Aims. Bacterial infection activates neutrophils to release neutrophil extracellular traps (NETs) in bacterial biofilms of periprosthetic joint infections (PJIs). The aim of this study was to evaluate the increase in NET activation and release (NETosis) and haemostasis markers in the plasma of patients with PJI, to evaluate whether such plasma induces the activation of neutrophils, to ascertain whether increased NETosis is also mediated by reduced DNaseI activity, to explore novel therapeutic interventions for NETosis in PJI in vitro, and to evaluate the potential diagnostic use of these markers. Methods. We prospectively recruited 107 patients in the preoperative period of prosthetic surgery, 71 with a suspicion of PJI and 36 who underwent arthroplasty for non-septic indications as controls, and obtained citrated plasma. PJI was confirmed in 50 patients. We measured NET markers, inflammation markers, DNaseI activity, haemostatic markers, and the thrombin generation test (TGT). We analyzed the ability of plasma from confirmed PJI and controls to induce NETosis and to degrade in vitro-generated NETs, and explored the therapeutic restoration of the impairment to degrade NETs of PJI plasma with recombinant human DNaseI. Finally, we assessed the contribution of these markers to the diagnosis of PJI. Results. Patients with confirmed PJI had significantly increased levels of NET markers (cfDNA (p < 0.001), calprotectin (p < 0.001), and neutrophil elastase (p = 0.022)) and inflammation markers (IL-6; p < 0.001) in plasma. Moreover, the plasma of patients with PJI induced significantly more neutrophil activation than the plasma of the controls (p < 0.001) independently of tumour necrosis factor alpha. Patients with PJI also had a reduced DNaseI activity in plasma (p < 0.001), leading to a significantly impaired degradation of NETs (p < 0.001). This could be therapeutically restored with recombinant human DNaseI to the level in the controls. We developed a model to improve the diagnosis of PJI with cfDNA, calprotectin, and the start tail of TGT as predictors, though cfDNA alone achieved a good prediction and is simpler to measure. Conclusion. We confirmed that patients with PJI have an increased level of NETosis in plasma. Their plasma both induced NET release and had an impaired ability to degrade NETs mediated by a reduced DNaseI activity. This can be therapeutically restored in vitro with the approved Dornase alfa, Pulmozyme, which may allow novel methods of treatment. A combination of NETs and haemostatic biomarkers could improve the diagnosis of PJI, especially those patients in whom this diagnosis is uncertain. Cite this article: Bone Joint J 2024;106-B(9):1021–1030

Purpose of the study: The aim of this work was to determine whether erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and alpha-1-antitrypsin (A1AT) levels are correlated significantly with early postoperative infectious complications after hip prosthetic surgery. Materials and methods: This prospective study was conducted on 100 total hip replacements performed between 1994 and 1995. ESR, CRP and A1AT were obtained before surgery then at 1, 2 and 6 weeks after surgery. Results: Seven bacteriologically proven cases of infection were reported. Infection was considered to be superficial if it did not extend deeper than the muscles fascia. There was a strong statistical correlation between A1AT level and infection for all postoperative times (p < 0.0001). A1AT was highly sensitive (87.5 p. 100) and specific (85.8 p. 100) for infection compared with ESR (sensibility 70 p. 100 and specificity 65.9 p. 100) and CRP (sensitivity 63.6 p. 100 and specificity 80.1 p. 100). Discussion and conclusion: In our hands, A1AT can be a most useful diagnostic tool for infection after prosthesis hip surgery. Although not totally specific, it is highly sensitive for infection compared with other tools such as ESR and CRP more frequently used. These findings suggest an avenue of research on the role of A1AT in infectious complications after prosthetic joint surgery

Purpose: The indication for humeral or total shoulder prosthesis in patients with avascular osteonecrosis of the shoulder depends on the radiographic stage of the necrosis. The purpose of this study was to analyse the prognostic radiographic features enabling proper identification of the indications for humeral or total prostheses. Material and methods: This retrospective multicentric study included 53 shoulders operated on for prosthetic repair of avascular osteonecrosis. There were 20 men and 29 women, mean age 57 years. A humeral prosthesis was used in 34 cases and a total prosthesis in 19. Clinical assessment was based on the Constant score and the radiographic analysis used the Arlet and Ficat classification. Staging was II (n=4), III (n=16), IV (n=21) and V (n=12). Independently of the radiographic stage of necrosis, three characteristic groups were defined. Group 1 (19 shoulders) included necrosis without bony collapse of the humeral head. Group 2 (20 shoulders) included necrosis with bony collapse of the humeral head with preservation of the anatomic relations with the glenoid cavity. Group 3 (14 shoulders) included necrosis with bony collapse and impaction of the humeral head in the glenoid with medialisation of the humerus. Results: Preoperatively, presence of bony collapse was associated with decreased pain and motion score. Major joint stiffness was noted in group 3 (8). The humeral prosthesis gave similar results for groups 1 and 2 (Constant score 73 and 75.3). Less satisfactory results was the rule in group 3 (Constant score 51.6). There was a postoperative erosion of the glenoid cavity in 83% of the shoulders in group 3 versus 12.5% in group 1 and 17% in group 2. The total prosthesis optimised results despite persistence of a difference between groups 2 and 3 (Constant score 83 and 64 respectively). Discussion: Destabilisation of the glenohumeral joint by impaction of the humeral head against the glenoid cavity has an effect on the clinical result of the prosthetic surgery. Preservation of the anatomic relations of the articulation (groups 1 and 2) appears to be necessary for good results. Impaction medialisation of the humerus has a negative effect on the clinical result of humeral prostheses with a risk of glenoid erosion. Conclusion: Independently of radiographic stage of necrosis, the presence of humeral impaction with medi-alisation should be considered individually as it has a negative effect on the clinical outcome of these prostheses, particularly humeral prostheses

The aim is: to point out, in respect of Italian case law trends, the concept and the boundaries of surgeon malpractice liability in evaluating and implanting new prosthesic materials.

The surgeon is liable for damages caused by fraudulent intention or fault during his clinical and operating activity. In a civil perspective, it could be the result of either a breach of a contract or a tort, depending on the existing relationship between the surgeon and the patient; but in both case there might be a serious inexperience or a light imprudence or negligence to admit a fair compensation for damages. While in a criminal perspective, the personal injuries might be the result of a serious fault also in the area of imprudence and negligence to admit the application of criminal sanctions. Of course, personal liability of surgeon stands by vicarious liability of health unit.

Civil sanctions are more effective than criminal sanctions, not only because they have a wider area of application, but also because they are more incisive in quantitative terms, considering the new guidelines on pecuniary and biological damages that make out, at the same time, a compensatory and punitive function.

The surgeon, to be sure not to be affected by civil and criminal actions, might inform the patient about the operating features and the consequences of non operating, follow standardized protocols, use products and materials tested and certified by the most influential scientific literature, be care of post-operating effects and adopt all remedies and treatments that can eliminate or reduce post-operating risks, use the best and up-to-date techniques available. In any case he is not liable for unforeseeable events, even if they are in a causative relationship with surgical activity.

Purpose

To assess the reliability of a biomimetic osteochondral scaffold Maioregen (Finceramica Faenza SpA, Faenza, Italt) as a salvage and joint-preserving procedure in the treatment of late stages of osteonecrosis of the knee.

Total temporomandibular joint (TMJ) replacements reduce pain and improve quality of life in patients suffering from end-stage TMJ disorders, such as osteoarthritis and trauma. Jaw kinematics measurements following TMJ arthroplasty provide a basis for evaluating implant performance and jaw function. The aim of this study is to provide the first measurements of three-dimensional kinematics of the jaw in patients following unilateral and bilateral prosthetic TMJ surgeries. Jaw motion tracking experiments were performed on 7 healthy control participants, 3 unilateral and 1 bilateral TMJ replacement patients. Custom-made mouthpieces were manufactured for each participant's mandibular and maxillary teeth, with each supporting three retroreflective markers anterior to the participant's lip line. Participants performed 15 trials each of maximum jaw opening, lateral and protrusive movements. Marker trajectories were simultaneously measured using an optoelectronic tracking system. Laser scans taken of each dental plate, together with CT scans of each patient, were used to register the plate position to each participant's jaw geometry, allowing 3D condylar motion to be quantified from the marker trajectories. The maximum mouth opening capacity of joint replacement patients was comparable to healthy controls with average incisal inferior translations of 37.5mm, 38.4mm and 33.6mm for the controls, unilateral and bilateral joint replacement patients respectively. During mouth opening the maximum anterior translation of prosthetic condyles was 2.4mm, compared to 10.6mm for controls. Prosthetic condyles had limited anterior motion compared to natural condyles, in unilateral patients this resulted in asymmetric opening and protrusive movements and the capacity to laterally move their jaw towards their pathological side only. For the bilateral patient, protrusive and lateral jaw movement capacity was minimal. Total TMJ replacement surgery facilitates normal mouth opening capacity and lateral and inferior condylar movements but limits anterior condylar motion. This study provides future direction for TMJ implant design

Introduction: The anatomic abnormalities associated with the dysplastic hip increase the complexity of hip arthroplasty, in addition previous femural osteotomy can deformate proximal femur.

Despite the fact that uncemented cup and stems are specifically designed for dysplasia to recover the true acetabular region in Crowe IV and sometimes Crowe III additional surgical procedure are required.

Purpose of the study is to analize surgical procedure and then reconstruction options on severe hip dysplasia.

Materials and methods: From 1984 till today 2308 cases of arthroplasty were performed in dysplastic hip, 565 cases have a previous femoral osteotomy; out of these 2308 cases 128 cases need treatment for corrections of femural side deformity.

64 cases were subjected to a greater trochanteric osteotomy. In 12 cases proximal femural shortening was associated. In 9 cases rotational abnormality and shortening were controlled with a distal femur osteotomy.

55 cases were treated by a shortening subtrochanteric osteotomy that allows corrections of any deformity. Only uncemented stems were used and in the majority of cases a specific device for displastic hip (Wagner Conus produced by Zimmer).

Discussion: Long-term results in these patients are steadily inferior to that in the general population (70% survival at 15 yrs). On femural side early failures are the reflection of learning curve and are due to insufficient fixation of the osteotomy.

Despite this, the more promising outcomes are concerning shortening subtrochanteric osteotomy with uncemented stem but only early and mid-term data are available.

Introduction: Angular and torsional deviations of femur are usually combined with Congenital Dislocation of the Hip (CDH) and increase the complications of hip arthroplasty. The aim of this study is to evaluate surgical and reconstructive options for the treatment of CDH.

Material and Methods: In this retrospective study, we evaluated the results and complications of 55 primary cementless total hip arthroplasties, all of whom had Crowe type-IV developmental dysplasia of the hip. The arthroplasty was performed in combination with a subtrochanteric shortening osteotomy and with placement of the acetabular component at the level of the anatomic hip center. The patients were evaluated at a mean of 8,1 years postoperatively.

Results: From 1984, more than 2000 cases of arthroplasty have been performed in dysplastic hip, 565 cases had a previous femoral osteotomy; 128 cases needed correction of femoral side deformity; 64 had a greater trochanteric osteotomy. In 9 cases rotational abnormality and shortening were controlled with plate and distal femur osteotomy. 55 cases were treated by a shortening subtrochanteric osteotomy. Only non-cemented stems were used. 4 failures occurred for the incorrect fixation of the metaphysis. The fixation can be obtained only by prosthetic press-fit, but it is preferable to use metal wires. There was no sciatic injury; indeed shortening osteotomy provides an easy control of deformity and lengthening, with a maximum of 4 cm. One case was reviewed for heterotopic calcification (grade 4). One infection of the soft tissue was medically cured. There were two revisions for polyethylene failure at 8 and 12 years postoperative.

Discussion: The anatomic abnormalities associated with CDH and previous femoral osteotomy increase the complexity of hip arthroplasty. We had best results with the femoral shortening subtrochanteric osteotomy where a rapid consolidation was obtained. Moreover, the functional result was better for the management of the insertion of the muscle tendons in particular the mediogluteus and also for the relatively correct positioning in favour of the reciprocal relationship of the pelvic-trochanter. The detachment of the greater trochanter associated with a metaphyseal proximal shortening, remains an effective technique for the treatment of malformations that are difficult to treat, but there is a high risk of pseudarthrosis of greater trochanter.

Conclusion: Femoral shortening subtrochanteric osteotomy preserves the proximal femoral anatomy, avoids the problems associated with reattachment of the greater trochanter, and facilitating a cementless femoral reconstruction in relatively young patients.

Introduction: Many publications have already shown the great interest of dual-mobility concept which significantly reduces the rate of prosthetic dislocation and thus find its place for patients at high risk of post operative instability. The aim of our study is to evaluate the prevalence of prosthetic instability in revision total hip arthroplasty using a dualmobility cup.

Materials and Methods: Our multicentric series consists of 163 revision total hip arthroplasties performed between may 1999 and may 2004. The mean age at revision was 70 years and the mean follow-up period was 56 months.

The primary etiology necessitating revision is aseptic loosening.

According to the SOFCOT classification, the acetabular deficiency was grade IV 9 times, grade III 47 times, grade I or II 107 times.

All the implanted acetabular components are SERF dual-mobility implants. This system consists of a metal back which can be HA-coated and Press Fit or cemented in a Kerboull cross or in a Novae Arm. The mobile-bearing insert which allows a dual articulation between the head and the metal back is of polyethylene.

We implanted 119 HA-coated press-fit cups and cemented 44 dual-mobility cups in a support ring or in a Kerboull cross.

Results: The mean Merle d’Aubigné and Postel score is 14,1 at the last follow-up and 4,2 in the preoperative period.

We reported 8 complications: 6 early dislocations and 2 acetabular revisions for secondary mobilisation of the cup.

Discussion: According to Huten’s 1996 SOFCOT teaching conference, this rate ranges between 2 and 5% and we have already published a series of 106 dual-mobility with no dislocation at a 10 year follow-up period.

With 4% dislocations at a mean follow-up of 56 months, the dual-mobility cup seems to provide high stability in revision hip surgery when other factors such as muscular deficiency, extended synovectomies, difficult implant placement, encourage an uncertain postoperative prosthetic stability.

These results have to be compared to those of other systems such as constrained acetabular cups or tripolar cups.

Conclusion: This is why dual-mobility remains an efficient and reliable choice to avoid prosthetic dislocation in revision surgery. Moreover, we encourage the use of dual-mobility cup in any high risk situation in terms of post-operative instability such as for old or neurological patients.

From 1998 to July 2003 admissions for elective arthroplasty surgery in Derriford Hospital were nursed alongside other orthopaedic and general medical patients. Since August 2003 a policy of pre-operative MRSA screening and a unit reserved exclusively for MRSA-free joint replacement patients have been used. No transfers from other wards were allowed. Patients positive on screening underwent eradication and were admitted to a different ward where they received teicoplanin on induction (in addition to standard policy cephradine). All post-operative wound infections following THR & TKR were monitored (NINSS surveillance system). Infections within 3 months were recorded. A control of non-screened hip hemi-arthroplasty patients was used to ensure a departmental wide reduction in MRSA was not occurring.

1.9% MRSA carriage rate was detected over the study. Before screening, 0.59% of 3386 cases were acutely infected with MRSA. After institution of screening and a dedicated MRSA free unit, 0.10% of 1034 were acutely infected. This was a 6-fold decrease (p<0.05). The infection noted was in a patient treated outside the ringfenced unit on High Dependency. In fact the infection rate on the ringfenced unit was zero. MRSA infection in the control was statistically unchanged during this period.

Since Aug‘03 pre-operative MRSA screening & a ward reserved exclusively for MRSA free joint replacement patients has been used. All postoperative wound infections within 3 months following THR & TKR were monitored.

Before screening, 0.59% of 3386 were acutely infected with MRSA. After institution of study policy, 0.10% of 1034, were infected with MRSA.. This was a 6 fold decrease (p< 0.05). The rate of MRSA infection in a control of hemiarthroplasties was unchanged during this period.

A policy of MRSA screening & an MRSA free joint replacement ward reduces the incidence of acute MRSA infections.

The use of implant biomaterials for prosthetic reconstructive surgery and osteosynthesis is consolidated in the orthopaedic field, improving the quality of life of patients and allowing for healthy and better ageing. However, there is the lack of advanced innovative methods to investigate the potentialities of smart biomaterials, particularly for the study of local effects of implant and osteointegration. Despite the complex process of osseointegration is difficult to recreate in vitro, the growing challenges in developing alternative models require to set-up and validate new approaches. Aim of the present study is to evaluate an advanced in vitro tissue culture model of osteointegration of titanium implants in human trabecular bone. Cubic samples (1.5×1.5 cm) of trabecular bone were harvested as waste material from hip arthroplasty surgery (CE AVEC 829/2019/Sper/IOR); cylindrical defects (2 mm Ø, 6 mm length) were created, and tissue specimens assigned to the following groups: 1) empty defects- CTR-; 2) defects implanted with a cytotoxic copper pin (Merck cod. 326429)- CTR+; 3) defects implanted with standard titanium pins of 6 µm-rough (ZARE S.r.l) -Ti6. Tissue specimens were cultured in mini rotating bioreactors in standard conditions, weekly assessing viability. At the 8-week-timepoint, immunoenzymatic, microtomographic, histological and histomorphometric analyses were performed. The model was able to simulate the effects of implantation of the materials, showing a drop in viability in CTR+, differently from Ti6 which appears to have a trophic effect on the bone. MicroCT and histological analysis supported the results, with lower BV/TV and Tb.Th values observed in CTR- compared to CTR+ and Ti6 and signs of matrix and bone deposition at the implant site. The collected data suggest the reliability of the tested model which can recreate the osseointegration process in vitro and can therefore be used for preliminary evaluations to reduce and refine in vivo preclinical models. Acknowledgment: This work was supported by Emilia-Romagna Region for the project “Sviluppo di modelli biologici in vitro ed in silico per la valutazione e predizione dell'osteointegrazione di dispositivi medici da impianto nel tessuto osseo”

The surgical treatment of a secondary gonarthrosis caused by haemophilic arthropathy needs high quality in soft tissue balancing and accurate alignment in total knee arthroplasty (TKA), which are essential for good long-term results. Due to the early-onset severe arthropathy, haemophiliacs undergo prosthetic surgery at a younger age than general population; therefore to ensure a longer duration of implantation is a major objective to be reached in this setting. As several prospective randomised studies could show, Computer navigation in prosthetic surgery improve precision concerning geometry of axes, resection planes and implant alignment, by the determination of joint centres (actual axis), amount of bone resection, size of prostheses and check of ligament balance. At our department, since January 2006, we implanted four TKA in four patients (age range 45–52 years) affected by severe Haemophilia B; the same surgeon used a single system (Orthopilot system) in all cases. The quality of implantation was studied on postoperative standardized long leg coronal and lateral x-rays. Our results showed that CAS had greater consistency and accuracy in implant placement. Complications influencing the clinical outcome did not occur. In our experience, drawbacks of the navigation systems are the additional costs and the additional operation time between 15 and 25 min. However, one of the most important advantages of using of this technique in patient affected by coagulation disease, according to the international literature, is the reduction of blood loss after operation. A long-term follow-up of these and of larger samples of patients is needed for testing cost/risk-benefit ratio of Orthopilot in prosthetic surgery of haemophiliacs. Therefore navigated total knee arthroplasty in haemophilic arthropathy is not yet a standard procedure, but this technique could become an important surgical choice in management of severe secondary osteoarthritis in the future

Post-surgical infections are still one of the most frequent adverse events in the prosthetic surgery. PMMA-based cements are widely employed in orthopaedic surgery as filler or prosthetic fixing device. The main problems associated with this material are poor bone integration and infection development. Aiming to avoid bacterial adhesion and to extend the longevity of implants, different solutions were proposed, both in terms of operative procedures and new materials development. Regarding the materials advancement, innovative PMMA-based composite bone cements, contemporaneously bioactive and antibacterial (without the use of antibiotics), were developed. The composites are based on a PMMA matrix containing a bioactive glass, doped with antibacterial ions (Ag+ or Cu++); so, the same filler shows at the same time the ability of promoting bone ingrowth and an antibacterial effect. Composite cements were characterized in terms of morphology and composition, curing parameters and mechanical properties; in vitro tests were performed to verify the material ability to release antibacterial ions and to promote the precipitation of hydroxyapatite. Moreover, cytotoxicity and antimicrobial properties were verified. The cements characteristics were tested using different commercial matrix and different viscosities; therefore, the proposed formulations represent an innovative solution for a new family of antibiotic-free, bioactive and antibacterial cements

Aims

We performed a systematic literature review to define features of patients, treatment, and biological behaviour of multicentric giant cell tumour (GCT) of bone.

Introduction and Objectives: In this study we assessed the usefulness of preoperative urine cultures as a tool to prevent infections due to Gram negative microorganisms in patients undergoing prosthetic surgery. Materials and Methods: In 2007 procedures were carried out to implant 259 knee prostheses and 101 hip prostheses, 47 of these were revision procedures. Pre-operative exams included urine culture to detect asymptomatic bacteriurias which could be treated before surgery with positive results. A urinary catheter was placed in all patients and removed after 24 hours. Results: Asymptomatic bacteriuria was found in 13% of patients. In 6 patients the urine culture was positive for more than one microorganism. The most frequently found pathogen was E. coli. All cases were treated with antibiotics and a new urinary culture was carried out before surgery. Our infection rate is 0.8% in primary hip replacements and 8.1% in revisions. And 1.9% in primary knee replacements and 6.7% in revisions. An infection caused by a Gram negative microorganism in a revision THR was caused by a subclavian catheter colonized by Pseudomona aeruginosa. Discussion and Conclusions: Our preoperative studies protocol includes urine culture. We have not seen any TKR or THR infections caused by Gram negative microorganisms. Therefore, based on this, we suggest that preoperative urine culture is useful to identify asymptomatic bacteriuria and treat it, thereby avoiding infections caused by Gram negative microorganisms in patients undergoing prosthetic surgery

Aim. Prosthetic joint infections (PJI) due to Enterobacter cloacae are rare and often severe. The aim of this study is to describe cases with E. cloacae PJI. Method. We conducted a retrospective and a monocentric study in an orthopedic unit where complex bone and joint infections are managed. From 2012 to 2016, we included patients with PJI which perioperative samples were positive with E. cloacae. We collected background, clinical, biological and microbiological data of the current infection, surgical and medical treatment, and the outcome of these patients. Results. A total of twenty patients were included which 8 were male. Location was hip in 14 cases, knee in 5 cases and ankle in one case. The median time between arthroplasty and revision for infection was 3 years. Fourteen patients had at least two surgeries for previous PJI. The median time between the last surgery and the revision for E. cloacae infection was 31 days. Eleven patients were infected by extended-spectrum beta-lactamases (ESBL) strains. Most frequently, the antibiotics used were carbapenem in 9 cases, cefepim in 7 cases, a quinolone in 7 cases and fosfomycin in 4 cases. Infection was cured in 10 cases (50%) with a median time of follow-up of 24 months. Five patients had a recurrent infection, three due to Staphylococcus epidermidis, one to Staphylococcus epidermidis and Propionibacterium acnes and one to Escherichia coli. Four patients had a relapse of E. cloacae infection. One patient died from non-infectious cause (stroke). Conclusions. PJI infections due to E.cloacae usually occur early after the last prosthetic surgery, typically in patients with complex surgical history. A poor outcome, observed in nearly half of the patients could be explained in part by an association of factors: multiple risks factors, complex infectious history, a high rate of multiple resistance to antibiotics, unfavorable skin conditions

Aim. When a prosthetic joint infection (PJI) is suspected, guidelines recommend performing periprosthetic samples, at least one for histopathological examination and 3 to 6 for microbiological culture. The diagnosis of infection is based on the presence of neutrophil granulocytes whose number and morphology can be variable, resulting in definition of “acute” inflammation. The acute inflammation of periprosthetic tissue is supportive of infection. Since 2007, in our hospital, for all patients with suspected PJI who underwent surgery, from each sample taken by the surgeon, one part has been sent to the pathologist and the other one to the microbiologist. Our aim was to compare histopathological to microbiological results from samples taken intraoperatively at the same site. Method. We conducted a retrospective study including all surgeries for which at least one couple “histopathology-culture” was found. Exclusion criterion was a history of antimicrobial treatment 2 weeks prior the surgery. Results. From July 2007 to April 2015, 309 surgeries for suspected PJI were performed in 181 patients. Median age of the study population was 70 years, 60% of patients were male, 45% had a history of joint infection. The location of arthroplasty was knee in 50% of cases and hip in 46%, ankle and shoulder in 4%. Surgery was performed within one month after the last prosthetic surgery in 15% of cases. According to the criteria from the Musculoskeletal Infection Society, 60% of cases should have been considered as having an infection. The median number of samples per surgery was 4 (IQR 3–5) for histopathological examination and 5 (IQR 4–6) for culture. Finally, 1247 couples “histopathology-culture” were available. Among them, histopathological examination showed acute inflammation in 292 cases (23%) and subacute inflammation in 327 cases (26%). Microorganisms considered to be pathogenic were found in 582 samples (47%). The presence of neutrophil granulocytes was well correlated with the presence of those microorganisms (OR=4.1; IC 95% 3.1–5.5). As expected, the highest correlation between acute inflammation and positive culture was observed for early infection (< 1 month) (OR = 9; 3.6–23.4) and Staphylococcus aureus infection (OR = 4.8; 3.3–7.0). There was no correlation between acute or low-grade inflammation and anaerobic or Candida infection. Conclusions. Our results confirmed histopathological examination is better correlated with culture in acute infection and/or infection due to highly virulent bacteria but must be interpreted with caution in case of chronic infection or infections due to microorganisms with low virulence

PJI du to Enterobacter cloacae are rare and often severe. The aim of our study is to define the history of patients with such infections and their outcome. We conducted a retrospective monocentric study in an orthopedic unit where complex bone and joint infections are supported. From 2011 to 214 we selected patients with E. cloacae PJI based on data from the microbiology laboratory. In their files we collected information on their background, their medical and surgical history, antibiotics they received in the year before infection, the suspected portal of entry, the management and the outcome. Twelve patients were included, 7 male and 5 female. PJI was located to the hip in 8 cases, the knee in 3 cases and the ankle in one case. The average time between the placing of the first prosthesis and infection was 3 years. Eleven patients had one or more surgery for previous PJI. The average time elapsed since the last surgery was 30 days. Eleven patients had been treated with antibiotic combinations for at least 6 weeks, in the year before E cloacae infection. A portal of entry was identified only two times: urinary tract infection in one patient and catheter-related infection in one patient. Antibiotics the more often prescribed were carbapenems (n = 5) and cefepime (n = 4), each combined with quinolones (n =4) or fosfomycin (n = 3). Two patients required an additional debridement within an average of 18 days. Infectious outcome was favorable in 8 cases (67%) with a median duration of follow-up of 26 months. Two patients had a recurrent infection, one due to Streptococcus oralis and one to Candida albicans. One patient had a relapse of E cloacae infection. One patient died from unknown cause. PJI infections due to E.cloacae usually occur early after prosthetic surgery, typically in patients with complex surgical history. Despite a high rate of multi-resistance to antibiotics, outcome may be favorable in a large majority of patients