Failure of the first step of two-stage revision due to polymicrobial prosthetic joint infection of the hip

Use of Hinged Implants for Multi-Stage Revision Knee Arthroplasty for Severe Periprosthetic Joint Infection: Remission Rate and Outcomes After a Minimum Follow-Up of Five Years

BACKGROUND

In severe periprosthetic joint infection after total knee arthroplasty (TKA), multistage procedures are indicated for ongoing signs of infection after implant removal during the spacer interval of an intended 2-stage exchange. In these cases, several additional debridement and spacer exchange surgeries may be necessary. Herein, we analyzed the complications, remission rates, and functional outcomes after multistage revision arthroplasty using hinged TKAs.

METHODS

Patients (n = 79) treated with multistage revision arthroplasty after chronic periprosthetic joint infection of the knee were included (2010 to 2018). During the prosthesis-free interval, a static spacer containing antibiotic-loaded bone cement was implanted. The mean number of surgeries, including implant removal and revision arthroplasty, was 3.8 (range, 3 to 8). The mean duration from implant removal to revision arthroplasty was 83 days (range, 49 to 318). Complications, remission, and mortality were analyzed after a minimum follow-up of 5 years. Outcomes were assessed based on the Knee Society Score (KSS) and the Western Ontario McMasters University Osteoarthritis Index.

RESULTS

During follow-up, 24 (30.4%) patients underwent revision surgery, with a mean time to surgical revision of 99 weeks (range, 1 to 261). After follow-up, the infection-free remission rate and overall mortality were 87.3 and 11.4%, respectively. The mean KSS was 74.3 (range, 24 to 99), the KSS Function Score was 60.8 (range, 5 to 100), and the Western Ontario McMasters University Osteoarthritis Index 30.2 (range, 5 to 83).

CONCLUSIONS

In difficult-to-treat cases, multistage revision arthroplasty showed high remission rates and low mortality after a follow-up of 5 years. The overall revision rate was comparably high, accounting for early and late reinfections most of the time. In cases of implant survival, functional outcomes comparable to those of revision hinge TKA reported in the literature can be achieved. Therefore, multistage procedures with additional debridement steps should be performed in cases of ongoing infections in intended 2-stage procedures.

The presence of a sinus tract is associated with reinfection after two-stage revision surgery for prosthetic hip joint infection: a case-control study

BACKGROUND

Reinfection rates after two-stage revision (TSR) for prosthetic joint infection (PJI) range from 7.9 to 14%. Many factors, including sinus tracts, are associated with reinfection after this procedure. This study aimed to delineate whether the presence of sinus tract could increase reinfection rate after TSR and to investigate other potential risk factors for reinfection after TSR.

METHODS

We conducted a case-control study by retrospectively reviewing patients who underwent TSR for prosthetic hip joint infection from 2002 to 2022. The case group included patients who developed reinfection after TSR, while the control group consisted of patients who did not experience reinfection. PJI and reinfection after TSR were defined based on Delphi-based international consensus criteria. Patient demographics, past medical history, clinical manifestations, laboratory results, interval between stages, microbiological culture results were collected. Univariate analyses were utilized to assess the effect of sinus tract on reinfection and to identify other risk factors for reinfection after TSR.

RESULTS

Six patients with reinfection after TSR were included as the case group and 32 patients without reinfection were in the control group. Significant difference was observed in percentage of patients with sinus tracts between the two groups (67% in the case group versus 19% in the control group, p = 0.031, OR = 8.7). Significant difference was also found in percentage of patients with positive cultures of synovial fluid and synovium harvested during the first-stage revision between the two groups (100% in the case group versus 50% in the control group, p = 0.030). Additionally, patients in the case group had a significantly higher C-reactive protein (CRP) level prior to the second stage revision than that of patients in the control group (8.80 mg/L versus 2.36 mg/L, p = 0.005), despite normal CRP levels in all patients.

CONCLUSIONS

Our study revealed that the presence of sinus tracts could significantly increase risk of postoperative reinfection after TSR. Positive cultures during the first stage revision and elevated CRP level prior to the second stage revision could also increase the risk of reinfection after TSR. Further studies with a larger sample size are required.

TRIAL REGISTRATION

Retrospectively registered.

Microbiology, Treatment, and Postoperative Outcomes of Gram-Negative Prosthetic Joint Infections-A Systematic Review of the Literature

INTRODUCTION

Gram-negative prosthetic joint infections (PJIs) represent 10% to 25% of all PJIs and are associated with worse outcomes than gram-positive infections. We sought to assess the microbiology, surgical treatment, and outcomes of patients with gram-negative PJIs.

METHODS

A systematic review using the PubMed and Embase databases was conducted. Our study was conducted following the PRISMA guidelines. Included studies were assessed for quality using the STROBE checklist. The primary outcome of analysis was treatment failure.

RESULTS

A total of 593 patients with gram-negative PJIs were included. Two-year survival free of treatment failure for hip and knee PJIs was 66% and 68% for acute infections, 39% and 78% for acute hematogenous infections, and 75% and 63% for chronic infections, respectively. Two-year survival free of treatment failure for acute infections treated with débridement, antibiotics, and implant retention was 65% and 67% for hip and knee PJIs, respectively. Exchange of the polyethylene during débridement, antibiotics, and implant retention was associated with higher treatment success (P = 0.045). Chronic PJIs treated with two-stage revision had a two-year treatment success rate of 87% and 65% for the hip and knee, respectively. Risk factors of treatment failure were chronic obstructive pulmonary disease and C-reactive protein ≥30 mg/L in acute PJIs and female sex, knee infection, and previously revised implant in chronic PJIs. Acute PJIs caused by Pseudomonas spp. were associated with lower treatment failure rates.

CONCLUSION

Gram-negative PJIs are associated with a high treatment failure rate. Patient comorbidities, preoperative biochemical tests, microorganism etiology, and PJI characteristics affected the treatment success rate.

Change in organism between first- and second-stage revision for periprosthetic joint infection of knee arthroplasty independently associated with increased risk of failure

Aims

Achievement of accurate microbiological diagnosis prior to revision is key to reducing the high rates of persistent infection after revision knee surgery. The effect of change in the microorganism between the first- and second-stage revision of total knee arthroplasty for periprosthetic joint infection (PJI) on the success of management is not clear.

Methods

A two-centre retrospective cohort study was conducted to review the outcome of patients who have undergone two-stage revision for treatment of knee arthroplasty PJI, focusing specifically on isolated micro-organisms at both the first- and second-stage procedure. Patient demographics, medical, and orthopaedic history data, including postoperative outcomes and subsequent treatment, were obtained from the electronic records and medical notes.

Results

The study cohort consisted of 84 patients, of whom 59.5% (n = 50) had successful eradication of their infection at a mean follow-up of 4.7 years. For the 34 patients who had recurrence of infection, 58.8% (n = 20) had a change in isolated organism, compared to 18% (n = 9) in the infection eradication group (p < 0.001). When adjusting for confound, there was no association when the growth on the second stage was the same as the first (odd ratio (OR) 2.50, 95% confidence interval (CI) 0.49 to 12.50; p = 0.269); however, when a different organism was identified at the second stage, this was independently associated with failure of treatment (OR 8.40, 95% CI 2.91 to 24.39; p < 0.001). There were no other significant differences between the two cohorts with regard to patient demographics or type of organisms isolated.

Conclusion

Change in the identified microorganism between first- and second-stage revision for PJI was associated with failure of management. Identification of this change in the microorganism prior to commencement of the second stage may help target antibiotic management and could improve the success of surgery in these patients.

Effectiveness of two-stage revision with commercial polymethylmethacrylate articulated hip spacer: similar outcomes against monomicrobial and polymicrobial hip periprosthetic joint infections

Background: orthopaedic surgeons still struggle against a devastating complication - periprosthetic joint infection (PJI). A two-stage revision is considered the gold standard for chronic PJI for several authors, with success rates over 90 %. This strategy implies the remotion of the prosthesis and the implantation of an antibiotic-impregnated cement spacer in the joint. The primary objective of this study was to assess the effectiveness of a two-stage revision approach using a commercial prefabricated antibiotic-impregnated cement hip spacer for the treatment of hip PJI regarding monomicrobial and polymicrobial infections. Secondly, to assess risk factors for failure of two-stage revision. Material and methods: we conducted a retrospective study on patients that underwent revision of total hip arthroplasty (THA) between January 2002 and January 20218. We included adult patients with a diagnosis of chronic hip PJI that underwent two-stage revision using a prefabricated gentamicin-impregnated cement of polymethylmethacrylate (PMMA) hip spacer. We assessed whether it was monomicrobial or polymicrobial infections and comorbidities. Treatment success was defined when eradication of the infection was observed and no further procedures or mortality were registered after the second stage. Persistence or recurrence of infection was considered a failure of treatment. Results: the final series consisted of 84 patients treated with the same hip spacer: 60 (71.4 %) monomicrobial and 24 (28.6 %) polymicrobial joint infections with an overall follow-up of 59.0 (36.0-84.0) months. The overall success rate was 90.5 %. Eight (9.5 %) patients failed. Smoking and BMI greater than 30 m kg- 2 were identified independent risk factors for failure in multivariate analysis. Conclusion: our study suggests that prefabricated gentamicin-impregnated PMMA spacer is an effective tool for the treatment of PJI, achieving similar outcomes whether it is monomicrobial or polymicrobial infections. Randomized prospective studies are needed to obtain more reliable conclusions.

The reasons for and mortality of patients unable to receive reimplantation after resection arthroplasty for chronic hip periprosthetic infection

BACKGROUND

Two-stage exchange arthroplasty is a feasible treatment for chronic PJI (periprosthetic joint infection) of total hip arthroplasty (THA). However, there are large numbers of patients who are unable to ultimately receive reimplantation after resection arthroplasty owing to uncontrolled infection and multiple comorbidities. The purpose of the current study was to identify patient-related risk factors and reasons for being unable to undergo revision THA.

METHODS

Individuals undergoing resection arthroplasty for chronic PJI treatment from 2013 to 2020 at our institution were retrospectively reviewed. A variety of patient comorbidities, laboratory data, isolated pathogens, and follow-up status were collected for analysis.

RESULTS

A total of 84 patients (46 men and 38 women) with a 2.7 ± 2.1-year follow-up were analyzed. Thirty-eight (45.2%) patients eventually underwent revision THA, while the other 46 (54.8%) did not receive reimplantation during follow-up. The patients without receiving reimplantation had higher Charlson comorbidity index (CCI) score (3.1 ± 2.9 versus 1.2 ± 1.5; p = 0.001). Lower cumulative incidence of receiving reimplantation was observed in patients with chronic kidney disease (log-rank test, p = 0.019), anemia (p = 0.011), presence of initial fever (p = 0.030), and oxacillin-resistant strain infection (p = 0.030). The most common reasons for not receiving reimplantation were uncontrolled infection, unstable medical conditions, and death. The patients without reimplantation had a relatively higher mortality rate (log-rank test, p = 0.002).

CONCLUSION

Chronic hip PJI with poor medical conditions or oxacillin-resistant strain infection decreased the chance of undergoing revision surgery. These patients had unfavourable outcomes and a higher mortality rate after resection arthroplasty.

Comparative analysis of pathogen structure in patients with PJI after primary total hip and knee arthroplasty

BACKGROUND

Microbiological profile of pathogens causing periprosthetic joint infection (PJI) after primary total hip (THA) and knee (TKA) arthroplasty varies in different regions, clinics and even departments. The objective of this study was to analyze the pathogen structure in patients with PJI after primary THA and TKA and its influence on the effectiveness of the infection eradication after two-stage reimplantation.

MATERIALS AND METHODS

We collected the retrospective data of 364 patients-161 with PJI after primary TKA (113 treated in two stages 48 with failure after spacer implantation) and 203 patients with infected THA (127 after successful two-stage reimplantation and 76 with PJI recurrence after the first stage) within the time period from January 2012 to December 2017, treated with two-stage protocol in the single center. A comparative analysis of pathogen structure was performed between cohorts of patients with hip and knee PJI. A subanalysis was made between the subsets comprised from patients with successful two-stage treatment and the subsets with failure to treat the infection.

RESULTS

Staphylococcus epidermidis was the most commonly identified pathogen in the full hip and knee cohorts: 30.1% and 32.5%, respectively. However, the percentage of methicillin-resistant Staphylococcus epidermidis (MRSE) among all S. epidermidis isolates was higher in the hip cohort-50% compared with 35% in the knee cohort (p = 0.073). Other coagulase-negative Staphylococci were more common to patients with PJI after primary TKA-10.3% compared with 5% (p < 0.02). Streptococcus sp. caused hip PJI in a larger percentage of cases than in knee PJI (p < 0.01)-7% and 2%, respectively (p < 0.01). Polymicrobial associations were significantly more common in hip PJI compared to knee PJI: 45.3% and 14% of cases, respectively (p < 0.001). The presence of polymicrobial infection significantly raised the risk of PJI recurrence [OR 2 (95% CI from 1.24 to 3.24)] in knee PJI patients and reduced the effectiveness of infection eradication from 73.9% to 47.8%.

CONCLUSION

Comparative analysis showed significant differences in the structure of PJI pathogens in the hip and knee. These findings are useful when choosing treatment strategies and empirical antibiotics regimens, in the management of patients with PJIs after primary hip and knee arthroplasty.

Antibacterial and cell-friendly copper-substituted tricalcium phosphate ceramics for biomedical implant applications

The development of new materials with antibacterial properties and the scope to decrease or eliminate the excessive antibiotic use is an urgent priority due to the growing antibiotic resistance-related mortalities. New bone substitute materials with intrinsic antibacterial characteristics are highly requested for various clinical applications. In this study, the choice of copper ions as substitutes for calcium in tricalcium phosphate (TCP) has been justified by their pronounced broad-spectrum antibacterial properties. Copper-substituted TCP (Cu-TCP) ceramics with the copper content of 1.4 and 0.1 wt% were synthesized by mechano-chemical activation. X-ray diffraction (XRD) analyses established that both pure and copper-containing compounds adopted the structure of whitlockite (β-TCP). XRD and electron paramagnetic resonance (EPR) spectroscopy revealed the partial isovalent substitution of calcium ions with copper ions in the β-TCP lattice. With the use of infrared and EPR spectroscopies, it was detected that carbonate ions got incorporated into the β-TCP structure during the synthesis procedure. By releasing the tension in the M(5)O6 octahedron consequential to the lower CaO bond length than the corresponding sum of ionic radii, the substitution of calcium with smaller copper ions stabilizes the structure of β-TCP. As concluded form the thermal analyses, the introduction of Cu prevented the polymorphic transformation of β- to α-TCP. At the same time, the introduction of Cu to the β-TCP structure enhanced the crystal growth and porosity of the ceramics, which had a positive effect on the cytocompatibility of the material. The MTT colorimetric assay showed that the metabolic activity of the mouse fibroblast NCTC L929 cell line during 24 h of incubation with 3-day extracts from Cu-TCP (1.4 wt%) and β-TCP pellets in the cell culture medium was similar to the negative control, indicating the absence of any inhibitory effects on cells. The seeding and the growth of human dental pulp stem cells on the surface of Cu-TCP (1.4 wt%) and β-TCP ceramics also showed the absence of any signs of cytotoxicity. Finally, microbiological assays demonstrated the antibacterial activity of Cu-TCP ceramics against Escherichia coli and Salmonella enteritidis, whereas β-TCP did not exhibit such an activity. Overall, the addition of Cu ions to β-TCP improves its antibacterial properties without diminishing the biocompatibility of the material, thus making it more attractive than pure β-TCP for clinical applications such as synthetic bone grafts and orthopaedic implant coatings.

The risk factors of polymicrobial periprosthetic joint infection: a single-center retrospective cohort study

BACKGROUND

Periprosthetic joint infection is a serious complication after total joint arthroplasty and polymicrobial PJI which compose a subtype of PJI often indicate worse outcomes compared to monomicrobial periprosthetic joint infection. However, a literature review suggested that there were limited number studies evaluating the risk factors of polymicrobial PJI.

MATERIALS AND METHODS

Between 2015 January and 2019 December, a total of 64 polymicrobial PJI patients and 158 monomicrobial PJI patients in a tertiary center were included in this study and corresponding medical records were scrutinized. The diagnosis of PJI was based on 2014 MSIS criteria. Logistic regression was used to identify the association between various variables and polymicrobial PJI and ROC curve was used to identify their efficiency.

RESULTS

The prevalence of polymicrobial PJI is 28.3% in our cohorts. After adjusting for the presence of sinus, previous and knee infection, isolation of enterococci (OR, 3.025; 95%CI (1.277,7.164) p = 0.012), infection with atypical organisms (OR, 5.032;95%CI: (1.470,17.229) p = 0.01), infection with gram-negative organisms (OR, 2.255; 95%CI (1.011,5.031) p = 0.047), isolation of streptococcus spp. (OR, 6; 95%CI (2.094,17.194) p = 0.001), and infection with CNS (OfR, 2.183;95%CI (1.148,4.152) p = 0.017) were risk factors of polymicrobial PJI compared to monomicrobial PJI. However, knee infection is related to a decreased risk of polymicrobial PJI with an adjusted OR = 0.479 (p = 0.023).

CONCLUSION

This study demonstrated that the prevalence of polymicrobial PJI is 28.3% in PJI patients. Moreover, the presence of sinus tract and previous joint revisions were risk factors for identifying different bacterial species in the intraoperative specimens. Therefore, in these PJI cases, it is necessary to examine multiple specimens of both intraoperative tissue and synovial fluid for increasing the detection rate and obtaining resistance information.

Is There a Difference in Microbiological Epidemiology and Effective Empiric Antimicrobial Therapy Comparing Fracture-Related Infection and Periprosthetic Joint Infection? A Retrospective Comparative Study

This study aims to investigate (1) microbial patterns in fracture-related infections (FRIs) in comparison to microbiological patterns of periprosthetic joint infections (PJIs), (2) the identification of effective empiric antibiotic therapy for FRIs and PJIs and (3) analysis of difficult-to-treat (DTT) pathogens. Patients treated for FRIs or PJIs from 2017 to 2020 were evaluated for pathogens detected during treatment. Antibiotic susceptibility profiles were examined with respect to broadly used antibiotics and antibiotic combinations. Resistance rates to rifampicin or fluoroquinolone were determined. A total of 81 patients with PJI and 86 with FRI were included in the study. For FRIs Staphylococcus aureus was the most common infection-causing pathogen (37.4% vs. 27.9% for PJI). Overall, there was no statistical difference in pathogen distribution (p = 0.254). For FRIs, combinations of gentamicin + vancomycin (93.2%), co-amoxiclav + glycopeptide and meropenem + vancomycin (91.9% each) would have been effective for empiric therapy, similar to PJIs. Difficult to treat pathogens were more frequently detectable in PJIs (11.6% vs. 2.3%). Empiric therapy combinations such as gentamicin + vancomycin, co-amoxiclav + glycopeptide or meropenem + vancomycin, are effective antibiotic strategies for both FRI and PJI patients. More DTT pathogens were detectable in PJIs compared to FRIs.

Two-stage exchange Arthroplasty for knee Periprosthetic joint infection exhibit high infection recurrence rate in patients with chronic viral hepatitis

BACKGROUND

Currently, there is little evidence about the outcome of two-stage exchange arthroplasty for the treatment of knee periprosthetic joint infection (PJI) in patients with chronic viral hepatitis. To evaluate it, we set the primary outcome as infection recurrence, and the secondary outcome as the difference between patients diagnosed with hepatitis B virus or hepatitis C virus.

PATIENTS AND METHODS

Between June, 2010 and December, 2016, 172 patients with knee PJIs were treated with two-stage exchange arthroplasty at our institute. Treatment success was defined using Delphi-based consensus. These patients were further divided into groups with or without chronic hepatitis. Variables were analyzed, including age, sex, comorbidities, microbiology, and operative methods. Minimum follow-up was 12 months (mean, 35 months; range, 12-85 months).

RESULTS

Of the 172 knee PJI patients, 25 were identified with chronic hepatitis. The infection recurrence rate in the hepatitis group (28%, 7 in 25) was significantly higher than that in the non-hepatitis group (9.5%, 14 in 147), p = 0.017. However, there was no significant difference in the infection recurrence rates between patients with HBV (24%, 4 in 16) and HCV (33.3%, 3 in 9). Regarding the outcomes of patients with infection recurrence, 4 of the non-hepatitis patients were treated with the debridement, antibiotic treatment, irrigation, and retention of prosthesis (DAIR) procedure, with a success rate of 75%. The other 17 patients (7 with hepatitis and 10 without) were treated with repeated two-stage exchange arthroplasty with 100% infection elimination rate until the final follow-up.

CONCLUSIONS

Knee PJI patients with chronic hepatitis have higher infection recurrence rate after two-stage exchange arthroplasty (28%).

Efficacy of 16S rRNA variable regions high-resolution melt analysis for bacterial pathogens identification in periprosthetic joint infections

BACKGROUND

Accurate and rapid identification of microorganisms causing periprosthetic joint infections (PJIs) are necessary for choosing an appropriate antibiotic therapy. Therefore, molecular techniques are suggested for diagnosis in suspected PJIs. The Broad-range PCR and High-Resolution Melt Analysis (HRMA) were evaluated for the identification of causative organisms of PJIs in this study.

RESULTS

For 47 of 63 specimens, both the culture and broad-range PCR were positive. The culture was found to be able of organism's detection in 74.6% (47/63) of patients. Of 47 positive cultures, 11 (23.4%) were polymicrobial and 36 (76.59%) were monomicrobial cultures, in which 34 (91.89%) cases were detected by HRM assay. The sensitivity, specificity of HRMA vs monomicrobial culture were 91.89, 93.75%, respectively. The sensitivity, specificity of total HRMA (mono + poly) vs culture were 82.92, 93.75%.

CONCLUSIONS

HRM assay coupled with broad-range PCR are effective screening, rapid, and relatively cost-effective methods for discrimination of PJIs especially in aiding culture method. Using computer programs such as the Matlab-2018b program for HRM data analysis is also valuable and helpful in diagnosis.

Microbial findings and the role of difficult-to-treat pathogens in patients with periprosthetic infection admitted to the intensive care unit

Little is known about patients with Periprosthetic Joint Infection (PJI) admitted to the Intensive Care Unit (ICU). The purpose of this study was threefold: i) To report the microbiological findings of ICUpatients with PJI. ii) To compare the clinical data between Difficult-To-Treat (DTT) and non-DTT PJI. iii) To identify risk factors for mortality. This is a retrospective study from a tertiary healthcare center in Germany from 2012-2016. A total of 124 patients with 169 pathogens were included. The most common bacteria were Staphyloccous aureus (26.6%), Staphyloccus epidermidis (12.4%), Enterococci ssp. and Escherichia coli (respectively 9.4%). DTT PJI was diagnosed in 28 patients (22.6%). The main pathogens of DTT PJI were Staphylococus epidermidis (14.5%), Escherichia coli (12.7%), Staphylococcus aureus and Candida spp. (respectively 9.1%). Polymicrobial PJI, number of pathogens, ICU stay and mortality were significantly differrent between DTT PJI and non-DTT PJI (p≤0.05). Multivariate logistic regression identified prolonged ICU stay and DTT PJI as risk factors for mortality. In conclusion, we suggest, that the term of DTT pathogens is useful for the intensivist to assess the clinical outcome in ICU-patients with PJI.

One-Stage Exchange Arthroplasty for Fistulizing Periprosthetic Joint Infection of the Hip: An Effective Strategy

Background: Prosthetic hip infection (PHI) is a disastrous scenario after an arthroplasty. International guidelines contraindicate one-stage exchange arthroplasty for fistulizing chronic prosthetic hip infection (FCPHI), nevertheless few surgical teams, mostly from Europe, support one stage procedure for this indication.

Questions/Purposes: Analysis of infection recurrence and implant failure of a series of FCPHIs treated with one stage arthroplasty.

Patients and Methods: Sixty-six FCPHIs treated with one-stage exchange arthroplasty were prospectively followed up at least 2 years. Clinical, radiological and bacteriological signs suggestive of reinfection were sought, as well as implant failures and PHI related deaths.

Results: Thirty-four females and thirty-two males with median age of 69.5 years [61–77] and BMI of 26 kg/m² [22-31] were included. Fistulae were productive in 50 patients (76%). Staphylococcus was responsible for 45% of PHI and 21% were polymicrobial. Twenty-nine patients (44%) received preoperative antibiotic therapy. After a median 60-month follow-up [35–82], 3 patients (4.5%) presented reinfection (two new infections, one relapse) and 3 patients experienced implant failure (1 femoral fracture, 1 stem breakage, 1 recurrent dislocation). One death was related to PHI. After a minimum of 2 years, the infection control rate was of 95.3% (±0.02).

Conclusion: One-stage exchange arthroplasty for FCPHIs showed a good infection control rate similar to that of non-fistulizing PHI. Systematic preoperative microbiological documentation with joint aspiration and, in some specific cases, the use of preoperative antibiotic therapy are among the optimizations accounting for the success of the one-stage arthroplasty. In light of these results, and those of other studies, international recommendations could evolve.

Level of Evidence: Descriptive therapeutic prospective cohort study. Level of evidence: IV.

Polymicrobial infections and microbial patterns in infected nonunions - a descriptive analysis of 42 cases

BACKGROUND

Frequencies of polymicrobial infection and pathogens evidenced in course of infected nonunion treatment are largely unknown. Therefore, this study aims at investigating microbial patterns in infected nonunions.

METHODS

Surgically treated patients with long bone infected nonunion admitted between January 2010 and March 2018 were included in the study. Microbiological culture and polymerase-chain-reaction results of tissue samples of initial and follow-up revision surgeries were assessed and compared with patient and treatment characteristics.

RESULTS

Forty two patients with a mean age of 53.9 ± 17.7 years were included. In six patients (14.3%) polymicrobial infection was evident. A change of pathogens evidenced in course of the treatment occurred in 21 patients (50%). In 16 patients (38.1%) previously detected bacteria could be determined by microbial testing after further revision surgery. Staphylococcus aureus was most often detected (n = 34, 30.6%), followed by Enterococcus spp. (n = 25, 22.5%) and Staphylococcus epidermidis (n = 18, 16.2%). Five Staphylococcus aureus were resistant to methicillin (MRSA). In patients without polymicrobial infection or further germ detection in course of the treatment, 86.4% of the infections were due to Staphylococcus spp.. Infections due to Streptococcus spp. and gram-negative bacteria were only present in patients with polymicrobial infection and germ-change in course of the treatment.

CONCLUSION

A low rate of polymicrobial infections was evidenced in the present study. Germ-change often occurs in course of revision surgeries. Prospective studies with more sensitive diagnostic tools are necessary to elucidate the therapeutical relevance of microbiological testing results for surgical as well as medical treatment in infected nonunions.

Bacteria drug resistance profile affects knee and hip periprosthetic joint infection outcome with debridement, antibiotics and implant retention

Background

Evaluate the effect of bacteria drug resistance profile on the success rates of debridement, antibiotics and implant retention.

Methods

All early acute periprosthetic infections in hip and knee arthroplasties treated with DAIR at our institution over the period from 2011 to 2015 were retrospectively analyzed. The success rate was evaluated according to the type of organism identified in culture: multidrug-sensitive (MSB), methicillin-resistant Staphylococcus aureus (MRSA), multidrug-resistant Gram-negative bacteria (MRB) and according to other risk factors for treatment failure. The data were analyzed using univariate and multivariate statistics.

Results

Fifty-seven patients were analyzed; there were 37 in the multidrug-sensitive bacteria (MSB) group, 11 in the methicillin-resistant Staphylococcus aureus (MRSA) group and 9 in the other multidrug-resistant Gram-negative bacteria (MRB) group. There was a statistically significant difference (p < 0.05) in the treatment failure rate among the three groups: 8.3% for the MSB group, 18.2% for the MRSA group and 55.6% for the MRB group (p = 0.005). Among the other risk factors for treatment failure, the presence of inflammatory arthritis presented a failure rate of 45.1 (p < 0.05).

Conclusion

DAIR showed a good success rate in cases of early acute infection by multidrug-sensitive bacteria. In the presence of infection by multidrug-resistant bacteria or association with rheumatic diseases the treatment failure rate was higher and other surgical options should be considered in this specific population. The MRSA group showed intermediate results between MSB and MRB and should be carefully evaluated.

[Resection Arthroplasty Using a Vastus Lateralis Muscle Flap in the treatment of patients with recurrent form of the hip prosthetic joint infection]

OBJECTIVE

To evaluate the efficacy of chronic recurrent hip periprosthetic joint infection (PJI) eradication after resection arthroplasty with non-free transplantation of vastus lateralis muscle flap of the thigh.

MATERIAL AND METHODS

There were 38 patients with chronic recurrent hip PJI who underwent resection arthroplasty with non-free transplantation of vastus lateralis muscle flap of the thigh in 2005-2016. The groups were compiled considering the absence or presence of recurrent infection in early postoperative period. Infection duration, number of operations, incidence of recurrent PJI, type of pathogen, laboratory parameters, bone defect size and presence of PJI remission within at least 2 years were investigated.

RESULTS

Uneventful early postoperative period after resection arthroplasty with non-free transplantation of vastus lateralis muscle flap was noted in 81.6% of cases (n=31, group 1). Postoperative wound revision was required in 18.4% of cases (n=7, group 2). Stable remission of infection within 2-8 years (Me - 4 years) was achieved in 36 (94.7%) patients. Relative risk of recurrent PJI increased by more than 4 times (RR 4,364, 95% CI 0,581-32,787) in cases of polymicrobial infection involving Gram-negative bacteria and decreased in cases of monomicrobial infection (RR 0,256, 95% CI 0,034-1,916). Significantly longer duration of surgery and more pronounced laboratory changes were revealed in group 2.

CONCLUSION

High efficacy of resection arthroplasty with non-free transplantation of vastus lateralis muscle flap of the thigh was established in patients with chronic recurrent hip PJI. This procedure might be considered as a stage treatment with the possibility for revision arthroplasty in case of failed initial debridement surgery due to PJI pathogens that are difficult for eradication.

Predicting Success of Two-Stage Exchange for Prosthetic Joint Infection Using C-Reactive Protein/Albumin Ratio

Two-stage exchange is most commonly used for treatment of prosthetic joint infections (PJI) but, this may fail to eradicate infections. C-reactive protein/albumin ratio (CAR) has been used to predict survival and operative success in other surgical subspecialties and so, we assess the association between CAR and reimplantation success during two-stage revision for PJI defined by the Musculoskeletal Infection Society following a primary total hip (THA) or knee (TKA) arthroplasty. From January, 2005 to December, 2015, two institutional databases were queried and patient demographics, antibiotic duration, C-reactive protein, and albumin were collected prior to reimplantation. Two-stage revisions were considered successful if patients were off of antibiotics and did not require a repeat surgery. CAR was available for 79 patients (34 hips and 46 knees) with 61 successful two-stage revisions and 18 failures. The average CAR for patients with successful reimplantation was 1.2 (0.2, 3.0) compared to 1.0 (0.4, 3.2) for treatment failure. However, this was not statistically significant (p=0.766). Therefore, CAR is not applicable in predicting the prognosis of two-stage revisions for PJI in total arthroplasty but other preoperative inflammatory-based prognostic scores should be explored.

Laboratory Tests for Diagnosis of Chronic Periprosthetic Joint Infection Can Help Predict Outcomes of Two-Stage Exchange

BACKGROUND

Although 2-stage exchange arthroplasty is the most effective treatment among available strategies for managing chronic periprosthetic joint infection (PJI), rates of its success vary greatly. The purpose of our study was to examine whether objective measurements collected at the time of the diagnosis of PJI could be used to identify patients at risk of failure of 2-stage exchange.

METHODS

We identified 205 patients across 4 institutions who underwent 2-stage exchange arthroplasty for the treatment of PJI following total hip or total knee arthroplasty. Demographic, surgical, and laboratory data were obtained for each patient from their medical chart. Laboratory values included serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP) level, synovial fluid white blood-cell (WBC) count and neutrophil percentage, synovial fluid and/or tissue culture, and Gram stain. Patients who underwent revision surgery for recurrent infection were considered to have failed the 2-stage procedure. Demographic, surgical, and laboratory variables were compared between the 2 groups. Receiver operating characteristic (ROC) curves were constructed to determine threshold cutoffs for significant laboratory values. Risk ratios and 95% confidence intervals were calculated.

RESULTS

Overall, 2-stage exchange was unsuccessful for 27.3% of the patients. Preoperative serum ESR (p = 0.035) and synovial fluid WBC count (p = 0.008) and neutrophil percentage (p = 0.041) were greater in patients with recurrent infection. ROC curve analysis revealed a threshold of >60,000 cells/μL for synovial fluid WBC count, >92% for synovial fluid WBC neutrophil percentage, and >99 mm/hr for serum ESR. Failure of 2-stage exchange was 2.5 times more likely for patients with an elevated preoperative synovial fluid WBC count, 2.0 times more likely for those with an elevated preoperative synovial fluid WBC neutrophil percentage, and 1.8 times more likely for those with an elevated preoperative serum ESR.

CONCLUSIONS

Our results demonstrated that a greater number of patients in whom 2-stage exchange arthroplasty ultimately failed had a preoperative synovial fluid WBC count of >60,000 cells/μL, a synovial fluid WBC neutrophil percentage of >92%, or a serum ESR of >99 mm/hr. Patients with elevated laboratory values had 1.8 to 2.5 times the risk of treatment failure. These data can serve as a clinical guideline to identify patients most at risk for failure of 2-stage exchange.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.