Aims

Pain is the most frequent complaint associated with osteonecrosis of the femoral head (ONFH), but the factors contributing to such pain are poorly understood. This study explored diverse demographic, clinical, radiological, psychological, and neurophysiological factors for their potential contribution to pain in patients with ONFH.

Aim. Antibiotic prophylaxis is central in preventing postoperative spine infections, yet knowledge of clinical spine tissue antibiotic concentrations remains limited. Pooled postoperative spine infection rates are constant (approximately 3%), resulting in severe patient morbidity, mortality, and prolonged hospitalization. Current antibiotic dosing regimens often involve fixed doses based on empirical knowledge, surrogate measures (plasma samples), non-clinical evidence (experimental models), and inferior methodology (tissue specimens). Therefore, personalized antibiotic dosing may be the future of antibiotic prophylaxis to prevent postoperative infections, especially implant infections. The aim was to continuously evaluate intra- and postoperative cefuroxime target spine tissue concentrations in long-lasting spine surgery after personalized dosing by repeated weight-dosed intravenous administrations. Method. Twenty patients (15 female, 5 male) scheduled for long-lasting spine deformity surgery with hypotensive anaesthesia were included; median age (range): 17.5 years (12-74), mean BMI (range): 22.2 (16.2-37.7), and mean surgery time (range): 4h 49min (3h 57min-6h 9min). Weight-dosed cefuroxime (20 mg/kg) was administered intravenously to all patients on average 25 min before incision and repeated after 4 hours. Microdialysis catheters were placed for sampling of cefuroxime concentrations in vertebral bone (only intraoperative sampling), paravertebral muscle, and subcutaneous tissue as soon as possible after surgery start. Upon wound closure, two additional catheters were placed in the profound and superficial part of the wound. Microdialysis and plasma samples were obtained continuously intra- and postoperative for up to 12 hours. The primary endpoint was (based on cefuroxime time-dependent efficacy) the time with cefuroxime concentrations above the clinical breakpoint minimal inhibitory concentration for Staphylococcus aureus of 4 µg/mL in percentage (%fT>MIC4) of. (a). patients’ individual surgery time,. (b). first dosing interval (0-4 hours),. (c). second dosing interval (4-12 hours). Results. Mean cefuroxime %fT>MIC4 (range) of:. (a). patients’ individual surgery time was 100% (100-100%) in all investigated tissues. (b). the first dosing interval was 93% (93-93%) in vertebral bone, paravertebral muscle, subcutaneous tissue, and 99% (99-100%) in plasma. (c). the second dosing interval was 87% (52-100%) in paravertebral muscle, 89% (52-100%) in subcutaneous tissue, 91% (71-100%) in the profound wound, 94% (72-100%) in the superficial wound, and 71% (42-100%) in plasma. Conclusions. Personalized cefuroxime dosing by repeated weight-dosed (20 mg/kg) intravenous administrations provided homogenous and therapeutic spine tissue exposure across all investigated tissues and plasma in long-lasting spine surgery with hypotensive anaesthesia (up to 11 hours). Thus, personalized cefuroxime dosing may decrease the risk of postoperative spine infection, especially in cases with implant insertion

Aim. Periprosthetic joint infections follow 1-3% of arthroplasty surgeries, with the biofilm nature of these infections presenting a significant treatment challenge. 1. Prevention strategies include antibiotic-loaded bone cement; however, increases in cementless procedures means there is an urgent need for alternative local antimicrobial delivery methods. 2. A novel, ultrathin, silica-based sol-gel technology is evaluated in this research as an anti-infective coating for orthopaedic prosthetic devices, providing local antibiotic release following surgery. Method. Reduction in clinically relevant microbial activity and biofilm reduction by antimicrobial sol-gel coatings, containing a selection of antibiotics, were assessed via disc diffusion and microdilution culture assays using the Calgary biofilm device. 3. Proliferation, morphology, collagen, and calcium production by primary bovine osteoblasts cultured upon antibiotic sol-gel surfaces were examined, and cytotoxicity evaluated using Alamar blue staining and lactate dehydrogenase assays. Concentrations of silica, calcium and phosphorus compounds within the cell layer cultured on sol-gel coatings and concentrations eluted into media, were quantified using ICP-OES. Furthermore, cellular phenotype was assessed using alkaline phosphatase activity with time in culture. Results. Low antibiotic concentrations within sol-gel had an inhibitory effect on clinically relevant biofilm growth, for example 0.8 mg ml. -1. tobramycin inhibited clinically isolated S. aureus (MRSA) growth with an 8-log reduction in viable colony forming units. There was no significant difference in metabolic activity between untreated and sol-gel exposed primary bovine osteoblasts in elution-based assays. Reduction (2-fold) in metabolic activity in direct contact assays after 48 hours exposure was likely to be due to increased osteoinduction, whereas no impact upon cell proliferation were observed (p=0.92 at 14 days culture). The morphology of primary osteoblasts was unaffected by culture on sol-gel coatings and collagen production was maintained. Calcium containing nodule production within bovine osteoblastic cells was increased 16-fold after 14 days culture upon sol-gel. Conclusions. The ultrathin sol-gel coating showed low cytotoxicity, strong biofilm reducing activity and antimicrobial activity, which was comparable to antibiotics alone, demonstrating that sol-gel delivery of antibiotics could provide local antimicrobial effects to inhibit PJI growth without the need for bone cement. Future work will develop and evaluate sol-gel performance in an ex vivo explant bone infection model which will reduce the need for animal experimentation

Aim. Predicting success of a Debridement, Antibiotics and Implant Retention (DAIR) procedure for Periprosthetic Joint Infection (PJI) remains a challenge. A failed DAIR might adversely affect the outcome of any future revision surgery for PJI. Hence, the ability to identify and optimise factors predictive of DAIR success would help target the procedure to the appropriate patient cohort and avoid unnecessary surgery for patients where a DAIR is unlikely to eradicate infection. Method. A retrospective review of our prospective Bone Infection Group database was performed to identify all patients who underwent a DAIR of their hip or knee arthroplasty. Diagnosis of PJI was confirmed using the Musculoskeletal Infection Society (MSIS) 2013 and the European Bone and Joint Infection Society (EBJIS) 2021 classification systems. DAIR surgery was grouped into “successful” or “unsuccessful” outcomes as per the MSIS working group outcome-reporting tool. Results. Sixty-Four consecutive patients with an acute PJI underwent a DAIR procedure between 2009 and 2020. Treatment was successful in 44 (69%). The chance of a successful DAIR was significantly greater if performed within one week of symptom onset compared to greater than one week duration (adjusted odds ratio (OR 0.11; p=0.027; 95% CI [0.02- 0.78]). The chances of a successful DAIR was not influenced by whether the surgeon was an arthroplasty or non-arthroplasty surgeon (OR 0.28; p=0.13; 95% CI [0.05- 1.48]). Isolated Streptococcus infection had a success rate of 100%; followed by Coagulasenegative Staphylococci 71% and Methicillin-susceptible Staphylococcus Aureus 65%. Polymicrobial infection had the worst outcome with a success rate of 47%. Conclusions. In our experience DAIR surgery performed within one week of symptom onset, significantly increased chances of successful infection eradication. Collaborative work is required to ensure arthroplasty patients access prompt appropriate surgical decision-making, remove barriers to early assessment and minimise delays to surgery

Aims

Osteoarthritis (OA) is a common degenerative disease. PA28γ is a member of the 11S proteasome activator and is involved in the regulation of several important cellular processes, including cell proliferation, apoptosis, and inflammation. This study aimed to explore the role of PA28γ in the occurrence and development of OA and its potential mechanism.

Introduction. Patients with external fixators are at risk of pin site infection. A more objective assessment of possible pin site infection is warranted, particularly for future home-based monitoring of pin sites. The aim was to determine if thermography can detect signs of inflammation around pin sites by 1) Establishing a maximum temperature cut-off value 2) Investigating the correlation between local temperature and visual signs of inflammation 3) Adjust for anatomical location and ambient room temperature. Method. This was a cross-sectional international multi-center study following STROBE guidelines. All patients with external ring-fixators scheduled for a visit in the out-patient clinic were eligible. Visual signs of inflammation were categorized using the Modified Gordon classification System (MGS, simplified sMGS). Thermographic imaging was done with an infrared camera (FLIR T540) and the maximum temperature within the ROI (MaxTp) was the primary outcome measure. Sample size and reliability were estimated. Cohen-Kappa, ROC-curve/AUC and Poisson regression were used for statistical analysis. Result. Data from 1970 pin sites were included. Inter-rater reliability of MGS was Kappa=0.79 and for MaxTp ICC=0.99 (95%CI: 0.99;0.99). Overall, a tendency of rising temperature with increasing sMGS was seen. The difference between sMGS=0 and sMGS>0 was significant. The performance of MaxTp as a screening tool to detect inflammation was reasonable with an AUC of 0.71 (95% CI: 0.65-0.76). The empirically optimal cut-off value was 34.1°C (Sensitivity=65%, Specificity=72%, Positive predictive value=23%, Negative Predictive value=94%). A 1°C increase in MaxTp increased the RR of visual signs of inflammation by a factor 1.5 (95% CI: 1.3; 1.7). Conclusion. We found a clinical positive association between the temperature at the pin site measured with thermography and visual signs of inflammation. The empirically optimal temperature cut-off value for inflammation screening was 34.1°C. Thermography may be a promising tool for a for a future point of care technology

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

Introduction. Current treatments of rotational deformities of long bones in children are osteotomies and fixations. In recent years, the use of guided growth for correction of rotational deformities has been reported in several pre-clinical and clinical studies. Various techniques have been used, and different adverse effects, like growth retardation and articular deformities, have been reported. We tested a novel plate concept intended for correction of rotational deformities of long bones by guided growth, with sliding screw holes to allow for longitudinal growth, in a porcine model. Method. Twelve, 12-week-old female porcines were included in the study. Surgery was performed on the left femur. The right femur was used as control. Plates were placed distally to induce external rotation, as longitudinal growth occurred. CT-scans of the femurs were processed to 3-D models and used for measuring rotation. Result. The plates rotated as intended in all 12 porcines. One porcine was excluded due to congenital deformity of the proximal part of the femurs. Two porcines had cut-out of the proximal screw on the lateral side, observed at the end of the intervention. These two porcines were included in the results. We observed a Δrotation of 5.7° ± 2° in external direction (CI: 3.7°– 7.7°). ΔFemur length was -0.4 cm [-0.7 cm – 0 cm] equal to 1.5% shortening of the operated femur. No significant difference was observed in coronal or sagittal plane. Conclusion. Significant external rotation was achieved with minimal effect on longitudinal growth. While the use of guided growth for correction of rotational deformities is already being used clinically, it is still to be considered an experimental procedure with sparse evidence. This study shows promising results for the feasibility of the method in a large animal model and is an important first step in validating the technique and detecting possible adverse effects, before future clinical studies

Introduction. Achieving an appropriate primary stability after implantation is a prerequisite for the long-term viability of a dental implant. Virtual testing of the bone-implant construct can be performed with finite element (FE) simulation to predict primary stability prior to implantation. In order to be translated to clinical practice, such FE modeling must be based on clinically available imaging methods. The aim of this study was to validate an FE model of dental implant primary stability using cone beam computed tomography (CBCT) with ex vivo mechanical testing. Method. Three cadaveric mandibles (male donors, 87-97 years old) were scanned by CBCT. Twenty-three bone samples were extracted from the bones and conventional dental implants (Ø4.0mm, 9.5mm length) were inserted in each. The implanted specimens were tested under quasi-static bending-compression load (cf. ISO 14801). Sample-specific homogenized FE (hFE) models were created from the CBCT images and meshed with hexahedral elements. A non-linear constitutive model with element-wise density-based material properties was used to simulate bone and the implant was considered rigid. The experimental loading conditions were replicated in the FE model and the ultimate force was evaluated. Result. The experimental ultimate force ranged between 67 N and 789 N. The simulated ultimate force correlated better with the experimental ultimate force (R. 2. =0.71) than the peri-implant bone density (R. 2. =0.30). Conclusion. The developed hFE model was demonstrated to provide stronger prediction of primary stability than peri-implant bone density. Therefore, hFE Simulations based on this clinically available low-radiation imaging modality, is a promising technology that could be used in future as a surgery planning tool to assist the clinician in evaluating the load-bearing capacity of an implantation site. Acknowledgements. Funding: EU's Horizon 2020 grant No: 953128 (I-SMarD). Dental implants: THOMMEN Medical AG

Introduction. Congenital scoliosis is a prevalent congenital spinal deformity, more frequently encountered than congenital lordosis or kyphosis. The prevailing belief is that most instances of congenital scoliosis are not hereditary but rather stem from issues in fetal spine development occurring between the 5th and 8th weeks of pregnancy. However, it has been linked to several genes in current literature. Our goal was to explore potential pathways through an exhaustive bioinformatics analysis of genes related to congenital scoliosis. Method. The literature from the 1970s to February 2024 was surveyed for genes associated with CS, and 63 genes were found to be associated with AIS out of 1743 results. These genes were analyzed using DAVID Bioinformatics. Result. Our pathway analysis has unveiled several significant associations with congenital scoliosis. Notably, “Glycosaminoglycan biosynthesis - chondroitin sulfate / dermatan sulfate” (P-Value:8.8E-3, Fold Enrichment: 20.6), “Central carbon metabolism in cancer” (P-Value:1.3E-3, Fold Enrichment: 10.3), and “Lysine degradation” (P-Value: 9.0E-3, Fold Enrichment: 9.1) emerge as statistically significant pathways. Additionally, “Endocrine resistance” (P-Value:4.4E-3, Fold Enrichment:7.4) and”EGFR tyrosine kinase inhibitor resistance” (P-Value: 1.7E-2, Fold Enrichment:7.3) pathways are noteworthy. These findings suggest a potential involvement of these pathways in the biological processes underlying congenital scoliosis. Furthermore, “Signaling pathways regulating pluripotency of stem cells” (P-Value:4.0E-4, Fold Enrichment:7.1), “Notch signaling pathway” (P-Value:6.7E-2, Fold Enrichment: 7.0), and “TGF-beta signaling pathway” (P-Value:6.2E-3, Fold Enrichment: 6.7) exhibit a less pronounced yet intriguing association that may warrant further investigation. Conclusion. In conclusion, our comprehensive analysis of the genetic etiology of congenital scoliosis has revealed significant associations with various pathways, shedding light on potential underlying biological mechanisms. While further research is needed to fully understand these associations and their implications, our findings provide a valuable starting point for future investigations into the management and treatment of congenital scoliosis

Introduction. The ability to walk over various surfaces such as cobblestones, slopes or stairs is a very patient centric and clinically meaningful mobility outcome. Current wearable sensors only measure step counts or walking speed regardless of such context relevant for assessing gait function. This study aims to improve deep learning (DL) models to classify surfaces of walking by altering and comparing model features and sensor configurations. Method. Using a public dataset, signals from 6 IMUs (Movella DOT) worn on various body locations (trunk, wrist, right/left thigh, right/left shank) of 30 subjects walking on 9 surfaces were analyzed (flat ground, ramps (up/down), stairs (up/down), cobblestones (irregular), grass (soft), banked (left/right)). Two variations of a CNN Bi-directional LSTM model, with different Batch Normalization layer placement (beginning vs end) as well as data reduction to individual sensors (versus combined) were explored and model performance compared in-between and with previous models using F1 scores. Result. The Bi-LSTM architecture improved performance over previous models, especially for subject-wise data splitting and when combining the 6 sensor locations (e.g. F1=0.94 versus 0.77). Placement of the Batch Normalization layer at the beginning, prior to the convolutional layer, enhanced model understanding of participant gait variations across surfaces. Single sensor performance was best on the right shank (F1=0.88). Conclusion. Walking surface detection using wearable IMUs and DL models shows promise for clinically relevant real-world applications, achieving high F1 levels (>0.9) even for subject-wise data splitting enhancing the model applicability in real-world scenarios. Normalization techniques, such as Batch Normalization, seem crucial for optimizing model performance across diverse participant data. Also single-sensor set-ups can give acceptable performance, in particular for specific surface types of potentially high clinical relevance (e.g. stairs, ramps), offering practical and cost-effective solutions with high usability. Future research will focus on collecting ground-truth labeled data to investigate system performance in real-world settings

Introduction. Shoulder arthroplasty (SA) has been performed with different types of implants, each requiring different replacement systems. However, data on previously utilized implant types are not always available before revision surgery, which is paramount to determining the appropriate equipment and procedure. Therefore, this meta-analysis aimed to evaluate the accuracy of the AI models in classifying SA implant types. Methods. This systematic review was conducted in Pubmed, Embase, SCOPUS, and Web of Science from inception to December 2023, according to PRISMA guidelines. Peer-reviewed research evaluating the accuracy of AI-based tools on upper-limb X-rays for recognizing and categorizing SA implants was included. In addition to the overall meta-analysis, subgroup analysis was performed according to the type of AI model applied (CNN (Convolutional neural network), non-CNN, or Combination of both) and the similarity of utilized datasets between studies. Results. 13 articles were eligible for inclusion in this meta-analysis (including 138 different tests assessing models’ efficacy). Our meta-analysis demonstrated an overall sensitivity and specificity of 0.891 (95% CI:0.866-0.912) and 0.549 (95% CI:0.532,0.566) for classifying implants in SA, respectively. The results of our subgroup analyses were as follows: CNN-subgroup: a sensitivity of 0.898 (95% CI:0.873-0.919) and a specificity of 0.554 (95% CI:0.537,0.570), Non-CNN subgroup: a sensitivity of 0.809 (95% CI:0.665-0.900) and specificity of 0.522 (95% CI:0.440,0.603), combined subgroup: a sensitivity of 0.891 (95% CI:0.752-0.957) and a specificity of 0.547 (95% CI:0.463,0.629). Studies using the same dataset demonstrated an overall sensitivity and specificity of 0.881 (95% CI:0.856-0.903) and 0.542 (95% CI:0.53,0.554), respectively. Studies that used other datasets showed an overall sensitivity and specificity of 0.995 (95% CI:969,0.999) and 0.678 (95% CI:0.234, 0.936), respectively. Conclusion. AI-based classification of shoulder implant types can be considered a sensitive method. Our study showed the potential role of using CNN-based models and different datasets to enhance accuracy, which could be investigated in future studies

Introduction. Cartilage comprises chondrocytes and extracellular matrix. The matrix contains different collagens, proteoglycans, and growth factors produced by chondroprogenitor cells that differentiate from proliferating to hypertrophic chondrocytes. In vitro chondrocyte growth is challenging due to differences in behaviour between 2D and 3D cultures. Our aim is to establish a murine 3D spheroid culture method using chondrocytes to study the complex interaction of cells on the chondro-osseous border during enchondral ossification. Method. Primary chondrocytes were isolated from the knee of WT new-born mice and used to form 10,000 cell number spheroids. We used the ATDC5-chondrocyte cell line as an alternative cell type. Spheroids were observed for 7, 14, and 21 days before embedding in paraffin for slicing. Alcian blue staining was performed to identify proteoglycan positive areas to prove the formation of extracellular matrix in spheroids. Collagen type 2, and Collagen type X expression were analyzed via quantitative real-time PCR and immunohistochemistry. Result. Alcian blue staining showed increasing matrix formation from day 7 to day 14 and proliferative chondrocytes at early time points. Both cell types showed increasing mRNA expression of Collagen type 2 from day 7 to day 21. Collagen type X positive staining starting from day 14 on confirmed the development of hypertrophic stage of chondrocytes. ATDC5 cells exhibited a slower progression in chondrogenic differentiation compared to primary chondrocytes. Conclusion. In chondrocyte spheroids, we observed proceeding differentiation of chondrocytes reaching hypertrophic phase. Primary chondrocytes showed faster development than ATDC5 cell line. Overall, spheroid culture of chondrocytes could be a good basis to study the interaction of different cells types of the chondro-osseous border by combination of chondrocytes with e.g., endothelial cells and osteoblasts within the spheroid. Those organoid cultures might also help to reduce animal experiments in the future, by mimicking complex regeneration procedures like bone growth or fracture healing. DFG(German Research Foundation)

Introduction. The healing of rotator cuff injuries poses significant challenges, primarily due to the complexity of recreating the native tendon-to-bone interface, characterized by highly organized structural and compositional gradients. Addressing this, our innovative approach leverages bioprinted living tissue constructs, incorporating layer-specific growth factors (GFs) to facilitate enthesis regeneration. This method aims to guide in situ zonal differentiation of stem cells, closely mirroring the natural enthesis tissue architecture. Method. Our strategy involves the utilization of advanced bioprinting technology to fabricate living tissue constructs. These constructs are meticulously designed with embedded microsphere-based delivery carriers, ensuring the sustained release of tenogenic, chondrogenic, and osteogenic growth factors. This layer-specific release mechanism is tailored to promote the precise differentiation of stem cells across different regions of the construct, aligning with the gradient nature of enthesis tissues. Result. In vitro studies demonstrated that our layer-specific tissue constructs significantly outperformed basal constructs without GFs, achieving region-specific differentiation of stem cells. More critically, in a rabbit model of rotator cuff tear, these bioprinted living tissue constructs expedited enthesis regeneration. Key outcomes included improved biomechanical properties, enhanced collagen deposition and alignment, and the formation of a gradient fibrocartilage interface with aligned collagen fibrils. After 12 weeks, the constructs achieved an ultimate load failure of 154.3 ± 9.5 N resembling that of native enthesis tissues, marking a notable achievement in tissue engineering. Conclusion. Our exploration introduces a viable and innovative strategy for engineering living tissue constructs that exhibit region-specific differentiation capabilities. This approach holds significant promise for the functional repair of gradient enthesis tissues, potentially revolutionizing the treatment of rotator cuff injuries by closely replicating the natural tendon-to-bone interface, thus offering a promising avenue for future clinical applications

Introduction

Orthopedics is experiencing a significant transformation with the introduction of technologies such as robotics and apps. These, integrated into the post-operative rehabilitation process, promise to improve clinical outcomes, patient satisfaction, and the overall efficiency of the healthcare system. This study examines the impact of an app called Mymobility and intra-operative data collected via the ROSA® robotic system on the functional recovery of patients undergoing robot-assisted knee arthroplasty.

Introduction. Osteoarthritis (OA) occurs due to a multi-scale degradation of articular cartilage (AC) surface which aggravates the disease condition. Investigating the micro-scale structural alterations and mechano-tribological properties facilitates comprehension of disease-mechanisms to improve future injectable-therapies. This study aims to analyze these properties using various experimental and analytical methods to establish correlations between their morpho-physiological features. Method. In this study, Raman-spectroscopy was used to investigate microscale changes in AC constituents and categorize OA damage regions in knee-joint samples from joint replacement patients (Samples = 5 and Regions = 40). Following, microscale indentation and sliding tests were performed on these regions to evaluate variations in aggregate-modulus (AM) and elastic-modulus (EM), with coefficient of friction (COF). Finally, scanning electron microscopy (SEM) was employed to analyze these morphological variations. Result. Raman spectroscopy revealed degree of collagen-damage (Amide-3 α-helix to random-coil ratio I-1250/I-1280), proteoglycan-damage (Sulphated bonds SO. 3-. to CH. 2. twist ratio I-1065/I-1206), amount of bone exposure (Phosphated-hydroxyapatite PO. 4. 3-. to Amide-1 ratio I-959/I-1669) and increased crystallinity (Carbonated hydroxyapatite CO. 3. 2-. to Amide-1 ratio I-1075/I-959) in ECM. Subsequently, these regions were categorized into different groups (G) based on these damages; G1 (Proteoglycan); G2 (Collagen + Proteoglycan); G3 (Collagen + Proteoglycan + Carbonated crystallinity) G4 (Collagen or Proteoglycan + bone exposure); and G5 (Collagen + Proteoglycan + Bone exposure). Further experimentation revealed the differences in mechano-tribological properties (AM, EM, and COF) between the different groups. G5 displayed the highest values of AM (1.5 ± 0.2MPa), EM (0.3 ± 0.01MPa) and COF (0.39 ± 0.08), compared to other groups. These altered properties were confirmed via SEM that revealed micro-asperity junctions, superficial fronding, fibrillations and bone exposure at these damaged regions. Conclusion. This study demonstrated micro-scale changes in AC among OA patients commensurate to the degree of tissue damage, which correlates with disease progression altering joint structure and function particularly in regions with high COF

Introduction. Osteoarthritis (OA) often results from joint misloading, which affects chondrocyte calcium signaling through mechano-sensitive receptors such as Piezo1, -2, and TRPV4. Activation of Piezo1, especially under inflammatory conditions, can trigger premature chondrocyte apoptosis. Intra-articular glucocorticoid therapy, while beneficial against inflammation and pain in osteoarthritis, may induce oxidative stress and chondrotoxicity at higher doses. This study aims to assess the effects of glucocorticoids, particularly triamcinolone, on chondrocyte elasticity and mechanosignaling. Method. Chondrocytes isolated from articular condyles obtained from patients undergoing knee replacement surgery (n= 5) were cultured for 7 days in triamcinolone acetonide (TA) at different concentrations (0.2µM – 2mM). Cytoskeletal changes were assessed by F-actin labeling. Cell elasticity was measured using atomic force microscopy (AFM). Labeling cells (n=6 patients) with the calcium-sensitive dye (Fluo-4) enabled monitoring changes in intracellular calcium fluorescence intensity during guided single-cell mechanical indentation (500 nN) by AFM. Result. Cell exposure to 2 mM TA led to cell death and crystallization of TA in the cell culture media. However, the concentration of TA for intra-articular application is 46 times higher at 92.1 mM (40 mg/ml). The maximal pharmacological effect on viable cells was observed at 0.2 mM. AFM results showed a significant decrease of elasticity (p<0.001), alongside significantly higher calcium intensities both prior to and during mechanical stimulation in the TA-treated samples (p<0.05). Conclusion. Administration of TA significantly impacts the mechanical properties of chondrocytes, reducing cellular elasticity while simultaneously enhancing calcium-dependent mechanosensitivity. This data suggests a correlation between glucocorticoid-induced changes in cell elasticity and cell mechanosensitivity. Finding ways to minimize the effect of glucocorticoids on cell mechanosensitivity could help to make future therapies safer and reduce side effects

Introduction. Functional Spine Units (FSUs) play a vital role in understanding biomechanical characteristics of the spine, particularly bone fracture risk assessment. While established models focus on simulating axial compression of individual bones to assess fracture load, recent models underscore the importance of understanding fracture load within FSUs, offering a better representation of physiological conditions. Despite the limited number of FSU fracture studies, they predominantly rely on a linear material model with an annulus fibrosus Young's modulus set at 500 MPa, significantly higher than stiffness values (ca. 4 MPa) utilized in other FSU and spine section biomechanical models. Thus, this study aims to study the effect of varying annulus fibrosus stiffness on FSU fracture load, aiming to identify physiologically relevant biomechanical parameters. Method. Subject-specific geometry and material properties of bones were derived from computed tomography (CT) image data of five human cadaveric FSU specimens. The annulus fibrosus and nucleus pulposus were manually recreated and assigned linear elastic material properties. By subjecting the model to axial compression, the fracture load of the FSU was deduced from the peak of the force-displacement graph. To explore the effect of stiffness of the annulus fibrosus on simulated fracture load, we conducted a parameter study, varying stiffness values from the high 500 MPa to a more physiologically relevant 25 MPa, aiming to approximate values applied in FSU kinematic models while achieving bone fracture. Result. Significant reductions in fracture load were observed, ranging from 23% to 46%, as annulus stiffness decreased from 500MPa to 25MPa. Additionally, a discernible, gradual decline in fracture load was observed with a decrease in stiffness values. Conclusion. The stiffness of the annulus fibrosus significantly influences the simulated fracture load of an FSU. Future investigations should prioritize biomechanically accurate modeling of the intervertebral disc, ensuring alignment with experimental findings regarding FSU fracture load while maintaining biomechanical fidelity

Aims

For rare cases when a tumour infiltrates into the hip joint, extra-articular resection is required to obtain a safe margin. Endoprosthetic reconstruction following tumour resection can effectively ensure local control and improve postoperative function. However, maximizing bone preservation without compromising surgical margin remains a challenge for surgeons due to the complexity of the procedure. The purpose of the current study was to report clinical outcomes of patients who underwent extra-articular resection of the hip joint using a custom-made osteotomy guide and 3D-printed endoprosthesis.

Aims

The incidence of limb fractures in patients living with HIV (PLWH) is increasing. However, due to their immunodeficiency status, the operation and rehabilitation of these patients present unique challenges. Currently, it is urgent to establish a standardized perioperative rehabilitation plan based on the concept of enhanced recovery after surgery (ERAS). This study aimed to validate the effectiveness of ERAS in the perioperative period of PLWH with limb fractures.