Abstract. Objectives. Our study evaluates financial impact to the Best Practice Tariff (BPT) of hip fracture patients on Novel Oral Anti-Coagulant (NOAC) medication. Since their approval by NICE for the prevention of stroke and systemic embolism in non-valvular atrial fibrillation, the incidence of hip fracture patients admitted to hospitals on NOAC medication (e.g. rivaroxiban, apixaban) has been increasing. BPT for hip fractures has two components: a base tariff and a conditional top-up tariff of £1,335 per patient (applied to patients of 60 years of age). For the top-up tariff, six criteria must be met, of which time-to-surgery within 36 hours is one. Our department currently recommends withholding NOAC medication and delaying surgery for at least 48 hours as per our Trust's haematology guidelines to reduce intra-operative bleeding risk. Therefore, the conditional top-up tariff cannot be claimed for these patients. Method. A retrospective review of our Trust hip fracture patients over 60 years of age admitted during 2019 on NOAC medication using National Hip Fracture Database (NHFD). Results. 545 hip fracture patients had operative treatment at our Trust during the one-year period of 2019. 31 of these patients were admitted on NOAC medication, and therefore had to stop the NOAC and wait for at least 48 hours before having surgery. This translates to a potential hip fracture BPT loss of £41,385 in 2019, as the conditional top-up tariff could not be claimed. Conclusion. This study illustrates the large financial impact to BPT that hip fracture patients admitted on NOAC medications has at our Trust. It raises the argument as to whether the BPT should allow for an increased length of time until surgery for such patients, to allow safe surgical treatment with reduced bleeding risk. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Tip-apex distance (TAD) has long been discussed as a metric for determining risk of failure in fixation of peritrochanteric hip fractures. This study seeks to investigate risk factors including TAD for hospital readmission one year after hip fixation surgery. A retrospective review of proximal hip fractures treated with single screw intramedullary devices between 2016 and 2020 was performed at a 327 bed regional medical center. Patients included had a postoperative follow-up of at least twelve months or surgery-related complications developing within that time. 44 of the 67 patients in this study met the inclusion criteria with adequate follow-up post-surgery. The average TAD in our study population was 19.57mm and the average one year readmission rate was 15.9%. 3 out of 6 patients (50%) with a TAD > 25mm were readmitted within one year due to surgery-related complications. In contrast, 3 out of 38 patients (7.9%) with a TAD < 25mm were readmitted within one year due to surgery-related complications (p=0.0254). Individual TAD measurements, averaging 22.05mm in patients readmitted within one year of surgery and 19.18mm in patients not readmitted within one year of surgery were not significantly different between the two groups (p=0.2113). Our data indicate a significant improvement in hospital readmission rates up to one year after hip fixation surgery in patients with a TAD < 25mm with a decrease in readmissions of over 40% (50% vs 7.9%). This result builds upon past investigations by extending the follow-up time to one year after surgery and utilizing hospital readmissions as a metric for surgical success. With the well-documented physical and financial costs of hospital readmission after hip surgery, our study highlights a reduction of TAD < 25mm as an effective method of improving patient outcomes and reducing financial costs to patients and medical institutions

Osteomyelitis is an inflammatory condition accompanied by the destruction of bone and caused by an infecting microorganism. Open contaminated fractures can lead to the development of osteomyelitis of the fractured bone in 3-25% of cases, depending on fracture type, degree of soft-tissue injury, degree of microbial contamination, and whether systemic and/or local antimicrobial therapies have been administered. Untreated, infection will ultimately lead to non-union, chronic osteomyelitis, or amputation. We report a case series of 10 patients that presented with post-operative infected non-union of the distal femur with or without prior surgery. The cases were performed at Padmashree Dr. D. Y. Patil Hospital, Nerul, Navi Mumbai, India. All the patients’ consents were taken for the study which was carried out in accordance with the Helsinki Declaration. The methodology involved patients undergoing a two-stage procedure in case of no prior implant or a three-stage procedure in case of a previous implant. Firstly, debridement and implant removal were done. The second was a definitive procedure in form of knee arthrodesis with ring fixator and finally followed by limb lengthening surgery. Arthrodesis was planned in view of infection, non-union, severe arthritic, subluxated knee, stiff knee, non-salvage knee joint, and financial constraints. After all the patients demonstrated wound healing in 3 months along with good radiographic osteogenesis at the knee arthrodesis site, limb lengthening surgeries by tibial osteotomy were done to overcome the limb length discrepancy. Distraction was started and followed up for 5 months. All 10 patients showed results with sound knee arthrodesis and good osteogenesis at the osteotomy site followed by achieving the limb length just 1-inch short from the normal side to achieve ground clearance while walking. Our case series is unique and distinctive as it shows that when patients with infected nonunion of distal femur come with the stiff and non-salvage knee with severe arthritic changes and financial constraints, we should consider knee arthrodesis with Ilizarov ring fixator followed by limb lengthening surgery

Abstract. There are numerous advantages of discharging patients early after any surgery. Day case arthroplasty in hip and knee is already brought into practice at many centres. We present our journey towards discharging elective shoulder arthroplasty patient on same after their surgery. An initial retrospective study of patients who underwent elective shoulder replacement between 2017 and 2020 were studied. It was identified that a selected group of patients could be discharged on the same of their surgery. The criteria to select a patient for this service was laid down that include ASA 1 or 2, good family support on discharge, personal wishes of patients and early identification of potential patients in the clinic and planning for day case shoulder arthroplasty56 consecutive patients underwent elective arthroplasty of shoulder. Among them 22 patients were discharges on the next day of surgery. The potential patients those could discharged on same were identified to be 11 out of 22 were under ASA 2 and had good family support at home on discharge. Average length of stay after surgery was 2.17 days. We have prospectively discharged 2 patients following the new criteria. This study demonstrates how outpatient elective shoulder could be implemented at other centres. Patient participation and selection with proper planning is key for success here. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Device-associated bacterial infections are a major and costly clinical challenge. This project aimed to develop a smart new biomaterial for implants that helps to protect against infection and inflammation, promote bone growth, and is biodegradable. Gallium (Ga) doped strontium-phosphate was coated on pure Magnesium (Mg) through a chemical conversion process. Mg was distributed in a graduated manner throughout the strontium-phosphate coating GaSrPO4, with a compact structure and a Ga-rich surface. We tested this sample for its biocompatibility, effects on bone remodeling and antibacterial activities including Staphylococcus aureus, S. epidermidis and E. coli - key strains causing infection and early failure of the surgical implantations in orthopaedics and trauma. Ga was distributed in a gradient way throughout the entire strontium-phosphate coating with a compact structure and a gallium-rich surface. The GaSrPO4 coating protected the underlying Mg from substantial degradation in minimal essential media at physiological conditions over 9 days. The liberated Ga ions from the coatings upon Mg specimens inhibited the growth of bacterial tested. The Ga dopants showed minimal interferences with the SrPO4 based coating, which boosted osteoblasts and undermined osteoclasts in in vitro co-cultures model. The results evidenced this new material may be further translated to preclinical trial in large animal model and towards clinical trial. Acknowledgements: Authors are grateful to the financial support from the Australian Research Council through the Linkage Scheme (ARC LP150100343). The authors acknowledge the facilities, and the scientific and technical assistance of the RMIT University and John Curtin School of Medical Research, Australian National University

Abstract. BACKGROUND. Hemi-arthroplasty (HA) as a treatment for fractured neck of femur has slightly increased since 2019 and remarkably after the COVID pandemic. The main drawback of the treatment is ongoing cartilage deterioration that may require revision to THR. OBJECTIVE. This study assessed cartilage surface damage in hip HA by reproducing anatomical motion and loading conditions in a hip simulator. METHODS. Experimental design. HA tests were conducted using porcine acetabula and CoCr femoral heads. Five groups (n=4) were included: a control group comprising natural tissue and four HA groups where the acetabula were paired with metal heads to allow radial clearance (RC) classed as small (RC<0.6mm), large (2mm<RC<4mm), extra-large (4mm<RC), and oversized (RC<−0.6mm). Tests were carried out in an anatomical hip simulator that reproduced a simplified twin peak gait cycle, adapted for porcine hip joints, from the ISO 14242 standard for wear of THR prostheses (peak load of 900N). The test length was 6 hours, with photogrammetry taken at 1-hour intervals. Ringers solution was used as a lubricant. RESULTS. No changes were observed in the control group. However, cartilage surface changes were observed in all hemi-arthroplasty groups. Discolouration on the cartilage surface was noticeable at the posterior-superior part of the acetabulum after 1-hour (extra-large and oversized groups). Damage severity and location were characteristic of each clearance group. Of all the groups, the oversized group showed more significant damage. No labrum separation was seen after the simulation. CONCLUSIONS. These results are relevant to understand the effect of femoral head clearance on cartilage damage risk after HA. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Ankle fractures are among the most common types of fractures. If surgery is not performed within 12 to 24 hours, ankle swelling is likely to develop and delay the operative fixation. This leads to patients staying longer in the ward waiting and increased hospital occupancy. This prolonged stay has significant financial implication as well as it is frustrating for both patients and health care professionals. The aim was to formulate a pathway for the ankle fracture patients coming to the emergency department, outpatients and planned for operative intervention. To identify whether pre-operative hospital admissions of stable ankle fracture patients are reduced with the implementation of the pathway. We formulated an ankle fracture fixation pathway, which was approved for use in December 2020. A retrospective analysis of 6 months hospital admissions of ankle fracture patients in the period between January to June 2020. The duration from admission to the actual surgery was collected to review if some admissions could have been avoided and patients brought directly on the surgery day. A total of 23 patients were included. Mean age was 60.5 years and SD was 17years. 94% of patients were females. 10 patients were appropriately discharged.7 Patients were appropriately admitted. 6 Patients were unnecessarily admitted. These 6 patients were admitted on presentation to ED. Retrospective analysis of this audit showed that this cohort of patients met the safe discharge criteria and could have been discharged. Duration of unnecessary stay ranged from 1 to 11 days (21 days in total). Total saving could have been £6300. Standards were met in 74% of cases. Preoperative hospital admission could be reduced with the proposed pathway. It is a valuable tool to be used and should be implemented to reduce unnecessary hospital admissions

While high-performance ceramics like alumina and zirconia exhibit excellent wear resistance, they provide poor osseointegration capacity. As osseointegration is crucial for non-cemented joint prostheses, new techniques have been successfully developed for biofunctionalizing high-performance ceramic surfaces. Stable cell adhesion can be achieved by covalently bound specific peptides. In this study we investigate the effect of sterilization processes on organo-chemically functionalized surfaces. To enhance the performance of alumina-toughened zirconia ceramics (ATZ), a 3-aminopropyldiisopropylethoxysilane (APDS) monolayer was applied and coupled with cyclo-RGD peptides (cRGD) by using bifunctional crosslinker bis(sulfosuccinimidyl)suberat (BS³). The samples were sterilized using e-beam or gamma-sterilization at 25 kGy, either before or after biofunctionalization with cRGD. Functionalization stability was investigated by contact angle measurements. The functionality of cRGD after sterilization was demonstrated using proliferation tests and cytotoxicity assays. Immunofluorescence staining (pFAK, Actin, DAPI) was conducted to evaluate the adhesion potential between the samples and human mesenchymal stem cells (hMSCs). Functionalized samples before and after sterilization showed no significant difference regarding their contact angles. A proliferation test demonstrated that the cells on functionalized samples proliferate significantly more than on untreated samples before and after sterilization. hMSCs showed a significant higher proliferation on gamma sterilized samples compared to all other groups after 14 days. It was confirmed that the samples did not exhibit cytotoxic behavior before or after sterilization. Fluorescence microscopy demonstrated that both, cells on sterilized and on non-sterilized samples, expressed high levels of pFAK-Y397. The investigated functionalization enables improved adhesion and proliferation of hMSCs and is stable against the investigated sterilization processes. This is of importance as the option of having a sterile product enables the start of the translation of this biofunctional coating towards preclinical and subsequently first-in-man applications. Acknowledgments: We acknowledge the financial support of the Federal Ministry of Education and Research, BMBF (13GW0452A-C)

Intervertebral disc (IVD) degeneration is the most frequent cause of Low Back Pain (LBP) affecting nearly 80% of the population [1]. Current treatments fail to restore a functional IVD or to provide a long-term solution, so, there is an urgent need for novel therapeutic strategies. We have defined the IVD extracellular matrix (ECM) profile, showing that the pro-regenerative molecules Collagen type XII and XIV, are uniquely expressed during fetal stages [2]. Now we propose the first fetal injectable biomaterial to regenerate the IVD. Fetal decellularized IVD scaffolds were recellularized with adult IVD cells and further implanted in vivo to evaluate their anti-angiogenic potential. Young decellularized IVD scaffolds were used as controls. Finally, a large scale protocol to produce a stable, biocompatible and easily injectable fetal IVD-based hydrogel was developed. Fetal scaffolds were more effective at promoting Aggrecan and Collagen type II expression by IVD cells. In a Chorioallantoid membrane assay, only fetal matrices showed an anti-angiogenic potential. The same was observed in vivo when the angiogenesis was induced by human NP cells. In this context, human NP cells were more effective in GAG synthesis within a fetal microenvironment. Vaccum-assisted perfusion decellularized IVDs were obtained, with high DNA removal and sGAG retention. Hydrogel pre-solution passed through 21-30G needles. IVD cells seeded on the hydrogels initially decreased metabolic activity, but increased up to 70% at day 7, while LDH assay revealed cytotoxicity always below 30%. This study will open new avenues for the establishment of a disruptive treatment for IVD degeneration with a positive impact on the angiogenesis associated with LBP, and on the improvement of patients’ quality of life. Acknowledgements: Financial support was obtained from EUROSPINE, ON Foundation and FCT (Fundação para a Ciência e a Tecnologia)

Mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) have great promise in the field of orthopaedic nanomedicine due to their regenerative, as well as immunomodulatory and anti-inflammatory properties. Researchers are interested in harnessing these biologically sourced nanovesicles as powerful therapeutic tools with intrinsic bioactivity to help treat various orthopaedic diseases and defects. Recently, a new class of EV mimetics has emerged known as nanoghosts (NGs). These vesicles are derived from the plasma membrane of ghost cells, thus inheriting the surface functionalities and characteristics of the parent cell while at the same time allowing for a more standardized and reproducible production and significantly greater yield when compared to EVs. This study aims to investigate and compare the osteoinductive potential of MSC-EVs and MSC-NGs in vitro as novel tools in the field of bone tissue engineering and nanomedicine. To carry out this investigation, MSC-EVs were isolated from serum-free MSC conditioned media through differential ultracentrifugation. The remaining cells were treated with hypotonic buffer to produce MSC-ghosts that were then homogenized and serially extruded through 400 and 200 nm polycarbonate membranes to form the MSC-NGs. The concentration, size distribution, zeta potential, and protein content of the isolated nanoparticles were assessed. Afterwards, MSCs were treated with either MSC-EVs or MSC-NGs under osteogenic conditions, and their differentiation was assessed through secreted ALP assay, qPCR, and Alizarin Red mineralization staining. Isolation of MSC-EVs and MSC-NGs was successful, with relatively similar mean diameter size and colloidal stability. No effect on MSC viability and metabolic activity was observed with either treatment. Both MSC-EV and MSC-NG groups had enhanced osteogenic outcomes compared to the control; however, a trend was observed that suggests MSC-NGs as better osteoinductive mediators compared to MSC-EVs. Acknowledgements: The authors would like to acknowledge Canada Research Chair – Tier 1 in Regenerative Medicine and Nanomedicine, CHRP, and McGill's Faculty of Dental Medicine and Oral Health Sciences for their financial support

Orthopaedic soft tissues, such as tendons, ligaments, and articular cartilage, rely on their unique collagen fiber architectures for proper functionality. When these structures are disrupted in disease or fail to regenerate in engineered tissues, the tissues transform into dysfunctional fibrous tissues. Unfortunately, collagen synthesis in regenerating tissues is often slow, and in some cases, collagen fibers do not regenerate naturally after injury, limiting repair options. One of the research focuses of my team is to develop functional fiber replacements that can promote in vivo repair of musculoskeletal tissues throughout the body. In this presentation, I will discuss our recent advancements in electrowriting 3D printing of natural polymers for creating functional fiber replacements. This manufacturing process utilizes electrical signals to control the flow of polymeric materials through an extrusion nozzle, enabling precise deposition of polymeric fibers with sizes that cannot be achieved using conventional extrusion printing methods. Furthermore, it allows for the formation of fiber organizations that surpass the capabilities of conventional electrospinning processes. During the presentation, I will showcase examples of electrowritten microfiber scaffolds using various naturally-derived polymers, such as gelatin (a denatured form of collagen) and silk fibroin. I will discuss the functional properties of silk-based scaffolds and highlight how they exhibit restored β-sheet and α-helix structures [1]. This restoration results in an elastic response of up to 20% deformation and the ability to withstand cyclic loading without plastic deformation. Additionally, I will present our latest results on the compatibility of this technique with patterning cell-laden fiber structures [2]. This novel biofabrication process allows for the printing of biomimetic microscale architectures with high cell viability, and offers a promising approach to understanding how shear and elongation forces influence cell development of hierarchical (collagen) fibers. Acknowledgements: The author would like to thank the Reprint project (OCENW.XS5.161) and the program “Materials Driven Regeneration” (024.003.013) by the Netherlands Organization for Scientific Research for the financial support

Introduction. Knee arthroplasty (KA), encompassing Total Knee Replacement (TKR) and Unicompartmental Knee Replacement (UKR), is one of the most common orthopedic procedures, aimed at alleviating severe knee arthritis. Postoperative KA management, especially radiographic imaging, remains a substantial financial burden and lacks standardised protocols for its clinical utility during follow-up. Method. In this retrospective multicentre cohort study, data were analysed from January 2014 to March 2020 for adult patients undergoing primary KA at Imperial NHS Trust. Patients were followed over a five-year period. Four machine learning models were developed to evaluate if post-operative X-ray frequency can predict revision surgery. The best-performing model was used to assess the risk of revision surgery associated with different number of X-rays. Result. The study assessed 289 knees with a 2.4% revision rate. The revision group had more X-rays on average than the primary group. The best performing model was Logistic Regression (LR), which indicated that each additional X-ray raised the revision risk by 52% (p<0.001). Notably, having four or more X-rays was linked to a three-fold increase in risk of revision (OR=3.02; p<0.001). Our results align with the literature that immediate post-operative X-rays have limited utility, making the 2nd post-operative X-ray of highest importance in understanding the patient's trajectory. These insights can enhance management by improving risk stratification for patients at higher revision surgery risk. Despite LR being the best-performing model, it is limited by the dataset's significant class imbalance. Conclusion. X-ray frequency can independently predict revision surgery. This study provides insights that can guide surgeons in evidence-based post-operative decision-making. To use those findings and influence post-operative management, future studies should build on this predictive model by incorporating a more robust dataset, surgical indications, and X-ray findings. This will allow early identification of high-risk patients, allowing for personalised post-operative recommendations

Cartilage lesions often undergo irreversible progression due to low self-repair capability of this tissue. Tissue engineered approaches based in extrusion bioprinting of constructs loaded with stem cell spheroids may offer valuable alternatives for the treatment of cartilage lesions. Human mesenchymal stromal cell (hMSC) spheroids can be chondrogenically differentiated faster and more efficiently than single cells. This approach allows obtaining larger tissues in a rapid, controlled and reproducible way. However, it is challenging to control tissue architecture, construct stability, and cell viability during maturation. In this study we aimed at the development of a reproducible bioprinting process followed by post-bioprinting chondrogenic differentiation procedure using large quantities of hMSC spheroids encapsulated in a xanthan gum-alginate hydrogel. Multi-layered constructs were bioprinted, ionically crosslinked, and chondrogenically differentiated for 28 days. The expression of glycosaminoglycan, collagen II and IV were observed. After 56 days in culture, the bioprinted constructs were still stable and show satisfactory cell metabolic activity with profuse extracellular matrix production. These results showed a promising procedure to obtain 3D cartilage-like constructs that could be potential use as stable chondral tissue implants for future therapies. Acknowledgments: The National Council for Scientific and Technological Development (CNPq, Brazil – Grants # 314 724/2021-4, 307 829/2018-9, 430 860/2018-8, 142 050/2018-0 and 465 656/2014-5), the Coordination for the Improvement of Higher Educational Personnel (CAPES, Brazil – PrInt 88 887.364849/2019-00 and PrInt 88 887.310405/2018-00), the Fund for Support to Teaching, Research and Extension from the University of Campinas (FAEPEX/UNICAMP, Brazil – Grants # 2921/18, 2324/21), and the European Union's Horizon 2020 JointPromise project – Precision manufacturing of microengineered complex joint implants, under grant agreement 874 837 are acknowledged for the financial support of this study

Introduction. The concept of same-day discharge has garnered increasing significance within orthopedic surgery, particularly in hip and knee procedures. Despite initial concerns surrounding the absence of prolonged hospital care, a burgeoning body of evidence highlights numerous advantages associated with same-day discharge, ranging from mitigating in-hospital infections to offering substantial financial and psychosocial benefits for both patients and healthcare providers. In this study, we aim to scrutinize the trends in same-day discharge specifically within the realm of total hip arthroplasties. Method. This retrospective analysis delves into the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database spanning from 2017 to 2021. Leveraging patient data sourced from the ACS NSQIP database, we sought to elucidate patterns and shifts in same-day discharge practices pertaining to total hip arthroplasties. Result. The preoperative analysis illuminated several notable disparities between patients undergoing same-day hip arthroplasty and those necessitating hospitalization. Notably, same-day hip patients skewed younger, comprising 48.3%females compared to 55.6% in hospitalized hip patients. Furthermore, a lower prevalence of medical comorbidities such as diabetes mellitus (8.5% vs.12.9%), current smoking (9.3% vs. 12.2%), and severe COPD(1.9% vs. 4.1%) was observed among same-day hip group. Operatively, same-day hip surgeries boasted shorter durations, averaging 83.9 minutes, in contrast to the 92.3minutes for hospitalized hip procedures. Postoperatively, same-day hip patients exhibited significantly diminished rates of 30-day readmissions (1.7%vs. 3.5%), procedure-related readmissions (1.0%vs.2.1%), reoperations (1.1%vs.1.9%), and mortality (0.02% vs. 0.04%). Moreover, the prevalence of the same-day discharge concept experienced a remarkable ascent from 2016 to 2021, with rates escalating from 1.5% to 25.6% of all total hip arthroplasties over a span of just six years. Conclusion. In conclusion, same-day discharge is a feasible and safe option for selected THA patients

Invertebral disc degeneration (IDD) is a degenerative disease involving a variety of musculoskeletal and spinal disorders such as lower back pain (LBP). Secretome derived from mesenchymal stem cells (MSCs) have exerted beneficial effect on tissue regeneration. In this study, the goal was to investigate the paracrine and the anti-inflammatory effects of secretome from interleukin IL1β preconditioned Bone Marrow MSCs (BMSCs) on human nucleus pulposus cells (hNPCs) in a 3D in vitro model. Secretome was collected from BMSCs (BMSCs-sec) after preconditioning with 10 ng/mL IL1β. hNPCs were isolated from surgical specimens, culture expanded in vitro, encapsulated in alginate beads and treated with: growth medium; IL1β 10 ng/mL; IL1β 10 ng/mL for 24 hours and then BMSCs-sec. We examined: i) cell proliferation and viability (flow cytometry), ii) nitrite production (Griess assay) and ROS quantification (Immunofluorescence) iii) glycosaminoglycan (GAG) amount (DMBB) and iv) gene expression levels of extracellular matrix (ECM) components and inflammatory mediators (qPCR). One-way ANOVA analysis was used to compare the groups under exam and data were expressed as mean ± S.D. In vitro tests showed an enhancement of hNPCs proliferation after treatment with BMSCs-sec (p ≤ 0.05) compared to IL1β group. After 24 hours, the percentage of dead cells was higher in IL1β treated hNPCs compared to control group and decreased significantly in combined IL1β and BMSCs-sec sample group (p ≤ 0.01). Nitrite and ROS production were significantly mitigated and GAGs content was improved by preconditioned BMSCs-sec (p ≤ 0.05). Furthermore, gene expression levels were modulated by BMSCs-sec treatment compared to controls. Our results supported the potential use of BMSCs' secretome as a cell-free strategy for IDD, overcoming the side effects of cell-therapy. Moreover, secretome derived from IL1β preconditioned BMSCs was able to reduce hNPCs death, attenuate ECM degradation and oxidative stress counteracting IDD progression. Acknowledgements: Financial support was received from the “iPSpine” and “RESPINE” Horizon 2020 projects

Critical size bone defects deriving from large bone loss are an unmet clinical challenge1. To account for disadvantages with clinical treatments, researchers focus on designing biological substitutes, which mimic endogenous healing through osteogenic differentiation promotion. Some studies have however suggested that this notion fails to consider the full complexity of native bone with respect to the interplay between osteoclast and osteoblasts, thus leading to the regeneration of less functional tissue2. The objective of this research is to assess the ability of our laboratory's previously developed 6-Bromoindirubin-3’-Oxime (BIO) incorporated guanosine diphosphate crosslinked chitosan scaffold in promoting multilineage differentiation of myoblastic C2C12 cells and monocytes into osteoblasts and osteoclasts1, 3, 4. BIO addition has been previously demonstrated to promote osteogenic differentiation in cell cultures5, but implementation of a co-culture model here is expected to encourage crosstalk thus further supporting differentiation, as well as the secretion of regulatory molecules and cytokines2. Biocompatibility testing of both cell types is performed using AlamarBlue for metabolic activity, and nucleic acid staining for distribution. Osteoblastic differentiation is assessed through quantification of ALP and osteopontin secretion, as well as osteocalcin and mineralization staining. Differentiation into osteoclasts is verified using SEM and TEM, qPCR, and TRAP staining. Cellular viability of C2C12 cells and monocytes was maintained when cultured separately in scaffolds with and without BIO for 21 days. Both scaffold variations showed a characteristic increase in ALP secretion from day 1 to 7, indicating early differentiation but BIO-incorporated sponges yielded higher values compared to controls. SEM and TEM imaging confirmed initial aggregation and fusion of monocytes on the scaffold's surface, but BIO addition appeared to result in smoother cell surfaces indicating a change in morphology. Late-stage differentiation assessment and co-culture work in the scaffold are ongoing, but initial results show promise in the material's ability to support multilineage differentiation. Acknowledgements: The authors would like to acknowledge the financial support of the Collaborative Health Research Program (CHRP) through CIHR and NSERC, as well as Canada Research Chair – Tier 1 in Regenerative Medicine and Nanomedicine, and the FRQ-S

The effects of dexamethasone (dex), during in vitro human osteogenesis, are contrasting. Indeed, dex downregulates SOX9 during osteogenic differentiation of human bone marrow mesenchymal stromal cells (HBMSCs). However, dex also promotes PPARG expression, resulting in the formation of adipocyte-like cells within the osteogenic monolayers. The regulation of both SOX9 and PPARG seems to be downstream the transactivation activity of the glucocorticoid receptor (GR), thus the effect of dex on SOX9 downregulation is indirect. This study aims at determining whether PPAR-γ regulates SOX9 expression levels, as suggested by several studies. HBMSCs were isolated from bone marrow of patients with written informed consent. HBMSCs were cultured in different osteogenic induction media containing 10 or 100 nM dex. Undifferentiated cells were used as controls. Cells were treated either with a pharmacological PPAR-γ inhibitor T0070907 (donors n=4) or with a PPARG-targeting siRNA (donors n=2). Differentiation markers or PPAR-γ target genes were analysed by RT-qPCR. Mineral deposition was assessed by ARS staining. Two-way ANOVA followed by a Tukey's multiple comparison test compared the effects of treatments. At day 7, T0070907 downregulated ADIPOQ and upregulated CXCL8, respectively targets of PPAR-γ-mediated transactivation and transrepression. RUNX2 and SOX9 were also significantly downregulated in absence of dex. PPARG was successfully downregulated by siRNA. ADIPOQ expression was also inhibited, while CXCL8 did not show any significant difference between siRNA treatment groups. RUNX2 was downregulated by the PPARG-siRNA treatment in presence of 100 nM dexamethasone, while SOX9 levels were not affected. ARS showed no change in the mineralization levels when PPARG expression or activity was inhibited. Understanding how dex regulates HBMSC differentiation is of pivotal importance to refine current in vitro models. These results suggest that PPARG does not mediate SOX9 downregulation. Unexpectedly, RUNX2 expression was also unaltered or even downregulated after PPAR-γ inhibition. Acknowledgements: AO Foundation, AO Research Institute (CH) and PRIN 2017 MUR (IT) for financial support

There is a lack of carriers for the local delivery of rifampicin (RIF), one of the cornerstone second defence antibiotic for Staphylococcus aureus deep bone infections (DBIs). RIF is also associated with systemic side effects, and known for causing rapid development of antibiotic resistance when given as monotherapy. We evaluated a clinically usedbi-phasic calcium sulphate/hydroxyapatite (CaS/HA) biomaterial as a carrier for dual delivery of RIF with vancomycin (VAN) or gentamicin (GEN). It was hypothesized that this combined approach could provide improved biofilm eradication and prevent the development of RIF resistance. Methods: 1) Biofilm eradication: Using a modified crystal violet staining biofilm quantification method, the antibiotics released at different time points (Day 1, 3, 7, 14, 21, 28 and 35) from the hemispherical pellets of CaS/HA(500 mg)-VAN (24.57 mg) / GEN (10.35 mg) composites with or without RIF (8.11 mg) were tested for their ability to disrupt the preformed 48-h old biofilms of S. aureus ATCC 25923, and S. aureus clinical strain P-3 in 96-well microtitre plate. For each tested group of antibiotic fractions, five separate wells were used (n=5). 2) Testing for resistance development: Similar to the method mentioned above the 48-h biofilm embeded bacteria exposed to antibiotic fractions from different time points continuously for 7 days. The biofilms remained were then tested for RIF resistant strains of bacteria. Overall, there was clear antibiofilm biofilm activity observed with CaS/HA-VAN/GEN+RIF combinations compared with CaS/HA-VAN/GEN alone. The S. aureus strains developed resistance to RIF when biofilms were subjected to CaS/HA-RIF alone but not with combinations of CaS/HA-VAN/GEN+RIF. Enhanced antibiofilm effects without development of RIF resistance indicates that biphasic CaS/HA loaded with VAN or GEN could be used as a carrier for RIF for additional local delivery in clinically demanding DBIs. Acknowledgement: We deeply acknowledge the Royal Fysiographic Society of Lund, Landshövding Per Westlings Minnesfond and the Stina and Gunnar Wiberg fond for financial support

Abstract. Background. Post operative radiographs following total joint arthroplasty are requested as part of routine follow up in many institutions. These studies have a significant cost to the local departments, in terms of financial and clinic resources, however, previous research has suggested they may not alter the course of the patients treatment. The purpose of this study was to assess the significance of elective post operative radiographs on changes in management of patients who underwent total joint arthroplasty. Method. All patients who underwent total knee arthroplasty and total hip arthroplasty at a District General Hospital from 2019 to 2020 were included. Data was collected retrospectively from medical records and radiograph requests. Alterations to clinical management based on radiographic findings were reviewed in clinic letters. Results. A total of 227 Total joint arthroplasty were retrieved. With 111(49%) total hip arthroplasty and 116 (51%) total knee arthroplasty. 54 were excluded due to having no clinical follow up and 173 met inclusion criteria. 56 (32%) had their post operative elective radiograph, while 93 (53.8%) patients had none. There were no abnormalities detected from the elective radiographs and none of the patients returned to the theatre. 24 patients (13%) presented with symptoms and had non-elective radiographs, 16 (67%) did not have any interventions and 8 (4.6%) required intervention and were taken to theatre. Discussion: Not performing these radiographs saves time, cost, and prevents unnecessary radiation exposure. In our institution, a 2-view joint radiograph costs £29 and takes roughly 15 minutes. This does not include indirect costs of additional clinic time and patient waiting time. In the larger context, the cost associated with elective radiographs is significant and our data suggests that routine post-operative radiographs are not beneficial as part of standard post-operative protocol for asymptomatic patients. However, performing imaging remains beneficial for patients who re-present with symptoms. Conclusion. Routine elective post-operative joint radiographs did not detect any true abnormalities. Information from elective radiographs has no clinical significance and did not change management. Therefore, this study recommends that there is no rationale requesting elective post-operative joint radiographs. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

The aim of this study was to investigate the regenerative effects of Wharton's Jelly Mesenchymal Stem Cells (WJ-MSCs) derived exosomes (WJ-Exos) on human nucleus pulposus cells (hNPCs) in an in vitro 3D model. WJ-Exos were isolated by tangent flow filtration of WJ-MSCs conditioned media and characterized by TEM, WB for markers expression and quantified with NTA. WJ-Exos PKH26-labeled uptake in hNPCs was detected by confocal microscopy. hNPCs, isolated from surgical specimens (n=4), culture expanded in vitro and encapsulated in alginate beads, were pre-treated with IL1β (10 ng/ml) for 24 hours, then with WJ-Exos at 10, 50 and 100 µg/ml. Cells with growth medium were used as control. We examined: i) cell proliferation and viability (flow cytometry), ii) nitrite production (Griess) iii) glycosaminoglycan (GAG) amount (DMBB), iv) histological staining for extracellular matrix (ECM) analysis and v) gene expression levels of catabolic and anabolic genes (qPCR). The investigations were performed in triplicate for each donor. One-way ANOVA analysis was used to compare the groups under exam and data were expressed as mean ± S.D. A dose dependent increase in hNPCs proliferation was noticed at all exos concentrations under study. Cell death decreased significantly in WJ-Exos 50 µg/ml samples (p ≤ 0,05) compared to IL1β treated hNPCs. Nitrite production was significantly attenuated at 10µg/ml of WJ-Exos (p ≤ 0,01). GAG content and histological analysis showed a difference in ECM synthesis between treated and untreated hNPCs (p ≤ 0,05). Catabolic and inflammatory markers were modulated by WJ-Exos at 100 µg/ml concentration (p ≤ 0,05) whereas 10 µg/ml group increased anabolic gene expression levels (p ≤ 0,05). These findings offer new opportunities for the potential use of exosomes as an attractive alternative cell-free strategy of IDD. WJ-MSC exosomes ameliorate hNPCs growth and viability, attenuate ECM degradation and oxidative stress-related IDD progression after IL1β stimulation. Financial support was received from the “iPSpine” and “RESPINE” Horizon 2020 projects