Using a rat model the characteristics of the sensory neurones of the dorsal-root ganglia (DRG) innervating the hip were investigated by retrograde neurotransport and immunohistochemistry. Fluoro-Gold solution (FG) was injected into the left hip of ten rats. Seven days later the DRG from both sides between T12 and L6 were harvested. The number of FG-labelled calcitonin gene-related peptide-immunoreactive or isolectin B4-binding neurones were counted. The FG-labelled neurones were distributed throughout the left DRGs between T13 and L5, primarily at L2, L3, and L4. Few FG-labelled isolectin B4-binding neurones were present in the DRGs of either side between T13 and L5, but calcitonin gene-related peptide-immunoreactive neurones made up 30% of all FG-labelled neurones. Our findings may explain the referral of pain from the hip to the thigh or lower leg corresponding to the L2, L3 and L4 levels. Since most neurones are calcitonin gene-related peptide-immunoreactive peptide-containing neurones, they may have a more significant role in the perception of pain in the hip as peptidergic DRG neurones

The use of impacted, morsellised bone grafts has become popular in revision total hip arthroplasty (THA). The initial stability of the reconstruction and the effectiveness of any subsequent process of revitalisation and incorporation will depend on the mechanical integrity of the graft. Our aim in this study was to document the time-dependent mechanical properties of the morsellised graft. This information is useful in clinical application of the graft, in studies of migration of the implant and in the design of the joint.

We used 16 specimens of impacted, morsellised cancellous bone from the sternum of goats to assess the mechanical properties by confined compression creep tests. Consideration of the graft material as a porous, permeable solid, filled with fluid, allowed determination of the compressive modulus of the matrix, and its permeability to fluid flow.

In all specimens the compression tests showed large, irreversible deformations, caused by flow-independent creep behaviour as a result of rolling and sliding of the bone chips. The mean permeability was 8.82 *10⁻¹² m⁴/Ns (SD 43%), and the compressive modulus was 38.7 MPa (SD 34%). No correlation was found between the apparent density and the permeability or between the apparent density and the compressive modulus. The irreversible deformations in the graft could be captured by a creep law, for which the parameters were quantified.

We conclude that in clinical use the graft is bound to be subject to permanent deformation after operation. The permeability of the material is relatively high compared with, for example, human cartilage. The confined compression modulus is relatively low compared with cancellous bone of the same apparent density. Designs of prostheses used in revision surgery must accommodate the viscoelastic and permanent deformations in the graft without causing loosening at the interface.

In an attempt to alleviate symptoms of the disease, patients with knee osteoarthrosis (KOA) frequently alter their gait patterns. Understanding the underlying pathomechanics and identifying KOA phenotypes is essential for improving treatments. We aimed to investigate altered kinematics in patients with KOA to identify subgroups. Sixty-six patients with symptomatic KOA scheduled for total knee arthroplasty and 12 age-matched healthy volunteers with asymptomatic knees were included. We used k-means to separate the patients based on dynamic radiostereometric assessed knee kinematics. Ligament lesions, KOA score, and clinical outcome were assessed by magnetic resonance imaging, radiographs, and patient reported outcome measures, respectively. We identified four clusters that were supported by clinical characteristics. Compared with the healthy group; The flexion group (n=20): revealed increased flexion, greater adduction, and joint narrowing and consisted primarily of patients with medial KOA. The abduction group (n=17): revealed greater abduction, joint narrowing and included primarily patients with lateral KOA. The anterior draw group (n=10): revealed greater anterior draw, external tibial rotation, lateral tibial shift, adduction, and joint narrowing. This group was composed of patients with medial KOA, some degree of anterior cruciate ligament lesion and the greatest KOA score. The external rotation group (n=19): revealed greater external tibial rotation, lateral tibial shift, adduction, and joint narrowing while no anterior draw was observed. This group included primarily patients with medial collateral and posterior cruciate ligament lesions. Patients with KOA can, based on their gait patterns, be classified into four subgroups, which relate to their clinical characteristics. The findings add to our understanding of associations between disease pathology characteristics in the knee and the pathomechanics in patients with KOA. A next step is to investigate if patients in the pathomechanic clusters have different outcomes following total knee arthroplasty

Menisci are crucial structures for knee homeostasis: they provide increase of congruence between the articular surfaces of the distal femur and tibial plateau, bear loading, shock absorption, lubrication, and proprioception. After a meniscal lesion, the golden rule, now, is to save as much meniscus as possible: only the meniscus tissue which is identified as unrepairable should be excised and meniscal sutures find more and more indications. Several different methods have been proposed to improve meniscal healing. They include very basic techniques, such as needling, abrasion, trephination and gluing, or more complex methods, such as synovial flaps, meniscal wrapping, or the application of fibrin clots. Basic research of meniscal substitutes has also become very active in the last decades. The features needed for a meniscal scaffold are: promotion of cell migration, it should be biomimetic and biocompatible, it should resist forces applied and transmitted by the knee, it should slowly biodegrade and should be easy to handle and implant. Several materials have been tested, that can be divided into synthetic and biological. The first have the advantage to be manufactured with the desired shapes and sizes and with precise porosity dimension and biomechanical characteristics. To date, the most common polymers are polylactic acid (PGA); poly-(L)-lactic acid (PLLA); poly- (lactic-co-glycolic acid) (PLGA); polyurethane (PU); polyester carbon and polycaprolactone (PCL). The possible complications, more common in synthetic than natural polymers are poor cell adhesion and the possibility of developing a foreign body reaction or aseptic inflammation, leading to alter the joint architecture and consequently to worsen the functional outcomes. The biological materials that have been used over time are the periosteal tissue, the perichondrium, the small intestine submucosa (SIS), acellular porcine meniscal tissue, bacterial cellulose. Although these have a very high biocompatibility, some components are not suitable for tissue engineering as their conformation and mechanical properties cannot be modified. Collagen or proteoglycans are excellent candidates for meniscal engineering, as they maintain a high biocompatibility, they allow for the modification of the porosity texture and size and the adaptation to the patient meniscus shape. On the other hand, they have poor biomechanical characteristics and a more rapid degradation rate, compared to others, which could interfere with the complete replacement by the host tissue. An interesting alternative is represented by hydrogel scaffolds. Their semi-liquid nature allows for the generation of scaffolds with very precise geometries obtained from diagnostic images (i.e. MRI). Promising results have been reported with alginate and polyvinyl alcohol (PVA). Furthermore, hydrogel scaffolds can be enriched with growth factors, platelet-rich plasma (PRP) and Bone Marrow Aspirate Concentrate (BMAC). In recent years, several researchers have developed meniscal scaffolds combining different biomaterials, to optimize the mechanical and biological characteristics of each polymer. For example, biological polymers such as chitosan, collagen and gelatin allow for excellent cellular interactions, on the contrary synthetic polymers guarantee better biomechanical properties and greater reliability in the degradation time. Three-dimensional (3D) printing is a very interesting method for meniscus repair because it allows for a patient-specific customization of the scaffolds. The optimal scaffold should be characterized by many biophysical and biochemical properties as well as bioactivity to ensure an ECM-like microenvironment for cell survival and differentiation and restoration of the anatomical and mechanical properties of the native meniscus. The new technological advances in recent years, such as 3D bioprinting and mesenchymal stem cells management will probably lead to an acceleration in the design, development, and validation of new and effective meniscal substitutes

Functionalization of biomimetic nanomaterials allows to reproduce the composition of native bone, permitting better regeneration, while nanoscale surface morphologies provide cues for cell adhesion, proliferation and differentiation. Functionalization of 3D printed and bioprinted constructs, by plasma-assisted deposition of calcium phosphates-based (CaP) nanostructured coatings and by nanoparticles, respectively, will be presented. Stoichiometric and ion doped CaP- based nanocoatings, including green materials (mussel seashells and cuttlefish bone), will be introduced to guide tissue regeneration. We will show interactions between biomimetic surfaces and MSCs to address bone regeneration and SAOS-2 cells for bone tumor models. Our results show that combining AM and nanostructured biomimetic films permits to reproduce the architecture and the mechanical and compositional characteristics of bone. Stability behavior of the coatings, as well as MSCs behavior strongly depend on the starting CaP material, with more soluble CaPs and ion-doped ones showing better biological behavior. Green materials appear promising, as biomimetic films can be successfully obtained upon conversion of the marine precursors into hydroxyapatite. Last-not-least, nanoparticles-loaded scaffolds could be bioprinting without loss of cell viability, but ink characteristics depend on ion-doping as demonstrated for SAOS-2 cells over 14 days of culture. Biomimetic nanomaterials for functionalization in AM is a promising approach for bone modelling and regeneration

Cell culture on tissue culture plastic (TCP) is widely used across biomedical research to understand the in vivo environment of a targeted biological system. However, growing evidence indicates that the characteristics of cells investigated in this way differ substantially from their characteristics in the human body. The limitations of TCP monolayer cell cultures are especially relevant for chondrocytes, the cell population responsible for producing cartilage matrix, because their zonal organization in hyaline cartilage is not preserved in a flattened monolayer assay. Here, we contrast the response of primary human chondrocytes to inflammatory cytokines, tumor necrosis factor-alpha and interferon-gamma, via transcriptional, translational, and histological profiling, when grown either on TCP or within a 3D cell pellet (scaffold-less). We focus on anti-apoptotic (Bcl2), pro-apoptotic (Bax, Mff, Fis1), and senescent (MMP13, MMP1, PCNA, p16, p21) markers. We find that the 3D environment of the chondrocyte has a profound effect on the behavior and fate of the cell; in TCP monolayer cultures, chondrocytes become anti-apoptotic and undergo senescence in response to inflammatory cytokines, whereas in 3D cell pellet cultures, they exhibit a pro-apoptotic response. Our findings demonstrate that chondrocyte culture environment plays a pivotal role in cell behavior, which has important implications for the clinical applicability of in vitro research of cartilage repair. Although there are practical advantages to 2D cell cultures, our data suggest researchers should be cautious when drawing conclusions if they intend to extrapolate findings to in vivo phenomena. Our data demonstrates opposing chondrocyte responses in relation to apoptosis and senescence, which appear to be solely reliant on the environment of the culture system. This biological observation highlights that proper experimental design is crucial to increase the clinical utility of cartilage repair experiments and streamline their translation to therapy development

In severe cases of total knee arthroplasty which cannot be treated with off-the-shelf implants anymore custom-made knee implants may serve as one of the few remaining options to restore joint function or to prevent limb amputation. Custom-made implants are specifically designed and manufactured for one individual patient in a single-unit production, in which the surgeon is responsible for the implant design characteristics in consultation with the corresponding engineer. The mechanical performance of these custom-made implants is challenging to evaluate due to the unique design characteristics and the limited time until which the implant is needed. Nevertheless, the custom-made implant must comply with clinical and regulatory requirements. The design of custom-made implants is often based on a underlying reference implant with available biomechanical test results and well-known clinical performance. To support surgeons and engineers in their decision whether a specific implant design is suitable, a method is proposed to evaluate its mechanical performance. The method uses finite element analysis (FEA) and comprises six steps: (1) Identification of the main potential failure mechanism and its corresponding FEA quantity of interest. (2) Reproduction of the biomechanical test of the reference implant via FEA. (3) Identification of the maximum value of the corresponding FEA quantity of interest at the required load level. (4) Definition of this value as the acceptance criteria for the FEA of the custom-made implant. (5) Reproduction of the biomechanical test with the custom-made implant via FEA. (6) Conclusion whether the acceptance criteria is fulfilled or not. The method was applied to two exemplary cases of custom-made knee implants. The FEA acceptance criteria derived from the reference implants were fulfilled in both custom-made implants. Subsequent biomechanical tests verified the FEA results. This study suggests and applies a non-destructive and efficient method for pre-clinical testing of a single-unit custom-made knee implant to evaluate whether the design is mechanically suitable

An increased number of neutrophils (NEUs) has long been associated with infections in the knee joints; their contribution to knee osteoarthritis (KOA) pathophysiology remains largely unexplored. This study aimed to compare the phenotypic and functional characteristics of synovial fluid (SF)-derived NEUs in KOA and knee infection (INF). Flow cytometric analysis, protein level measurements (ELISA), NEU oxidative burst assays, detection of NEU phagocytosis (pHrodo. TM. Green Zymosan Biparticles. TM. Conjugate for Phagocytosis), morphological analysis of the SF-derived/synovial tissue NEUs, and cultivation of human umbilical vein endothelial cells (HUVECs) using SF supernatant were used to characterise NEUs functionally/morphologically. Results: Compared with INF NEUs, KOA NEUs were characterised by a lower expression of CD11b, CD54 and CD64, a higher expression of CD62L, TLR2 and TLR4, and lower production of inflammatory mediators and proteases, except CCL2. Functionally, KOA NEUs displayed an increased production of radical oxygen species and phagocytic activity compared with INF NEUs. Morphologically, KOA and INF cells displayed different cell sizes and morphology, histological characteristics of the surrounding synovial tissues and influence on endothelial cells. KOA NEUs were further subdivided into two groups: SF containing <10% and SF with 10%–60% of NEUs. Analyses of two KOA NEU subgroups revealed that NEUs with SF <10% were characterised by 1) higher CD54, CD64, TLR2 and TLR4 expression on their surface; 2) higher concentrations of TNF-α, sTREM-1, VILIP-1, IL-1RA and MMP-9 in SFs. Our findings reveal a key role for NEUs in the pathophysiology of KOA, indicating that these cells are morphologically and functionally different from INF NEUs. Further studies should explore the mechanisms that contribute to the increased number of NEUs and their crosstalk with other immune cells in KOA. This study was supported by the Ministry of Health of the Czech Republic (NU20-06-00269; NU21-06-00370)

Abstract. BACKGROUND. Cell culture on tissue culture plastic (TCP) is widely used across biomedical research to understand the in vivo environment of a targeted biological system. However, growing evidence indicates that the characteristics of cells investigated in this way differ substantially from their characteristics in the human body. The limitations of TCP monolayer cell cultures are especially relevant for chondrocytes, the cell population responsible for producing cartilage matrix, because their zonal organization in hyaline cartilage is not preserved in a flattened monolayer assay. OBJECTIVE. Here, we contrast the response of primary human chondrocytes to inflammatory cytokines, tumor necrosis factor-alpha and interferon-gamma, via transcriptional, translational, and histological profiling, when grown either on TCP or within a 3D cell pellet (scaffold-less). We focus on anti-apoptotic (Bcl2), pro-apoptotic (Bax, Mff, Fis1), and senescent (MMP13, MMP1, PCNA, p16, p21) markers. RESULTS. We find that the 3D environment of the chondrocyte has a profound effect on the behavior and fate of the cell; in TCP monolayer cultures, chondrocytes become anti-apoptotic and undergo senescence in response to inflammatory cytokines, whereas in 3D cell pellet cultures, they exhibit a pro-apoptotic response. CONCLUSION. Our findings demonstrate that chondrocyte culture environment plays a pivotal role in cell behavior, which has important implications for the clinical applicability of in vitro research of cartilage repair. Although there are practical advantages to 2D cell cultures, our data suggest researchers should be cautious when drawing conclusions if they intend to extrapolate findings to in vivo phenomena. Our data demonstrates opposing chondrocyte responses in relation to apoptosis and senescence, which appear to be solely reliant on the environment of the culture system. This biological observation highlights that proper experimental design is crucial to increase the clinical utility of cartilage repair experiments and streamline their translation to therapy development. 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

Introduction. Recent studies suggested that the progression of osteoarthritis (OA), a chronic degenerative joint disease, may be affected by the autonomic nervous system (ANS). Under healthy conditions, the sympathetic (SNS) and parasympathetic (PNS) branches of the ANS are well coordinated to maintain homeostasis. However, pathological conditions are frequently associated with a disturbance of this fine-tuned balance. Therefore, we analyzed whether an autonomic dysfunction occurs in OA patients. Method. 225 participants with early- or late-stage knee OA as well as 40 healthy age-matched probands were included in this study. Autonomic activity was investigated by analyzing heart rate variability (HRV), which decreases under chronic sympathetic overactivity. Time- and frequency-domain HRV indices SDRR, RMSSD, pRR50 and LF were examined. Linear regression analysis was performed to adjust for clinical characteristics, such as age, sex, BMI, or medication. Moreover, perceived chronic stress (PSQ) and pain (WOMAC) were assessed via questionnaires. In addition, the serum stress hormones cortisol, DHEA-S and IL-6 were analyzed via ELISA. Result. SDRR, RMSSD, and pRR50 were slightly reduced in the early stage of OA and showed significant decrease in the later stage of the disease. Also LF decreased significantly with OA progression. HRV was significantly influenced by the grade of OA, but not other patient characteristics. Moreover, late-stage OA patients demonstrated significantly higher PSQ and WOMAC levels compared to healthy controls. In addition, cortisol/DHEA-S ratio and IL-6 serum concentrations were significantly higher in late-stage than in early-stage OA patients and healthy controls. Conclusion. Reduced HRV, increased cortisol/DHEA-S ratio and PSQ level as well as elevated systemic IL-6 concentration indicated an autonomic shift towards a more pronounced SNS activity due to PNS deficiency in OA patients, particularly in the late-stage of the disease. Therefore, modulation of the ANS, for example by vagus nerve stimulation, might be a potential treatment strategy for of knee OA patients

Quantitative ultrasound (QUS) is a promising tool to estimate bone structure characteristics and predict fragile fracture. The aim of this pilot cross-sectional study was to evaluate the performance of a multi-channel residual network (MResNet) based on ultrasonic radiofrequency (RF) signal to discriminate fragile fractures retrospectively in postmenopausal women. Methods. RF signal and speed of sound (SOS) were obtained using an axial transmission QUS at one‐third distal radius for 246 postmenopausal women. Based on the involved RF signal, we conducted a MResNet, which combines multi-channel training with original ResNet, to classify the high risk of fragility fractures patients from all subjects. The bone mineral density (BMD) at lumber, hip and femoral neck acquired with DXA was recorded on the same day. The fracture history of all subjects in adulthood were collected. To assess the ability of the different methods in the discrimination of fragile fracture, the odds ratios (OR) calculated using binomial logistic regression analysis and the area under the receiver operator characteristic curves (AUC) were analyzed. Results. Among the 246 postmenopausal women, 170 belonged to the non-fracture group, 50 to the vertebral group, and 26 to the non-vertebral fracture group. MResNet was discriminant for all fragile fractures (OR = 2.64; AUC = 0.74), for Vertebral fracture (OR = 3.02; AUC = 0.77), for non-vertebral fracture (OR = 2.01; AUC = 0.69). MResNet showed comparable performance to that of BMD of hip and lumbar with all types of fractures, and significantly better performance than SOS all types of fractures. Conclusions. the MResNet model based on the ultrasonic RF signal can significantly improve the ability of QUS device to recognize previous fragile fractures. Moreover, the performance of the proposed model modified by age, weight, and height is further optimized. These results open perspectives to evaluate the risk of fragile fracture applying a deep learning model to analyze ultrasonic RF signal

Biphasic calcium phosphate (BCP) with a characteristic needle-shaped submicron surface topography (MagnetOs) has attracted much attention due to its unique bone-forming ability which is essential for repairing critical-size bone defects such as those found in the posterolateral spine. Previous in vitro and ex-vivo data performed by van Dijk LA and Yuan H demonstrated that these specific surface characteristics drive a favorable response from the innate immune system. This study aimed to evaluate and compare the in vivo performance of three commercially-available synthetic bone grafts, (1) i-FACTOR Putty. ®. , (2) OssDsign. ®. Catalyst Putty and (3) FIBERGRAFT. ®. BG Matrix, with that of a novel synthetic bone graft in a clinically-relevant instrumented sheep posterolateral lumbar spine fusion (PLF) model. The novel synthetic bone graft comprised of BCP granules with a needle-shaped submicron surface topography (MagnetOs) embedded in a highly porous and fibrillar collagen matrix (MagnetOs Flex Matrix). Four synthetic bone grafts were implanted as standalone in an instrumented sheep PLF model for 12 weeks (n=3 bilateral levels per group; levels L2/3 & L4/5), after which spinal fusion was determined by manual palpation, radiograph and µCT imaging (based on the Lenke scale), range-of-motion mechanical testing, and histological and histomorphological evaluation. Radiographic fusion assessment determined bilateral robust bone bridging (Lenke scale A) in 3/3 levels for MagnetOs Flex Matrix compared to 1/3 for all other groups. For µCT, bilateral fusion (Lenke scale A) was found in 2/3 levels for MagnetOs Flex Matrix, compared to 0/3 for i-FACTOR Putty. ®. , 1/3 for OssDsign. ®. Catalyst Putty and 0/3 for FIBERGRAFT. ®. BG Matrix. Fusion assessment for MagnetOs Flex Matrix was further substantiated by histology which revealed significant graft resorption complemented by abundant bone tissue and continuous bony bridging between vertebral transverse processes resulting in bilateral spinal fusion in 3/3 implants. These results show that MagnetOs Flex Matrix achieved better fusion rates compared to three commercially-available synthetic bone grafts when used as a standalone in a clinically-relevant instrumented sheep PLF model

The Spine Surgery Unit of IRCCS Istituto Ortopedico Rizzoli is dedicated to the diagnosis and the treatment of vertebral pathologies of oncologic, degenerative, and post-traumatic origin. To achieve increasingly challenging goals, research has represented a further strength for Spinal Surgery Unit for several years. Thanks to the close synergy with the Complex Structure Surgical Sciences and Technologies, IRCCS Istituto Ortopedico Rizzoli, extensive research was carried out. The addition of the research activities intensifies a complementary focus and provides a unique opportunity of innovation. The overall goal of spine research for the Spine Surgery Unit and for the Complex Structure Surgical Sciences and Technologies is and has been to:. - investigate the factors that influence normal spine function;. - engineer and validate new and advanced strategies for improving segmental spinal instrumentation, fusion augmentation and grafting;. - develop and characterize advanced and alternative preclinical models of vertebral bone metastasis to test drugs and innovative strategies, taking into account patient individual characteristics and specific tumour subtypes so predicting patient specific responses;. - evaluate the clinical characteristics, treatment modalities, and potential contributing and prognostic factors in patients with vertebral bone metastases;. - realize customized prosthesis to replace vertebral bodies affected by tumours or major traumatic events, specifically engineered to reduce infections, and increase patients’ surgical options. These efforts have made possible to obtain important results that favour the translation of basic research to application at the patient's bedside, and from here to routine clinical practice (without excluding the opposite pathway, in which the evidence generated by clinical practice helps to guide research). Although translational research can provide patients with valuable therapeutic resources, it is not risk-free. Thus, it is therefore necessary an always close collaboration between researchers and clinicians in order to guarantee the ethicality of translational research, by promoting the good of individuals and minimising the risks

Our knowledge of primary bone marrow edema (BME) of the knee is still limited. A major contributing factor is that it shares several radiological findings with a number of vascular, traumatic, and inflammatory conditions having different histopathological features and etiologies. BME can be primary or secondary. The most commonly associated conditions are osteonecrosis, osteochondritis dissecans, complex regional pain syndrome, mechanical strain such as bone contusion/bruising, micro-fracture, stress fracture, osteoarthritis, and tumor. The etiology and pathogenesis of primary BME are unclear. Conservative treatment includes analgesics, non-steroidal anti-inflammatory drugs, weight-bearing limitations, physiotherapy, pulsed electromagnetic fields, prostacyclin, and bisphosphonates. Surgical treatment, with simple perforation, fragment stabilization, combined scraping and perforation, and eventually osteochondral or chondrocyte transplant, is reserved for the late stages. This retrospective study of a cohort of patients with primary BME of the knee was undertaken to describe their clinical and demographic characteristics, identify possible risk factors, and assess treatment outcomes. We reviewed the records of 48 patients with primary BME of the knee diagnosed on MRI by two radiologists and two orthopedists. History, medications, pain type, leisure activities, smoking habits, allergies, and environmental factors were examined. Analysis of patients’ characteristics highlighted that slightly overweight middle-aged female smokers with a sedentary lifestyle are the typical patients with primary BME of the knee. In all patients, the chief symptom was intractable day and night pain (mean value, 8.5/10 on the numerical rating scale) with active as well as passive movement, regardless of BME extent. Half of the patients suffered from thyroid disorders; indeed, the probability of having a thyroid disorder was higher in our patients than in two unselected groups of patients, one referred to our orthopedic center (odds ratio, 18.5) and another suffering from no knee conditions (odds ratio, 9.8). Before pain onset, 56.3% of our cohort had experienced a stressful event (mourning, dismissal from work, concern related to the COVID-19 pandemic). After conservative treatment, despite the clinical improvement and edema resolution on MRI, 93.8% of patients described two new symptoms: a burning sensation in the region of the former edema and a reduced ipsilateral patellar reflex. These data suggest that even though the primary BME did resolve on MRI, the knee did not achieve full healing

Abstract. Objectives. Osteoarthritis (OA) is a painful and debilitating disorder of diarthroidal joints. Progressive degeneration of the cartilage extracellular matrix (ECM) together with abnormal chondrocyte characteristics occur leading to a switch to a fibroblast-like phenotype and production of mechanically-weak cartilage. Early changes to chondrocytes within human cartilage have been observed including chondrocyte swelling. [1]. together with the development of thin cytoplasmic processes which increase in number and length with degeneration. [2]. Changes to chondrocyte phenotype in degenerate cartilage are associated with F-actin redistribution and stress fibres (SF) formation, leading to morphologically-dedifferentiated (fibroblast-like) chondrocytes. [3,4]. It is unclear if these processes are a consequence of ‘passive’ cell swelling into a defective ECM or an ‘active’ event driven by changes in cell metabolism resulting in alterations to cell shape. To address this, we have quantified and compared the distribution and levels of F-actin, a key cytoskeletal protein involved in the formation of cytoplasmic processes, within in situ chondrocytes in non-degenerate and mildly degenerate human cartilage. Methods. Human femoral head cartilage was obtained from 21 patients [15 females, 6 males, average age 69.6yrs, (range 47–90yrs)] following femoral neck fracture, with Ethical Approval and patient's permission. Cartilage explants were removed from areas graded non-degenerate grade 0 (G0) or mildly degenerate grade 1 (G1) and cultured for up to 3wks in Dulbecco's Modified Eagle's Medium (DMEM) +/− 25% human serum (HS). In situ chondrocytes were stained with CMFDA (5-chloromethylfluoresceindiacetate, Cell-Tracker Green®) and phalloidin (F-actin labelling) and imaged by confocal microscopy and analysed quantitatively using ImageJ and Imaris® software. Results. There were significant increases in the total amount (TA) of F-actin and its distribution [intense punctuate (IP) and intense areas (IA)] between the whole chondrocyte populations of G0 and G1 cartilage (P=0.0356; 0.0112; 0.016, respectively). Where the volume of chondrocytes was divided into normal (<1000 µm³) and swollen (≥1000 µm³) cells, F-actin TA increased in swollen cells (P=0.036 within G0 and G1, and P=0.0009 between grades) compared to chondrocytes of normal volume in each grade. Moreover, IP and IA within and between G0 and G1 were higher compared to normal chondrocytes (with P<0.0001 for IP and P<0.001 for IA). In addition, tissue culture experiments demonstrated that 90% of chondrocytes with cytoplasmic processes had strong F-actin intensity (either IP or IA with P<0.0001). Furthermore, 83% of this F-actin was associated with cytoplasmic processes, with >65% situated at the base of the process (P<0.0001). Conclusions. The increases in chondrocyte F-actin levels (TA) and its localisation (IP, IA) appear to be associated with cell swelling and development of cytoplasmic processes, which are both characteristics of early OA cartilage. [1]. This suggests the formation of chondrocyte cytoplasmic processes is an ‘active’ event potentially involving changes to matrix metabolism rather than a ‘passive’ cell swelling into a defective extracellular matrix. 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

Abstract. Objectives. Spinal stiffness and flexibility terms are typically evaluated from linear regression of experimental data and are then assembled into 36-element matrices. Summarising in vitro test results in this manner is quick, computationally cheap and has the distinct advantage of outputting simple characteristic values which make it easy to compare results. However, this method disregards many important experimental features such as stiffening effects, neutral and elastic zones magnitudes, extent of asymmetry and energy dissipation (hysteresis). Alternatives to the linear least squares method include polynomials, separation of the load-displacement behaviour into the neutral and elastic zones using various deterministic methods and variations on the double sigmoid and Boltzmann curve fits. While all these methods have their advantages, none provide a comprehensive and complete characterisation of the load-displacement behaviour of spine specimens. In 1991, Panjabi demonstrated that the flexion-extension and mediolateral bending behaviour of functional spinal units could be approximated using the viscoelastic model consisting of a nonlinear spring in series with a linear Kelvin element. Nowadays viscoelastic models are mainly used to describe creep and stress relaxation, rather than for cyclic loading. The aim of this study was to conclusively prove the viscoelastic nature of spinal behaviour subject to cyclic loading. Being able to describe the behaviour of spine specimens using springs and dampers would yield characterising coefficients with recognisable physical meaning, thus providing an advantage over existing techniques. Methods. Six porcine isolated spinal disc specimens (ISDs) were tested under position and load control. Visual inspection of the load-displacement graphs from which the principal terms of the stiffness and flexibility matrices are derived suggest that the load-displacement behaviour could be idealised by a nonlinear spring system with damping. It was hypothesised that the contributions arising from non-linear spring-like behaviour and damping could be separated for each of the principal load-displacement graphs. Results. The principal elements from position and load control tests were plotted with load on the vertical axis and displacement on the horizontal axis, and a polynomial representing spring force was fitted to the data. This polynomial was subtracted from the experimental data. The remainder - representing damping force - was plotted against displacement and velocity and compared to idealised plots for different types of damping behaviour. Applying this reasoning to the six principal load-displacement plots obtained from stiffness and flexibility tests revealed that four of six exhibit behaviour which is a combination of a nonlinear hardening spring and viscous damper. However, for flexion-extension and mediolateral bending, the damping behaviour is more akin to coulomb damping with viscous influences, characterised by a steep central linear region and near horizontal regions at the extremes. These trends were common amongst all six specimens within the study sample size. Conclusions. The unique approach described here has allowed the characterisation of the load-displacement behaviour of ISDs in terms of characteristic mass-spring-damper systems. This is an important development which allows experimental findings to be framed in terms of mechanical contributions to a given load-displacement behaviour. 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

Infection in orthopedics is a challenge, since it has high incidence (rates can be up to 15-20%, also depending on the surgical procedure and on comorbidities), interferes with osseointegration and brings severe complications to the patients and high societal burden. In particular, infection rates are high in oncologic surgery, when biomedical devices are used to fill bone gaps created to remove tumors. To increase osseointegration, calcium phosphates coatings are used. To prevent infection, metal- and mainly silver-based coatings are the most diffused option. However, traditional techniques present some drawbacks, including scarce adhesion to the substrate, detachments, and/or poor control over metal ions release, all leading to cytotoxicity and/or interfering with osteointegration. Since important cross-relations exist among infection, osseointegration and tumors, solutions capable of addressing all would be a breakthrough innovation in the field and could improve clinical practice. Here, for the first time, we propose the use antimicrobial silver-based nanostructured thin films to simultaneously discourage infection and bone metastases. Coatings are obtained by Ionized Jet Deposition, a plasma-assisted technique that permits to manufacture films of submicrometric thickness having a nanostructured surface texture. These characteristics, in turn, allow tuning silver release and avoid delamination, thus preventing toxicity. In addition, to mitigate interference with osseointegration, here silver composites with bone apatite are explored. Indeed, capability of bone apatite coatings to promote osseointegration had been previously demonstrated in vitro and in vivo. Here, antibacterial efficacy and biocompatibility of silver-based films are tested in vitro and in vivo. Finally, for the first time, a proof-of-concept of antitumor efficacy of the silver-based films is shown in vitro. Coatings are obtained by silver and silver-bone apatite composite targets. Both standard and custom-made (porous) vertebral titanium alloy prostheses are used as substrates. Films composition and morphology depending on the deposition parameters are investigated and optimized. Antibacterial efficacy of silver films is tested in vitro against gram+ and gram- species (E. coli, P. aeruginosa, S. aureus, E. faecalis), to determine the optimal coatings characteristics, by assessing reduction of bacterial viability, adhesion to substrate and biofilm formation. Biocompatibility is tested in vitro on fibroblasts and MSCs and, in vivo on rat models. Efficacy is also tested in an in vivo rabbit model, using a multidrug resistant strain of S. aureus (MRSA, S. aureus USA 300). Absence of nanotoxicity is assessed in vivo by measuring possible presence of Ag in the blood or in target organs (ICP-MS). Then, possible antitumor effect of the films is preliminary assessed in vitro using MDA-MB-231 cells, live/dead assay and scanning electron microscopy (FEG-SEM). Statistical analysis is performed and data are reported as Mean ± standard Deviation at a significance level of p <0.05. Silver and silver-bone apatite films show high efficacy in vitro against all the tested strains (complete inhibition of planktonic growth, reduction of biofilm formation > 50%), without causing cytotoxicity. Biocompatibility is also confirmed in vivo. In vivo, Ag and Ag-bone apatite films can inhibit the MRSA strain (>99% and >86% reduction against ctr, respectively). Residual antibacterial activity is retained after explant (at 1 month). These studies indicate that IJD films are highly tunable and can be a promising route to overcome the main challenges in orthopedic prostheses

Introduction and Objective. Clinically, it is considered that spastic muscles of patients with cerebral palsy (CP) are shortened, and produce higher force in shorter muscle lengths. Yet, direct quantification of spastic muscles’ forces is rare. Remarkably, previous intraoperative tests in which muscle forces are measured directly as a function of joint angle showed for spastic gracilis (GRA) that its passive forces are low, and only a small percentage of its maximum active force is measured in flexed knee positions. However, the relationship of force characteristics of spastic GRA with its muscle-tendon unit length (l. MTU. ) is unknown. Combining intraoperative experiments with participants’ musculoskeletal models developed based on their gait analyses, we aimed to test if spastic GRA muscle (1) operates at short l. MTU. compared to that of typically developing (TD) children, and exerts higher (2) passive and (3) active forces at shorter lengths, within gait-relevant l. MTU. range. Materials and Methods. Ten limbs of seven children with CP (GMFCS-II) were tested. Pre-surgery, gait analyses were conducted. Intraoperatively, isometric spastic GRA distal forces were measured in ten hip-knee joint angle combinations, in two conditions: (i) passive state and (ii) maximal activation of the GRA exclusively. In OpenSim, gait_2392 model was used for each limb to calculate l. MTU. 's per each hip and knee angle combination and the gait-relevant l. MTU. range, and to analyze gait relevant spastic muscle force - l. MTU. data. l. MTU. values were normalized for the participants’ thigh lengths. Two-way ANOVA was used to compare the patients’ l. MTU. to those of the seven age-matched TD children to test the first hypothesis. In order to test the second and the third hypotheses, Spearman's rank correlation coefficient (ρ) was calculated to seek a correlation between the muscle's operational length (represented by mean l. MTU. within gait cycle) and muscular force characteristics (the percent force at shortest l. MTU. of peak force, either in passive or in active conditions) within gait-relevant l. MTU. range. Results. ANOVA showed that l. MTU. 's of spastic GRA are shorter (on average by 15.4%) compared to those of TD. At the shortest gait-relevant l. MTU. , the GRA passive force was 84.6 (13.7)% of the peak passive force; and the active force was 55.8 (33.9)% of the peak active force. Passive state forces show an increase at longer lengths, whereas active state force characteristics vary in a patient-specific way. Spearman's rank correlation indicated weak correlations between muscle's operational length and muscular force characteristics (ρ= −0.30 P= 0.40, and ρ= −0.27 P= 0.45, for passive and active states, respectively). Therefore, only the first hypothesis was confirmed. Conclusions. Novel muscle force - l. MTU. data for spastic GRA were obtained using intraoperative data and modelling combined. The modelling showed in concert with the clinical considerations that spastic GRA may be a shortened muscle. However, because the model does not distinguish the muscle-belly and tendon lengths, it cannot isolate shorter muscle belly length and how this compares to the data of TD children remains unknown. Moreover, the absence of a strong correlation between shorter operational muscle length and higher force production either in passive or in active conditions highlights the influence of other factors (e.g., muscle structural proteins, and muscle mechanical characteristics including intermuscular interactions etc.) on the pathology rather than ascribing it solely to the length of a spastic muscle itself

After initial hesitance and failures, with growing knowledge about advanced products and their characteristics, increasingly more medtech and also pharma companies enter the advanced therapies market. However, due to the specifics of the biology and regulation of advanced therapy products, a lot of new know-how is necessary to be successful in this highly promising field

Intra-articular cartilage pressure distribution in the knee joint is critical in the understanding of osteoarthritis. Combining personalized statistical modeling of the morphological characteristics with discrete element modeling enables patient-specific predictions of the pressure on the tibial plateau. However, modeling of the meniscus during gait is complicated by the dynamic nature of the structure. Nevertheless, the position of the meniscus has a substantial impact on intra-articular stress distribution. Therefore, the focus of this presentation will be on how modeling of meniscal movement during knee flexion improves insight in general meniscal kinematics for the use in tibiofemoral stress distribution calculations