Degenerative meniscal tears are the most common meniscal lesions, representing huge clinical and socio-economic burdens. Their role in knee osteoarthritis (OA) onset and progression is well established and demonstrated by several retrospective studies. Effective preventive measures and non-surgical treatments for degenerative meniscal lesions are still lacking, also because of the lack of specific and accurate animal models in which test them. Thus, we aim to develop and validate an accurate animal model of meniscus degeneration. Three different surgical techniques to induce medial meniscus degenerative changes in ovine model were performed and compared. A total of 32 sheep (stifle joints) were subjected to either one of the following surgical procedures: a) direct arthroscopic mechanical meniscal injury; b) peripheral devascularization and denervation of medial meniscus; c) full thickness medial femoral condyle cartilage lesion. In all the 3 groups, the contralateral joint served as a control.Introduction
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There is a lack of evidence-based treatments for patients with chronic pain after total knee arthroplasty (TKA). It is well-established that knee extensor and flexor muscle strength are markedly impaired following TKA, but no studies have examined muscle strength and power in patients with chronic pain after TKA. Therefore, the aim was to investigate if neuromuscular exercises and pain neuroscience education (PNE) were superior to PNE alone for improvement of muscle strength and power in patients with chronic pain after TKA. This report presents the exploratory analysis of a randomized controlled trial (NCT03886259). Participants with chronic moderate-to-severe average daily pain intensity and no signs of prosthesis failure at least one year after primary TKA were included. Participants were randomized to receive either supervised neuromuscular exercise and PNE or the same PNE sessions alone. The outcomes were changes from baseline to 12-months for peak leg extension power and maximum muscle strength, measured during maximal voluntary isometric contractions, for the knee extensors and flexors.Introduction
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Polyacrylamide hydrogel (iPAAG1), is CE marked for treating symptomatic knee osteoarthritis (OA), meeting the need for an effective, long-lasting, and safe non-surgical option. This study evaluates the efficacy and safety of a single 6 ml intra-articular injection of iPAAG in participants with moderate to severe knee OA over a 5-year post-treatment period, presenting data from the 4-year follow up. This prospective multicentre study (3 sites in Denmark) involved 49 participants (31 females) with an average age of 70 (range 44 – 86 years). They received a single 6 mL iPAAG injection. All participants provided informed consent and re-consented to continue after 1 year. The study followed GCP principles and was approved by Danish health authorities and local Health Research Ethics committees. Twenty-seven participants completed the 4-year follow-up. The study evaluated WOMAC pain, stiffness, function, and Patient Global Assessment (PGA) of disease impact. Changes from baseline were analysed using a mixed model for repeated measurement (MMRM). Sensitivity analyses were applied on the extension data, where the MMRM analysis was repeated only including patients in the extension phase and an ANCOVA model was used, replacing missing values at 4-years with baseline values (BOCF).Introduction
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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. 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.Introduction
Method
Most western countries have implemented fast-track hip fracture aiming at surgery within 24 hours, since the mortality rate hereafter rises markedly. In Greenland, it is not achievable to operate within 24 hours. Arctic people live in sparsely populated areas and Greenland's population is scattered along the vast coastline. All patients must be chartered to Nuuk by airplane which can take up till several days to weeks, due to logistics and the Arctic weather. This presents a challenge regarding adhering to western guidelines. The operative delay may be acceptable though, as it is the impression that the Greenlandic population survives and endures better than patients of western populations. However, as data are lacking, we aimed to describe mortality among hip fracture patients in Greenland taking frailty and comorbidities into account. All patients with ICD-10 codes DS720, DS721 and DS722 from 2018-2022 were identified as 261 patients diagnosed with hip fractures. Variables including time of diagnosis, time to operation, reasons for delay, ASA-score, Charlson Comorbidity index, time of death, and other possible confounding variables were analyzed. Primary outcome was mortality rates at 30-day post-OP and 1-year post-OP.Introduction
Method
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. 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.Introduction
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Endochondral ossification (EO) is the process of bone development via a cartilage template. It involves multiple stages, including chondrogenesis, mineralisation and angiogenesis. Importantly, how cartilage mineralisation affects angiogenesis during EO is not fully understood. Here we aimed to develop a new in vitro co-culture model to recapitulate and study the interaction between mineralised cartilage generated from human mesenchymal stromal cells (hMSCs) and microvascular networks. Chondrogenic hMSC pellets were generated by culture with transforming growth factor (TGF)-β3. For mineralised pellets, β-glycerophosphate (BGP) was added from day 7 and TGF-β3 was withdrawn on day 14. Conditioned medium (CM) from the pellets was used to evaluate the effect on human umbilical vein endothelial cells (HUVECs) in migration, proliferation and tube formation assays. To perform direct co-cultures, pellets were embedded in fibrin hydrogels containing vessel-forming cells (HUVECs, adipose stromal cells) for 10 days with BGP to induce mineralisation. The pellets and hydrogels were characterised by immunohistochemistry and confocal imaging.Introduction
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Analogous to articular cartilage, changes in spatial chondrocyte organisation have been proposed to be a strong indicator for local tissue degeneration and destruction in the intervertebral disc (IVD). While a progressive structural and functional degradation of the extracellular (ECM) and pericellular (PCM) matrix occurs in osteoarthritic cartilage, these processes have not yet been biomechanically elucidated in the IVD. We aimed to evaluate the local stiffness of the ECM and PCM in the anulus fibrosus of the IVD on the basis of local cellular spatial organisation. Using atomic force microscopy, we measured the elastic modulus of the local ECM and PCM in human disc samples using the spatial chondrocyte patterns as an image-based biomarker.Introduction
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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. 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.Introduction
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Piezo1 is a mechanosensitive Ca2+ ion channel that has been shown to transduce hyper-physiologic mechanical loads in chondrocytes. In osteoarthritic cartilage, Piezo1 expression was shown to be upregulated by interleukin-1 alpha (IL-1α) and resulted in altered calcium dynamics and actin cytoskeleton rarefication. Together these studies highlight the importance of Piezo1 channels during joint injury. However, the mechanism by which Piezo1 regulates chondrocyte physiology and mechanotransduction during homeostasis is still largely unknown. In this study, we investigate the impact of Piezo1 activation on nuclear mechanics and chromatin methylation state. Porcine chondrocytes (n=3-5 pigs) were treated with Yoda1, a Piezo1-specific agonist, for either 2, 5, 15 or 180 minutes. To characterize chromatin state, we monitored the abundance of a chromatin methylation marker (H3K9Me3) using immunofluorescence (IF). Atomic force microscopy (AFM, 25 nm cantilever) was employed to quantify the nuclear elastic modulus (NEM) of individual cell nuclei. To explore the interplay between cytoskeletal dynamics and nuclear mechanics, chondrocytes were treated with Latrunculin A (LatA), an actin polymerization inhibitor.Introduction
Methods
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. 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.Introduction
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Bereft of their optimal tissue context, cells lose their phenotype, function and therapeutic potential during Thermal imprinted was used to pattern (groove depth: 2,000 nm, groove width: 2,000 nm, line width: 2,000 nm) polydimethylsiloxane substrates of different rigidity (50 kPa, 130 kPa, 1,000 kPa). Grooved and planar substrates were subsequently coated with collagen type I and used to culture the aforementioned cell populations without and with macromolecular crowding (100 μg/ml carrageenan). After 3, 7 and 14 days in culture, cell morphology, viability, metabolic activity, proliferation, protein synthesis and deposition and gene expression analyses were conducted.Introduction
Methods
Intervertebral disc degeneration (IDD) is a progressive process affecting all disc tissues, namely the nucleus pulposus (NP), annulus fibrosus (AF), and cartilaginous endplates (CEPs). Several cell-based therapies have been proposed to replenish the disc cell population and promote tissue regeneration. However, cell-free therapeutics have been increasingly explored due to potentially higher advantages and cost-effectiveness compared to cell transplantation. Recently, extracellular vesicles (EVs) isolated from healthy Tie2+-NP cells (NPCs) have shown promising regenerative outcomes on degenerative NPCs (dNPCs). The aim of this study was to assess the effect of such EVs on all disc cell types, including AF cells (AFCs) and CEP cells (CEPCs), compared to EVs isolated from bone-marrow derived mesenchymal stromal cells (BM-MSCs). NPCs harvested from young donors underwent an optimized culture protocol to maximize Tie2 expression (NPCsTie2+). BM-MSCs were retrieved from a commercial cell line or harvested during spine surgery procedures. EV characterization was performed via particle size analysis (qNano), expression of EV markers (Western blot), and transmission electron microscopy. dNPCs, AFCs, and CEPCs were isolated from surgical specimens of patients affected by IDD, culture-expanded, and treated with NPCsTie2+-EVs or BM-MSC-EVs ± 10 ng/mL IL-1b. EV uptake was assessed with PKH26 staining of EVs under confocal microscopy. Cell proliferation and viability were assessed with the CCK-8 assay.Introduction
Method
Unplanned reoperations (UROs) following corrective surgery for adult spinal deformity (ASD) present significant challenges for both patients and surgeons. Understanding the specific UROs types is crucial for improving patient outcomes and refining surgical strategies in ASD correction. This retrospective analysis utilized data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database spanning from 2017 to 2021. Patient information was extracted using specific CPT codes related to posterior pedicle fixation.Introduction
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Healthy tendons are mainly composed of aligned collagen hierarchically organized from collagen fibrils to fiber bundles with a scarce cellular population mainly composed of tenocytes and tendon stem/progenitor cells. However, injured tendon acquires a fibrotic state characterized by a loss of ECM alignment and increased cellularization. The lack of reliable 3D models that recreate the organization and microenvironment of healthy and diseased tendons is one of the main obstacles faced by the scientific community. To recreate the architecture of healthy and diseased tendons, electrospun nanofiber scaffolds with anisotropic and isotropic nanotopography were developed. These scaffolds were coated with a shell consisting of cell-laden hydrogels encapsulating human adipose-derived stem cells (hASCs) to include the living component. To show the versatility of the system, extracellular vesicles (EVs) were encapsulated in the hydrogel as biological cues. The living fibers were characterized by microscopy and morphological analysis. The morphology and phenotype of cells was evaluated using microscopy, gene expression analysis and immunostainings for tendon markers.Introduction
Method
Articular cartilage has a low self-regeneration capacity. Cartilage defects have to be treated to minimize the risk of the onset of osteoarthritis. Bioactive glass (BG) is a promising source for cartilage tissue engineering. Until now, conventional BGs (like BG1393) have been used, mostly for bone regeneration, as they are able to form a hydroxyapatite layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to study the effect of 3D printed hydrogel scaffolds supplemented with spheres of the BG CAR12N to improve the chondrogenesis of mesenchymal stem cells (MSCs). Based on our new glass composition (CAR12N), small BG spheres (25-40 µm) were produced and mixed with hydrogel and primary human (h) MSCs. Grid printed scaffolds were cultivated up to 21 days in expansion or chondrogenic differentiation medium. Macroscopical images of the scaffolds were taken to observe surface changes. Vitality, DNA and sulfated glycosaminoglycan (GAG) content was semiquantitatively measured as well as extracellular matrix gene transcription.Introduction
Method
Hip fractures, with a global age-standardised incidence rate (per 100,000 population) of 187.2 (2019), are a major public health problem. With a 7.71 billion population worldwide in 2019, hip fractures, in general, are affecting around 14.43 million people per year globally. We aim to provide a nationwide epidemiological analysis of trochanteric fractures and their respective surgical treatments. In this study we research the epidemiology of trochanteric and subtrochanteric fractures, as well as their most common kinds of osteosynthesis, on a nationwide scale in Germany. Data was retrieved from the national database of the German Ministry of Interior. ICD-10-GM and OPS-data from the period of 2006-2020 were analyzed, all patients with trochanteric/subtrochanteric fractures were included. Patients were grouped by age/gender and linear-regression was performed to calculate statistically significant correlations between variables/incidences.Introduction
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The incidences of fragility fractures, often because of osteoporosis, are increasing. Research has moved towards bioresorbable scaffolds that provide temporary mechanical stability and promote osteogenesis. This research aims to fabricate a 3D printed composite Poly (l-lactic-co-glycolic acid)-strontium doped tricalcium phosphate (PLGA-SrTCP) scaffold and evaluate in an in vitro co culture study containing osteoporotic donor cells. PLGA, PLGA TCP, and PLGA SrTCP scaffolds were produced using Fused Filament Fabrication (FFF). A four-group 35-day cell culture study was carried out using human bone marrow derived mesenchymal stem cells (hMSCs) from osteoporotic and control donors (monoculture) and hMSCs & human monocytes (hMCs) (Co culture). Outcome measures were biochemical assays, PCR, and cell imaging. Cells were cultured on scaffolds that had been pre-degraded for six weeks at 47°C prior to drying and gamma sterilisation.Introduction
Method
Bernese periacetabular osteotomy (PAO) repositions the acetabulum to increase femoral head coverage (FHC) in hip dysplasia. Currently, there is a paucity of objective peri-operative metrics to plan for optimal acetabular fragment repositioning. The MSk Lab Hip 3D Planner (MSkL-HP) measures acetabular morphology and simulates PAO cuts to achieve optimal FHC. We evaluated how adjusting location and orientation of cutting planes can alter FHC. MSkL-HP simulated 274 feasible PAOs on four dysplastic hips. Femoroacetabular anatomy was landmarked to simulate cutting planes. Posterior column and ischial cuts were standardised, whilst iliac and pubic cut combinations varied. The slope of the iliac cut was either neutral (aligned to pelvis), exit point 5mm above the entry point (+5), or 5mm below (-5). The slope of the pubic cut was either 90°, 50°, or 70° (medial-to-lateral). Iliac and pubic cuts were simulated 0, 5 and 15mm - distal and medial – to a classic cut. Outcome measures were achieved LCEA, Tönnis, FHC and % bone overlap at the pubic cut. Targets were LCEA >30°, Tönnis angle <10°, and FHC >70% and minimum bone overlap ≥10%.Introduction
Method
The ACTIVE(Advanced Cartilage Treatment with Injectable-hydrogel Validation of the Effect) study investigates safety and performance of a novel dextran-tyramine hydrogel implant for treatment of small cartilage defects in the knee (0.5-2.0cm2). The hydrogel is composed of a mixture of natural polymer conjugates that are mixed intra-operatively and which cross-link in situ through a mild enzymatic reaction, providing a cell-free scaffold for cartilage repair. The ACTIVE study is split into a safety (n=10) and a performance cohort (n=36). The Knee Injury and Osteoarthritis Outcome Score (KOOS), pain (numeric rating scale, NRS), Short-Form Health Survey (SF-36) were compared at baseline and 3, 6, and 12 months after surgery. The primary performance hypothesis is an average change in the KOOS from baseline to 12 months (ΔKOOS) greater than a minimal clinically important change (MIC) of 10. No statistical tests were performed as these are preliminary data on a smaller portion of the total study.Introduction
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