Key risk factors and adverse outcomes in metachronous vertebral osteomyelitis following periprosthetic joint infection: A 5-year retrospective study.

Purpose: Periprosthetic joint infection (PJI) is a leading cause of joint arthroplasty failure, potentially leading to critical complications like vertebral osteomyelitis (VO). The factors contributing to VO after PJI and the outcomes for these patients are not well understood. Our study aims to (1) identify risk factors for VO following PJI and (2) assess the clinical outcomes in these cases. Methods: We included PJI patients treated surgically at our centre from January 2006 to December 2020, excluding those with simultaneous VO post-PJI. Our focus was on patients with VO occurring after PJI, monitored for at least 5 years. Analysis included patient comorbidities, PJI treatment approaches, pathogen identification and clinical outcomes. Results: Of 1701 PJI cases, 21 (1.23%) developed VO. Key risk factors for VO post-PJI were identified: systemic inflammatory response syndrome, substance misuse, polymicrobial infection and undergoing at least three stages of resection arthroplasty (odds ratios: 1.86, 54.28, 52.33 and 31.88, respectively). Adverse outcomes were noted in VO patients, with recurrent VO in 6/21 and repeated PJIs in 18/21 cases. Conclusions: Patients with PJI, especially those with certain risk factors, have an increased likelihood of developing VO and encountering negative outcomes. The potential role of bacteremia in the development of VO after PJI needs further exploration. Level of Evidence: Level III.

Survivorship of the fixed-bearing medial unicompartmental knee arthroplasty: mean 14-year follow-up in a single medical center.

BACKGROUND: This study aimed to report the long-term survival of fixed-bearing medial unicompartmental knee arthroplasty (UKA) with a mean of 14-year follow-up, and to determine possible risk factors of failure. METHODS: We retrospectively evaluated 337 fixed-bearing medial UKAs implanted between 2003 and 2014. Demographic and radiographic parameters were measured, including pre-operative and post-operative anatomical femorotibial angle (aFTA), posterior tibial slope (PTS), and anatomical medial proximal tibial angle (aMPTA). Multivariate logistic regression analysis was applied to figure out risk factors. RESULTS: The mean follow-up time was 14.0 years. There were 32 failures categorized into implant loosening (n = 11), osteoarthritis progression (n = 7), insert wear (n = 7), infection (n = 4), and periprosthetic fracture (n = 3). Cumulative survival was 91.6% at 10 years and 90.0% at 15 years. No statistically significant parameters were found between the overall survival and failure groups. Age and hypertension were significant factors of implant loosening with odds ratio (OR) 0.909 (p = 0.02) and 0.179 (p = 0.04) respectively. In the insert wear group, post-operative aFTA and correction of PTS showed significance with OR 0.363 (p = 0.02) and 0.415 (p = 0.03) respectively. Post-operative aMPTA was a significant factor of periprosthetic fracture with OR 0.680 (p < 0.05). CONCLUSIONS: The fixed-bearing medial UKA provides successful long-term survivorship. Tibial component loosening is the major cause of failure. Older age and hypertension were factors with decreased risk of implant loosening.

Clinical outcomes of various types of revision surgeries after unicompartmental knee arthroplasty failure.

PURPOSE: The advantages of unicompartmental knee arthroplasty (UKA) have led to the procedure being increasingly performed worldwide. However, revision surgery is required after UKA failure. According to the literature review, the choice of implant in revision surgery remains a debatable concern. This study analyzed the clinical results of different types of prostheses used in treating failed UKA. MATERIALS AND METHODS: This is a retrospective review of 33 failed medial UKAs between 2006 and 2017. Demographic data, failure reason, types of revision prostheses, and the severity of bone defects were analyzed. The patients were classified into three groups: primary prosthesis, primary prosthesis with a tibial stem, and revision prosthesis. The implant survival rate and medical cost of the procedures were compared. RESULTS: A total of 17 primary prostheses, 7 primary prostheses with tibial stems, and 9 revision prostheses were used. After a mean follow-up of 30.8 months, the survival outcomes of the three groups were 88.2%, 100%, and 88.9%, respectively (P = 0.640). The common bone defect in tibia site is Anderson Orthopedic Research Institute [AORI] grade 1 and 2a (16 versus 17). In patients with tibial bone defects AORI grade 2a, the failure rates of primary prostheses and primary prostheses with tibial stems were 25% and 0%, respectively. CONCLUSIONS: The most common cause for UKA failure was aseptic loosening. The adoption of a standardized surgical technique makes it easier to perform revision surgeries. Primary prostheses with tibial stems provided higher stability, leading to a lower failure rate due to less risk of aseptic loosening in patients with tibial AORI grade 2a. In our experience, we advise surgeons may try using primary prostheses in patients with tibial AORI grade 1 and primary prostheses with tibial stems in patients with tibial AORI grade 2a.

Nontuberculous mycobacteria peri-prosthetic joint infection: An outcome analysis for two stage revision arthroplasty.

PURPOSE: Nontuberculous mycobacteria periprosthetic joint infection (NTMPJI) is a rare complication of hip or knee joint arthroplasty. The experience for outcomes of NTMPJI treatment is still limited. The objective of this study was to investigate the outcome of hip or knee nontuberculous mycobacteria periprosthetic joint infection following treatment with two-stage exchange arthroplasty. MATERIAL AND METHODS: From 1995 to 2020, 12 patients with NTMPJI were treated with two-stage exchange arthroplasty at our institution. We collected and analyzed variables including demographic data, comorbidity, microbiological data, treatment outcome and antibiotic formula in bone cement. RESULTS: Mycobacterium abcessus (n = 6) and Mycobacterium chelonae (n = 2) constitute the majority of the cases. Five patients had early-onset PJIs and the other seven patients were late onset. The success rate of two-stage exchange arthroplasty was 66.7% (8 of 12). Three patients experienced infection relapse, and one patient had soft tissue compromise complication. Post-operative antibiotic therapy may not improve the success rate (4 of 6 cases, 66.7%). Based on in vitro study, the most commonly used effective antibiotic in bone cement spacer for nontuberculous mycobacteria was amikacin. CONCLUSIONS: nontuberculous mycobacteria is a rare cause of PJIs and should be suspected especially in relatively immunocompromised patients. Resection arthroplasty with staged reimplantation is the preferred approach. Prolonged post-operative antibiotic therapy before reimplantation may not improve the success rate. Delayed revision surgery may not be needed and can be performed once C-reactive protein level is normal after a drug holiday.

Characterization of the phenotypes of methicillin- and vancomycin-susceptible Staphylococcus argenteus after vancomycin passages.

OBJECTIVES: Staphylococcus argenteus is generally more susceptible to antibiotic treatments than Staphylococcus aureus; however, the study showed that the daptomycin/vancomycin-resistant S. argenteus was isolated from a patient with repeated antibiotic treatments. In this study, the methicillin- and vancomycin-susceptible S. argenteus isolates were used to characterize the phenotypes of S. argenteus after vancomycin passages in vitro. METHODS: Eleven S. argenteus isolates were used for passaging under different concentrations of vancomycin. The minimal inhibitory concentration (MIC) of vancomycin was determined by the agar dilution assay, and the biofilm mass of the passaged variants was quantified by the crystal violet staining assay and observed under the confocal microscope. RESULTS: The MIC of vancomycin for eight of 11 S. argenteus isolates was increased from ≤2 µg/mL to ≤4-8 µg/mL after vancomycin passages. Two variants with the high-level vancomycin-intermediate (vancomycin MIC ≤8 µg/mL) phenotype were identified, and the parental strains of these variants did not have the heterogeneous vancomycin-intermediate population determined by the population profile analysis. Further, three S. argenteus isolates showed an increase in biofilm production and icaA transcription after the low-dose (2 µg/mL) vancomycin passages. CONCLUSIONS: S. argenteus is capable of acquiring a vancomycin-tolerant phenotype and/or converting to a strong biofilm producer after vancomycin passages, which could contribute to the decrease of their antibiotic susceptibility.

Revision Total Hip Arthroplasty with Primary Stem or Full-Porous-Coated Long Stem for Aseptic Femoral Component Loosening: A Matched-Pair Study.

BACKGROUND: Revision total hip arthroplasty (RTHA) for loosening the femoral stem is a technical challenge. Distally fixed, full-porous-coated long stems are widely accepted as the standard selection for these revisions. However, the success of primary stems in RTHA is not well known. METHODS: This study enrolled 24 patients with aseptic loosening of the femoral stem who underwent RTHA using primary stems. Another 72 patients with aseptic loosening who underwent RTHA using full-porous-coated long stems were matched in terms of operation date, proximal femoral bone stock (Paprosky classification), sex, and age. The primary and secondary outcomes of failure were the need for revision for any reason and the radiographic change in the stem respectively. RESULTS: In the primary stem group, one patient had a periprosthetic fracture and received a second RTHA 2 years after the previous one. The primary outcome's 5-and 10-year survival rates were both 95.8%. For the matched comparison group, one patient had an immediate periprosthetic fracture of the femoral shaft requiring further open reduction internal fixation surgery. Another patient had a full-porous-coated long stem breakage 6 years postoperatively, which required a second RTHA. The primary outcome's 5-and 10-year survival rates were 98.6% and 97.2%, respectively. CONCLUSION: Primary stems can achieve non-inferior clinical success compared to a full-porous-coated long stem for aseptic stem loosening RTHA in patients with adequate proximal femoral bone stock.

The Risk Factor and Outcome of Metachronous Periprosthetic Joint Infections: A Retrospective Analysis With a Minimum Ten-Year Follow-Up.

BACKGROUND: Patients with multiple prosthetic joints are at risk of developing periprosthetic joint infections (PJIs). We aimed to determine whether PJI development at one site may lead to infection at another prosthetic joint site and assess the risk factors leading to this subsequent infection. METHODS: We reviewed all cases (294 patients with first-time PJI [159 hips, 135 knees]) with PJI treated at our institute between January 1994 and December 2020. The average follow-up period was 11.2 years (range 10.1-23.2). Patients were included if they had at least one other prosthetic joint at the time of developing a single PJI (96 patients). Patients with synchronous PJI were excluded from the study. The incidence of metachronous PJI was assessed, and the risk factors were determined by comparing different characteristics between patients without metachronous PJI. RESULTS: Of the 96 patients, 19.79% developed metachronous PJI. The identified causative pathogen was the same in 63.16% of the patients. The time to developing a second PJI was 789.84 days (range 10-3386). The identified risk factors were PJI with systemic inflammatory response syndrome, ≥3 stages of resection arthroplasty, and PJI caused by methicillin-resistant Staphylococcus aureus. CONCLUSION: PJI may predispose patients to subsequent PJI in another prosthesis with identified risks. Most causative organisms of metachronous PJI were the same species as those of the first PJI. We believe that bacteremia may be involved in pathogenesis, but further research is required.

Outcome and cost analysis of primary total knee arthroplasty in end-stage renal disease patients: A nationwide population-based study.

BACKGROUND: A number of patients with end-stage renal disease (ESRD) undergo total knee arthroplasty (TKA) due to advanced knee joint osteoarthritis. There are few studies describing the incidence, morbidities, mortality rate, and cost analysis regarding ESRD patients receiving TKA. METHODS: We retrospectively retrieved patient data from National Health Insurance Research Database in Taiwan during 2005-2011, and evaluated the outcomes of TKA in patients with (ESRD group) and without ESRD (non-ESRD group). Patients' demographic data, comorbidities, mortality, and in-hospital cost were recorded. RESULTS: A total of 578 TKAs and 110,895 TKAs were identified in the ESRD and non-ESRD group, respectively. The incidence of patients receiving TKA was higher in the ESRD than in non-ESRD group by at least 2 folds. The ESRD group showed significantly more medical complications (pneumonia, peptic ulcer disease, and acute myocardial infarction) after surgery. In prosthesis-related complications, the ESRD group also had more periprosthetic joint infections, and prosthetic loosenings by one year. The one-year mortality rate was more than 6 times higher in the ESRD than in the non-ESRD group. The ESRD group had higher in-hospital medical expense than the non-ESRD group, especially when there were complications, even when the dialysis-related costs were exempted. CONCLUSION: The complication rate, mortality rate, and cost were higher in the ESRD patients receiving TKA. When considering TKA in ESRD patients, it is crucial to weigh the risks against benefits of TKA, and have a thorough discussion with the patients.

Increased incidence, morbidity, and mortality in cirrhotic patients with hip fractures: A nationwide population-based study.

OBJECTIVES: Hip fractures mostly require surgical treatment and are associated with increased health-care costs and mortality rates. Patients with cirrhosis have low bone marrow density and inferior immune status which contribute to a higher fracture rate and higher surgical complication rate. This population-based study evaluated the prevalence, complication, and mortality rates due to hip fractures in cirrhotic patients. METHODS: Taiwan National Health Insurance Research Database data were used. The study group included 117,129 patients with hip fractures diagnosed from 2004 to 2010, including 4048 patients with cirrhosis. The overall prevalence, morbidity, and mortality rates of the cirrhosis group with hip fractures were compared with the rates of a general group with hip fractures. RESULTS: The cirrhosis group patients were younger than the general group patients (71.2 vs. 73.96 years, p < 0.001). The annual incidence of hip fractures in the cirrhosis and general groups was 46-54 and 7-7.5 per 10,000 person-years, respectively, with an incidence rate ratio of 6.95 (95% confidence interval 6.74-7.18). The rates of infection, urinary tract infection, and peptic ulcer disease were higher in the cirrhosis group (3.46% vs. 1.91%, 9.56% vs. 9.11%, and 8.05% vs. 3.55%, respectively; all p < 0.001). The mortality rate after hip fracture was also higher in the cirrhosis group than in the general group (within 3 months: 8.76-12.64% vs. 4.96-5.30% and within 1 year: 29.72-37.99% vs. 12.84-14.57%). Conclusion: Cirrhotic patients with hip fractures were relatively younger; had a seven times higher annual hip fracture incidence; had higher complication rates of infection, urinary tract infection, and peptic ulcer disease; and had two to three times higher a mortality rate at 3 months and 1 year. Clinicians should pay particular attention to the possibility of osteoporosis and hip fractures in patients with liver cirrhosis. LEVEL OF EVIDENCE: Level III, case-control study.

Increased periprosthetic hip and knee infection projected from 2014 to 2035 in Taiwan.

BACKGROUND: Periprosthetic joint infection (PJI) is a disastrous complication associated with hip and knee arthroplasty. The literature suggests that the economic consequences associated with treating PJI are substantial. Our study aimed to investigate the past trends of PJI rates, and to estimate the projected number of PJI cases, consequent bed-day requirements, and medical expenses in Taiwan up to year 2035. METHODS: A nationwide epidemiological study was conducted using the inpatient database of the Bureau of National Health Insurance from 2004 through 2013. Patients with the International Classification of Disease-Clinical Modification, ninth revision (ICD9-CM) code 99,666 (PJI) who had received surgical treatment including debridement, removal of hip or knee prosthesis, or revision of total hip/knee arthroplasty (THA/TKA) were identified. Projections were performed with Poisson regression on historical incidence rates in combination with projections of arthroplasty numbers from 2014 to 2035. RESULTS: A total of 4935 hip (1871) and knee (3064) PJIs were identified between 2004 and 2013. The rates of PJI were 2.46% for hip arthroplasty and 1.63% for knee arthroplasty. The number of PJIs was expected to increase markedly with time from 728 in 2013 to 3542 in 2035 (a 4.87-fold increase). The bed-day requirements for treating PJI was 17,205 in 2013 and is expected to be 82,509 bed-days in 2035 (a 4.79-fold increase). The total hospitalization cost will increase 4.86-fold by 2035. CONCLUSIONS: The number of PJI cases is increasing rapidly due to the increasing numbers of arthroplasty surgery and the cumulative number of latent infection. This may place a large economic burden on the health care system.

Predictors for Unfavorable Early Outcomes in Elective Total Hip Arthroplasty: Does Extreme Body Mass Index Matter?

BACKGROUND: Studies of previous cohorts have demonstrated a controversial association between extreme body mass index (BMI) and complication rates following total hip arthroplasty (THA). The purpose of this study was to compare 30-day perioperative complications in underweight (BMI <18.50 kg/m2), normal-weight (BMI 18.50-24.99 kg/m2), overweight (BMI 25.00-29.99 kg/m2), class I obesity (BMI 30.00-34.99 kg/m2), and morbidly obese (BMI ≥35.00 kg/m2) groups. METHODS: We performed a cohort study including patients who underwent unilateral primary THA by a single surgeon between January 2010 and December 2015 at our institution. We assessed 30-day complications, operation time, operative blood loss, and length of hospital stay. RESULTS: We identified 1565 primary THAs that were performed in patients with varying BMI levels. Compared with the normal-weight patients, the morbidly obese group had a higher 30-day complication rate (8.9% vs. 2.4%), longer operative time (79 minutes vs. 70 minutes), and more blood loss (376 mL vs. 302 mL). Underweight patients did not present any 30-day complications, and there were no differences among underweight and normal-weight patients regarding complication rates, operative time, or blood loss. The mean length of hospital stay was comparable among the different BMI groups. In the multivariate regression model, higher BMI was not associated with a higher risk of 30-day complications. Independent risk factors for 30-day complications were advanced age, prolonged operative time, and cardiovascular comorbidities. CONCLUSION: Although increased operative time, blood loss, and perioperative complications were seen in the morbidly obese patients, BMI alone was not an independent risk factor for a higher 30-day complication rate. Therefore, our data suggest clinicians should make elderly patients aware of increased 30-day complications before the procedure, particularly those with cardiovascular comorbidities. Withholding THA solely on the basis of BMI is not justified.

Rapid analysis of bacterial composition in prosthetic joint infection by 16S rRNA metagenomic sequencing.

OBJECTIVES: Prosthetic joint infection (PJI) is the most common cause of arthroplasty failure. However, infection is often difficult to detect by conventional bacterial cultures, for which false-negative rates are 23% to 35%. In contrast, 16S rRNA metagenomics has been shown to quantitatively detect unculturable, unsuspected, and unviable pathogens. In this study, we investigated the use of 16S rRNA metagenomics for detection of bacterial pathogens in synovial fluid (SF) from patients with hip or knee PJI. METHODS: We analyzed the bacterial composition of 22 SF samples collected from 11 patients with PJIs (first- and second-stage surgery). The V3 and V4 region of bacteria was assessed by comparing the taxonomic distribution of the 16S rDNA amplicons with microbiome sequencing analysis. We also compared the results of bacterial detection from different methods including 16S metagenomics, traditional cultures, and targeted Sanger sequencing. RESULTS: Polymicrobial infections were not only detected, but also characterized at different timepoints corresponding to first- and second-stage exchange arthroplasty. Similar taxonomic distributions were obtained by matching sequence data against SILVA, Greengenes, and The National Center for Biotechnology Information (NCBI). All bacteria isolated from the traditional culture could be further identified by 16S metagenomics and targeted Sanger sequencing. CONCLUSION: The data highlight 16S rRNA metagenomics as a suitable and promising method to detect and identify infecting bacteria, most of which may be uncultivable. Importantly, the method dramatically reduces turnaround time to two days rather than approximately one week for conventional cultures.Cite this article: M-F. Chen, C-H. Chang, C. Chiang-Ni, P-H. Hsieh, H-N. Shih, S. W. N. Ueng, Y. Chang. Rapid analysis of bacterial composition in prosthetic joint infection by 16S rRNA metagenomic sequencing. Bone Joint Res 2019;8:367-377. DOI: 10.1302/2046-3758.88.BJR-2019-0003.R2.

Different microbiological profiles between hip and knee prosthetic joint infections.

PURPOSE: The study aims to analyze the demographics and microbiological profiles of hip and knee prosthetic joint infection (PJI) and to compare the microbiological differences between hip and knee PJI. METHODS: We performed a retrospective study of all PJI cases between January 2006 and December 2014 at a referral medical center in Taiwan. RESULTS: A total of 294 PJI cases were collected: 159 were identified as hip PJI and 135 as knee PJI. The most common causative pathogen was Staphylococcus aureus (78 cases, 27%), followed by coagulase-negative staphylococci (CoNS, 42 cases, 14%). Methicillin-resistant staphylococci (MRS) accounted for 21% of all PJI cases. Fungus and mycobacterium were only involved in 12 cases (4.1%) of all PJI cases. Polymicrobial pathogens, anaerobes, and enteric gram-negative bacilli (GNB) were more likely to occur in hip joint prostheses than in knee joint prostheses (22 vs. 6 cases, p = 0.006; 11 vs. 0 cases; p = 0.002; 20 vs. 6 cases; p = 0.014, respectively). CONCLUSION: The prevalence of polymicrobial pathogens, anaerobes, and enteric GNB was higher in the prosthetic hip infection than in the prosthetic knee infection. The high prevalence of MRS, including Methicillin-resistant (MR) S. aureus and MR-CoNS in PJI, may warrant the need for empiric antibiotic therapy with broader coverage while pending the culture result of PJI. Although fungal and mycobacterial PJI cases are rare, the incidence of these infections is relatively high in Taiwan. Fungus and mycobacterium should also be taken into consideration whenever a persistent PJI case is encountered.

Vascular injury during primary total knee arthroplasty: A nationwide study.

PURPOSE: To evaluate the incidence, risk factors, mortality, and complications of direct vascular injury (VI) in patients who underwent primary total knee arthroplasty (TKA) using data from a nationwide database. METHODS: Data were collected from the National Health Insurance Research Database of Taiwan. The study group included 111,497 patients who underwent TKA from January 2004 to December 2011. In total, 15 cases of direct VI were reported (VI group). We analyzed the incidence, risk factors, mortality, complications of direct VI and hospital stays between groups (VI group and non-VI group). RESULTS: Average incidence of VI was 13.74 per 100,000 person-years. No patient-dependent risk factors for VI were identified. Surgeons with low surgical volume highly correlated with incidence of VI (P < 0.05). 90-day mortality was significantly higher (33.3% vs. 0.37%) and length of hospital stay was significantly longer (19.43 days vs. 7.26 days) in the VI group than in the control group. In addition, incidence of periprosthetic joint infection, restenosis at the injury site, and limb loss were significantly higher in the VI group than in the control group. CONCLUSION: VI during primary TKA was associated with significantly higher incidence of periprosthetic joint infection, restenosis at the injury site, and limb loss, as well as higher 90-day mortality. Therefore, surgeons should be aware of VI during primary TKA, especially those with low surgical volume.

Symptomatic pulmonary embolism following hip fracture: A nationwide study.

INTRODUCTION: This study evaluated the incidence of symptomatic pulmonary embolism (PE), subsequent mortality, risk factors, and the effects of pharmacological thromboprophylactic intervention following hip fracture surgery in Taiwan. MATERIALS AND METHODS: A nationwide study was conducted from February 2004 to September 2013. Hip fracture patients were placed into two groups: without symptomatic PE (control group) and with symptomatic PE (PE group). We analyzed the incidence of and risk factors for symptomatic PE, post-operative mortality rate, and effects of pharmacological thromboprophylactic intervention. RESULTS: We identified 165,748 hip fracture patients. The 3-month cumulative incidence of post-operative symptomatic PE was 0.24% (n = 392). The cumulative 1-, 3-, and 6-month mortality rates were significantly higher in the PE group (16.1%, 23.0%, and 28.6%, respectively) than in the controls (3.3%, 6.7%, and 10.2%, respectively). Increased risk of post-operative symptomatic PE was associated with prior history of PE (adjusted odds ratio [OR], 40.00; 95% CI, 24.75-64.67; P < 0.001), female sex (adjusted OR, 1.33; 95% CI, 1.07-1.65; P = 0.009), older age (>75 years) (adjusted OR, 1.51; 95% CI, 1.20-1.91; P < 0.001), and hemiarthroplasty (adjusted OR, 1.23; 95% CI, 1.01-1.51; P < 0.043). Pharmacological thromboprophylaxis significantly reduced the incidence of post-operative PE (adjusted hazard ratio, 4.54; 95% CI, 2.08-9.88; P < 0.001). CONCLUSIONS: The incidence of symptomatic PE after hip fracture surgery was not low in Asian patients, and PE significantly decreased patient survival rates. Some groups were at higher risk for PE; in these instances, thromboprophylaxis, prompt diagnosis, and subsequent intervention are advised.

Two-stage revision arthroplasty for Mycobacterium Tuberculosis periprosthetic joint infection: An outcome analysis.

BACKGROUND: Mycobacterium tuberculosis periprosthetic joint infection (TBPJI) is a rare complication of hip/knee joint arthroplasty. The outcomes of hip/knee TBPJI treatment are still unreported. The objective of this study was to investigate the outcomes of hip/knee TBPJI following treatment with two-stage exchange arthroplasty. MATERIALS AND METHODS: From 2003 to 2013, 11 patients with TBPJI (six hips and five knees) were treated with two-stage exchange arthroplasty at our institution. We collected and analyzed variables including demographic data, comorbidities, microbiological data, duration of symptoms, and types of antibiotic used in bone cement. RESULTS: At the most recent follow-up, the success rate of two-stage exchange arthroplasty was 63.3% (7 of 11). All five knee treatments resulted in infection eradication and successful prosthesis reimplantation. However, only two hip TBPJI treatments resulted in successful outcomes; two patients died and two experienced chronic infection. Overall, secondary bacterial infections were common in patients with TBPJI (5 of 11 cases, 45.5%). Streptomycin in bone cement increased the success rate (83.33% vs. 40%). CONCLUSION: More than one third of the patients treated with two-stage exchange arthroplasty for TBPJI showed infection relapse or uncontrolled infection. Streptomycin-loaded interim cement spacers appeared to help ensure successful treatment. Routine M. tuberculosis culture is recommended when treating TBPJI in areas of high tuberculosis prevalence.

Risk factors of treatment failure and 30-day mortality in patients with bacteremia due to MRSA with reduced vancomycin susceptibility.

Bacteremia caused by MRSA with reduced vancomycin susceptibility (MRSA-RVS) frequently resulted in treatment failure and mortality. The relation of bacterial factors and unfavorable outcomes remains controversial. We retrospectively reviewed clinical data of patients with bacteremia caused by MRSA with vancomycin MIC = 2 mg/L from 2009 to 2012. The significance of bacterial genotypes, agr function and heterogeneous vancomycin-intermediate S. aureus (hIVSA) phenotype in predicting outcomes were determined after clinical covariates adjustment with multivariate analysis. A total of 147 patients with mean age of 63.5 (±18.1) years were included. Seventy-nine (53.7%) patients failed treatment. Forty-seven (31.9%) patients died within 30 days of onset of MRSA bacteremia. The Charlson index, Pitt bacteremia score and definitive antibiotic regimen were independent factors significantly associated with either treatment failure or mortality. The hVISA phenotype was a potential risk factor predicting treatment failure (adjusted odds ratio 2.420, 95% confidence interval 0.946-6.191, P = 0.0652). No bacterial factors were significantly associated with 30-day mortality. In conclusion, the comorbidities, disease severity and antibiotic regimen remained the most relevant factors predicting treatment failure and 30-day mortality in patients with MRSA-RVS bacteremia. hIVSA phenotype was the only bacterial factor potentially associated with unfavorable outcome in this cohort.

One- and two-stage surgical revision of peri-prosthetic joint infection of the hip: a pooled individual participant data analysis of 44 cohort studies.

One-stage and two-stage revision strategies are the two main options for treating established chronic peri-prosthetic joint infection (PJI) of the hip; however, there is uncertainty regarding which is the best treatment option. We aimed to compare the risk of re-infection between the two revision strategies using pooled individual participant data (IPD). Observational cohort studies with PJI of the hip treated exclusively by one- or two-stage revision and reporting re-infection outcomes were retrieved by searching MEDLINE, EMBASE, Web of Science, The Cochrane Library, and the WHO International Clinical Trials Registry Platform; as well as email contact with investigators. We analysed IPD of 1856 participants with PJI of the hip from 44 cohorts across four continents. The primary outcome was re-infection (recurrence of infection by the same organism(s) and/or re-infection with a new organism(s)). Hazard ratios (HRs) for re-infection were calculated using Cox proportional frailty hazards models. After a median follow-up of 3.7 years, 222 re-infections were recorded. Re-infection rates per 1000 person-years of follow-up were 16.8 (95% CI 13.6-20.7) and 32.3 (95% CI 27.3-38.3) for one-stage and two-stage strategies respectively. The age- and sex-adjusted HR of re-infection for two-stage revision was 1.70 (0.58-5.00) when compared with one-stage revision. The association remained consistently absent after further adjustment for potential confounders. The HRs did not vary importantly in clinically relevant subgroups. Analysis of pooled individual patient data suggest that a one-stage revision strategy may be as effective as a two-stage revision strategy in treating PJI of the hip.

Fracture of cobalt chrome, fully-coat beaded femoral revision long stem, a clinical outcomes study.

BACKGROUND: Femoral bone loss during revision total hip arthroplasty poses a challenging problem. Bypass fixation over the diaphysis has achieved clinical success in cases of proximal femoral bone loss. Fracture of cementless, fully bead-coated femoral stem is an uncommon complication. The purpose of this study is to analyze the patients with and without fracture stem and find out the possible risk factors. METHODS: From 2006 to 2012, a total of 251 revision long stems (Zimmer, Warsaw, IN) were implanted. In the same period, 17 broken stems that underwent treatment were included for analysis. Patients' demographic data, pattern of femoral bone loss, stem size, medial calcar support in the proximal region of the stem, and the timing of stem breakage were collected and analyzed. RESULTS: The stem size in patients with a broken stem was smaller (p < 0.001), and medial calcar defect was 12.4% and 100% (p < 0.001), respectively. The bone defect was greater in broken group (p = 0.024). The mean duration between revision surgery and stem breakage was 58.07 ± 36.98 months. Smaller stem size, greater bone defect, and inadequate medial calcar bone support were major risk factors for stem breakage. CONCLUSIONS: Bypass fixation in the distal diaphysis with a long stem prosthesis without adequate bone support over medial calcar area may cause stress concentration in the long stem and a fatigue fracture. Use of a smaller prosthesis is the major risk of stem broken. It is essential to repair the proximal femoral bone deficiency and implant selection for better metaphyseal engagement to prevent further stem complications. LEVEL OF EVIDENCE: Level III, case control study.

Rapid identification of pathogens responsible for necrotizing fasciitis on an integrated microfluidic system.

Necrotic fasciitis (NF) is a particularly aggressive and serious infection of the fascia that can penetrate into the musculature and internal organs, resulting in death if not treated promptly. In this work, an integrated microfluidic system composed of micropumps, microvalves, and micromixers was used to automate the detection of pathogens associated with NF. The entire molecular diagnostic process, including bacteria isolation, lysis, nucleic acid amplification and optical detection steps, was enacted on this developed system. Mannose binding lectin coated magnetic beads were first used as probes to isolate all bacteria in a sample. In this work, polymerase chain reaction assays featuring primers specific to genes from each of four NF-causing bacteria (Vibrio vulnificus, Aeromonas hydrophila, and methicillin-sensitive and resistant Staphylococcus aureus) were used to rapidly and exclusively verify the presence of the respective bacterial strains, and the limits of detection were experimentally found to be 11, 1960, 14, and 11 400 colony forming units/reaction, respectively; all values reflect improvement over ones reported in literature. This integrated microfluidic chip may then be valuable in expediting diagnosis and optimizing treatment options for those with NF; such diagnostic improvements could ideally diminish the need for amputation and even reduce the morality rate associated with this life-threatening illness.