Correct diagnosis of infection is crucial for an adequate treatment of orthopedic implant-related infections. In the orthopedic field, infections can be difficult to diagnose(1). As a consequence, patients may suffer from an undiagnosed and untreated implant-related infection. To solve this problem, we are searching for a diagnostic method to detect these so-called low-grade infections. The technique fluorescence in situ hybridization (FISH) can detect slow-growing and even dead bacteria. Further, as FISH results are available within an hour after tissue collection it is an ideal candidate for diagnostic purposes. AIM: to evaluate the FISH technique for its potential to detect and identify orthopedic infections. Sonication fluid (SF) was collected by sonicating retrieved implants(2) from 62 patients. All samples were subjected to bacterial culture for clinical diagnostics. In addition, a commercially available FISH kit (miacom diagnostics, Germany), specifically designed for blood analysis (hemoFISH Masterpanel), was used. The kit contained 16S rRNA probes (positive control), non-sense probes (negative control), probes for Staphylococcus spp., Staphylococcus aureus, Streptococcus spp., Streptococcus pneumoniae, Streptococcus agalactiae, Enterococcus faecium, Enterococcus faecalis, Enterobacteriaceae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Acetinobacter spp., and Stenotrophomonas maltophilia. All FISH analyses were performed according to the protocol provided with the kit. Culture and FISH results were compared, considering culture as the gold standard. Culture resulted in 27 positive and 35 negative samples. Comparing FISH (16S rRNA probe) with culture, 24 samples tested true-positive and 32 samples true-negative. Furthermore, 3 samples tested false-negative and 3 samples false-positive. The species cultured with the highest incidence were Propionibacterium acnes and Staphylococcus epidermidis, both from 8 SF samples. As the kit did not contain a probe for Propionibacterium acnes, these strains were only detected by the 16S rRNA probe. In addition, the latter samples tested positive with the Staphylococcus spp. probe. Interestingly, 3 samples tested positive with FISH that were culture negative. This result could indicate a higher sensitivity for detection of bacteria with FISH than with culture. Before FISH can be used for diagnostic purposes, the technique needs to be optimized to prevent false-negative results, for use on other patient materials and for detection of bacterial strains relevant for the orthopedic field like Propionibacterium acnes. In conclusion, FISH holds promise to be used as a diagnostic tool for identifying orthopedic infections

Aim. Nasal colonization with S.aureus (SA) is a risk factor for developing nosocomial infections in cardiac surgery. However, the risk in orthopedic surgery remains unclear, especially in adolescent idiopathic scoliosis (AIS) surgery were data are missing. This study aims to evaluate the efficacy of a preoperative nasal decontamination program in SA healthy carriers on early surgical site infections (SSI) after AIS posterior surgery in a pediatric universitary Parisian hospital. Method. Between 01-01-2014 and 03-31-2017, all AIS patients were screened preoperatively with nasal swabs and decontaminated with mupirocine if positive during the 5 days before surgery. Early SSI were prospectively identified and microorganisms' findings were compared to a previous serie published before the beginning of the decontamination program (2007–2011). Results. Among the 316 AIS posterior procedures performed during the study period, nasal swabs were performed at the average of 100 ± 92 days before surgery. Incidence of positive nasal swab was 22 % (n=71) and all were preoperatively decontaminated. Compared to the series (n=496) published before the decontamination program, the early SSI rate remains stable (8.2% versus 8.5%). But incidence of S.aureus early SSI decreased to 1% (n=4), while it represented 5% (n=25) in the previous study. In our study, none of the S. aureus decontaminated patients had an early S.aureus SSI. For the 4 S.aureus early SSI, preoperative nasal swab was negative, but done with a mean delay of 328 days before surgery, suggesting a possible S.aureus intermittent carriage and the need of shorter delays between nasal swab and surgery to improve the screening. Moreover, the stable rate of early SSI between the 2 periods is due to an increase rate of Propionibacterium acnes, which incidence grown from 0.08% to 6% in our actual series. Conclusions. To conclude, in our study, nasal decontamination divided by 5 the incidence of S.aureus SSI. It seems that nasal swabs should be performed as close as possible to the surgery to optimise the S.aureus screening. In addition, the SSI rate remains very high with the emergence of Propionibacterium acnes and is currently addressed by a multifactorial approach

Aim. Spinal infection is the most frequent complication of spine surgery. Its incidence varies between 1% and 14% in the literature, depending on various studied populations and surgical procedures. The aim of this study was to describe a consecutive 2706 case series. Method. We analyzed a prospective cohort of 2706 patients operated for spine disease between 2013 and 2016 in a University Hospital. The infection rates, germs, time between surgery and infection and outcomes after surgical revision were assessed with a minimum follow-up of 7 months. We developed a mathematical model to analyze risk factors in this difficult-to-treat population. Results. Among 2706 patient who underwent spinal surgery during the three-year study period, 106 developed a postoperative spine infection. Clinical indicators for infection were the sudden onset of local pain and swelling without fever after an initial pain-free interval. We observed a masculine predominance (68%); the median age was 56 years. The rate of infection was comprised between 0,3% (discal herniation surgery) to over 20% in posterior cervical instrumented surgery (acute cervical fractures), with a global rate of 4%. Polymicrobial infections with more than 3 germs were found in only 2 case, with 3 germs in 8 cases, 2 germs in 27 cases and 1 germ in 69 cases. Staphylococcus aureus, Propionibacterium acnes and Staphylococcus epidermidis were the three main germs identified (53, 36 and 22 respectively). Propionibacterium acnes was involved with a higher rate in instrumented surgery but also in 8% of conventional non-instrumented surgery, with a median relapse time of 24 days (12 days to 4 years). Staphylococcus aureus was involved at a higher rate in posterior non-instrumented surgery with a median relapse time of 18 days (8–66 days). The rate of infection per month was globally stable along the year except an increased rate in February-March. All patients with a suspicion of post-op infection were initially treated with wound/deep tissues revision within the first month after surgery and associated with implant removal after one-month post-op. Pejorative outcomes were associated with incomplete revision surgery, several surgeries and polymicrobial infection. Conclusions. In this study, the rate of postoperative infection is comparable to the literature. In contrast, Propionibacterium incidence is high, especially for acute infections. This unexpected rate can be linked to technical improvements in culture detection but this should also lead us to further discuss the natural process of spine/disk colonization of this germ

Daptomycin has a unique mechanism of action against Gram-positive bacteria. Daptomycin is only bactericidal in the presence of calcium ions. [1]. Kanellakopoulou et al [2] investigated elution of daptomycin from calcium sulfate. The results indicated above MIC elution concentrations out to 28 days. Experience reports that the ability for calcium sulfate to set hard when combined with daptomycin can be problematic.[3] This study aimed to investigate the combination of daptomycin with a synthetic recrystallised form of calcium sulfate and investigate zone of inhibition (ZOI) testing against susceptible organisms. 6mm hemispherical beads, were prepared using a commercially available calcium sulfate hemihydrate powder (CSH) – CaSO4 ·1/2H2O. [4] In order to combine daptomycin [5] with the CSH and enable it to set hard, 7mls of saline solution was added to 20g CSH powder and mixed for 80 seconds to initiate the setting reaction. Then 1g of daptomycin powder was added and mixed for a further 30 seconds. The resultant paste was applied to a bead mat and allowed to set. Tryptone soya agar plates were seeded with 0.2ml of a 10e6 – 10e8 cfu/ml suspension of the relevant organism. The plates were incubated at 33 °C ± 2 °C for 30 minutes. The plates were then removed from the incubator and the beads placed on the surface. The plates were then incubated at 33 °C ± 2 °C for 24 hours before examination for the absence of growth as seen by a clear zone around the test sample. Triplicate samples were tested against Staphylococcus epidermidis, Staphylococcus aureus, MRSA, VRE Enterococcus faecium and Propionibacterium acnes. Repeat tests were carried out for beads that had been stored at 37 °C for 21 days to simulate in-vivo conditions. Setting times for the CSH/daptomycin beads were approximately 20 minutes. ZOIs indicating efficacy were seen for all samples both ‘fresh’ and ‘incubated’ with MRSA and Propionibacterium acnes having the largest ZOIs at 31–33mm. A mixing protocol was established to enable set beads to be formed with daptomycin loaded calcium sulfate. As assessed by ZOI testing, the eluted antibiotic maintained efficacy against susceptible pathogens. Results obtained in-vitro may not be indicative of in-vivo performance

Reverse shoulder arthroplasty is becoming a frequent treatment of choice for patients with shoulder disorders. Complication rates after reverse shoulder arthroplasty may be three-fold that of conventional total shoulder arthroplasty especially in high risk patient populations and diagnoses like revision arthroplasty, fracture sequelae, and severe glenoid bone loss. Complications include component malposition, stiffness, neurological injury, infection, dislocation or instability, acromial or scapular spine fractures, scapular notching, and loosening of implants. Recognition of preoperative risk factors and appropriate 3D planning are essential in optimizing patient outcome and intraoperative success. Failure of reverse shoulder arthroplasty is a significant challenge requiring appropriate diagnosis of the failure mode. The most common neurological injuries involve the brachial plexus and the axillary nerve due to traction, manipulation of the arm, aberrant retractor placement, or relative lengthening of the arm. Intraoperative fractures are relatively uncommon but include the greater tuberosity, acromion, and glenoid. Tuberosity fracture can be repaired intraoperatively with suture techniques, glenoid fractures may be insignificant rim fractures or jeopardise baseplate fixation and require abandoning RSA until glenoid fracture ORIF heals and then a second stage RSA. Periprosthetic infection after RSA ranges from 1 to 10% and may be higher in revision cases and frequently is Propionibacterium acnes and Staphylococcus epidermidis. Dislocation was one of the most common complications after RSA approximately 5% but with increased surgeon experience and prosthetic design, dislocation rates are approaching 1–2%. An anterosuperior deltoid splitting approach has been associated with increased stability as well as subscapularis repair after RSA. Scapular notching is the most common complication after RSA. Notching may be caused by direct mechanical impingement of the humerosocket polyethylene on the scapular neck and from osteolysis from polyethylene wear. Sirveaux classified scapular notching based on the defect size as it erodes behind the baseplate towards the central post. Acromial fractures are infrequent but more common is severely eroded acromions from CTA, with osteoporosis, with excessive lengthening, and with superior baseplate screws that penetrate the scapular spine and create a stress riser. Nonoperative care is the mainstay of acromial and scapular spine fractures. Recognizing preoperative risk factors and understanding component positioning and design is essential to maximizing successful outcomes

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

Infection prevention in shoulder arthroplasty is an evolving challenge as further understanding of the pathogens becomes available. Infection rates for reverse TSA is higher than anatomic TSA. Standard decolonization protocols from our hip and knee colleagues has decreased the acute post-operative infection risk to less than 1%. By identifying at risk populations anti-MRSA precautions including intranasal antibiotics and anti-bacterial soaps for pre-surgical skin preparation have reduced the incidence of staphylococcus infections. The emerging understanding of propionibacterium acnes (P. acnes) as a primary pathogen in late shoulder periprosthetic joint infection (PJI) has led to new recommendations including pre-operative skin cleansing with 5% benzoyl peroxide to reduce infection risk. Pre-operative IV antibiotic is recommended and chlorhexidine skin prep for surgery. In the operating room, the concern is the surgeon's exposure to skin and sebaceous glands where P. acnes is prevalent. After skin incision the surgeon should use a new blade for deep incision. Application of vancomycin powder to the subcutaneous tissue may be beneficial after incision to treat potential contamination from the incision through skin. Glove change prior to handling implants and thorough irrigation before implantation is prudent. The role of antibiotic loaded bone cement for infection prevention remains unproven. Topical vancomycin powder at closure is a low cost option and has shown benefit in spine surgery but efficacy is unproven in the shoulder. Silver impregnated wound dressings may also prevent infection and are a convenient option for patient care with regards to bathing. Preventing infections in shoulder arthroplasty, particularly P. acnes, remains a challenge. A significant number of revision TSAs are found to have positive cultures for P. acnes creating a significant burden for patients and surgeons

Aim. Unexpected positive infections are distinct entity in prosthetic revision surgery. The prevalence and characteristics of unexpected positive cultures in internal fixation are however less established. The aim of this study was to describe the prevalence and characteristics of unexpected diagnosis of infection in a prospective cohort of revision surgeries following internal fixation. Method. We reviewed the microbiological results following 356 surgeries that included partial or complete removal of internal fixation, performed in 328 patients (54% male, mean age 53 ± 17 years), in which infection was not initially suspected. This prospective study was performed in a large single center for musculoskeletal surgery from 2013–2017. The implants most commonly removed were plate and/or screws (281 cases, 78,9%), followed by intramedullary nails (64 cases, 18,0%). The main indications for surgery were nonunion (89 cases, 25%) and symptomatic hardware (70 cases, 19,7%). All removed implants were sonicated, and tissue cultures were obtained depending on the surgeon's criteria. Diagnosis of infection was established by the presence of 2 or more positive tissue cultures (1 with a highly virulent microorganism), or ≥ 50 colony-forming units found in the sonication fluid. Results. Infection was confirmed in 47 cases (13,2%); diagnosis was obtained with tissue cultures in 5 cases (1,4%), sonication in 14 cases (3,9%) and a combination of both sonication and tissue samples in 28 cases (7,9%). In another 24 cases (6,7%), ≥ 50 CFU of low-virulence microorganisms were isolated in the sonication fluid, but no tissue samples were available to confirm the diagnosis. Low-virulent microorganisms such as Propionibacterium acnes (22 cases / 46,8%) or coagulase-negative Staphycoccci (13 cases, 27,7%) were most commonly isolated. Sonication was key for the diagnosis of 61,7% of unexpected-positive surgeries. Nearly half of the patients received a new implant (internal fixation in 40,4%; arthroplasty in 6,4%), but only 34% of the patients were treated with antibiotics on discharge. Conclusions. Unexpected diagnosis of infection occurs in approximately 13,2% of revision surgeries following internal fixation, most commonly due to low-virulent microorganisms. Sonication was key for the diagnosis of the majority of these infections. The clinical relevance of these infections remains unclear, though the insertion of new implants raises concern. We recommend sonication of all internal fixation devices removed, especially if new implants are inserted in the revision surgery

Aim. Shoulder prosthesis chronic infection is a rare but serious complication, likely to lead to re-interventions and poor functional outcome. Two-stage exchange surgery is considered the standard procedure by most authors. Our hypothesis was that one-stage revision procedure is a valid therapeutic option in the management of chronic infections of shoulder arthroplasty. Method. This was a mono-center retrospective cohort study. All patients who underwent, during the inclusion period, a one-stage revision procedure for a chronic infection of shoulder arthroplasty were included. All patients underwent clinical evaluation (Constant-Murray score), radiological examination (standard X-rays) and a blood test (Complete Blood Count and C-reactive protein), at a minimal one-year follow-up. Primary endpoint of this study was the infectious outcome and secondary endpoints were the functional and radiographic outcomes. Results. 16 shoulder prosthesis in 14 patients (5 females, 9 males) were included. Mean time between primary prosthesis implantation and exchange surgery was 40 months (1–145). Mean follow up was 30,5 months. The principal micro-organism involved was Propionibacterium acnes (9/16) and multiple organisms were found in 6 patients. In 14/16 (87,5%) shoulders, we found no sign of persistent infection at last follow-up. 2/16 (12,5%) shoulders were considered as still infected. On these 2 patients still infected, one refused further revision and the other was not in a good enough medical condition to undergo another procedure. 2 patients required an additional one-stage procedure for a new infection (new pathogen) after a period of two years, both free of infection at last follow-up. At last follow-up, mean Constant score was 54,8 (23–82). 7/14 (50%) patients were satisfied or very satisfied with the global fonctionnal result. Conclusions. One-stage revision procedure seems to be a valid therapeutic option in the management of infected shoulder prosthesis, as it allowed us to eradicate the infection in 87,5% patients in our serie, with a fair clinical result

The number of shoulder arthroplasty procedures performed in the United States continues to rise. Currently, the number of procedures performed per year ranges from 55,000–80,000 and is expected to increase more than 300% in the coming years. Periprosthetic joint infection (PJI) is one of the most serious complications associated with arthroplasty surgery, leading to poor outcomes, increased cost, and technically difficult revision surgery. The incidence of infection following primary shoulder arthroplasty has been reported between 0.7% and 4%, representing 2.9–4.6% of all complications. Prosthetic shoulder joint infections are unlike prosthetic joint infections of the hip and knee. Shoulder PJIs are primarily indolent in nature and difficult to diagnose using traditional methods that have been shown to be accurate for periprosthetic infections of the hip and knee. The majority of infected revision shoulder arthroplasties are associated with growth of Propionibacterium acnes (P. Acnes). This slow-growing, anaerobic organism requires longer than normal incubation times for culture (7–21 days), and typically demonstrates a subtle, non-specific clinical presentation that can make the presence of infection difficult to identify. In the reported literature, P. Acnes accounts for about 70% of cases with positive cultures associated with revision for treatment of a painful shoulder arthroplasty and due to the bacteria's slow growing nature and virulence profile, the rate of infection following shoulder arthroplasty may often be underestimated. A more recent and promising tool for evaluation of periprosthetic infection has been analysis of synovial fluid. Synovial fluid biomarkers have been identified as part of the innate response to pathogens, and include pro-inflammatory cytokines and anti-microbial peptides, and marker levels have shown promise for improved diagnostic efficacy in hip and knee PJI. Currently, no highly predictive clinical test for diagnosis of PJI in the shoulder exists, however, several of these synovial biomarkers have recently been analyzed for their diagnostic capacity in the setting of periprosthetic shoulder infection. Synovial fluid cytokine analysis shows the potential to improve diagnosis of infection in revision shoulder arthroplasty. This information can help to guide decision-making in the management of PJI of the shoulder, including the decision to perform a single- vs. two-stage revision surgery, and the need for post-operative antibiotics following an unexpected positive culture result after revision surgery. However, there are still challenges to broader use of these synovial biomarkers. Synovial α-defensin (Synovsure, CD Diagnostic) is the only marker currently available as a commercial test, and no point-of-care test is currently available for any of the biomarkers to allow for intraoperative decision-making. While a preoperative synovial aspirate is possible to send for α-defensin analysis currently, with results back in approximately 24 hours, dry fluid aspirations are frequent in the shoulder because of the predominance of indolent pathogens and may limit utility of the test. In summary, indolent infection associated with P. acnes is a common cause for the painful total shoulder arthroplasty. Pre-operative diagnosis of infection is difficult as a result of the poor diagnostic accuracy of traditional methods of testing. Synovial biomarker testing may ultimately improve our ability to more accurately diagnosis and treat prosthetic shoulder joint infections

Aims. Microbiological diagnosis of bone and joint infections (BJIs) is pivotal. However, no consensus exists about the best choice for techniques to be used and the best indications for molecular methods. Our objectives were: (i) to compare the performance of various microbiological diagnostic methods (cultural and molecular) on synovial fluid specimens and (ii) to select an algorithm for optimizing the diagnosis of BJIs in adults. Methods. This prospective multicentric study (in Lyon and Saint-Etienne, France) included 423 joint fluid samples, collected from 333 adult patients (median age 69 years) suspected for BJI on the basis of medical history and clinical symptoms. For each inclusion, joint fluid and blood culture were collected concomitantly. The synovial fluid was also inoculated into blood culture bottles. Cytology, culture (using 5 solid media and an enrichment broth, incubated for 15 days), universal 16S rRNA PCR and PCR targeting Staphylococcus spp, S.aureus, Streptococcus spp, S.pneumoniae, Kingella kingae, Borrelia burgdorferi and Propionibacterium acnes were systematically performed on synovial fluid. Results. Prosthetic materials were present in 65.0% of the cases and 31.7% of the patients had received antibiotics in the 15 days before puncture. Out of 423 joint fluids, 265 (62.6%) were positive by at least one diagnostic technique (cultural or molecular): 219 mono- and 46 poly-microbial, for a total of 322 bacteria. Identified bacteria were staphylococci in 54.0%, streptococci-enterococci in 15.2%, Gram-negative bacilli in 14.0%, anaerobic species in 10.9% and other bacteria in 5.9% of cases. Comparing the individual performance of each cultural technique, blood culture bottles showed the highest rate of positivity (detecting 61.4 and 58.4% of the bacteria, for the paediatric and anaerobic bottles, respectively) but cannot be performed alone and require to be combined with solid media. The 16S rDNA PCR was positive in only 49.2% of the cases whereas higher detection was obtained with specific PCR. Blood cultures performed concomitantly with joint puncture were positive in only 9.7% of the cases. Conclusions. In order to simplify the culture procedures and to precise the place of PCR for synovial fluid, we propose the following algorithm: joint fluids should be inoculated onto 3 solid media (blood and chocolate agars for 2 days, anaerobic blood agar for 10 days), associated with inoculation into blood culture bottles for 10 days. If culture remains negative, 16S rDNA PCR and/or Staphylococcus PCR should be added. Applying this algorithm on our cohort, 93.6% of the bacteria would have been detected

Aim. Propionibacterium acnes (PA) is an important cause of shoulder prosthetic joint infections (SPJIs) for which the optimal treatment has not yet been determined. Rifampicin and Levofloxacin both showed not benefit in recent experimental models of PA-SPJIs. We describe herein the experience of five different medical French centers in order to assess factors associated with patient's outcome with special emphasize on antibiotic regimens. Method. A multicentric retrospective study was performed, on consecutive patients with PA – related SPJIs diagnosed on the basis of at least 2 or more positive cultures of either per-operative or joint aspiration and clinical history compatible with a PJI according to the current guidelines. All patients had surgical management, followed by systemic antibiotic therapy. Remission was defined as an asymptomatic patient with functioning prosthesis at the last contact. Results. Fifty-nine patients of mean age 66.2 ± 10.5 years were included. Most patients were at least ASA 2 (66%), 8 (14%) diabetes mellitus, 3 (5%) had neoplasia. Fourteen patients (24%) had acute, 34 (58%) subacute, and 11 late infections (19%). The mean delay from symptoms of infection to surgery was 89 ± 141 days (1–660). Surgical management consisted in implant exchange in 40 (68%) patients. Antibiotic treatment included mainly clindamycin (49%), levofloxacin (44%) and rifampin (17%), with a mean duration of 52.3 ± 31.9 days. The mean follow-up duration was 540 days ± 488 (range 12 ™ 1925). Forty-five patients were in remission (76%) in this study, 8 patients had a relapsing infection (14%), 1 a recurrence (2%) and 5 a superinfection ™ i.e, due to a different pathogen − (8%). In monovariate analysis, rifampicin/levofloxacin treatment was significantly associated with failure (p=0.038). In multivariate analysis, levofloxacin use and implants retention were significantly related to failure (p=0.02 and p=0.003, respectively). Conclusions. Our results suggest that implant retention and levofloxacin use are two independents factors of failure in patients treated for PA – related SPJIs

Total shoulder arthroplasty (TSA) and reverse shoulder arthroplasty (RSA) are excellent surgical options for individuals with shoulder arthritis, providing good to excellent results in the vast majority of patients. Complications are rare, but can be devastating for both the patient and surgeon. An uncommon, but extremely problematic complication following shoulder arthroplasty is shoulder stiffness. While substantial literature discussing post-arthroplasty stiffness is available for other joints such as the hip, knee, and elbow, there is a paucity of research available discussing this complication in the shoulder. As noted in multiple reviews, diminished range of motion following TSA or RSA may be due to a number of factors, including pre-operative diagnosis of proximal humerus fracture, inadequate post-operative rehabilitation, implant-related factors such as malpositioning and/or inappropriate-sized implants, and heterotopic ossification. Often, pathology leading to post-arthroplasty stiffness involves scarring of the long head of the biceps tendon, rotator cuff impingement, as well as cuff tendonitis. Periprosthetic joint infection (PJI) is also important to recognise, and may be difficult to diagnose, especially in cases of Propionibacterium acnes infections. Importantly, PJI may present with stiffness as well as instability, and thus a high index of suspicion with a low threshold to aspirate is necessary in these challenging patients. Treatment of patients with stiffness following arthroplasty is challenging, and may involve arthroscopic intervention with or without manipulation, as well as manipulation under anesthesia alone. This paper will discuss the etiology, work-up, and treatment of patients with shoulder stiffness following TSA and RSA

Aim. Periprosthetic joint infection (PJI) is nowadays the most important problem leading to failure in primary and revision total knee (TKA) and total hip arthroplasty (THA), therefore accurate diagnosis of PJI is necessary. We evaluated a commercial multiplex PCR system1 for diagnosis of PJI in joint aspiration fluids prior to surgery. Method. A total of 32 patients were included in the study. Twenty-four patients had TKA and eight had THA. Joint aspiration fluids were examined by standard bacteriological procedures. Excess material of joint aspirates was frozen at −20°C until testing by multiplex PCR1. Inclusion criteria were a minimum leucocyte count of 2.000 per ml and at least 60% of polymorphonucleaur neutrophils (PNN) in the joint aspiration fluid. Results. For 21 patients with TKA, both standard bacteriological culture and PCR1 were negative. In these patients the mean leucocyte count in the joint fluid was 15.385/ml with 80% PNN. For three patients culture was negative, but PCR1 was positive. In one patient PCR1 detected Corynebacterium sp. which was considered as contamination as this patient had crystal arthropathy; for the second patient Propionibacterium acnes was detected by PCR1, this patient was treated as having an infection of unknown origin in another hospital. For the third patient PCR1 detected Pseudomonas aeruginosa. This patient was known as having chronic P. aeruginosa infection of his TKA and joint aspiration was done shortly after arrest of antibiotic therapy by ciprofloxacin. The mean leucocyte count in the patients with positive PCR was 61.800/ml with 89% PNN. In three of the eight patients with THA, standard bacterial culture and PCR1 were both negative. The mean leucocyte count in joint aspirates of these patients was 10.087/ml with 77% PNN. In five patients with THA, both culture and PCR1 were positive and concordant. In one case culture and PCR1 detected Staphylococcus aureus, and in the other culture and PCR1 detected P. acnes. In two cases culture grew S. epidermidis and PCR1 detected coagulase negative Staphylococcus. In the fifth patient culture grew C. jeikeium and PCR1 detected Corynebacterium spp. Conclusions. We found concordant results for culture and PCR1 in all eight patients with THA and in 22/24 patients (92%) with TKA. Multiplex PCR1 results are available in 4 hours whereas culture results may demand several days. The commercial multiplex PCR system1 designed for diagnosis of implant and tissue infection can be helpful for the diagnosis of PJI. *Unyvero i60©, Curetis Strasbourg, France

Aim. Although there are no treatment guidelines for Propionibacterium acnes (PA) bone and joint infections (Corvec et al Acta Orthopedica 2016), these infections can be treated with a combination of fluoroquinolones and rifampicin. Rifampicin resistance have already been reported either in in vitro selected mutants or clinical isolates (Furustrand et al JAC 2013, Anaerobe 2015). Minimal inhibitory concentrations of levofloxacin (LVX) ranging from 0,12 to 0.5mg/L are regularly observed but resistance has not yet been investigated. We investigated the in vitro emergence of LVX resistance and characterized the mutations involved in gyrA gene. Method. The strain of PA ATCC11827 (MIC LVF = 0.25 mg/L) was used. The frequency of mutation was determined after inoculation of 108 PA on blood agar containing concentrations of 2 to 128 times the MIC incubated for 7 days in anaerobiosis at 35 ° C. The emergence of high-level of resistance was also studied from the low-level mutants after a second exposure. For the resistant mutants, the gyrA and parC genes were sequenced and compared to the PA reference sequences. Results. The mutation frequency was 3.8 cfu × 10–8 (8×MIC) and 1.6 cfu × 10–7 (4×MIC), respectively. A low or high-level resistance to LVX was observed. MICs varied between 0.75 and> 32 mg/L and were stable after three subcultures. 87 mutants were studied including 40 with a mutation in gyrA gene. 10 different genotypes could be demonstrated with either high-level resistance: G99 (n = 4), G99 D (n = 3), D100N (n = 1), S101 L (n = 14), S101W N = 5) or low-level resistance D100H (n=1), D100G (n=1), A102P (n=5), D105 H (n = 4), D105 G (n = 2). Substitution 101 always leads to a high level of resistance. No mutation was found in parC gene. Conclusions. To our knowledge, this is the first description of the emergence of LVX resistance in PA. The MIC increases from sensitivity to low or high-level resistance. This resistance is stable and associated exclusively with mutations in the gyrA gene. Six different positions give rise to ten different genotypes. The passage from a low to a high-level resistance is done mainly by the selection of the mutation at position 101. Finally, some mutants do not exhibit mutations in QRDRs, suggesting the existence of an efflux system

Aim. Propionibacterium acnes is a skin commensal colonizing the deeper structures of the pilous bulb. It is responsible for 5–10% of lower limb prosthetic joint infections (PJI) but accounts for as many as 50% of shoulder arthroplasty infections. P. acnes PJIs characteristically feature limited systemic inflammation, limited polymorphonuclear infiltration and clinical signs compatible with aseptic loosening. All current microbiological definitions of PJI require two or more identical commensal isolates to be recovered from the same procedure to diagnose PJI to increase specificity and rule out contamination. Whereas the antimicrobial susceptibility patterns of coagulase negative staphylococci are highly polymorphic and commonly allow the ready distinction of unrelated strains, P. acnes shows a highly stereotypical susceptibility profile and it is impossible to phenotypically assess the clonal relationship of isolates. In order to determine the clonal relationship of multiple P. acnes isolates recovered from arthroplasty revisions, we analyzed by multi-locus sequence typing (MLST) P. acnes isolates grown from PJI in a reference center for bone and joint infection. Method. We retrospectively selected all cases of microbiologically documented monomicrobial PJI caused by P. acnes diagnosed in our center from January 2009 to January 2014. Microorganisms were identified by MALDI-TOF mass spectrometry (Bruker Daltonics). All corresponding P.acnes isolates biobanked in cryovials frozen at −80°C were subcultured on anaerobic blood agar, DNA extracted by freeze-thawing and bead-milling, and typed according to the 9 gene MLST scheme proposed by Lomholt HB. and al. Results. Over the 5-year period, 39 cases of PJI positive with P. acnes were diagnosed in our center. Three to ten intraoperative samples were sent for microbiological analysis per surgery. Overall, 113 P. acnes isolates were grown from 210 samples. On average, four samples were positive out of six. In 34/39 cases, all isolates belonged to the same ST. In 5 cases, multiples STs were found among the P.acnes isolates. In 3/39 cases (7.7%), a single ST was found to be microbiologically significant, with a single isolate of the alternate ST. In 2/39 cases (5.1%), we found that each isolate belonged to a different ST. Conclusions. P. acnes PJI were found to be polyclonal by MLST in 12.8% of cases in our experience, with more than 5% of cases not fulfilling the requirements for microbiological significance. The criteria for microbiological significance do not necessarily apply to commensal agents with no antimicrobial susceptibility pattern variation such as P. acnes

Aim. Pre-operative distinction between prosthetic joint infections (PJI) and non-infectious causes of joint failure is particularly challenging, especially in chronic situations. Guidelines propose different algorithms using numerous preoperative tests. We evaluated place of serology. Method. During a 9 month period, we included consecutive patients undergoing arthroplasty revision for a suspected chronic hip or knee infection. Serologies were sampled at the same day than the other blood tests. Results were compared with the final diagnosis, determined with peroperative bacteriological and histological results. Serology was performed using a multiplex antibody detection*. This multiplex antibody detection assay detects antibodies against Staphylococcus species, Propionibacterium acnes and Streptococcus agalactiae. Results. A total of 52 patients were enrolled. Median time from last arthroplasty was 30 months (extremes 8 months − 17 years). Median clinical signs duration was 6 months (extremes 1 – 40 months). Median CRP value was 6 mg/l (extremes 2 – 150) and sedimentation rate 12 mm (extremes 2 – 82). Diagnostic of PJI was finally retained for 17 patients and ruled out for 35. It was Staphylococcus aureus 3 times, coagulase negative staphylococci (CoNS) 5 times, P. acnes 4 times, candida sp. 2 times, Streptococcus agalactiae one time, Enterobacter cloacae one time and undetermined one time. Serology was concordant and accurate with the final diagnosis for 38 patients (27 sterile and 11 infected). For 7 of them, serology was the key parameter. In these cases, a CoNS or a P. acnes was isolated per-operatively on a single culture, out of 5 samples. Serology allowed confirming a contamination in 5 cases; and in 2 cases, even if not fulfilling the definition, it determined a PJI. In this study, serology had a global sensitivity of 65%, 77% specificity, 58% positive predictive value, and 82% negative predictive value. Serology reached 89% sensitivity with unchanged specificity in the subgroup of 11 patients with a CRP > 10 mg/l. Conclusions. We evaluated place of serology in the most complex cases of suspected chronic PJIs, with finally, only 33% cases with an infection. Modest results of serology can be explained because antigens included in the assay were not those expressed in sessile bacteria. And by persistence of a humoral response, witnesses of past infections, for patients who had past surgeries on the joint. However, simple and practical, when combined with all other parameters, serology could provide a valuable support in preoperative evaluation of chronic PJIs. * BJI InoplexTM

Aim. Culture of multiple periprosthetic tissue samples is the current gold-standard for microbiological diagnosis of prosthetic joint infections (PJI). Additional diagnostic information may be obtained through sonication fluid culture of explants. These current techniques can have relatively low sensitivity, with prior antimicrobial therapy or infection by fastidious organisms particularly influencing culture results. Metagenomic sequencing has demonstrated potential as a tool for diagnosis of bacterial, viral and parasitic infections directly from clinical samples, without the need for an initial culture step. We assessed whether metagenomic sequencing of DNA extracts from sonication fluid can provide a sensitive tool for diagnosis of PJI compared to sonication fluid culture. Method. We compared metagenomic sequencing with standard aerobic and anaerobic culture in 97 sonication fluid samples from prosthetic joint and other orthopaedic device-related infections. Sonication fluids were filtered to remove whole human cells and tissue debris, then bacterial cells were mechanically lysed before DNA extraction. DNA was sequenced and sequencing reads were taxonomically classified using Kraken. Using 50 derivation samples, we determined optimal thresholds for the number and proportion of bacterial reads required to identify an infection and confirmed our findings in 47 independent validation samples. Results. A total of 131 sonication fluids were aerobically and anaerobically cultured and underwent metagenomic sequencing. From the first 72 sonication fluid samples sequenced 22 samples from six batches were excluded, as these samples and negative controls from the same batches showed similar contamination. The remaining 50 samples, the derivation set, were used to determine optimal sequence thresholds for identifying true infection. Of 59 subsequently sequenced validation samples, 12 from a single batch were excluded as the negative control was contaminated with Propionibacterium acnes, leaving 47 validation samples. Compared to sonication fluid culture, the species-level sensitivity of metagenomic sequencing was 61/69(88%,95%CI 77–94%)(derivation samples 35/38[92%,79–98%]; validation samples 26/31[84%,66–95%]), and genus-level sensitivity was 64/69(93%,84–98%). Species-level specificity, adjusting for plausible fastidious causes of infection, species found in concurrently obtained tissue samples, and prior antibiotics, was 85/97(88%,79–93%)(derivation 43/50[86%,73–94%], validation 42/47[89%,77–96%]). High levels of human DNA contamination were seen despite use of laboratory methods to remove it. Conclusions. We demonstrate as a proof of principle that metagenomic sequencing can provide accurate diagnostic information in PJI. Further depletion of human DNA will lead to improved genomic information on the cause of infection, strengthening the case for metagenomic sequencing as a diagnostic tool in PJI

Aim. Acute postoperative infection is reported to occur in 0.3–2% after arthroscopic rotator cuff repair. Few reports have addressed this dreaded complication although the costs are high both for the patient and for society. The aim of this prospective study was to describe incidence, treatment and outcome after acute postoperative infections following arthroscopic rotator cuff repair. Method. Patients undergoing arthroscopic rotator cuff repair in our department have been prospectively registered since 2009. 11 out of 1072 patients undergoing surgery developed an acute postoperative infection. The patients were examined with an MRI scan and/or functional scores (Constant Murley (CM) and WORC) at final follow-up. Results. All 11 patients that developed acute postoperative infections were male. Mean age was 54 (41–68) years. Except for male gender, no common underlying predisposing risk factor for infection could be identified. 1/11 patient had diabetes mellitus and 2/11 smoked. Average BMI was 27 (21–36). 1/11 was categorized as ASA 3 and the rest of the patients were ASA 1 and 2. All patients underwent arthroscopic debridement and biopsies were collected 26 (14–50) days after primary surgery. In 10 patients Propionibacterium acnes was cultured, and 6 of these patients also had positive cultures for coagulase negative staphylococci. In the remaining patient only coagulase negative staphylococcus was cultured. 5/11 patients were treated with one arthroscopic debridement, 5/11 had two arthroscopic debridements, whereas 1/11 required arthroscopic debridement four times before the infection was eradicated. Only 2/11 patients had to have their implants removed during the reoperation due to loosening of the suture anchors. All 11 patients were treated with parenteral antibiotics for 7–28 days, followed by oral treatment for 1–5 weeks, and all infections had resolved at final follow-up. Median CM score was 84 and median WORC score was 81% at follow-up median 22(11–28) months. 10 patients had a postoperative MRI scan after median 23 (3–49) months, 8 of them showing a healed cuff repair. Conclusions. Acute postoperative infections after arthroscopic rotator cuff repair can be eradicated with arthroscopic debridement(s) and removal of implants may not be necessary if patency is adequate. Despite the postoperative acute infection our patients presented good functional results and were satisfied at last follow-up

Propionibacterium acnes infection of the shoulder after arthroplasty is a common complication. Current detection methodologies for P. acnes involve prolonged anaerobic cultures that can take up to three weeks before findings can be reported. Our aim was to develop a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) approach that is both sensitive and specific to P. acnes that would enable a 24-hour turnaround between biopsy and results. Comparisons between the 16S ribosomal sequences of P. acnes and closely related bacteria identified two unique regions in P.acnes to which PCR primers were designed. Additionally, two unique restriction enzyme cut sites for HaeIII were identified within this amplicon. To test the PCR method, arthroscopic surgical biopsies were mechanically homogenised and boiled for 20 minutes to lyse the cellular membranes. PCR was performed using standard conditions followed by a one hour HaeIII enzymatic digest of the PCR product. Resultant fragments were visualised on polyacrylamide gels stained with ethidium bromide. All experiments included no-template controls to rule out reagent contamination and independently confirmed P. acnes DNA as a positive control. Serial dilutions of P. acnes cultures in Robertson's cooked-meat broth and spectrophotometric analysis of cellular concentration were used to assess the sensitivity of the PCR reaction. A unique 564 base-pair PCR amplicon was derived from different strains of P. acnes. This amplicon was confirmed as P. acnes DNA by gel excision and DNA sequencing. HaeIII digests of the amplicon yielded 3 restriction fragments at the sizes predicted by in silico analyses. Sensitivity testing confirmed that as few as 10 P. acnes cells in a 50µl reaction volume could be detected using this assay. P. acnes was also detected in surgical biopsy samples. P. acnes infections following shoulder arthroplasty are a serious complication placing a burden on the healthcare system and the patient due to the lengthy surgical revision process that follows. The infections are also difficult to diagnose. This unique assay combines the sensitivity of PCR with the specificity of RFLP mapping to specifically identify P. acnes in surgical isolates. We anticipate that this assay will allow us to determine if a biopsy is P. acnes positive within 24-hours of sampling, allowing for more aggressive antibiotic therapy and monitoring to avoid implant failure and revision surgery. Additionally, this PCR-RFLP method may decrease the false positive rate of extended length cultures due to P. acnes contamination