Short-course antibiotics for prosthetic joint infections treated with prosthesis retention

The purpose of the present study was to evaluate the significance of shortening the antibiotic treatment duration in prosthetic joint infections (PJI) treated with debridement, antibiotics and implant retention (DAIR). In April 2006 we shortened the total antibiotic treatment duration in total knee arthroplasty (TKA) PJIs from 6 months to 3 months and in total hip arthroplasty (THA) PJIs from 3 months to 2 months. All patients with TKA or THA PJI treated with DAIR between February 2001 and August 2009 were reviewed retrospectively. There were 132 patients treated with DAIR, of whom 86 (65%) completed the antibiotic therapy and were therefore eligible for comparison concerning the length of antibiotic treatment. There were 32 (37%) THA and 54 (63%) TKA PJIs in the comparison. The treatment succeeded in 34 (89.5%) patients treated with longer antibiotic treatment and in 42 (87.5%) of those treated with shorter antibiotic treatment (p 0.78). Our conclusion is that if the patient completes the antibiotic therapy, treatment duration of 3 months in TKA PJIs and 2 months in THA PJIs is as good as longer antibiotic treatment of 6 months or 3 months, respectively, in patients treated with DAIR.     

Gram-negative prosthetic joint infection: outcome of a debridement,antibiotics and implant retention approach. A large multicentre study

We aim to evaluate the epidemiology and outcome of gram-negative prosthetic joint infection (GN-PJI) treated with debridement, antibiotics and implant retention (DAIR), identify factors predictive of failure, and determine the impact of ciprofloxacin use on prognosis. We performed a retrospective, multicentre, observational study of GN-PJI diagnosed from 2003 through to 2010 in 16 Spanish hospitals. We define failure as persistence or reappearance of the inflammatory joint signs during follow-up, leading to unplanned surgery or repeat debridement >30 days from the index surgery related death, or suppressive antimicrobial therapy. Parameters predicting failure were analysed with a Cox regression model. A total of 242 patients (33% men; median age 76 years, interquartile range (IQR) 68–81) with 242 episodes of GN-PJI were studied. The implants included 150 (62%) hip, 85 (35%) knee, five (2%) shoulder and two (1%) elbow prostheses. There were 189 (78%) acute infections. Causative microorganisms were Enterobacteriaceae in 78%, Pseudomonas spp. in 20%, and other gram-negative bacilli in 2%. Overall, 19% of isolates were ciprofloxacin resistant. DAIR was used in 174 (72%) cases, with an overall success rate of 68%, which increased to 79% after a median of 25 months' follow-up in ciprofloxacin-susceptible GN-PJIs treated with ciprofloxacin. Ciprofloxacin treatment exhibited an independent protective effect (adjusted hazard ratio (aHR) 0.23; 95% CI, 0.13–0.40; p <0.001), whereas chronic renal impairment predicted failure (aHR, 2.56; 95% CI, 1.14–5.77; p 0.0232). Our results confirm a 79% success rate in ciprofloxacin-susceptible GN-PJI treated with debridement, ciprofloxacin and implant retention. New therapeutic strategies are needed for ciprofloxacin-resistant PJI.     

术前KLIC评分对清创、假体保留联合抗生素治疗急性假体周围感染效果的预测价值

目的 探讨KLIC（kidney, liver, index surgery, cemented prosthesis and C reactive protein value）评分系统用于预测清创、假体保留联合抗生素方案（DAIR）治疗急性假体周围感染（PJI）结果的准确性。方法 回顾性研究。纳入2015年1月—2020年12月南京大学医学院附属金陵医院骨科急性PJI患者44例,其中男17例、女27例,年龄21~86岁,均行DAIR。结合病史和检验结果,计算患者术前KLIC评分,并按评分结果将患者分为KLIC评分≤2分组、2.5~3.5分组、4~5分组、5.5~6.5分组和≥7分组。比较各组患者基线资料、住院时间和DAIR治疗结果的差异。采用受试者操作特征曲线（ROC）来评价KLIC评分系统预测DAIR治疗结果的准确性;以DAIR失败作为终点事件,采用Kaplan-Meier绘制累积治疗成功率曲线。结果 5组患者年龄、性别、体质量指数（BMI）、病变部位、感染分类、感染症状持续时间、术后住院时间等基线资料比较,差异均无统计学意义（P值均>0.05）。5组患者总体治疗成功率为61.36%（27/44）、失败率为38.64%（17/44）;KLIC评分≤2、2~3.5、4~5、5.5~6.5分和≥7分5组的失败率分别为0/8、2/8、5/13、6/10、4/5,组间比较差异有统计学意义（P=0.018）;趋势χ²检验结果提示,随着KLIC评分的增加,DAIR失败率也随之增加,差异有统计学意义（χ²=10.86,P=0.001）。ROC曲线显示KLIC评分在预测DAIR治疗结果上具有较高的准确性（AUC=0.876,95%可信区间0.773~0.978,P<0.001）。Kaplan-Meier曲线提示：KLIC评分≥7分的患者累积治疗成功率低于KLIC评分<7分者,差异有统计学意义（χ²=8.95,P=0.003）。结论 KLIC评分对于DAIR治疗结果具有良好的预测性;对于KLIC评分≥7分的急性PJI患者,DAIR治疗的失败率较高,不建议采用。     

Should we expand the indications for the DAIR (debridement,antibiotic therapy,and implant retention) procedure for <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> prosthetic joint infections? A multicenter retrospective study

To evaluate factors associated with failure in patients treated with DAIR (debridement, antibiotic therapy, and implant retention) for Staphylococcus aureus prosthetic joint infections (PJIs). We retrospectively analyzed consecutive patients with stable PJI due to S. aureus treated with DAIR at six hospitals between 2010 and 2014. Cox proportional hazards regression was used to study factors associated with treatment failure at 2 years. Of 154 eligible patients, 137 were included (mean age 73?±?13 years; male 56%). The estimated success rate according to the Kaplan–Meier method was 76.2 [95% CI 68–83] at 2 years of follow-up. In multivariate analysis, longer duration of treatment (hazard ratio (HR) 0.78 [0.69–0.88]; p?<?0.001) and combination therapy including rifampin (HR 0.08 [0.018–0.36]; p?=?0.001) were independently associated with success, whereas active smoking was independently associated with failure (HR 3.6 [1.09–11.84]; p?=?0.036). When the analysis was restricted to patients with early infection onset (<?3 months), early acute infection was also predictive of a better prognosis (HR 0.25 [0.09–0.7]; p?=?0.009). Failure was not associated with time from prosthesis insertion to debridement, nor with duration of symptoms >?3 weeks and type of prosthesis (hip or knee). These results remained unchanged when the 14 patients under immunosuppressive therapy were removed from analysis. These data suggest that DAIR can be performed even if infection and symptoms are delayed but reserved to patients who are able to follow rifampin-based combination therapy for a prolonged duration that should not be different for hip and knee PJI.     

Characteristics and outcome of 27 elbow periprosthetic joint infections: results from a 14-year cohort study of 358 elbow prostheses

Elbow arthroplasty is increasingly performed in patients with rheumatic and post-traumatic arthritis. Data on elbow periprosthetic joint infection (PJI) are limited. We investigated the characteristics and outcome of elbow PJI in a 14-year cohort of total elbow arthroplasties in a single centre. Elbow prosthesis, which were implanted between 1994 and 2007 at Schulthess Clinic in Zurich, were retrospectively screened for infection. PJI was defined as periprosthetic purulence, the presence of sinus tract or microbial growth. A Kaplan–Meier survival method and Cox proportional hazard analysis were performed. Of 358 elbow prostheses, PJI was identified in 27 (7.5%). The median patient age (range) was 61 (39–82) years; 63% were females. Seventeen patients (63%) had a rheumatic disorder and ten (37%) had osteoarthritis. Debridement and implant retention was performed in 78%, followed by exchange or removal of the prosthesis (15%) or no surgery (7%). The relapse-free survival (95% CI) was 79% (63–95%) after 1 year and 65% (45–85%) after 2 years. The outcome after 2 years was significantly better when patients were treated according to the algorithm compared to patients who were not (100% vs. 33%, p <0.05). In 21 patients treated with debridement and retention, the cure rate was also higher when the algorithm was followed (100% vs. 11%, p <0.05). The findings of the present study suggest that the treatment algorithm developed for hip and knee PJI can be applied to elbow PJI. With proper patient selection and antimicrobial therapy, debridement and retention of the elbow prosthesis is associated with good treatment outcome.     

Outcome and predictors of treatment failure in early post-surgical prosthetic joint infections due to Staphylococcus aureus treated with debridement

Experience with debridement and prosthesis retention in early prosthetic joint infections (PJI) due to Staphylococcus aureus is scarce. The present study aimed to evaluate the outcome and predictors of failure. Patients prospectively registered with an early PJI due to S. aureus and 2 years of follow-up were reviewed. Demographics, co-morbidity, type of implant, clinical manifestations, surgical treatment, antimicrobial therapy and outcome were recorded. Remission was defined when the patient had no symptoms of infection, the prosthesis was retained and C-reactive protein (CRP) was ≤1 mg/dL. Univariate and multivariate analysis were performed. Fifty-three patients with a mean ± SD age of 70 ± 10.8 years were reviewed. Thirty-five infections were on knee prosthesis and 18 were on hip prosthesis. The mean ± SD duration of intravenous and oral antibiotics was 10.6 ± 6.7 and 88 ± 45.9 days, respectively. After 2 years of follow-up, 40 (75.5%) patients were in remission. Variables independently associated with failure were the need for a second debridement (OR 20.4, 95% CI 2.3–166.6, p 0.006) and a CRP > 22 mg/dL (OR 9.8, 95% CI 1.5–62.5, p 0.01). The onset of the infection within the 25 days after joint arthroplasty was at the limit of significance (OR 8.3, 95% CI 0.8–85.6, p 0.07). Debridement followed by a short period of antibiotics is a reasonable treatment option in early PJI due to S. aureus. Predictors of failure were the need for a second debridement to control the infection a CRP > 22 mg/dL and the infection onset within the first 25 days after joint arthroplasty.     

Outcome of prosthetic knee-associated infection: evaluation of 40 consecutive episodes at a single centre

Few studies have compared the long-term success of different surgical strategies in prosthetic knee-associated infection. Accordingly, a retrospective cohort study was performed of 40 episodes in 35 consecutive patients undergoing revision surgery for prosthetic knee-associated infection at a single centre between 1988 and 2003. The median patient age was 70 (44-90) years; the median follow-up period was 28 (2-193) months; 45% of infections were early, 23% were delayed, and 32% were late; and 55% of infections were caused by staphylococci. The probability of survival without prosthesis failure was 92.4% (95% CI, 84.1-100) after 1 year, and 88.7% (95% CI, 78-99.4) after 2 years. Recurrence-free survival was observed in 20 (95%) of 21 patients treated with debridement and retention, in both patients with one-stage exchange, and in 11 (85%) of 13 patients with two-stage exchange. Patients with delayed infection had a worse outcome than those with early or late infection (67% vs. 97%; p < 0.03). Patients with at least partially adequate antimicrobial therapy had a higher success rate than those with inadequate treatment (94% vs. 60%; p 0.069). The outcome was similar for patients with a duration of therapy of 3 to < 6 months, and those with a duration of therapy of > or = 6 months (91% vs. 87% success). Different surgical procedures had similar success rates, provided that the type of infection, the pathogen, the stability of the implant and the local skin and soft-tissue condition were considered. Adherence to an algorithm defining a rational surgical and antibiotic treatment strategy contributed to a favourable outcome.     

Challenges in periprosthetic knee-joint infection

The number of knee arthroplasty procedures is growing and projected to further increase. The risk for periprosthetic joint infection (PJI) is estimated to be low (<1%). However, considering the increasing number of total knee arthroplasty, the increasing number of patients with multiple comorbidities, and the lifelong risk for acquiring hematogenous infection, the total number of PJI will further increase. Despite existing treatment concepts for PJI of the knee, there are still questions to solve, such as type of debridement surgery in case of implant retention, the role of a spacer from a microbiological perspective, and the optimal duration of antimicrobial therapy. In this REVIEW, these questions will be analyzed according to the available literature and the experience of the authors. Moreover, we REVIEW the most recent data on infection, risk factors, and microbiology of PJI.     

Debridement,antibiotics and implant retention (DAIR) for the management of knee prosthetic joint infection

BackgroundWhile two-stage revision arthroplasty is viewed as the gold standard for the treatment of knee periprosthetic joint infection (PJI) in terms of infection eradication, it is associated with significant cost along with patient morbidity and mortality. Debridement, antibiotics, and implant retention (DAIR) is an attractive option as it has demonstrated better patient outcomes, comparable implant longevity to primary arthroplasty, and significantly reduced cost when successful. Given the heterogeneity of what is defined as a DAIR the literature is highly variable in terms of its efficacy from the perspective of infection eradication.MethodsIn the setting of a previously well-functioning, well-fixed arthroplasty with an acceptable soft tissue envelope and a treatable organism we report our methods for proceeding with a DAIR procedure, both unicompartmental and total knee.ResultsWith the above methods we have demonstrated improved patient outcomes when compared to one- or two-stage arthroplasty with lower patient morbidity. Implant longevity in the setting of a successful DAIR is equivalent to those of a primary arthroplasty.ConclusionsWith appropriate indications and good surgical technique as described we believe DAIR is an excellent option in the treatment of periprosthetic joint infection. We hope that with a well-defined protocol as outlined we can gain a better understanding of the efficacy of DAIR procedure with more homogeneity to the procedure to better define when they are most successful while improving patient outcomes and reducing cost.     

Microbiologic epidemiology depending on time to occurrence of prosthetic joint infection: a prospective cohort study

Objectives

The high microbiologic diversity encountered in prosthetic joint infection (PJI) makes the choice of empirical antimicrobial therapies challenging, especially in cases of implant retention or one-stage exchange. Despite the risk of dysbiosis and toxicity, the combination of vancomycin with a broad-spectrum β-lactam is currently recommended in all cases, even if Gram-negative bacilli (GNB) might be less represented in late PJI. In this context, this study aimed to describe the microbiologic epidemiology of PJI according to the chronology of infection.

Two-stage knee arthrodesis with a modular intramedullary nail due to septic failure of revision total knee arthroplasty with extensor mechanism deficiency

Background

Periprosthetic joint infection is a serious complication and reconstruction after failed revision total knee arthroplasty with significant bone loss and compromised soft-tissues can be challenging. Objective of this study was to assess clinical and functional results, implant survival and infection recurrence rates in patients treated with two-stage arthrodesis after failed revision TKA with extensor mechanism deficiencies due to PJI, and to identify the factors that affect outcomes after surgery.

Periprosthetic knee infection reconstruction with a hinged prosthesis: Implant survival and risk factors for treatment failure

BackgroundSevere bone and soft tissue defects are common after failed two-stage exchange arthroplasty for periprosthetic joint infection (PJI). There is a paucity of evidence on the outcomes of using a hinged prosthesis for knee PJI reconstruction during second-stage re-implantation, especially regarding implant survivorship, reinfection risk factors, and functionality after successful reconstruction.MethodsA total of 58 knee PJI patients with Anderson Orthopaedic Research Institute (AORI) type II/III defect and soft tissue insufficiency underwent reconstruction with hinged prosthesis. Enrolled patients adhered to a two-stage exchange arthroplasty protocol and were evaluated for a mean follow up of 65.1 months. Kaplan–Meier analysis was conducted for implant survivorship and infection-free survival. Multivariate analysis was used to determine independent risk factors for recurrent infections. Knee Society Score (KSS) was used to evaluate functional outcomes.ResultsThe survivorship of hinged prosthesis was 86.2% at 2 years and 70.2% at 5 years. Infection-free analysis revealed an estimation of 68.9% at 2 years and 60.6% at 5 years. Of the 58 patients, 13 (22.4%) developed recurrent PJI, three (5.2%) aseptic loosening, and one (1.7%) periprosthetic fracture. Multivariate analysis revealed that obesity (hazard ratio (HR), 3.11), high-virulent pathogen (HR, 3.44), and polymicrobial infection (HR, 3.59) were independent risk factors for reinfection. Patients showed a mean improvement of 32.8 ± 7.7 in Knee Society Clinical Score (KSCS) and 30.8 ± 11.0 in Knee Society Function Score (KSFS) after successful reconstruction (P < 0.001).ConclusionsUsing hinged knee prosthesis for PJI reconstruction provided an overall implant survival of 70.2% and an infection-free survival of 60.6% at mid-term follow up. Obesity, virulent pathogens, and polymicrobial infections were independent risk factors for infection recurrence.     

Clinical behavior of implant infections due to Staphylococcus epidermidis

Surgical implants and other foreign material are increasingly used in modern medicine to restore or to improve the function of the human body. Infection of an implant is associated with considerable morbidity due to frequent hospitalizations, surgery and antimicrobial treatment. The underlying mechanism is the formation of a bacterial biofilm on the surface of the implanted body. The recognition and diagnosis of implant infections is essential for further therapy and, above all, the decision to remove and exchange the implant. METHODS: We compared the data of 60 patients with implant infections with those of 60 patients with transient bacteremia caused by Staphylococcus epidermidis. The pathogens isolated from blood were characterized with regard to antimicrobial susceptibility and formation of biofilms using a static microtiter plate model. Wild type skin isolates from non-hospitalized healthy volunteers served as control with regard to antimicrobial susceptibility and biofilm formation. RESULTS: Clinical signs and symptoms, underlying diseases and outcome were not different in either group. However, patients with implant infection had fever over a longer time (mean 12 days versus 3 days, respectively, p < 0.05) and more often positive blood cultures than patients with transient bacteremia (3.1 versus 1.2, p < 0.05). Thrombocytopenia was observed in patients with implant infections but not in patients with transient bacteremia (p < 0.05). Biofilms were formed in 86.4 % of the isolates in implant infection, in 88.8 % in transient bacteremia and in 76.9 % of the isolates from healthy volunteers (not significant). Multi-resistance to penicillin, oxacillin, erythromycin, clindamycin, ciprofloxacin and trimethoprim was more common in the hospital strains than in the wild type strains (75.6 % versus 48.7 %, p < 0.05). CONCLUSIONS: The clinical features of implant infections are indistinguishable from those of transient bacteremia. Persisting fever and multiple blood culture yielding the growth of skin flora bacteria are strong indicators for infection of implanted material. Biofilm formation and antimicrobial multi-resistance, as common in implant infection as in transient bacteremia, seem to be accessory factors in infections due to Staphylococcus epidermidis.     

Characteristics and prognosis in patients with prosthetic vascular graft infection: a prospective observational cohort study

Prosthetic vascular graft infection (PVGI) is a devastating complication, with a mortality rate of up to 75%, which is especially caused by aortic graft infection. The purpose of this study was to evaluate factors associated with in-hospital mortality of patients with definite graft infection, and with long-term outcome. We reviewed medical records of 85 patients treated for PVGIs defined by positive bacterial culture of intraoperative specimens or blood samples, and/or clinical, biological and radiological signs of infection. In-hospital patient mortality was defined as any death occurring during the initial treatment of the graft infection. Cure was defined as the absence of evidence of relapsing infection during long-term follow-up (≥1 year). Eighty-five patients (54 aortic and 31 limb graft infections) treated by surgical debridement and removal of the infected prosthesis (n=41), surgical debridement without removal of prosthesis (n=34) or antimicrobial treatment without surgery (n=10) were studied. The only microbiological difference observed between patients with early (occurring within 4 months after surgery) vs. late PVGI and between those with aortic vs. limb PVGI was the incidence of PVGI caused by Staphylococcus aureus, which was greater in patients with limb PVGI. Overall cure was observed in 93.2% of 59 patients with a follow-up of a minimum of 1 year. Overall in-hospital mortality was 16.5% (n=14). Two variables were independently associated with mortality: age >70 years (OR 9.1, 95% CI 1.83-45.43, p 0.007) and aortic graft infection (OR 5.6, 95% CI 1.1-28.7, p 0.037).     

Characteristics of prosthetic joint infections due to Enterococcus sp. and predictors of failure: a multi-national study

The objective of this study was to review the characteristics and outcome of prosthetic joint infections (PJI) due to Enterococcus sp. collected in 18 hospitals from six European countries. Patients with a PJI due to Enterococcus sp. diagnosed between January 1999 and July 2012 were retrospectively reviewed. Relevant information about demographics, comorbidity, clinical characteristics, microbiological data, surgical treatment and outcome was registered. Univariable and multivariable analyses were performed. A total of 203 patients met the inclusion criteria. The mean (SD) was 70.4 (13.6) years. In 59 patients the infection was diagnosed within the first 30 days (29.1%) from arthroplasty, in 44 (21.7%) between 31 and 90 days, in 54 (26.6%) between 91 days and 2 years and in 43 (21%) after 2 years. Enterococcus faecalis was isolated in 176 cases (89%). In 107 (54%) patients the infection was polymicrobial. Any comorbidity (OR 2.53, 95% CI 1.18–5.40, p 0.01), and fever (OR 2.65, 95% CI 1.23–5.69, p 0.01) were independently associated with failure. The only factor associated with remission was infections diagnosed later than 2 years (OR 0.25, 95% CI 0.09–0.71, p 0.009). In conclusion, prosthetic joint infections due to Enterococcus sp. were diagnosed within the first 2 years from arthroplasty in >70% of the patients, almost 50% had at least one comorbidity and infections were frequently polymicrobial (54%). The global failure rate was 44% and patients with comorbidities, fever, and diagnosed within the first 2 years from arthroplasty had a poor prognosis.     

Efficacy and safety of rifampin containing regimen for staphylococcal prosthetic joint infections treated with debridement and retention

The aim of this study was to evaluate the efficacy and safety of rifampin for Staphylococcus aureus (SA) or coagulase negative staphylococci (CNS) prosthetic joint infection (PJI) treated with debridement and retention (D/R). We calculated the treatment failure cumulative incidence (TF) of a cohort of 101 patients with SA or CNS PJI treated with D/R and antimicrobial therapy. The effect of the use of a rifampin-based regimen was evaluated. Cox proportional hazards regression evaluated the association between treatment and time-to-TF controlling for the propensity to treat with rifampin and temporal confounders. Seven percent (1/14) of the prospective rifampin-treated patients, 32% (10/31) of the historical rifampin-treated patients and 38% (21/56) of the historical non-rifampin treated patients developed TF. After controlling for the propensity to treat with rifampin and American Society of Anesthesia scores, patients in the prospective cohort had a lower risk of TF compared to patients in the historical cohort not treated with rifampin (HR 0.11; 95%CI 0.01–0.84). None (0/14) of the patients in the prospective study developed hepatotoxicity. The outcome of staphylococcal PJI treated with D/R and rifampin-based regimens was better when compared with a historical cohort treated without rifampin.     

Evaluation of a Genus- and Group-Specific Rapid PCR Assay Panel on Synovial Fluid for Diagnosis of Prosthetic Knee Infection

We evaluated a genus- and group-specific PCR assay panel using 284 prosthetic knee synovial fluid samples collected from patients presenting to our institution with implant failure. Using the Musculoskeletal Infection Society diagnostic criteria, 88 and 196 samples were classified as showing prosthetic joint infection (PJI) and aseptic failure (AF), respectively. Sensitivities of the synovial fluid PCR panel and culture were 55.6% and 76.1% (P ≤ 0.001), respectively, and specificities were 91.8% and 97.4% (P = 0.016), respectively. Among the 70 subjects who had received antibiotics within the month preceding synovial fluid aspiration (48 of whom had PJI), PCR panel and synovial fluid culture sensitivities were 64.5% and 85.4%, respectively (P < 0.0001). In this group, the PCR panel detected Staphylococcus aureus in two culture-negative PJI cases. Overall, the evaluated molecular diagnostic tool had low sensitivity when applied to synovial fluid.     

Is it Safe to do a Single-stage Implant Exit and Primary Hip Replacement? Clinical and Microbiological Profiling

Background: A single-stage implant revision for failed fixation of proximal femoral fractures is performed only when there is no evidence of infection. Else, a two-staged revision is preferred - where the definitive revision surgery is done a few months after the implant exit. This study aims to audit the safety and incidence of culture positivity in single-stage revisions. Materials and Methods: Forty one of 284 patients that presented over the last 12 years for implant exchange of the hip, had a single stage revision surgery for failed fixation of a fracture of the hip, as there was no obvious evidence of infection at the time of implant exit. Results: Micro-organisms were grown in 51% of the 41 hips. 76% were gram positive, of which 63% were Coagulase negative staphylococci (CoNS). 50% of CoNS and 75% of S. aureus were resistant to oxacillin, but susceptible to Vancomycin. Of the gram negative organisms, 2 (Enterobacter sp) were resistant to carbapenam, while others were susceptible. Preoperative ESR and CRP, individually, had low specificity – 50% for ESR >30mm at 1 hour and 62% for CRP>10. The combined use of ESR > 30mm and CRP>10 increased the specificity to 90%. 12% of the patients had immediate postoperative complications that required a wash out in theatre. The long term clinical follow up of these patients is limited. Conclusion: This study suggests that implant exit and simultaneous arthroplasty for failed fracture fixation should be done with caution due to the high possibility of infection. It may be prudent to opt for a 2 stage revision.     

Prosthetic joint infection of the knee - arthroscopic biopsy identifies more and different organisms than aspiration alone

BackgroundProsthetic joint infection (PJI) causes significant morbidity and mortality following knee replacement surgery. Identifying causative organisms and antibiotic sensitivities is critical in increasing the chance of infection eradication. This study investigated whether biopsy alone was superior to aspiration alone for serological diagnosis in PJI following knee replacement. Secondly, we investigated whether biopsy identifies the same or new/different microbiological flora as aspiration.MethodsSince December 2014, the Exeter Knee Reconstruction Unit (EKRU) has prospectively collated data regarding all PJIs referred from our local/regional network which have been reviewed via our Multi-Disciplinary Team (MDT). We identified and included consecutive patients from this MDT from Dec.2014-Mar.2020 and analysed their electronic records. Statistical analysis was performed using Stata.Results65/100 patients studied had both pre-operative aspiration and biopsy. 31/65 (48%) had positive aspiration and biopsies. No aspirate samples were positive with corresponding biopsies negative. In 19/65 (29%) of infection positive patients, biopsy identified new (7) or additional (12) organisms not identified by aspiration. Aspiration had a sensitivity of 70%, specificity of 88%, positive predictive value of 90.3% and negative predictive value of 64.7%. Biopsy had a sensitivity of 97.5%, specificity of 88%, positive predictive value of 92.9% and negative predictive value of 95.7%.ConclusionIn 29% of confirmed PJI cases, arthroscopic biopsy identified either additional organisms in a polymicrobial PJI when compared to aspiration, or new positive results when aspiration alone was negative. This study demonstrates the benefits of arthroscopic biopsy for serological diagnosis in cases of knee PJI and aids treatment planning.