Introduction. Accurate acetabular cup orientation could lead to successful surgical results in total hip arthroplasty (THA). We introduce a novel CT-based three-dimensional (3D) planning system, HipCOMPASS (Fig.1) and TARGET (Fig.2), which enable to design suitable alignment not only cup also surgical devices calculatingly, according to each pelvic inclination. Patients and Methods. We performed THA in 45 hips in 43 patients (female 37 and 6 men) between April 2014 and October 2015. Average age were 68 years old. THA operation was based on each parameter of the cup and device, providing a preoperative planning by ZedView system. HipCOMPASS and TARGET is linked with ZedView software, which is simultaneously calibrated adjustable parameters on this devices. Cup alignment was assessed by ZedView as well. Results. The differences of component alignment from the preoperative planning were shown in Tables. Conclusion. HipCOMPASS and TARGET might be more accurate than conventional method and more accessible system than navigation system in THA

Introduction. Accurate acetabular cup orientation could lead to successful surgical results in total hip arthroplasty (THA). We introduce a novel CT-based three-dimensional (3D) planning system, HipCOMPASS (Fg.1) and TARGET (Fig.2), which enable to design suitable alignment not only cup also surgical devices calculatingly, according to each pelvic inclination. Patients and methods. We performed THA in 13 patients (10 female and 3 men) between September 2014 and April 2014. Average age were 67 years old. THA operation was based on each parameter of the cup and device, providing a preoperative planning by ZedView system. HipCOMPASS and TARGET is linked with ZedView software, which is simultaneously calibrated adjustable parameters on this devices. Cup alignment was assessed by ZedView as well. Result. The differences of component alignment from the preoperative planning were shown in table. Conclusion. HipCOMPASS and TARGET might be more accurate than conventional method and more accessible system than navigation system in THA

In total hip arthroplasty (THA), acetabular cup orientation is critical for avoiding edge-loading and implant-implant impingement, which may lead to serious complications such as dislocation, mechanical loosening, accelerated wear, or implant breakage. Many studies recommended to place the acetabular cup radiographically at an inclination of <50° to avoid edge-loading. Simultaneously, larger prosthetic ROMs than the patients’ ROM during daily activities are needed to minimize impingement related complications. Several three-dimensional computer simulation studies have been done for optimal cup orientation to avoid prosthetic impingement within possible hip ROMs in the late 1990s. However, the reference angles in the directions of flexion, extension, external rotation and internal rotation at 90 ° flexion as possible hip ROMs have not been consistent in previous simulation studies. Thus, different reference angles of hip ROMs resulted in different optimal cup orientation. Therefore, to give accurate information about the reference hip ROM, we measured passive hip ROMs intraoperatively using a navigation system in 91 patients. Pelvic and femoral coordinate systems referred a functional pelvic plane in the supine position and a retrocondylar plane, respectively. The neutral position of the hip ROM was defined as the position in which corresponding axes of the pelvic and femoral coordinate systems were parallel. Maximum flexion, extension, external rotation and abduction were 120°, 36 °, 43 ° and 55 °, respectively. Moreover, we investigated the hip ROM during five traditional Japanese hip positions which required large hip flexion and internal rotation angles in five healthy female volunteers by a 3D image matching technique using an open-configuration MRI. Maximum flexion was 122 ° and maximum internal rotation was 40 ° at more than 90 ° of flexion position. Therefore, we recommended using 120 ° for flexion, 40 ° for extension, 40 ° for external rotation and 40 ° for internal rotation at 90 ° flexion as the reference ROM when calculating an optimum cup orientation. We calculated radiographic cup anteversion, when radiographic cup inclination was 40 °, without prosthesis impingement in the reference hip ROMs using computer aided design models of prosthesis, which included a cementless CentPillar stem with a head 32mm in diameter and cementless Trident cup with a flat liner. The results showed the optimal cup target zone existed when the stem anteversion was between 20 ° and 45 °. The size of the target zone was widest when the stem anteversion was 30 °, and then it was plus or minus 5 ° of inclination and anteversion from the center of the zone. To eliminate outliers of cup orientation form the target zone, a computer assisted system such as navigation is recommended

Introduction. Soft tissue balancing in total knee arthroplasty surgery may prove necessary to elevate patient satisfaction and functional outcome beyond the current fair average. A new generation of contact load sensors embedded in trial tibial liners provides quantification of loads, direction, and an indirect assessment of ligamentous tension. With this technology, quantified intra-operative balancing may potentially restore compartmental load distribution to a more physiological and functional degree. Objective. 1). To define a clinically useful target zone for balancing of the soft tissue envelope of knees at the time of surgery using numerical data from load sensors in tibial liner trial components. 2). To validate the boundaries of the target zone on a medial v. lateral contact load scatterplot with PROMs. Method. This study is a prospective IRB approved clinical study of 104 patients (112 knees) from a single surgeon. The intra-operative balancing aim was the restoration of a physiological compartmental load distribution, defined as less than 15 pounds of load differential between the medial and lateral compartments throughout flexion. This was performed using an algorithmic method of soft tissue releases combined with minor joint line obliquity adjustments within 3 degrees of neutral. Medial v. lateral contact load data was produced at 10, 45, 90° flexion as part of the balancing and final verification process. For all cases the pre and post-operative (4weeks, 3months, 6months) varus and valgus soft tissue envelope was measured with a calibrated and validated knee fixture. The KSS scores were obtained at each measurement interval. Results. The majority of knees were successfully balanced within a cluster zone as shown in Fig. 1. The concept of a safe target zone was developed to define a safe zone of balancing with higher predictive value for satisfaction and function. This was created using a best-fit rhomboid area, whose perimeter uses the fusion of a square area defined by min / max absolute loads and a triangular area defined by relative compartmental load ratios (Compartmental Load Ratio=Med Load/Total Load). The best-fit load boundaries to optimize patient satisfaction are 12.5 lbs.-38 lbs. (static load) and 44%–59% (relative load distribution) (Fig.2). Using these boundaries 83% of the cases in the safe zone area scored above 80% on the satisfaction score at 6 months compared to 36% for those outside the rhomboid area (Fig. 3). Conclusions. Balancing by load distribution uses a combination of distinct single surgical variable corrections of soft tissue releases and minor bone adjustments. Using a systematic balancing algorithm, the medial and lateral compartmental loads can predictably be balanced within a defined target zone, delineated by absolute load values and by relative compartmental load ratios. Based on this series the method is proving reproducible. The accuracy obtained by matching patient satisfaction values appears to validate the potential of a target zone as a safe and predictable clinical tool for balancing. For figures/tables, please contact authors directly.

INTRODUCTION. Soft tissue balancing in knee arthroplasty remains an art. To make it a science reliable quantification and reference values for soft tissue tension and contact loads are necessary. This study intends to prove the concept of a compartmental load safe target zone as a clinical tool for balancing total knee arthroplasties by studying the relationship between post- balancing compartmental load distribution and patient satisfaction at 6 months. MATERIALS AND METHODS. In this prospective non-randomised clinical series of 102 patients (110 knees), medial and lateral loads were recorded intra-operatively using a tibial liner load sensor system. All knees were balanced using specific algorithm sequences with a goal of equal distribution between compartments. A safe target zone area was defined on a scatterplot graph displaying lateral versus medial loads. Individual points on the graft were coded with their satisfaction score at 6 months. RESULTS. Eighty-two (82) cases satisfied the study criteria and were analysed. The boundaries of the safe zone were defined by combining absolute and relative load values. Fifty-seven (57) knees fitted in the defined zone and 25 lied outside. Excellent satisfaction scores were 4.2 times more likely to be in the safe zone. Poor scores were twice more likely to lie outside the zone. In the zone the median satisfaction score was 36/40, whereas outside the zone it fell to 31/40. DISCUSSION. Load balancing of knee arthroplasty is a useful clinical tool. Early studies by a developing group showed increased satisfaction rates. One problem remains the subjectivity of testing at the time of surgery. Other studies have also pointed to the difficulty in defining a target zone for balancing. Using specific ligamentous balance algorithms it is now possible to predictably achieve a balanced load differential within 15 lbs between compartments. In this paper, we have demonstrated in a prospective series that a target zone can be defined as an area rather than a single ideal value. Within this zone satisfaction scores reach 90–95%. Of all excellent results there are 4.2 more within the zone than outside. Balancing a knee arthroplasty to medial and lateral compartment load values defined by a safe target zone can therefore be predictive of patient satisfaction

Background

Although described as a commensal bacterium with low pathogenicity, Cutibacterium acnes involvement has been reported in many clinical entities: infections associated with devices, such as shoulder prosthetic joint infections, osteosynthesis, breast implants or cerebrospinal fluid shunts. Various studies show that C. acnes grows as a biofilm, contributing to its persistence by allowing its escape from the action of the immune system and antibiotics.

Purpose. The prevention of a subsequent, contralateral hip fracture is targeted as an avoidable event in the elderly. Fall prevention and bone strengthening measures have met with limited success and the urgency of their effect is undetermined. Our objective was to evaluate the time to second hip fracture (the time between a first and a subsequent, contralateral fracture) in elderly patients, using a population-based administrative health data set. Method. The 58,286 records of persons older than 60 yrs and hospitalized for a hip fracture between 1985 and 2005 were obtained from a Provincial administrative health database. We excluded non-traumatic cases and identified the care episodes related to a subsequent hip fracture for each patient using unique identifiers. We used a 5 year “wash-out period” to avoid counting a second fracture as a first one. We calculated the proportion of first and second fractures and sex distribution over time (fiscal years) and quantified the time between first and second fracture, while correlating it to age, sex and fracture type. Results. Overall, 3,866 patients sustained a second hip fracture between 1990 and 2005; 3,119 (81%) were women, in contrast to 73% for primary fractures (chi-square =137.8, df=1, p<0.001). In 33% cases, the type of a subsequent fracture (transcervical vs pertrochanteric) was different from the first. The median time from first fracture was 3 years, 90% occurred by 9yrs. The age at the first fracture most influenced the time to second fracture. The median time (90th percentile in parentheses) between fractures decreased as patients got older and was 5 (13), 4 (10), 3 (7), 2 (5) years for patients who were correspondingly 60–69, 70–79, 80–89 and 90+ years old at first fracture. Conclusion. Among survivors of an initial hip fracture, the occurrence of a second hip fracture appears to affect a greater proportion of women than primary fractures. Our results identify the time frame which preventative interventions should target when aiming at reducing second hip fractures, that target being increasingly small (from 5 to 2 years) as patients age. This information identifies a time frame researchers must target as they seek new fracture prevention methods. In the shorter term however, these data could influence health administrators and policy makers as they decide to support one hip fracture prevention method over another

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.

The lifetime prevalence of symptomatic osteoarthritis at the knee is 50% osteoarthritis of the ankle occurs in only 1% of the population. This variation in prevalence has been hypothesised to result from the differential responsiveness of the joint cartilages to catabolic stimuli. Human cartilage explants were taken from the talar domes (n=12) and the femoral condyles (n=7) following surgical amputation. Explants were cultured in the presence of either a combination of high concentration cytokines (TNFα, OSM, IL-1α) to resemble a post traumatic environment or low concentration cytokines to resemble a chronic osteoarthritic joint. Cartilage breakdown was measured by the percentage loss of Sulphated glycosaminoglycan (sGAG) from the explant to the media during culture. Expression levels of the pro-inflammatory molecules nitric oxide and prostaglandin E. 2. were also measured. Significantly more sGAG was lost from knee cartilage exposed to TNFα (22.2% vs 13.2%, P=0.01) and TNFα in combination with IL-1α (27.5% vs 16.0%, P=0.02) compared to the ankle; low cytokine concentrations did not affect sGAG release. Significantly more PGE. 2. was produced by knee cartilage compared to ankle cartilage however no significant difference in nitrite production was noted. Cartilage from the knee and ankle has a divergent response to stimulation by pro-inflammatory cytokines, with high concentrations of TNFα alone, or in combination with IL-1α amplifying cartilage degeneration. This differential response may account for the high prevalence of knee arthritis compared to ankle OA and provide a future pharmacological target to treat post traumatic arthritis of the knee

Periprosthetic joint infection (PJI) is a potentially devastating complication of joint replacement surgery. Osteocytes comprise 90–95% of all cells in hard bone tissue, are long-lived and are becoming increasingly recognised as a critical cell type in the regulation of bone and systemic physiology. The purpose of this study was to examine role of these cells in PJI pathophysiology and aetiology, with the rationale that their involvement could contribute to the difficulty in detecting and clearing PJI. This study examined the ability of human osteocytes to become infected by Staphylococcus aureus and the responses of both the host cell and pathogen in this scenario.

Several S. aureus (MRSA) strains were tested for their ability to infect human primary osteocyte-like cells in vitro and human bone samples ex vivo. Bone biopsies were retrieved from patients undergoing revision total hip arthroplasty for either aseptic loosening associated with osteolysis, or for PJI. Retrieved bacterial colony number from cell lysates and colony morphology were determined. Gene expression was measured by microarray/bioinformatics analysis and/or real-time RT-PCR.

Exposure to planktonic S. aureus (approx. 100 CFU/cell) resulted in intracellular infection of human osteocyte-like cells. We found no evidence of increased rates of osteocyte cell death in bacteria exposed cultures. Microarray analysis of osteocyte gene expression 24h following exposure revealed more than 1,500 differentially expressed genes (fold-change more than 2, false discovery rate p < 0.01). The gene expression patterns were consistent with a strong innate immune response and altered functionality of the osteocytes. Consistent patterns of host gene expression were observed between experimentally infected osteocyte-like cultures and human bone, and in PJI patient bone samples. Internalised bacteria switched to the quasi-dormant small colony variant (SCV) form over a period of 5d, and the ensuing infection appeared to reach a stable state. S. aureus infection of viable osteocytes was also identified in bone taken from PJI patients.

We have demonstrated [1] that human osteocytes can become infected by S. aureus and respond robustly by producing immune mediators. The bony location of the infected osteocyte may render them refractory to clearance by immune cells, and osteocytes may therefore be an immune-privileged cell type. The phenotypic switch of S. aureus to SCV, a form less sensitive to most antibiotics and one associated with intracellular survival, suggests that infection of osteocytes may contribute to a chronic disease state. The osteocyte may therefore serve as a reservoir of bacteria for reinfection, perhaps explaining the high prevalence of infections that only become apparent after long periods of time or recur following surgical/medical treatment. Our findings also provide a biological rationale for the recognised need for aggressive bone debridement in the surgical management of PJI.

Introduction

Theatre cancellation is unpleasant experience to patient and it is expensive to service provider. There are various causes for cancellation which are avoidable and unavoidable as well. Nationwide, there has been several measures put in place to reduce avoidable theatre cancellations.

We describe retrospective review of 158 cancellations and root cause analysis & solutions in relation to the National standard.

The poor prognosis of patients with soft-tissue sarcoma as not changed in the past several decades, highlighting the necessity for new therapeutic approaches. T-cell based immunotherapies are a promising alternative to traditional cancer treatments due to their ability to target only malignant cells, leaving benign cells unharmed. The development of successful immunotherapy requires the identification and characterization of targetable immunogenic tumor antigens. Cancer-testis antigens (CTA) are a group of highly immunogenic tumor-associated proteins that have emerged as potential targets for CD8+ T-cell recognition. In addition to identifying a targetable antigen, it is crucial to understand the tumor immune microenvironment. The level of immune infiltration and mechanisms of immune suppression within the tumor play important roles in the outcome of immunotherapy. The goal of this study is to identify targetable immunogenic antigens for T-cell based immunotherapy and to characterize the tumor immune microenvironment in human dedifferentiated liposarcoma (DDLS) by Nanostring and IHC. To assess the complexity of the human DDLS tumor immune microenvironment and to identify target antigens we used the nCounter NanoString platform to generate a gene expression profile for hundreds of genes from RNA obtained from 29 DDLS and 10 control fat FFPE samples. To classify inflammatory status of DDLS tumors, we performed hierarchical clustering based on expression levels of selected tumor inflammatory signature genes (CCL5, CD27, CD274, CD276, CD8A, CMKLR1, CXCL9, CXCR6, HLA-DQA1, HLA-E, IDO1, LAG3, PDCDILG2, PSMB10, STAT1, TIGIT). To confirm protein expression and distribution of identified antigens, we performed immunohistochemistry on human tissue micro-arrays encompassing DDLPS tumor tissues and matched normal control tissue from 63 patients. IHC for the cancer testis antigens PBK, SPA17, MAGE-A3, NY-ESO-1 and SSX2 was performed, and the staining results were scored by two authors based on maximal staining intensity on a scale of zero to three (absent=0, weak=1, moderate=2, or strong=3) and the percentage of tumor cells that stained. Hierarchical clustering of DDLS tumors based on expression of tumor inflammation signature genes revealed two distinct groups, consisting of 15 inflamed tumor and 14 non-inflamed tumors, demonstrating tumor heterogeneity within the DDLS sarcoma subtype. All antigens were found to be expressed in DDLS at an mRNA level. SPA17 was expressed at the highest levels in DDLS, however, this antigen was expressed at high levels in normal fat. Notably, antigens PBK and TTK had the largest fold change increase in expression in DDLS compared to normal fat controls. Immunohistochemical analysis of selected antigens revealed that PBK was found to be expressed in 96% (52/54) of DDLS samples at high levels. Other antigens were absent or expressed at low levels in DDLS; MAGEA3 in 15.87% (10/63) NY-ESO-1 in 6.35% (4/62) and SSX2 in 12.7% (8/63) and SPA17 in 5.5% (3/54). This data shows considerable inter-tumoral heterogeneity of inflammation, which should be taken into consideration when designing an immunotherapy for DDLS. To date, these results show promising expression of PBK antigen in DDLS, which may be used as a target in the future development of an immunotherapy for sarcoma

Aim. Prompt and sufficient broad spectrum empirical antibiotic treatment is key to prevent infection following open tibial fractures. Succeeding co-administration, we dynamically assessed the time for which vancomycin and meropenem concentrations were above relevant epidemiological cut-off minimal inhibitory concentrations (T>MIC) in tibial compartments for the bacteria most frequently encountered in open fractures. Low and high MIC-targets were applied: 1 and 4 µg/mL for vancomycin and 0.125 and 2 µg/mL for meropenem. Materials and methods. 8 pigs received a single dose of 1000 mg vancomycin and 1000 mg meropenem simultaneously over 100 min and 10 min, respectively. Microdialysis catheters were placed for sampling over 8 h in tibial cancellous bone, cortical bone, and adjacent subcutaneous adipose tissue. Venous blood samples were collected as references. Results. Across the targeted epidemiological cut-off values, vancomycin displayed longer T>MIC in all the investigated compartments in comparison to meropenem. For both drugs, cortical bone exhibited the shortest T>MIC. For the low MIC targets and across compartments, T>MIC ranged between 208–499 min (46–100%) for vancomycin and 189–406 min (42–90%) for meropenem. For the high MIC targets, T>MIC ranged between 30–446 min (7–99%) for vancomycin and 45–181 min (10–40%) for meropenem. Conclusion. The differences in the T>MIC between the low and high targets illustrates how the interpretation of these results is highly susceptible to the defined MIC target. To encompass any trauma, contaminating or individual tissue differences, a more aggressive dosing approach may be considered to achieve longer T>MIC in all the exposed tissues and thereby lowering the risk of acquiring an infection after open tibial fractures

Arthroscopic electrosurgical tools for ablative, desiccating or coagulative effect are delivered as monopolar or bipolar probes. Monopolar electrosurgery delivers various profiles of heat energy directly to the tissue within a non-conductive irrigant (such as water or glycine) whereas bipolar electrosurgery creates an energy source by producing an electrical arc between the bipolar electrodes on the instrument head within an electro-conductive irrigation solution (saline) - and the heat generated is then transferred to the target tissues. This study investigated the heat generation within the simulated in-vitro test model to review the level of local heat production and potential local tissue heat. In a simulated In-vitro testing environment the local heat generation using bipolar or monopolar electrosurgical probes at standard power setting in either saline or water was tested, both touching and not touching a simulated tissue target, and for variable on-times. Monopolar generated relatively little heat when used in water and not touching the tissue. By contrast the bipolar wand generated potentially damaging local tissue temperature rises when used in saline and not touching the tissue. Both probes generated high local tissue heat when touching the tissue in their recommended irrigation solution. Monopolar electrosurgery delivered high localized temperature to the simulated tissue surface, but produced relatively little heat when not touching the tissue in a water solution. Bipolar however created high local temperature within the fluid adjacent to the probe irrespective if it was touching the tissue or not. Activation of the bipolar probe away from the tissue in saline irrigation may create a potential harmful temperature within the fluid medium without delivering therapeutic thermal effect to the target tissues. Monopolar electrosurgery appears to deliver a more controlled thermal effect, and only when in contact with the target tissues – potentially creating a reduced collateral thermal footprint

Background and aim. Implant-associated osteomyelitis is one of the most feared complications following orthopedic surgery. Although the risk is low it is crucial to achieve adequate antibiotic concentrations proximate to the implant for a sufficient amount of time to protect the implant surface and ensure tissue integration. The aim of this study was to assess steady-state piperacillin concentrations in the proximity of an orthopedic implant inserted in cancellous bone. Method. Six female pigs received an intravenous bolus infusion of 4 g/0.5 g piperacillin/tazobactam over 30 min every 6 h. Steady state was assumed achieved in the third dosing interval (12–18 h). Microdialysis catheters were placed in a cannulated screw in the proximal tibial cancellous bone, in cancellous bone next to the screw, and in cancellous bone on the contralateral tibia. Dialysates were collected from time 12 to 18 h and plasma samples were collected as reference. Results. Time above the minimal inhibitory concentration (fT>MIC) was evaluated for MIC of 8 (low target) and 16 μg/mL (high target). For the low piperacillin target (8 μg/mL), comparable mean fT>MIC across all the investigated compartments (mean range: 54–74%) was found. For the high target (16 μg/mL), fT>MIC was shorter inside the cannulated screw (mean: 16%) than in the cancellous bone next to the screw and plasma (mean range: 49–54%), and similar between the two cancellous bone compartments. Conclusions. To reach more aggressive piperacillin fT>MIC targets in relation to the implant, alternative dosing regimens such as continuous infusion may be considered

Aim. The β-lactam penicillin is often used in the treatment of soft tissue infections and osteomyelitis caused by penicillin susceptible Staphylococcus aureus. Oral antibiotic treatment has been shown to be non-inferior to intravenous (IV) therapy when used during the first 6 weeks in complex orthopedic infections (OVIVA trial). However, the use of oral β-lactams in osteomyelitis treatment remains a topic of debate due to low and variable bioavailability. The aim was to assess the time for which the unbound penicillin concentration exceeded targeted minimum inhibitory concentrations (fT>MIC) in cancellous bone and subcutaneous tissue after IV (penicillin G) and oral (penicillin V) treatment in a porcine microdialysis model. Method. 12 female pigs (75kg) were assigned to standard clinical regimens of either three doses of IV penicillin G (1.2g) or oral penicillin V (0.8g) every 6h over 18h. Microdialysis catheters were placed for sampling in tibial cancellous bone and adjacent subcutaneous tissue. Data was collected in the first dosing interval (0–6h; prophylactic situation) and the third dosing interval (12–18h; assumed steady state). Plasma samples were collected for reference. MIC targets of 0.125μg/mL (Staph. aureus breakpoint), 0.25μg/mL (Strep. Group A, B, C and G breakpoint) and 0.5μg/mL (4xMIC) were applied. Results. For all investigated MIC targets, IV penicillin G resulted in a longer mean fT>MIC in cancellous bone during the first dosing interval, and in both cancellous bone and subcutaneous tissue during the third dosing interval compared to oral penicillin V. Across compartments, mean fT>MIC for IV penicillin G (MIC: 0.125, 0.25 and 0.5μg/mL) were ≥97%, ≥84% and ≥75% during the first dosing interval, and 100%, ≥95% and ≥88%, during the third dosing interval. The mean fT>MIC for oral penicillin V were ≥40%, ≥24% and ≥7% during the first dosing interval, and ≥42%, ≥36% and ≥18% during the third dosing interval. Conclusions. The findings suggest that standard clinical dosing of IV penicillin G provides superior fT>MIC in cancellous bone and subcutaneous tissue compared to oral penicillin V, particularly in the third dosing interval. This emphasizes the importance of appropriate route of administration when applying penicillin treatment. Acknowledgements. Funding was received from The Kirsten and Freddy Johansen Foundation, The Novo Nordisk Foundation, The Beckett Foundation, The Hede Nielsen Family Foundation, King Christian the 10. th. Foundation, The A.P. Møller Foundation, The Dagmar Marshalls Foundation, and The Carl and Ellen Hertz Foundation

Aim. Bone and joint infections (BJIs) are serious infections requiring early optimized antimicrobial therapy. BJIs can be polymicrobial or caused by fastidious bacteria, and the patient may have received antibiotics prior to sampling, which may decrease the sensitivity of culture-based diagnosis. Furthermore, culture-based diagnosis can take up to 14 days. Molecular approaches can be useful to overcome these concerns. The BioFire® system performs syndromic multiplex PCR in 1 hour, with only a few minutes of sample preparation. The BioFire® Joint Infection (JI) panel (BF-JI), recently FDA-cleared, detects both Gram-positive (n=15) and Gram-negative bacteria (n=14), Candida, and eight antibiotic resistance genes directly from synovial fluids. The aim of this study was to evaluate its performance in acute JIs in real-life conditions. Method. BF-JI was performed on synovial fluid from patients with clinical suspicion of acute JI, either septic arthritis or periprosthetic JI, in 6 French centers. The results of BF-JI were compared with the results of culture of synovial fluid and other concomitantly collected osteoarticular samples obtained in routine testing in the clinical microbiology laboratory. Results. From July 2021 to May 2022, 319 patients (including 10 children < 5y and 136 periprosthetic infections) had been included in the study. The BF-JI test was invalid for one patient (not retested). Among the 318 remaining patients, overall concordance with comparative microbiology methods was 88% (280/318): 131 samples were negative with both BF-JI and culture, and 149 samples were positive with the same microorganisms using complementary techniques. In 33 cases (10.4%), BF-JI was negative while culture was positive: 18 microorganisms were not targeted by BF-JI (including Staphylococcus epidermidis, n=10, and Cutibacterium acnes, n=2); 15 microorganisms targeted by BF-JI were obtained in culture but not by the molecular test (false-negative 4.7%). In 20 cases, BF-JI was positive while culture was not: 12 patients had received antibiotics before sampling, and 7 cases involved fragile and fastidious bacteria (Kingella kingae, n=5; Neisseria gonorrhoeae, n=2). In 6 cases, both BF-JI and culture were positive, but no yielding the same bacteria (polymicrobial specimens). Conclusions. In acute JIs, the BF-JI panel shows a good concordance with culture for the microorganisms targeted by the panel. Therefore, this molecular tool may have a place in microbiological diagnosis of acute JIs in order to confirm JI faster than culture. Moreover, it allows easy detection of difficult-to-culture bacteria. Acknowledgements. study was supported by bioMérieux, who provided all reagents

Total Knee Arthroplasty (TKA) is a successful treatment for end stage osteoarthritis of the knee joint. However, post-operative pain can lead to patient dissatisfaction and poorer outcomes. Cooled radiofrequency nerve ablation (CRNA) has reportedly been effective at treating pain osteoarthritic knee pain by targeting the periarticular nerves of the knee. We undertook a prospective, controlled pilot study to determine if CRNA provides effective post-operative analgesia when utilised intra-operatively during total knee arthroplasty. Participants were recruited from January 2019 to February 2020. Those meeting inclusion criteria underwent TKA with intraoperative CRNA to 6 target sites prior to the cementing of implants. The primary outcomes were pain scores and opiate usage in the first 4 days post-operatively, then weekly up to 6 weeks. A total of 62 patients were screened and allocated sequentially; 18 were recruited to the control group and 12 recruited to the study group. The two groups did not have any significant difference in demographics. There were no clinically significant differences between the two groups in terms of pain scores nor opiate usage. There were complications as a result of the intervention. This study demonstrated no benefit of using intraoperative CRNA for improving post-operative pain scores or reducing opiate use after TKA

Aim. Implant infections caused by Staphylococcus aureus are difficult to treat due to biofilm formation, which complicates surgical and antibiotic treatment. Herewith we introduce an alternative approach using monoclonal antibodies (mAbs) targeting S. aureus and provide the biodistribution and specificity in a mouse implant infection model. Methods. 4497-IgG1targeting S. aureus Wall Teichoic Acid was labeled to Indium-111 using “CHXA” as a chelator. SPECT-CT scans were performed at 24, 72 and 120 hours after administration in Balb/cAnNCrl mice with a subcutaneous implant pre-colonized with biofilm of S. aureus. Biodistribution over the various organs of this labelled antibody was visualized and quantified using SPECT-CT imaging and compared to uptake at the target tissue with implant infection. Results. Uptake of the . 111. In-4497 mAbs (half-life 59 hours) at the infected implant gradually increased from 8.34%ID/g at 24 hours to 9.22%ID/g at 120 hours. Uptake at the heart/blood pool decreased over time from 11.60 to 7.58%ID/g whereas the uptake in other organs decreased from 7.26 to less than 4.66%ID/g at 120 hours. Conclusion. 111. In-4497 mAbs was found to specifically detect S. aureus and its biofilm with excellent and prolonged accumulation at the colonized implant site. Therefore, it holds great promise as a drug delivery system for diagnostic and bactericidal treatment of biofilm. However, high activity in the blood pool must be considered as it could pose a risk to healthy tissue

Introduction. Individuals with significant hip and knee trauma receive total knee (TKA) and total hip arthroplasty (THA) as definitive end-stage procedures. In Aotearoa, injury-related costs, including workers compensation, may be funded by ACC. With a steady increase of arthroplasty procedures in Aotearoa, we aim to understand the magnitude and characteristics of such procedures to inform future healthcare strategies. Method. This is a longitudinal collaborative study from 1st January 2000 to 31st December 2020, using ACC and New Zealand Joint Registry databases. Total cost was subcategorised into social and medical cost for analysis. Results. ACC funded 10179 TKA and 5611 THA, amounting to 918 million New Zealand Dollars. Most clients were between 55 and 65 years of age at time of surgery, with greater representation by Male sex and European prioritised ethnicity. Māori and Pacific peoples represent less than 10% of the study population. ACC identified requiring more than 182 days of workers’ compensation as a significant marker for needing additional supports. Risk of this was 21% for TKA and 11% for THA, with risk factors being younger age (RR 0.96), Male sex (TKA RR 1.12, THA RR 1.23), and heavy work-types (TKA RR 1.50, THA RR 1.57). Discussion. Supporting individuals with post-traumatic lower limb arthroplasty is costly. Workers’ compensation contributes to a significant proportion of social expenditure. Risk factors for increased cost utilisation can be used to highlight vulnerable clients and target interventions. Conclusions. This is one of few nationwide studies investigating the healthcare cost of post-traumatic lower limb arthroplasty. We need to focus on injury prevention, targeted treatment, and rehabilitation protocols to improve recovery and reduce time off work. These findings would be of interest to multiple stakeholders