Aim. Our aim was to evaluate the prevalence and impact of unexpected intraoperative cultures on the outcome of total presumed aseptic knee and hip revision surgery. Method. Data regarding patients prospectively recruited in our center, who had undergone elective complete hip and knee revision surgery from January 2003 to July 2017 with a preoperative diagnosis of aseptic loosening was retrospectively reviewed. Partial revisions and patients with follow up below 60 months were excluded from the study. The protocol of revision included at least 3 intraoperative cultures. Failure was defined as the need for re-revision due to any-cause at 5 years and/or the need for antibiotic suppressive therapy. Results. A total of 608 cases were initially included in the study, 53 patients were excluded. 123 hip and 432 knee revision surgeries were included. 420 cases (75.7%) had all cultures negative, 114 (20.5%) a single positive culture or two of different microorganisms and 21 (3.8%) had at least 2 positive cultures for the same microorganism. Early failure was found in 4.8% (1/21) of the patients with missed low grade infection. The presence of positive cultures during total exchange was not associated with a higher failure rate than in those with negative cultures (44 of 420, 10.5%). In contrast, patients revised before 24 months had a significant higher rate of re-revision, 18% (15/83) vs. 8.4%. Conclusions. Total hip and knee revisions with unexpected positive cultures were not significantly associated with a higher re-revision risk at 5 years of follow-up. Representing an overall good prognosis. However, revision surgeries performed within the first 24 months have a higher rate of failure

To wake up in the morning facing a complex total hip revision can be unpleasant. Modern designs have greatly facilitated dealing with the most difficult revision situations both on the acetabular and femoral side. The surgeon faces blood loss, dislocation, infection, and a litany of other potential complications. Our advances in total hip revision have been outstanding but can pose very complex issues. Total knee revision on the other hand is easier. The surgeon needs to ask a series of questions pre-operatively and intra-operatively. Pre-operatively, one must know the mechanism of failure. You also need to know “what is missing” in terms of skin, soft tissue, extensor mechanism, bone and ligaments. Intra-operatively, the surgeon must know the difference between the flexion and extension gap, the position of the joint line, the extent of the bone loss and whether it is load bearing or non-load bearing, the ligamentous stability and the intramedullary shaft. Most modern knee revision designs allow the surgeon to create a paradigm to deal with all of these potential problems. There, of course, are complex problems of malalignment, periprosthetic fracture and other deformities that add a level of complexity but most of these can be dealt with using standard revision designs without requiring custom prostheses

Introduction. Bone loss management represents one of the most challenging issues for the orthopaedic surgeon. In most cases, stems, structural allograft, TMcones, and sleeves are adequate to allow optimal implant stability and durable fixation. In selected cases of wide metadiaphyseal bone defects, these devices do not provide proper intraoperative stability. In such scenarios, further steps are needed and include complex modular reconstruction, substitution with megaprosthesis (exposing patients at high risk of early failure) or joint arthrodesis that can yield unacceptable results. The aim of this paper is to present early results obtained with a new custom-made implant for complex metadiaphyseal bone defects management in knee revision surgery. By means of case presentations the authors would highlight the possibilities and technical notes of this novel device in complex knee revision surgery. Methods. Since2015, 8 custom-made porous titanium devices were implanted for massive bone defect management in 6 knee arthroplasty revision procedures. Five patients were staged revision for periprosthetic joint infection (PJI) and one patient underwent a staged revision for post-traumatic septic arthritis. Main demographic and surgical data were collected. Clinical (Range of Movement [ROM], Knee Society Score [KSS] and Oxford Knee Score [OKS]), radiological findings and complications were recorded at different time points and statistically evaluated. Mean follow up was 19.5 ± 9.6months. Results. The study group included 4 males and 2 females with a mean age of 63.7 ± 5.5 years and a mean Body Mass Index of 29.3 ± 4.1. Globally, the mean number of previous surgeries was 4.8 ± 2.7. The custom made device was combined with a hinged prosthesis in 5 cases and with a constrained condylar implant in 1 patient. Hybrid fixation was used in all cases. The mean KSS and OKS of the entire population improved significantly from 35.3 ±6.5 and 19.2 ±3.5 preoperatively to 85.8 ±4.0 and 39.3 ±3.1 at the time of last follow-up evaluation (p<0.01). The range of motion improved from 46.7 ±9.8 of mean preoperative flexion and 7.8 ±6.8 of mean preoperative flexion contracture to 93.3 ±10.3 and 1.2 ±2.9 respectively (p<0.01). Radiological analysis showed no migration or implant loosening. No intraoperative or postoperative complication was recorded. One patient required a prolonged antibiotic therapy for positive culture samples of sonication of the retrieved spacer. No implant mismatch between the preoperative planning and the final implant was reported. Conclusion. The presented custom-made implant showed promising early clinical and radiological results. In extremely selected cases, this new device can be considered a safe and effective surgical step between “off the shelf” reconstruction implants and knee substitution with a tumor megaprosthesis. Accurate surgical planning and intraoperative management of soft tissues and residual bone stock are of paramount importance

Introduction. 3 main challenges encountered in knee revision of Asians:. systemic: such as osteoporosis and laxity. anatomical variance: established in literature making revision system not appropriate. Neglected case revised late owes to extensive bone loss demanding bone substitute and increased constrain. Therefore we like to alert surgeon apprehending enhanced challenges while indulging in revision of Asian. Our emiratus author with USA background/qualification/experience has excuted 216 revision in 8yrs with at least 3yrs follow-up. Material & Method. Between 2003–2010 we performed 216 revision TKR, reviewed all parameters & compared our results with European revision statistics depicting a) intermedullary canal smaller b) metaphysis narrower & more triangular in comparision to Caucasian causing housing mechanism fit impossible, also increase impingment of stem at times. Bone loss is normally quiet extensive & available implant including the Tantalum cone sometimes is difficult to fit in a tight metaphyseal area, we had satisfactory outcome inspite of owing to intra-operative complication which lead to 3 intramedullary fracture resulting from inadequate avalibity of smaller size, incomplete seating of tibial component, overhang of femoral component.it also leads to more translucent line quoted in 15 cases. Centre of IM canal in both tibia & femur is positioned more posteriorly especially in smaller size proven by CT anatomical study analysis. These data we related to anatomic variance rather then surgical technique therefore representing deficit of proper size thereby contributing to inability to surgeon. Conclusion. Restoring joint line to tibia to prevent impingment of tibial housing is crucks, enabled by utilizing certain surgical tricks which all surgeon revising small stature Asian should bear in mind.in certain instances use totally cemented stubby stem. 2 important aspect of our abstract:. a). Present: we will review all tricks enabling appropriate/maximum utilization of inadequate current revision system. b). Future: we will also present specific recommendation to Industry based on anatomy variation alerting them need of. 1). asymmetrical tibial component. 2). natural femoral component. 3). repositioning of stem. Multiple factors contributes more challenges in Asian revision:. 1). mainly anatomy attributed to metaphyseal morphology. 2). unable to apply certain surgical tricks to fit implant in small patient. strong recommendation to Industry to alter revision system inorder to achieve more success in Asian revision surgery

The designs available today have greatly improved our ability as surgeons to perform successful total knee revision surgery. However, as more and more knee replacements are in service for longer periods of time, the numbers of revisions have increased and have required us as surgeons to address challenging problems including infection, instability and bone loss from wear, osteolysis and loosening. Understanding the problems needed to be addressed is paramount. Careful preoperative planning is key. Knowing the cause of failure and the aspects of reconstruction that need to be addressed including skin, soft tissues, extensor mechanisms, bone and ligament loss is critical. Intraoperatively, understanding and applying principles related to establishing joint lines, balancing flexion extension gaps, addressing bone loss and ligament instability and constructing stable knee replacements with the use of stabilising implant articulations, bone deficiency reconstruction with augments and grafts as well as cones and sleeves, and stems for implant stability is also essential. Postoperatively, rehabilitation and follow-up must be tailored to the individual patient because of the marked nuances of construct in the various revision scenarios

This is a prospective review of consecutive patients who underwent knee revision surgery using the Legion knee system. Clinical and functional assessments (American Knee Scores-AKS, WOMAC and Oxford knee score-OKS) were carried out preoperatively, one year and 2 years post op. Radiographic evaluation was done at 1 and 2 years included review of standing AP, lateral and skyline views. Figgie's method was used to measure the joint line reproduction. 210 patients underwent revision knee system 103 male: 107 females with a mean age of 66.4 (44–87) yrs. Mean BMI-26.03 (21–50). We had a 2-year follow up for 110 patients. Surgery was carried out at a single centre and performed by Bristol knee specialists. Indications for surgery were aseptic loosening (84), infection (27) instability (47), pain and stiffness (31), progression of disease (6), peri-prosthetic fractures (15). The AKS and WOMAC scores at, 1 year and 2 years follow up showed significant improvements in pain and function. The mean total AKS improved from 75.7/200 pre-operatively to 140.5/200 at 2 yrs. Radiographic assessment showed a mean AP coronal femoral angle of 95.3 degrees (89.6–99.9), coronal tibial angle of 90.1 degrees (88–92). The mean sagittal femoral and tibial angles were 88.4 and 90.4 degrees respectively. The short-term results showed significant improvement in functional and pain scores irrespective of indications for revision surgery. The Legion system has showed good outcome scores that match or beat published series on revisions. It also showed a good ability to restore joint line

Aim. Femoral or tibial massive bone defects (AORI F2B-F3 / T2B-T3) are common in septic total knee replacement. Different surgical techniques are described in literature. In our study we show clinical and radiological results associated with the use of tantalum metaphyseal cones in the management of cavitary bone defects in two-stage complex knee revision. Method. Since 2010 we have implanted 70 tantalum metaphyseal cones associated with constrained or semiconstrained knee prostheses in 47 patients. The indication for revision was periprosthetic knee infection (43 cases, 91.5%) or septic knee arthritis (4 patients, 8.5%) with massive bone defect. All cases underwent a two-stage procedure. Patients were screened for main demographic and surgical data. Clinical and radiological analysis was performed in the preoperative and at 3,6 months, 1 years and each year thereafter in the postoperative. The mean follow-up was 31.1 months ± 18.8. No dropout was observed. Results. Objective and subjective functional scores (KSS, OKS) showed a statistically significant improvement from the preoperative to last follow-up (p <0.001). All cones but one (98.6%) showed radiological osteointegration. We did not find any cone-related intraoperative or postoperative mechanical complication with a 100% survival rate when we consider aseptic loosening as cause of revision. Six non progressive radiolucencies were observed. Two septic failures (4.3%) with implant and cone removal were reported. Conclusions. The ideal treatment for cavitary bone defects in two-stage TKA septic revision is still unclear. The use of metaphyseal tantalum cones showed excellent clinical and radiographic results with a low rate of related complications. The main finding of our study is the cone-related infection rate (2.9%) in this particular series of patients. This data is comparable or better than other previous report about this topic with unhomogeneous cohort of patients

Aim. One of the most challenging problems in total knee arthroplasty (TKA) is periprosthetic infection. A major problem that arises in septic revision TKA (RTKA) are extended bone defects. In case of extended bone defects revision prostheses with metaphyseal sleeves are used. Only a few studies have been published on the use of metaphyseal sleeves in RTKA - none were septic exclusive. The aim of our study was to determine the implant survival, achieved osseointegration as well as the radiological mid-term outcomes of metaphyseal sleeve fixation in septic two-stage knee revision surgery. Method. Clinical and radiological follow-up examinations were performed in 49 patients (25 male and 24 female). All patients were treated with a two-stage procedure, using a temporary non-articulating bone cement spacer. The spacer was explanted after a median of 12 weeks (SD 5, min. 1 – max. 31) and reimplantation was performed, using metaphyseal sleeves in combination with stem fixation. Bone defects were classified on preoperative radiographs using the Anderson Orthopaedic Research Institute (AORI) classification. During follow-up postoperative range of motion (ROM) was measured and radiographs were performed to analyse: (i) osseointegration (radiolucent lines and spot welds), (ii) leg alignment, (iii) patella tilt and shift. Results. All types of bone defects were found on the tibial (4× type 1, 7× type 2a, 26× type 2b, 9× type 3) as well as on the femoral side (1× type 1, 4× type 2a, 20× type 2b, 6× type 3). Mean follow-up time was 4.7 years (minimum 1 year). In total 12 knees (24.5%) had to be re-revised, all due to re-infection. We did not encounter any case of aseptic loosening. In 3 patients (6.8%) we detected an insufficient osseointegration, but no patient had to be re-revised due to only minimal or to the absence of symptoms and no clinical signs of loosening. The ROM (mean 93°, SD 20.6, min. 25° max. 125°) has shown very satisfying results at the time of follow-up. Malalignment was detected in 4 patients (10.3%), a patella tilt in 7 (19.4%) and a patella shift in 14 (48.3%). Conclusions. Metaphyseal Sleeves have shown very promising mid-term results regarding osseointegration and aseptic implant survival in RTKA with compromised metaphyseal bone stock. Our results indicate that they are a reliable fixation option in septic RTKA patients

Introduction. We discuss the use of the SMILES (Stanmore Modular Individualised Lower Extremity System) in salvage revision knee surgery and review the medium-long term results of 42 cases. Methods. This is a prospective, single-centre study. The SMILES prosthesis is a custom-made implant incorporating a rotating hinge knee joint. 42 prostheses were used in 40 patients as salvage revision procedures between September 1991 and September 1999. Patients undergoing surgery for tumours were excluded. The minimum follow-up was seven years with a mean follow-up of ten years and six months. Patients were independently assessed using the Knee Society Rating Score. The age of the patients ranged from 36-85 years (mean 68 years and 6 months). 23 of the patients were male. The original pathology was osteoarthritis in 32 patients and rheumatoid arthritis in 8 patients. The number of previous arthroplasties ranged from 1-4. The main indications for a SMILES prosthesis were aseptic loosening, periprosthetic fracture and infection in the presence of bone loss and ligamentous laxity. Results. There was a highly statistically significant improvement in overall Knee Society scores from a mean of 26 pre-op to 72 post-op. The mean knee score improved from 26 pre-op to 68 post-op while the mean function score improved from 27 to 75. The average range of motion was 60 degrees pre-op and 90 degrees post-op. Complications included: failure to eradicate infection in two patients, with one patient needing amputation; infection of the prosthesis leading to revision in one, and failure of the tibial component needing revision. Conclusion. The SMILES has produced satisfactory results in the medium to long term, offering an alternative to amputation in some cases. The cost compares favourably with other designs and the use is increasing in frequency

Revision surgery for total knee replacement is a complex procedure, carrying an increased risk for the patient and cost for hospitals. As well as increased cost of peri-operative investigations, blood transfusions, surgical instrumentation, implants and theatre time, there is a well documented increased length of stay (LOS), accounting for the majority of actual costs associated with surgery. We compared revision surgery for infection vs. other causes (aseptic loosening, dislocation, mal-alignment). Clinical, demographic and economic data were obtained for 180 consecutive revision total knee replacements performed at a tertiary referral centre between 2003 and 2012. Actual costs and National Health Service tariffs were compared per patient and mean difference calculated. Mean age was 66 years (range 17–87) with 62 male and 117 female patients. Mean LOS for aseptic cases was 10 days (range 1–62) and 20 days (range 4–103) for infection. Mean cost difference in aseptic cases (n = 125) was £−933 (SD = £12,204), and £−3907 (SD = £7,256) for infection (n = 54). Surgery for infection was associated with increased operating times, blood loss and complications compared to revision for aseptic causes. LOS for infection was on average double that for aseptic cases (p < 0.05). Current NHS tariffs do not fully reimburse the increased costs associated with providing a revision knee surgery service, with even greater cost incurred by the treating hospital for infected cases. These losses may negatively influence the provision of revision surgery in the NHS

Aim

Due to medical and organizational factors, it occurs in everyday practice that spacers are left in place longer than originally planned during a two-stage prosthesis exchange in the case of prosthetic joint infections. Patients are severely restricted in their mobility and, after initial antibiotic administration, the spacer itself only acts as a foreign body. The aim of this study is to analyze whether the duration of the spacer in situ has an influence on the long-term success of treatment and mortality.

Introduction

PSI technology have proved helpful in difficult primary Total Knee Replacement. However applying it to revision was impossible due to multiple factor. To Start with the landmark We usually destroy it. There is an extensive damage at the bone at the epiphysis, the implant prevent an accurate visualization and debridement usually change the surface of the bone as well which make applying the psi dyed impossible, we are proposing a new way of using psi in revision where we don't depend on the all masses adjusted in primary. However we depend on the metaphysical area of the bone.

Patients with severe knee instability remain a surgical challenge. Furthermore, in the presence of extensive bone loss, constrained condylar implants may be unsuitable.

Hinged knee replacements have served an important role in the management of such complex knee pathologies.

A combined prospective and retrospective study of 138 consecutive hinge knee arthroplasties (42 primary and 96 revisions) of 8 different models performed in our institution between 2004 and 2010 at a mean follow up of 4.2years.

Outcomes were reviewed and knee scores preoperatively and postoperatively at 1, 2 and 5 years using the American knee scoring system.

The mean preoperative American knee score of 31 improved to 87 postoperatively.

Complication rate was 19%, 15% of which required re-revisions for: loosening (4%), Infection (4%), periprosthetic fracture (3%), Implant fracture (2%), Component disassembly (1%) and dislocation (1%). Overall implant failure rate was 9% and implant survivorship was greater than 80% at 4 years.

In our study, hinge prostheses provided good stability and symptom relief with a lower complication rate compared to some previous studies.

In addition, we believe hinge prostheses can also serve as reasonable alternatives to amputation and arthrodesis in many complex knees cases.

Restoration of bone loss is a major challenge of revision TKA surgery. It is critical to achieve of a stable construct to support implants and achieve successful results. Major bone defects of the femoral and/or tibia (AORI type IIB/III) have been reconstructed using impaction grafting, structural allografts or tumor prostheses. The major concerns with structural allograft are graft resorption, mechanical failure, tissue availability, disease transmission, considerable surgical skill required and prolonged operative time. Porous tantalum metaphyseal cones, are becoming the established method of choice to correct large bone defects with several recent studies demonstrating promising results. The high coefficient of friction of these implants provides structural support for femoral and tibial components. The high degree of porosity has excellent potential for bone ingrowth and long-term biologic fixation. Several published series, although with relatively small cohorts of patients, have reported good short-term results with trabecular metal cones for major femoral and tibial bony defects in revision TKA. In a recent study, 16 femoral and 17 tibial cones were reviewed at an average follow up of 33 months (range, 13 to 73 months) the mean Knee Society Score improved from 42 pre-operatively to 83 at last follow up with an improvement of the functional score from an average of 34 to 66 (p<0.0001). Radiological follow up revealed no evidence of loosening or migration of the constructs. No evidence of complications were noted in correlation with the use of trabecular metal cones.

Introduction

Patients with severe knee instability and extensive bone loss remain a surgical challenge. In such cases, regular knee implants and constrained condylar implants may not be suitable or have been attempted and failed.

Hinged knee replacements have developed an important role in the management of such complex knee cases. They also have an increasingly important role in cases such as rheumatoid arthritis and other cases of severe joint destruction.

We present a review of 138 consecutive hinge knee arthroplasties of 8 different Hinge models performed in our unit between 2004 and 2010.

Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion.

We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The “SMILES spacer” was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24–70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients.

In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation.

Aim. Aim was to compare revision rates when using single versus dual antibiotic loaded cement (ABLC) in hip fracture arthroplasty and aseptic revision hip or knee arthroplasty using data from the Dutch national joint registry (LROI). Methods. All primary cemented (hemi-)arthroplasties for acute hip fractures and cemented aseptic hip or knee revision arthroplasties, were incorporated in 3 datasets. All registered implants between 2007 and 2018 were included (minimum 2 years follow-up). Primary end-point was subsequent revision rates for infection and for any reason in the single and dual ABLC groups. Cumulative crude incidence of revision was calculated using competing risk analysis. Results. A total of 22,308 hip fracture arthroplasties, 2,529 hip revision and 7,124 knee revision arthroplasties were registered and analyzed in the study period. The majority of hip fracture patients (97.1%) was treated with single ABLC. For hip and knee revision arthroplasties dual ABLC was used in 33.8% and 25.7%. The revision rate for infection in the fracture arthroplasty group was not different between groups (0.5% versus 0.8%, p=0.27). The re-revision rate following hip or knee revision based on single versus dual ABLC was not different between groups (3.2% versus 2.8%, p=0.82 for hip revision and 1.8% versus 2.5%, p=0.36 for knee revision). In addition, the re-revision rate for any reason was not different in all three datasets. The crude cumulative revision and re-revision rates for any reason based on single ABLC versus dual ABLC showed no differences in all three datasets. The crude cumulative 7-year re-revision rate for any reason following revision THA with Gentamicin ABLC use was 11.8%, with Gentamicin + Clindamycin ABLC use 13.1% and with Erythromycin + Colistin ABLC use 14.8% (ns). The crude cumulative 9-year re-revision rate for any reason following revision TKA with Gentamicin ABLC use was 17.7% and with Gentamicin + Clindamycin ABLC use 16.5% (ns). Conclusions. In conclusion, we could not show a difference in revision rate for hip fracture arthroplasty or re-revision rates for revision hip- or knee arthroplasty with the use of dual ABLC compared to single ABLC bone cement, with 7and 9 year follow up. The low percentage of dual ABLC in hip fracture arthroplasties in our registry do not enable us to make a reliable estimation of the added value in this patient category. The results of this study do not confirm the potential benefit of dual ABLC use in revision cases

The incidence of PJI in knee replacements is 2.8% and slightly lower with hip replacement surgery. PJI make up 15% (or even more) of knee revisions. To combat PJI, antibiotic laden bone cement has been used for many decades, but antibiotic stewardship dictates more prudent management of antimicrobials. Projected increase in infection rate, due to increased surgery and latent infection to be almost 5-fold up to 2035. Biofilm is a complex structure of bacteria and polysaccharide matrix and, is recognised as a major component in PJI and other orthopaedic infections. Biofilm is responsible for high incidence of resistance to antimicrobials and ineffective host immune response. Method. Stabilized hypochlorous acid has been reported to have a rapid kill rate on all pathogens, including MDR pathogens associated with chronic and acute wound infections. It destroys biofilm on contact, is not cytotoxic, reduces inflammation and stimulates wound healing. 0,038% of Hypochlorous acid was used as prophylaxis against infection and to treat PJI. We report on our experience with hypochlorous acid as a wound irrigation as prophylaxis against infection (more than 600 cases) and for PJI. We also report on a University study where a head to head analysis was done on the anti-biofilm efficacy between hypochlorous acid 0,038% (Trifectiv Surgical Wound Irrigation) and Product X (an industry-standard product for the prevention and treatment of biofilm infection. Hypochlorous acid offers a valuable addition to the armamentarium of wound antiseptics, with added anti-inflammatory value. An in vitro study demonstrated superior efficacy against biofilm when compared to Product X

Periprosthetic joint infection (PJI) in geriatric and/or multimorbid patients is an enormous challenge for orthopaedic surgeons. Revision procedures have also been demonstrated to expose patients to higher infection risks. Prior patient stratification according to presumed infection risks, followed by a more potent local antibiotic prophylaxis protocol with selective use of DALBC, is an interesting strategy to decrease the burden of PJI in high risk patients. The PubMed & EMBASE databases were screened for publications pertaining to the utilization of DALBC in cement for infection prophylaxis & prosthesis fixation. 6 preclinical & 7 clinical studies were identified which met the inclusion criteria and were stratified by level of clinical evidence. Only those studies were considered which compared the PJI outcome in the DALBC vs the SALBC group. (1). DALBC have been shown to exert a much stronger and longer lasting inhibition of biofilm formation on many PJI relevant bacteria (gram-positive and gram-negative pathogens) than single gentamicin-only containing cements. (2). DALBC use (COPAL G+C) in the intervention arm of 7 clinical studies has led to a significant reduction of PJI cases in a) cemented hemiarthroplasty procedures (3 studies, evidence level I and III), in b) cemented septic revision surgeries (2 studies, evidence level III), in c) cemented aseptic knee revisions (1 study, evidence level III) and in d) cemented primary arthroplasties in multi-morbid patients (1 study, evidence level III-IV). These benefits were not associated with more systemic side effects or a higher prevalence of broad antimicrobial resistancies. Use of DALBC is likely to be more effective in preventing PJI in high risk patients. The preliminar findings so far may encourage clinicians to consolidate this hypothesis on a wider clinical range

Aim. In 10% of the presumed aseptic hip or knee revisions, a low-grade infection is unexpectedly diagnosed based on the tissue samples taken during revision. Extended antimicrobial prophylaxis can possibly reduce the failure rate in cases of unexpected PJI, because the prophylaxis can be considered as early empiric treatment. In this randomized controlled study we analysed whether extended antimicrobial prophylaxis compared to a single dose is beneficial to improve the outcome of treatment in unexpected PJI in revision arthroplasty. Method. This study was nested in a randomized clinical trial comparing single-dose cefazolin with prolonged prophylaxis (15 doses of cefazolin over 5 days) for revision arthroplasty of the hip or knee. For this analysis, patients were included if an unsuspected PJI (defined as ≥2 positive intraoperative tissue samples with the same microorganism) was diagnosed. PJI treatment consisted of 12 weeks of a rifampicin-based regimen in Staphylococcal PJI, without removal of the prosthesis. We examined Infection characteristics and success of treatment after one year, defined as the absence of signs or treatment for PJI during follow-up. Results. After randomization of 662 patients, 68 unexpected PJI were diagnosed. In 5 cases no antimicrobial treatment was started. The success rate after one year follow-up for those who received PJI treatment was 96% (28/29) in the single dose group and 91% (31/34) in the extended prophylaxis group (p=1.00). The most frequently identified pathogens in unexpected PJI were Cutibacterium acnes (n=50) and Staphylococcus epidermidis (n=14). The causatives were susceptible for the cefazolin prophylaxis in 61 of the 63 cases. The interval between the stopped prophylaxis and the re-start of antimicrobial treatment was on average 10 days (SD 4) for the single dose and 5 days (SD 4) for the extended group. The mean duration of antimicrobial treatment was 83 days (SD 12) and did not differ between both groups (p=0.16). Conclusions. This is the first randomized controlled trial in which extended prophylaxis showed no benefit on the prosthesis survival for patients with an unexpected PJI after assumed aseptic revision of the hip or knee prosthesis. The results imply that extended prophylaxis should not be given as part of early empiric therapy