THA revisions performed for presumed aseptic loosening from 2012 to 2016 were reviewed. In addition to obtaining intraoperative tissue cultures from all patients, synovial and sonication fluid samples of the removed implant were obtained in 215 cases (79%) and 101 cases (37%), respectively. Histopathological analysis was performed in 250 cases (91%). Patients were classified as having low-grade infections according to institutional criteria and Musculoskeletal Infection Society (MSIS) International Consensus Meeting (ICM) 2013 criteria. Low-grade infections according to institutional criteria were treated with targeted antibiotics for six weeks postoperatively. Implant failure was defined as the need for re-revision resulting from periprosthetic joint infection (PJI) and aseptic reasons. The mean follow-up was 68 months (26 to 95).

RESULTS

Unexpected positive intraoperative samples were found in 77 revisions (28%). Low-grade infection was diagnosed in 36 cases (13%) using institutional criteria and in nine cases (3%) using MSIS ICM 2013 criteria. In all, 41 patients (15%) had single specimen growth of a low-virulent pathogen and were deemed contaminated. Coagulase-negative Staphylococcus and anaerobes were the most commonly isolated bacteria. Implant failure for PJI was higher in revisions with presumed contaminants (5/41, 12%) compared to those with low-grade infections (2/36, 6%) and those with negative samples (5/197, 3%) (p = 0.021). The rate of all-cause re-revision was similar in patients diagnosed with low-grade infections (5/36, 14%) and those with presumed contaminants (6/41, 15%) and negative samples (21/197, 11%) (p = 0.699).

CONCLUSION

Our findings suggest that the presumption of culture contamination in aseptic revision hip arthroplasty may increase the detection of PJI. In this cohort, the presence of low-grade infection did not increase the risk of re-revision. Further studies are needed to assess the relevance of single specimen growth and the benefits of specific postoperative antibiotic regimens. Cite this article: Bone Joint J 2021;103-B(6):1070-1077.

Low value of platelet count to mean platelet volume ratio to diagnose chronic PJI: A case control study

INTRODUCTION

Numerous tests are being evaluated in order to aid the diagnosis of periprosthetic infections since it is a complicated and sometimes inconclusive process. The purpose of this study was to assess the diagnostic performance of platelet count to mean platelet volume ratio as a tool to aid the diagnosis of periprosthetic joint infections. The investigated questions were: "Is platelet count/mean platelet volume ratio more sensitive or specific than C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) in the diagnosis of periprosthetic joint infections?" and "Does platelet count/mean platelet volume ratio increase the accuracy of periprosthetic joint infection diagnosis?".

HYPOTHESIS

Platelet count/mean platelet volume ratio increases the accuracy of periprosthetic joint infection diagnosis.

MATERIALS AND METHODS

This study was performed retrospectively on patients who underwent revision hip or knee arthroplasty between 2016 and 2019. 62 patients with 33 aseptic (AR) and 29 septic revision (SR) who met our inclusion criteria were included. The sensitivity, specificity and diagnostic performance of CRP, ESR and platelet count/mean platelet volume values were analyzed and compared.

RESULTS

The demographic characteristics were similar between groups. Staphylococcus aureus and Staphylococcus epidermidis were the most commonly encountered microorganisms, while seven patients had negative cultures in SR group. ESR, CRP and platelet count/mean platelet volume values were significantly higher in SR group compared to AR group (p<0.01). ROC analysis for platelet count/mean platelet volume ratio revealed a cut-off value at 35.3 which provided 75.9% sensitivity and 78.8% specificity for periprosthetic joint infections. Platelet count/mean platelet volume ratio yielded lower sensitivity and similar specificity compared to ESR and CRP values. Platelet count/mean platelet volume had a lower area under curve value, indicating a poorer diagnostic performance compared to ESR and CRP.

DISCUSSION

The diagnostic performance of platelet count/mean platelet volume ratio is low and current findings do not support its usage to increase the accuracy of periprosthetic joint infections diagnosis.

LEVEL OF EVIDENCE

III; diagnostic case-control study.

Does the alpha-defensin lateral flow test conserve its diagnostic properties in a larger population of chronic complex periprosthetic infections? Enlargement to 112 tests, from 42 tests in a preliminary study, in a reference center

BACKGROUND

Diagnosis of periprosthetic infection (PPI) is crucial for management of bone and joint infection. The preoperative gold-standard is joint aspiration, providing results after 2-14 days' culture, with non-negligible false negative rates due to the fragility of certain micro-organisms and/or prior antibiotic treatment. The Synovasure™ alpha-defensin lateral flow test (Zimmer, Warsaw, IN, USA) contributes within minutes to joint fluid diagnosis of almost all infectious agents, including in case of concomitant antibiotic therapy. Validity remains controversial, notably in complex microbiological situations: multi-operated patients, diagnostic doubt despite iterative sterile culture, long-course antibiotic therapy. We extended a prospective study reported in 2018, to determine whether the test maintained diagnostic value in a larger population, assessing 1) negative (NPV) and positive (PPV) predictive value, and 2) sensitivity and specificity.

HYPOTHESIS

Synovasure™ maintains NPV above 95% in a broader population of microbiologically complex suspected PPI.

MATERIAL AND METHODS

Synovasure™'s performance was assessed between October 2015 and October 2019 in 106 patients (112 tests) in complex diagnostic situations: 37 discordant cultures (discordant findings between 2 samples), 65 cases with clinically or biologically suspected infection but iterative sterile culture, 10 emergencies (requiring surgery, precluding antibiotic window, or mechanical failure in suspected infection), including 5 with ongoing antibiotic therapy for infection in another organ. Six tests were repeated in the same patient and same joint at >6 months' interval for strong clinical suspicion of infection. The main endpoint was the MSIS score (MusculoSkeletal Infection Society, 2018).

RESULTS

NPV was 98.8%, PPV 72.4%, sensitivity 95.5% and specificity 91%. Prevalence of infection was 19.6%. Only 1 of the 22 infected patients had negative Synovasure™ tests, compared to 81 of the 84 non-infected patients.

CONCLUSION

Synovasure™ is a reliable novel diagnostic test, contributing mainly to ruling out infection thanks to its strong NPV. The cost imposes sparing use, but medico-economic assessment would be worthwhile.

LEVEL OF EVIDENCE

III; prospective of diagnostic performance.

Single-stage revision for the infected total knee arthroplasty : the Cardiff experience

Aims

Periprosthetic joint infection (PJI) is a devastating complication following total knee arthroplasty (TKA). Two-stage revision has traditionally been considered the gold standard of treatment for established infection, but increasing evidence is emerging in support of one-stage exchange for selected patients. The objective of this study was to determine the outcomes of single-stage revision TKA for PJI, with mid-term follow-up.

Methods

A total of 84 patients, with a mean age of 68 years (36 to 92), underwent single-stage revision TKA for confirmed PJI at a single institution between 2006 and 2016. In all, 37 patients (44%) were treated for an infected primary TKA, while the majority presented with infected revisions: 31 had undergone one previous revision (36.9%) and 16 had multiple prior revisions (19.1%). Contraindications to single-stage exchange included systemic sepsis, extensive bone or soft-tissue loss, extensor mechanism failure, or if primary wound closure was unlikely to be achievable. Patients were not excluded for culture-negative PJI or the presence of a sinus.

Results

Overall, 76 patients (90.5%) were infection-free at a mean follow-up of seven years, with eight reinfections (9.5%). Culture-negative PJI was not associated with a higher reinfection rate (p = 0.343). However, there was a significantly higher rate of recurrence in patients with polymicrobial infections (p = 0.003). The mean Oxford Knee Score (OKS) improved from 18.7 (SD 8.7) preoperatively to 33.8 (SD 9.7) at six months postoperatively (p < 0.001). The Kaplan-Meier implant survival rate for all causes of reoperation, including reinfection and aseptic failure, was 95.2% at one year (95% confidence interval (CI) 87.7 to 98.2), 83.5% at five years (95% CI 73.2 to 90.3), and 78.9% at 12 years (95% CI 66.8 to 87.2).

Conclusion

One-stage exchange, using a strict debridement protocol and multidisciplinary input, is an effective treatment option for the infected TKA. This is the largest single-surgeon series of consecutive cases reported to date, with broad inclusion criteria.

Cite this article: Bone Jt Open 2021;2(5):305–313.

The Expanding Role of Biomarkers in Diagnosing Infection in Total Joint Arthroplasty: A Review of Current Literature

Consistent diagnosis of periprosthetic infection in total joint arthroplasty continues to elude the orthopedic surgeon because no gold standard test exists. Therefore clinicians must rely on a combination of tests to help aid the diagnosis. The expanding role of biomarkers has shown promising results to more accurately diagnose an infection when combined with clinical suspicion and bacterial culture testing. This paper reviews the diagnostic capabilities of the most current serum and synovial biomarkers as well as next generation sequencing in the setting of periprosthetic joint infection. Future research and high-powered studies will be necessary to determine sensitivity and specificity of each biomarker.

Does Early Debridement, Antibiotic Therapy and Implant Retention (DAIR) have a Role in Managing Periprosthetic Joint Infection of the Knee in Indian Scenario: A Retrospective Analysis of Outcomes

PURPOSE

To report outcomes of Debridement, Antibiotic therapy and Implant Retention (DAIR) for periprosthetic knee joint infections (PJI) in the Indian population and to study factors influencing outcomes.

METHODS

This was a Retrospective study of 80 cases of acute PJI after total knee arthroplasty who were treated by DAIR, within 2 weeks of onset of infection. A standardised institutional management protocol was applied to all cases. Patients were followed up for a minimum 1 year. Outcomes of DAIR were classified as successful or unsuccessful based on resolution or persistence of infection, and subsequent requirement of revision surgery. Influence of factors, like comorbidities, culture status and microbiological characteristics of causative organism, on outcomes was assessed.

RESULTS

Overall 55 patients (68.75%) had successful eradication of infection after DAIR. 27 (33.7%) patients were culture negative and 53 (66.2%) patients grew organisms on culture. There was no statistically significant difference in outcomes (p = 0.082) between culture-positive cases (69.8% success rate) and (66.7% success rate) in culture negative cases. Furthermore, no difference in outcomes was observed in culture-positive patients between those who grew Gram-positive organisms versus Gram-negative organisms (p = 0.398) Similarly, patient comorbidities did not significantly alter the outcomes after DAIR (p = 0.732).

CONCLUSION

Our study demonstrates that early DAIR within 2 weeks of onset of infection using a standard protocol during surgery and postoperatively can result in good outcomes. Patient comorbidities, culture status (positive versus negative), Gram staining characteristics of organisms and the identity of pathogenic bacteria did not influence outcomes of DAIR for acute PJI.

Knee arthrodesis as last resort for persistent knee joint infections : Comparison of extramedullary and intramedullary treatment

Background

Knee joint arthrodesis is an established treatment for periprosthetic infections (PPI) providing stability and pain relief. In this study the outcome after arthrodesis of the knee joint for persistent infections was compared and evaluated depending on the surgical procedure (intramedullary vs. extramedullary).

Material and methods

In a retrospective case analysis, all patients who underwent knee joint arthrodesis between 1 January 2010 and 31 December 2016 were identified and divided into two groups: IMA and EMA. All patients were examined clinically and radiologically and the patient files were evaluated. In addition, the FIM score, the LEFS, the WHOQOL-BREF and NRS were evaluated.

Results

The median LEFS score for the IMA group was 26 points and in the EMA group 2 points (p = 0.03). The IMA patients showed a median pain scale at rest of 0 and during exercise of 2. The EMA group recorded a pain scale of 3 at rest and 5 during exercise (p = 0.28 at rest; p = 0.43 during exercise). In the IMA group the median postsurgical leg length difference was −2.0 cm and −2.5 cm in the EMA group (p = 0.31). At the end of the follow-up examinations, the FIM score of patients in the IMA group was 74.5 points and 22 points in the EMA group (p = 0.07).

Conclusion

The study showed that no arthrodesis procedure is obviously superior with respect to the postoperative outcome. The IMA combines advantages especially in the early phase after surgery in terms of function as well as patient comfort and is therefore currently the procedure of choice. The attending physician should be familiar with the advantages and disadvantages of the various procedures in order to be able to make an individual decision and thus maximize the chance of treatment success.

Surgical drainage after limb salvage surgery and endoprosthetic reconstruction: is 30 mL/day critical?

Background

Periprosthetic infection is a major cause of failure after segmental endoprosthetic reconstruction. The purpose of this study is to determine whether certain aspects of drain output affect infection risk, particularly the 30 mL/day criterion for removal.

Methods

Two hundred and ninety-five patients underwent segmental bone resection and lower limb endoprosthetic reconstruction at one institution. Data on surgical drain management and occurrence of infection were obtained from a retrospective review of patients’ charts and radiographs. Univariate and multivariate Cox regression analyses were performed to identify factors associated with infection.

Results

Thirty-one of 295 patients (10.5%) developed infection at a median time of 13 months (range 1–108 months). Staphylococcus aureus was the most common organism and was responsible for the majority of cases developing within 1 year of surgery. Mean output at the time of drain removal was 72 mL/day. Ten of 88 patients (11.3%) with ≤ 30 mL/day drainage and 21 of 207 patients (10.1%) with > 30 mL/day drainage developed infection (p = 0.84). In multivariate analysis, independent predictive factors for infection included sarcoma diagnosis (HR 4.13, 95% CI 1.4–12.2, p = 0.01) and preoperative chemotherapy (HR 3.29, 95% CI 1.1–9.6, p = 0.03).

Conclusion

Waiting until drain output is < 30 mL/day before drain removal is not associated with decreased risk of infection for segmental endoprostheses of the lower limb after tumor resection. Sarcoma diagnosis and preoperative chemotherapy were independent predictors of infection.

Outcomes of hip arthroplasty with concomitant hardware removal: influence of the type of implant retrieved and impact of positive intraoperative cultures

INTRODUCTION

The impact of residual internal fixation devices on subsequent procedures about the hip has not been clearly well defined. The objective of the current study is to evaluate the outcome of hip arthroplasty after hardware retrieval as a one-stage replacement, to analyze possible differences related to the type of removed implant, and to assess the impact of unexpected intraoperative cultures during implant retrieval.

MATERIALS AND METHODS

We present a retrospective study including all those cases undergoing hip arthroplasty with concomitant hardware removal (cannulated screws, intramedullary nail, or dynamic hip screw) from 2005 to 2018. We evaluated demographics, intraoperative cultures, early infection rate, and other complications.

RESULTS

A total of 55 cases were included in the study. The median time between the implant surgery and the hip arthroplasty was 113 days. The removed devices included 6 cannulated screws, 34 intramedullary nails, and 15 dynamic hip screws. Up to 74.5% of the failed osteosynthesis belonged to intertrochanteric femoral fractures. Dislocation rate was 9.1% (1.8% requiring revision surgery), 25.5% of the cases needed further new surgeries after the hip arthroplasty, and 49.1% died during the follow-up period. Any-cause revision surgery and mortality rates were significantly increased after intramedullary nail removal. Intraoperative cultures were performed in 46 cases, and in 9 (16.4%), there was bacterial contamination: 6 cases (10.9%) presented one single positive culture and 3 (5.5%) presented ≥ 2 positive cultures for the same microorganism. A total of five cases (9.1%) presented early prosthetic joint infection that required debridement. None of these five cases had presented positive cultures at the implant removal.

CONCLUSION

According to our results, hip arthroplasty with concomitant hardware removal is related to a high 5-year mortality rate, mainly when intramedullary nail is retrieved. Whereas a high risk of early prosthetic joint infection is associated, it seems not to be related to the elevated presence of unexpected positive cultures.

Do not exchange the spacer during staged TKA exchange!

Purpose

The aim of this study was to investigate the reinfection rate and risk factors for septic failure after two-stage exchange for chronic periprosthetic joint infections of primary total knee arthroplasties. Reinfections should be classified as new infection or as infection recurrence after two-stage exchange.

Methods

We performed a retrospective study of 60 knees with chronic periprosthetic joint infections. Follow-up information was extracted from the departments electronic database.

Results

The reinfection rate after a mean follow-up of 35.6 months (1–135) was 20.0%. The only significant risk factor for reinfection was spacer exchange during two-stage exchange (OR = 10.42; p = 0.001). Of the 12 cases with reinfection 6 cases were classified as new infection and 2 as infection recurrence.

Conclusions

Patient specific factors for reinfection remain furtive. If a spacer exchange is preformed, the risk of reinfection increases. Culture results indicate that the benefit of spacer exchanges during two-stage exchange is highly questionable, particularly because reinfection is an issue of new infection rather than of infection recurrence.

[Advances on treatment of periprosthetic infection and antibiotic delivery system after total hip arthroplasty]

Periprosthetic infection after hip replacement is a clinical catastrophic disease, which often leads to the failure of the prosthesis. It needs the combination of systemic antibiotics to cure the infection, which brings huge burden to doctors and patients. There are strict indications for debridement and one-stage revision of the prosthesis, and few cases meet the requirements. The second revision is still the gold standard for the treatment of periprosthetic infection. It is suitable for all infection conditions and has a high success rate. On the second phase of renovation, the antibiotic sustained release system plays a key role, and the carrier of antibiotic sustained-release system is the focus of current research, including classic bone cement and absorbable biomaterials. Bone cement has strong mechanical strength, but the antibiotic release shows a sharp decline trend; the absorbable biomaterials can continuously release antibiotics with high concentration, but the mechanical strength is poor, so it could not use alone. The combination of bone cement and absorbable biomaterials will be an ideal antibiotic carrier. PMMA is the most commonly used antibiotic carrier, but the antibiotic release concentration is decreased sharply after 24 hours. It will be difficult to control the infection and increase the risk of bacterial resistance if it is lower than the minimum inhibitory concentration. The biodegradable materials can release antibiotics completely, with long release time and high concentration, but low mechanical strength. Antibiotic spacer plays an important role in the control of infection. In the future, how to further extend the antibiotic release time of antibiotic sustained-release system, increase the amount of antibiotic release and maintain the mechanical strength of the material will be studied.

Periprosthetic Infection After Reverse Shoulder Arthroplasty: a Review

PURPOSE OF REVIEW

Periprosthetic infection is a relatively rare but potentially devastating complication after shoulder arthroplasty. The purpose of this article is to review the incidence, diagnosis, prevention, and management of periprosthetic infections after reverse shoulder arthroplasty, with a focus on literature published within the last 5 years.

RECENT FINDINGS

The 2018 International Consensus Meeting on Musculoskeletal Infection provides us with a framework for the diagnosis and management of periprosthetic infections after shoulder arthroplasty. Reverse shoulder arthroplasty has a higher reported rate of infection compared with anatomic total shoulder arthroplasty. Our current diagnostic tests do not appear to be as sensitive when compared with the hip and knee literature. Similar success has been reported with single and two-stage revision protocols, although prospective comparative data are lacking. The significance of unexpected positive cultures during revision arthroplasty remains unclear. We report current diagnostic and therapeutic options for periprosthetic infection after reverse shoulder arthroplasty. Much of the current literature does not distinguish between anatomic and reverse shoulder arthroplasty. Further high-level studies are warranted to refine these definitions and guide management.

Management of Expander- and Implant-Associated Infections in Breast Reconstruction

BACKGROUND

Periprosthetic infection remains the most common complication after implant-based breast reconstruction. Objectives of the study were to (1) describe our clinical approach and treatment protocol for managing patients with suspected periprosthetic infection, (2) identify the microorganisms causing periprosthetic infections at our institute, and (3) report on outcomes of implant salvage versus explantation.

METHODS

A retrospective chart review of patients who were treated with parenteral antibiotics for periprosthetic infection was carried out. Patient characteristics, clinical and laboratory findings, outcomes, treatment modalities and complications were extracted from electronic medical records. Data were compared between patients whose implants were salvaged versus explanted.

RESULTS

Fifty-nine patients with 67 tissue expander (TE)/implants underwent parenteral antibiotic treatment for suspected infection. Thirty-three (49%) of the TE/implants were salvaged. Mean follow-up was 14.3 months. The most commonly cultured organisms were P. aeruginosa followed by S. epidermidis. All suspected infections were treated with broad spectrum parenteral antibiotics with MRSA coverage. The most common combination was daptomycin 6 mg/kg combined with Zosyn 4.5 g. Explantations were significantly more common in patients with history of chemotherapy (p = 0.03), hypertension (p = 0.04) and those who underwent therapeutic mastectomy (p = 0.04).

CONCLUSION

Risk factors for explantation due to postoperative periprosthetic infections following TE/implant-based breast reconstruction include chemotherapy, hypertension and therapeutic mastectomy. Prompt diagnosis and effective treatment of periprosthetic infection, particularly in these high-risk patients, are imperative to salvage the breast reconstruction. Gram-negative bacteria are increasingly found in breast implant infections and should be covered when employing empiric antibiotherapy.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Sodium hypochlorite is more effective than chlorhexidine for eradication of bacterial biofilm of staphylococci and Pseudomonas aeruginosa

PURPOSE

Periprosthetic infection is a common reason for surgical revision. Given the increasing resistance of bacteria to antibiotics (e.g., VRE, 4-MRGN) local antiseptic treatment is gaining in importance. However, no standard guideline-based treatment recommendation is yet available. The aim of this study was to investigate the effectiveness of sodium hypochlorite and chlorhexidine against bacterial biofilms. Furthermore, the toxicity of both antiseptics towards human chondrocytes was examined.

METHODS

Human chondrocytes were isolated, cultivated and treated with sodium hypochlorite and chlorhexidine. The viability of cultures was assessed by determination of cell count, XTT and MTT ELISAs, and fluorescent staining with propidium iodide. Bacterial strains of Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa were added to liquid media and incubated overnight. After determination of bacterial concentrations polyethylene (PE) devices were inoculated with bacteria for 48 h until biofilms formed. The devices were then washed, treated with antiseptics for 2 and 5 min and subsequently spread on agar plates.

RESULTS

Sodium hypochlorite is more effective than chlorhexidine in penetrating biofilms of S. aureus, S. epidermidis and P. aeruginosa. Both antiseptics are chondrotoxic, but sodium hypochlorite damages human chondrocytes less than chlorhexidine in vitro.

CONCLUSIONS

The findings confirm the effectiveness of sodium hypochlorite and chlorhexidine against bacterial biofilms. Both antiseptics can be recommended for the treatment of periprosthetic infections. The toxic effects of sodium hypochlorite and chlorhexidine towards chondrocytes may mean there is a risk of damage to cartilage tissue.

LEVEL OF EVIDENCE

Controlled experimental study.

[Distribution and drug resistance of pathogens causing periprosthetic infections after hip and knee arthroplasty]

OBJECTIVE

To study the distribution and drug resistance of pathogens causing periprosthetic infections after hip and knee arthroplasty, and to formulate prevention and treatment strategies for drug-resistant bacteria.

METHODS

The data of 146 cases of periprosthetic infection after primary hip and knee arthroplasty from 2010 to 2015 were collected, including 111 cases of periprosthetic infection after hip arthroplasty and 35 cases of periprosthetic infection after knee arthroplasty. The culture positive rate, pathogenic bacteria composition and drug resistance rate were counted over the years, and the change trend of pathogen distribution and drug resistance was analyzed.

RESULTS

One hundredand eight strains of pathogenic bacteria were detected in 146 cases, and the positive rate of culture was 73.97%. Gram positive bacteria accounted for 55.48%, Staphylococcus epidermidis and Staphylococcus aureus accounted for 25.34% and 15.07% respectively. Gram negative bacteria accounted for 13.01%, including Enterobacter cloacae, Pseudomonas aeruginosa and Escherichia coli. There were 4 cases of Mycobacterium tuberculosis infection and mixed infection. The results of culture over the years showed that the constituent ratio of Gram positive bacteria had an increasing trend, fluctuating from 39.13% to 76.47%. The results of drug sensitivity showed that the pathogens were highly resistant to β-lactams, quinolones, clindamycin and gentamicin, and the drug resistance rate was increasing, but it was still sensitive to rifampicin, nitrofurantoin, tigecycline, linezolid and vancomycin.

CONCLUSION

Gram positive bacteria are the main pathogens of periprosthetic infection, and the proportion is increasing gradually.The pathogens have high resistance to many kinds of antibiotics, and the resistance rate is still increasing. To strengthen the monitoring of the distribution and drug resistance of pathogenic bacteria is helpful to grasp its change trend and formulate targeted prevention and control strategies.

Antibiotic treatment and prophylaxis of periprosthetic infections: Evaluation of 666 consecutive breast implant removals

Periprosthetic infections are feared complications in esthetic and reconstructive breast surgery. The purpose of our study is to evaluate our institution's specific culture data and to identify most common organisms and suitable antibiotics for prophylaxis and first-line treatment. We evaluated all patients with a change or removal of breast implants from 01.01.2012 to 31.12.2017 retrospectively. Based on the medical records, the surgical indications were identified and specifically analyzed for signs of infection, reasons for primary and secondary surgery, and all available microbiological data of these interventions. A total of 666 implant removals or exchanges were performed in 431 patients. Microbiological smears were gathered from 291 patients (449 implants). Bacteria were cultured from 63 implants (56 patients). In six additional patients (ten implants), a periprosthetic infection was seen, without bacteria detection. Advanced capsular contracture correlated with a higher proportion of positive swabs (p<0.05). In 11.5% of smears, bacterial contamination was found despite absence of clinical signs of infection. Coagulase-negative staphylococci were the dominant pathogen in clinical inapparent infections, while Staphylococcus aureus was when there was clinical evidence of infection. All pathogens were sensitive to vancomycin. In the majority of cases, bacterial contamination was an incidental finding, which was more common in the presence of advanced capsular contracture. In our institution, cefuroxime and amoxicillin/clavulanic acid have been proven to be reasonable choices for prevention and treatment of periprosthetic infections. In the treatment of fulminant infections and for the prophylaxis during implant replacement due to advanced capsular contracture, vancomycin became our first choice.

Difficult to treat: are there organism-dependent differences and overall risk factors in success rates for two-stage knee revision?

OBJECTIVES

Failure after two-stage procedure for periprosthetic joint infection (PJI) is a rare, but devastating complication. Some authors assume a correlation of underlying organisms and recurrence rate. Methicillin-resistant Staphylococci (MRS) and other organisms (quinolone-resistant Gram-negative bacteria, rifampicin-resistant Staphylococcus, Enterococcus, and Candida) are meant to be "difficult to treat" (DTT) with an inferior outcome for two-stage revision. In addition to the type of bacteria, some more risk factors seem to be present. The aim of this study was (1) to detect a difference of reinfection rates between reinfection-causing groups of bacteria ["difficult to treat" (DTT), "easy to treat" (ETT) and methicillin-resistant staphylococci (MRS)] after a two-stage procedure, and (2) find overall risk factors for reinfection in a standardized long (spacer insertion for at least 6 weeks) two-stage procedure for periprosthetic knee infection.

METHODS

One hundred and thirty-seven two-stage revisions for periprosthetic knee infection were performed at one tertiary referral center. Finally, 96 patients could be included for analyses. Possible risk factors (comorbidities, prior surgery, etc.) and the types of organisms were documented. Quinolone-resistant Gram-negative bacteria, rifampicin-resistant Staphylococcus, Enterococcus, and Candida were classified as "difficult to treat" (DTT). Methicillin-resistant Staphylococci were summarized as "MRS", all other organism are summarized as "easy to treat" (ETT). Statistical analyses included univariate analysis (t test, Fisher's exact test, Chi square test) and logistic regression analysis.

RESULTS

There were no statistical significant differences in recurrent infection rates between organism groups (DTT vs. ETT, p = 0.674; DTT vs. MRS, p = 0.705; ETT vs. MRS, p = 0.537). Risk factors seem to be "need of revision after first stage" (p = 0.019, OR 5.62) or completed second stage (p = 0.000, OR 29.07), numbers of surgeries (p = 0.028) and alcohol abuse (p = 0.019, OR 5.62).

CONCLUSIONS

Revision needed during or after a two-stage exchange, numbers of surgeries and alcohol abuse are risk factors for recurrence, a different recurrence rates between organism-groups cannot be shown. The absence of significant differences in recurrence rates points to the importance of the individuality of each periprosthetic infection case: a reduction of necessary surgeries (with a thorough debridement, appropriate antibiotic addition to spacers) and the control of comorbidities (alcohol abuse) appear to be essential components of a two-stage exchange.

Fungal Periprosthetic Knee Joint Infection in a Patient with Metamizole-Induced Agranulocytosis

We present the case of a 55-year-old female patient with metamizole-induced agranulocytosis after total knee arthroplasty, leading to septic periprosthetic joint infections (PJIs). Owing to metamizole-induced agranulocytosis, the synovial leukocyte count was negative. Here, we discuss the diagnostic challenges evolving from sepsis and neutropenia in patients with suspected PJIs. We suggest an urgent surgical approach, mainly focusing on the clinical presentation preoperatively. Later, our patient developed candidemia and periprosthetic tissue samples were positive for Candida albicans. For fungal PJIs, long-term follow-up studies are lacking and therapeutic recommendations differ. Here, we present our therapeutic approach, including staged revision and 12 weeks of systemic antifungal therapy, and discuss recent findings regarding the therapy of fungal PJIs.