Surgical education of fracture fixation biomechanics relies mainly on simplified illustrations to distill the essence of the underlying principles. These mostly consist of textbook drawings or hands-on exercises during courses, both with unique advantages such as broad availability and haptics, respectively. Computer simulations are suited to bridge these two approaches; however, the validity of such simulations must be guaranteed to teach the correct aspects. Therefore, the aim of this study was to validate finite element (FE) simulations of bone-plate constructs to be used in surgical education in terms of fracture gap movement and implant surface strain. The validation procedure was conducted in a systematic and hierarchical manner with increasing complexity. First, the material properties of the isolated implant components were determined via four-point bending of the plate and three-point bending of the screw. Second, stiffness of the screw-plate interface was evaluated by means of cantilever bending to determine the properties of the locking mechanism. Third, implant surface strain and fracture gap motion were measured by testing various configurations of entire fixation constructs on artificial bone (Canevasit) in axial compression. The determined properties of the materials and interfaces assessed in these experiments were then implemented into FE models of entire fixation constructs with different fracture width and screw configurations. The FE-predicted implant surface strains and fracture gap motions were compared with the experimental results. The simulated results of the different construct configurations correlated strongly with the experimentally measured fracture gap motions (R. 2. >0.99) and plate surface strains (R. 2. >0.95). In a systematic approach, FE model validation was achieved successfully in terms of fracture gap motion and implant deformation, confirming trustworthiness for surgical education. These validated models are used in a novel online education tool OSapp (. https://osapp.ch/. ) to illustrate and explain the biomechanical principles of fracture fixations in an interactive manner

The regenerative capacity of hyaline cartilage is greatly limited. To prevent the onset of osteoarthritis, cartilage defects have to be properly treated. Cartilage, tissue engineered by mean of bioactive glass (BG) scaffolds presents a promising approach. Until now, conventional BGs have been used mostly for bone regeneration, as they are able to form a hydroxyapatite (HA) layer and are therefore, less suited for cartilage reconstruction. The aim of this study is to compare two BGs based on a novel BG composition tailored specifically for cartilage (CAR12N) and patented by us with conventional BG (BG1393) with a similar topology. The highly porous scaffolds consisting of 100% BG (CAR12N, CAR12N with low Ca2+/Mg2+ and BG1393) were characterized and dynamically seeded with primary porcine articular chondrocytes (pACs) or primary human mesenchymal stem cells (hMSCs) for up to 21 days. Subsequently, cell viability, DNA and glycosaminoglycan contents, cartilage-specific gene and protein expression were evaluated. The manufacturing process led to a comparable high (over 80%) porosity in all scaffold variants. Ion release and pH profiles confirmed bioactivity for them. After both, 7 and 21 days, more than 60% of the total surfaces of all three glass scaffold variants was densely colonized by cells with a vitality rate of more than 80%. The GAG content was significantly higher in BG1393 colonized with pACs. In general, the GAG content was higher in pAC colonized scaffolds in comparison to those seeded with hMSCs. The gene expression of cartilage-specific collagen type II, aggrecan, SOX9 and FOXO1 could be detected in all scaffold variants, irrespectively whether seeded with pACs or hMSCs. Cartilage-specific ECM components could also be detected at the protein level. In conclusion, all three BGs allow the maintenance of the chondrogenic phenotype or chondrogenic differentiation of hMSCs and thus, they present a high potential for cartilage regeneration

Abstract. OBJECTIVES. Application of deep learning approaches to marker trajectories and ground reaction forces (mocap data), is often hampered by small datasets. Enlarging dataset size is possible using some simple numerical approaches, although these may not be suited to preserving the physiological relevance of mocap data. We propose augmenting mocap data using a deep learning architecture called “generative adversarial networks” (GANs). We demonstrate appropriate use of GANs can capture variations of walking patterns due to subject- and task-specific conditions (mass, leg length, age, gender and walking speed), which significantly affect walking kinematics and kinetics, resulting in augmented datasets amenable to deep learning analysis approaches. METHODS. A publicly available (. https://www.nature.com/articles/s41597-019-0124-4. ) gait dataset (733 trials, 21 women and 25 men, 37.2 ± 13.0 years, 1.74 ± 0.09 m, 72.0 ± 11.4 kg, walking speeds ranging from 0.18 m/s to 2.04 m/s) was used as the experimental dataset. The GAN comprised three neural networks: an encoder, a decoder, and a discriminator. The encoder compressed experimental data into a fixed-length vector, while the decoder transformed the encoder's output vector and a condition vector (containing information about the subject and trial) into mocap data. The discriminator distinguished between the encoded experimental data from randomly sampled vectors of the same size. By training these networks jointly using the experimental dataset, the generator (decoder) could generate synthetic data respecting specified conditions from randomly sampled vectors. Synthetic mocap data and lower limb joint angles were generated and compared to the experimental data, by identifying the statistically significant differences across the gait cycle for a randomly selected subset of the experimental data from 5 female subjects (73 trials, aged 26–40, weighing 57–74 kg, with leg lengths between 868–931 mm, and walking speeds ranging from 0.81–1.68 m/s). By conducting these comparisons for this subset, we aimed to assess the synthetic data generated using multiple conditions. RESULTS. We visually inspected the synthetic trials to ensure that they appeared realistic. The statistical comparison revealed that, on average, only 2.5% of the gait cycle showed significantly differences in the joint angles of the two data groups. Additionally, the synthetic ground reaction forces deviated from the experimental data distribution for an average of 2.9% of the gait cycle. CONCLUSIONS. We introduced a novel approach for generating synthetic mocap data of human walking based on the conditions that influence walking patterns. The synthetic data closely followed the trends observed in the experimental data, also in the literature, suggesting that our approach can augment mocap datasets considering multiple conditions, an approach unfeasible in previous work. Creation of large, augmented datasets allows the application of other deep learning approaches, with the potential to generate realistic mocap data from limited and non-lab-based data. Our method could also enhance data sharing since synthetic data does not raise ethical concerns. You can generate and download virtual gait data using our GAN approach from . https://thisgaitdoesnotexist.streamlit.app/. . 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. Focal articular cartilage defects do not heal and, left untreated, progress to more widespread degenerative changes. A promising new approach for the repair of articular cartilage defects is the application of cell-based regenerative therapies using mesenchymal stromal cells (MSCs). MSCs are however present in a number of tissues and studies suggest that they vary in their proliferation, cell surface characterisation and differentiation. As the phenotypic properties of MSCs vary depending on tissue source, a systematic comparison of the transcriptomic signature would allow a better understanding of these differences between tissues, and allow the identification of markers specific to a MSC source that is best suited for clinical application. Tissue was used from patients undergoing total knee replacement surgery for osteoarthritis following ethical approval and informed consent. MSCs were isolated from bone, cartilage, synovium and infrapatellar fat pad. MSC number and expansion were quantified. Following expansion in culture, MSCs were characterised using flow cytometry with several cell surface markers; the cells from all sources were positive for CD44, CD90 and CD105. Their differentiation potential was assessed through tri-lineage differentiation assays. In addition, bulk mRNA-sequencing was used to determine the transcriptomic signatures. Differentially expressed (DE) genes were predicted. An enrichment analysis focused on the DE genes, against GO and pathway databases (KEGG and Reactome) was performed; protein-protein interaction networks were also inferred (Metascape, Reactome, Cytoscape). Optimal sourcing of MSCs will amplify their cartilage regeneration potential. This is imperative for assessing future therapeutic transplantation to maximise the chance of successful cartilage repair. A better understanding of differences in MSCs from various sources has implications beyond cartilage repair

Introduction and Objective. Local cartilage defects in the knee are painful and mostly followed by arthritis. In order to avoid impaired mobility, the osteochondral defect might be bridged by a synthetic compound material: An osteoconductive titanium foam as an anchoring material in the subchondral bone and an infiltrated polymer as gliding material in contact with the surrounding natural cartilage. Materials and Methods. Titanium foam cylinders (Ø38 mm) with porosities ranging from 57% to 77% were produced by powder metallurgy with two different grain sizes of the space holder (fine: 340 ± 110 μm, coarse: 530 ± 160 μm). The sintered titanium foam cylinders were infiltrated with UHMWPE powder on one end and UHMWPE bulk at the other end, at two different temperatures (160 °C, 200 °C), using a pressure of 20 MPa for 15 minutes. Smaller cylinders (Ø16 mm) were retrieved from the compound material by water jet cutting. The infiltration depths were determined by optical microscopy. The anchoring of the UHMWPE was measured by a shear test and the mechanical properties of the titanium foam were verified by a subsequent compression test. The tribological behaviour was investigated in protein containing liquid using fresh cartilage pins (Ø5 mm) sliding against a UHMWPE disc with or without a notch to simulate the gap between the implant and the surrounding cartilage. Friction coefficients were determined in a rotation tribometer and the cartilage wear in a multidirectional six-station tribometer from AMTI (load 10 – 50 N, sliding speed 20 mm/s, 37 °C). Results. UHMWPE could be infiltrated into titanium foam by 1.1 – 1.3 mm with fine pores and by 1.5 – 1.8 mm with coarse pores. The infiltration was neither dependent on the type of UHMWPE (powder or bulk) nor on the temperature. The polymer was so well anchored inside the titanium foam pores that the shear forces for the compounds exceeded the shear strength obtained for a UHMWPE-cylinder. This effect was due to the increased stiffness of the compound plug. Uniaxial compression of the titanium foams after the shear-off of the polymer revealed yield strengths ranging from 50 – 88 MPa for porosities of 62 – 73%. The Ø16 mm samples yielded beyond physiological loads in the knee (≥ 10x body weight) and behaved in a strain hardening and fully ductile manner, reaching deformations of at least 50 % of their initial height without the appearance of macroscopically visible cracks. For smaller plug diameters down to Ø8 mm, however, the lower porosity / higher strength foam should be used to limit elastic deformation of the compound to < 0.1 mm. Pore size did not significantly influence the strength and stiffness values. The elevated coefficient of friction between cartilage and UHMWPE of about 1 was not negatively affected by the presence of the gap. The height loss of the cartilage pin after 1 hour (respectively after 3600 reciproque wear cycles) was 0.2 ± 0.1 mm using a flat disc. For discs with a 1 mm wide V-notch, the wear increased to 0.9 ± 0.3 mm. Conclusions. The tested titanium foams are well suited to act as an anchoring material in the subchondral bone as mechanical properties can be tailored by choosing the adequate porosity and as bone ingrowth has previously been demonstrated for the used pore sizes. UHMWPE is not an ideal gliding partner against cartilage because the friction coefficients of frictions were high. The presence of a V-notched gap was detrimental for cartilage wear. More hydrophilic polymers like PCU should be tested as potential gliding materials

Objectives. The treatment of osteoporotic fractures is a major challenge, and the enhancement of healing is critical as a major goal in modern fracture management. Most osteoporotic fractures occur at the metaphyseal bone region but few models exist and the healing is still poorly understood. A systematic review was conducted to identify and analyse the appropriateness of current osteoporotic metaphyseal fracture animal models. Materials and Methods. A literature search was performed on the Pubmed, Embase, and Web of Science databases, and relevant articles were selected. A total of 19 studies were included. Information on the animal, induction of osteoporosis, fracture technique, site and fixation, healing results, and utility of the model were extracted. Results. Fracture techniques included drill hole defects (3 of 19), bone defects (3 of 19), partial osteotomy (1 of 19), and complete osteotomies (12 of 19). Drill hole models and incomplete osteotomy models are easy to perform and allow the study of therapeutic agents but do not represent the usual clinical setting. Additionally, biomaterials can be filled into drill hole defects for analysis. Complete osteotomy models are most commonly used and are best suited for the investigation of therapeutic drugs or noninvasive interventions. The metaphyseal defect models allow the study of biomaterials, which are associated with complex and comminuted osteoporotic fractures. Conclusion. For a clinically relevant model, we propose that an animal model should satisfy the following criteria to study osteoporotic fracture healing: 1) induction of osteoporosis, 2) complete osteotomy or defect at the metaphysis unilaterally, and 3) internal fixation. Cite this article: R. M. Y. Wong, M. H. V. Choy, M. C. M. Li, K-S. Leung, S. K-H. Chow, W-H. Cheung, J. C. Y. Cheng. A systematic review of current osteoporotic metaphyseal fracture animal models. Bone Joint Res 2018;7:6–11. DOI: 10.1302/2046-3758.71.BJR-2016-0334.R2

Whilst home-based exercise rehabilitation plays a key role in determining patient outcomes following orthopaedic intervention (e.g. total knee replacement), it is very challenging for clinicians to objectively monitor patient progress, attribute functional improvement (or lack of) to adherence/non-adherence and ultimately prescribe personalised interventions. This research aimed to identify whether 4 knee rehabilitation exercises could be objectively distinguished from each other using lower body inertial measurement units (IMUs) and principle components analysis (PCA) in the hope to facilitate objective home monitoring of exercise rehabilitation. 5 healthy participants performed 4 repetitions of 4 exercises (knee flexion in sitting, knee extension, single leg step down and sit to stand) whilst wearing lower body IMU sensors (Xsens, Holland; sampling at 60 Hz). Anthropometric measurements and a static calibration were combined to create the biomechanical model, with 3D hip, knee and ankle angles computed using the Euler sequence ZXY. PCA was performed on time normalised (101 points) 3D joint angle data which reduced all joint angle waveforms into new uncorrelated PCs via an orthogonal transformation. Scatterplots of PC1 versus PC2 were used to visually inspect for clustering between the PC values for the 4 exercises. A one-way ANOVA was performed on the first 3 PC values for the 9 variables under analysis. Games-Howell post hoc tests identified variables that were significantly different between exercises. All exercises were clearly distinguishable using the PC scatterplot representing hip flexion-extension waveforms. ANOVA results revealed that PC1 for the knee flexion angle waveform was the only PC value statistically different across all exercises. Findings demonstrate clear potential to objectively distinguish between different knee rehabilitation exercises using IMU sensors and PCA. Flexion-extension angles at the hip and knee appear most suited for accurate separation, which will be further investigated on patient data and additional exercises

To date there has been no material for endoprosthetics providing excellent resistance to abrasion and corrosion combined with great tensile strength, fracture toughness, and bending strength, as well as adequate biocompatibility. Carbon-fiber-reinforced silicon carbide (C/SiC, C/C-SiC or C/SiSiC) is as a ceramic compound a potentially novel biomaterial offering higher ductility and durability than comparable oxide ceramics. Aim of this investigation was to test the suitability of C/SiC ceramics as a new material for bearing couples in endoprosthetics. One essential quality that any new material must possess is biocompatibility. For this project the in-vitro biocompatibility was investigated by using cuboid like scaffolds made of CMC. To determine whether the material is suited as a lubricant partner in endoprosthetics, we measured its abrasion coefficient and wear tolerance against various antibodies. The C/SiC samples tested were produced via the Liquid Silicon Infiltration (LSI) of pyrolized porous fiber preforms made by warm-flow pressing free-flowing granulates on a hydraulic downstroking press with a heated die of the type HPS-S, 1000 kN. After preparation of the composites, the tribological characteristics are determined. Flexural strength was determined at room temperature according to DIN685-3 with an universal testing machine Z100 and the Young”s -modulus was carried out via resonant frequency-damping analysis RFDA. The samples”surface as well as cell adhesion and cell morphology were assessed via ESEM. The human osteoblast-like cell line MG-63 and human ostoeblast were used for cel culture ecperiments (WST, Live/dead, Cytotoxicity, cell morphology). Based on the raw data the mean value and the standard deviation were calculated. The Mann-Whitney-U-Test was used to evaluate the differences between experiment and control samples. The flexural strength at room temperature is approx. 180 MPa, while the elongation at break is about 0.13%. The Young”s modulus is detected between 120 and 150 GPa. The density lies between 2.5 and 3.0 g/cm. 3. We noted a friction coefficient µ between 0.31. The cell lines exhibited no morphological alterations, and adhered well to the C/SiC samples. Vitality was not impaired by contact with the ceramic composite. Cell growth was observed evenly distributed over a 21-day period. In the future, investigators aiming to apply this composite in endoprosthetics will have to focus on its efficacy in conjunction with sudden, strong demands, and long-term performance in bodily fluids within joint simulators, etc. In conclusion: C/SiC can definitely be considered a new material with genuine potential for use in endoprosthetics

Control of stem cell fate and function is critical for clinical and academic work. By combining surface chemistry-driven extracellular matrix (ECM) assembly with mesenchymal stem cells (MSCs) we are developing a system which can be used to regulate the behaviour of MSCs. The conformation of the ECM glycoprotein fibronectin (Fn) is different when adsorbed onto poly methylacrylate (PMA) where it is globular, and on poly ethylacrylate (PEA) where it forms a physiologically-similar network. [1]. (Fig. 1). Using these polymers to govern Fn conformation, we are developing a 3D system incorporating MSC-responsive growth factors (GFs) and bone marrow MSCs capable of regulating MSC behaviour. Toluene-dissolved PMA and PEA were spin coated onto glass coverslips before solvent extraction in vacuo and UV sterilisation. 20 mg ml. −1. human plasma FN was adsorbed onto the surfaces followed by 25 ng ml. −1. recombinant human BMP2/VEGF. FN conformations were characterised by atomic force microscopy (AFM). A collagen hydrogel was placed above the substrate. Adult human bone marrow STRO-1+ were cultured on the substrates for 3 weeks in supplemented DMEM. Expression of MSC stemness and HSC maintenance factors were analysed by In-Cell Western assay. To establish the best combination of polymer/FN/GF, MSC stemness markers (ALCAM, NESTIN and STRO1), osteogenic differentiation markers (OCN and OPN) and bone marrow markers (SCF and VCAM1) were measured in MSCs cultured for 3-weeks on substrates. OCN, SCF, and VCAM1 expression was enhanced across all combinations compared to glass control, while for ALCAM/STRO1/NESTIN and OPN, PEA combinations enhanced their expression. PEA + FN + VEGF appeared to be system best suited to maintaining MSC stemness and supporting expression of osteogenesis markers and bone marrow markers. We have shown that MSCs maintain their stem cells state and express high levels of SCF and VCAM-1 when cultured on PEA with adsorbed Fn and VEGF or BMP2. Next stages of this work will use PCR to verify results and analyse expression of other MSC markers to develop a role for these synthetic polymers as biomaterials

The posterolateral approach to ankle joint is well suited for ORIF of posterior malleolar fractures. There are no major neurovascular structures endangering this approach other than the sural nerve. The sural nerve is often used as an autologous peripheral nerve graft and provides sensation to the lateral aspect of the foot. Hence every attempt must be made to protect the sural nerve. The aim of this paper is to measure the precise distance of the sural nerve from surrounding soft tissue structures. This is a retrospective image review study including patients with MRI of their ankle from January 09 - Nov 2010. We indentified 78 MRI scans out of which 64 were deemed eligible for assessment. All measurements were made from Axial T1 slices. Measurements were made from the lateral aspect of the TA to the central of the sural nerve, central of sural nerve to the posterior aspect of the peronei muscles and central of the sural nerve to the posterior aspect of fibula. Data were collected on a Microsoft Excel spreadsheet and the descriptive statistics calculated. The key findings of the paper is the safety window for the sural nerve from the lateral border of TA is 7mm, 1.3cm and 2cm at 3 cm above ankle joint, at the ankle joint and at the distal tip of fibula respectively. Similarly the safety window for the nerve from the posterior aspect of fibula is 2cm, 1.6cm, 1.6cm at 3cm above ankle, at the ankle joint and the distal tip of fibula respectively. Our study demonstrates the close relationship of the nerve in relation to tendoachilles, peronei and fibula in terms of exact measurements. The safety margins established in this study should enable the surgeon in preventing endangerment of the sural nerve encountered in this approach

Summary Statement. Computational models are the primary tools for efficient design-phase exploration of knee replacement concepts before in vitro testing. To improve design-phase efficiency, a subject-specific computational platform was developed that allows designers to assess devices in realistic conditions by directly integrating subject-specific experimental data in these models. Introduction. Early in the design-phase of new implant design, numerous in vitro tests would be desirable to assess the influence of design parameters or component alignment on the performance of the device. However, cadaveric testing of knee replacement devices is a costly and time-consuming procedure, requiring manufacture of parts, preparation of cadaveric specimens, and personnel to carry of the experiments. Validated computational models are ideally suited for pre-clinical, high-volume design evaluation. Initial development of these models requires substantial time and expertise; once developed, however, computational simulations may be applied for comparative evaluation of devices in an extremely efficient manner [Baldwin et al. 2012]. Still, computational models are complementary of experimental testing and for this reason, computational models tuned with subject-specific experimental data, e.g. soft tissue parameters, could bring even more efficiency in the design phase. The objective of the current study was to develop a platform of tools that easily allows for subject-specific knee simulations. The system integrates with commercially available medical imaging and finite element software to allow for direct, efficient comparison of designs and surgical alignment under a host of different boundary conditions. Patients & Methods. MRI image was acquired, and 3D bone models were generated using the Mimics Innovation Suite® (Materialise NV, Leuven, Belgium). The two models (1) tibiofemoral (TF) joint laxity including ligamentous constraint and (2) whole joint (TF and patellofemoral (PF)) mechanics during dynamic activities of daily living (e.g. gait, squat, chair-rise), developed in Abaqus/Explicit (SIMULIA, Providence, RI), were then be adapted with integrated subject-specific attachment sites. Results. The suite of tools provides a platform for baseline evaluation of design factors, comparison of new implant designs with predicate devices, and assessment of robustness to surgical alignment. This platform is currently capable of taking into account subject-specific factors in order to provide realistic results in relation with experimental data. Implant material properties, ligament properties and initial conditions can be varied, and results compared, to evaluate the influence of a host of design and surgical factors on implant performance. The interface allows users without complex finite element expertise to setup, analyze and compare devices and interpret results. Discussion/Conclusion. A platform which allows implant designers to evaluate their design ideas in realistic conditions integrating subject-specific parameters and to compare with predicate devices has the potential to substantially decrease the development time for new devices. Designers can perform iterative modification to their devices to focus on an optimal design solution prior to in vitro testing, reducing the number of pre-clinical cadaveric experiments that may be required, and ultimately improving TKR mechanics in the patient population

Summary Statement. Corin has developed bone conserving prosthesis (MiniHip™) to better replicate the physiological load distribution in the femur. This study assessed whether the MiniHip™ prosthesis can better match the pre-osteoarthritic head centre for patient demographics when compared to contemporary long stem devices. Introduction. Leg length and offset discrepancy resulting from Total Hip Replacement (THR) is a major cause of concern for the orthopaedic community. The inability to substitute the proximal portion of the native femur with a device that suitably mimics the pre-operative offset and head height can lead to loss of abductor power, instability, lower back pain and the need for orthodoses. Contemporary devices are manufactured based on predicate studies to cater for the variations within the patient demographic. Stem variants, modular necks and heads are often provided to meet this requirement. The number of components and instruments that manufacturers are prepared to supply however is limited by cost and an unwillingness to introduce unnecessary complexity. This can restrict the ability to achieve the pre-osteoarthritic head centre for all patient morphologies. Corin has developed MiniHip™ to better replicate the physiological load distribution in the femur. This study assessed whether the MiniHip™ prosthesis can better match the pre-osteoarthritic head centre for patient demographics when compared to contemporary long stem devices. Methods. The Dorr classification is a well accepted clinical method for defining femoral endosteal morphology. This is often used by the surgeon to select the appropriate type and size of stem for the individual patient. It is accepted that a strong correlation exists between Flare Index (FI), characterising the thinning of cortical walls and development of ‘stove-pipe’ morphology, and age, in particular for females. A statistical model of the proximal femur was built from 30 full length femoral scans (Imorphics, UK). Minimum and maximum intramedullary measurements calculated from the statistical model were applied to relationships produced by combining Corins work with that of prior authors. This data was then used to generate 2D CAD models into which implants were inserted to compare the head centres achievable with the MiniHip™ compared to those of a contemporary long stem. Results. Results for the CAD overlay indicated the MiniHip prosthesis is better suited to restoring head centre for a range of morphological variations. In contrast, the long stem prosthesis requires a larger size range and increased inventory in terms of stem variants and modular components to achieve the same array of head centres. The disparity between the Corin FI and that of prior authors can be accounted for by the methods employed; the greyscale-based edge detection (Imorphics) compared to a manual identification method. Discussion/Conclusion. By overlaying the Corin MiniHip™ over the CAD representation of anticipated flare index, it is evident that the MiniHip™ stem is more suitable for the anticipated range of morphologies. The versatility of this design enables the restoration of head height and offset regardless of canal geometry, degree of offset and or CCD angle. This is not the case for contemporary long stem devices which rely on a more diaphyseal region for anchorage and stability and therefore depend on stem variants and modularity to cater for morphology changes

INTRODUCTION. There is increasing worldwide interest in the assessment of wear in explanted hip components. This is due is part to high profile failures of orthopaedic components in the US, whilst in the UK hip resurfacings have been experiencing a higher than expected failure rate. The reasons for these failures are not well understood, with data from the NJR suggesting the 43% of MoM resurfacing failures are unexplained. Wear analysis is a vital tool in determining failure mechanisms and ultimately improving the longevity of joint replacements through improved design and manufacturing control. There are currently no relevant measurement standards for the evaluation of retrieved orthopaedic components. This paper will assess two of the most commonly used techniques namely roundness measurement and co-ordinate measurement. The advantages and disadvantages of both techniques are considered in this paper. ROUNDNESS MACHINE. The Talyrond 365 is a stylus based roundness machine. The component is located on a rotating table and the stylus measures the deviation from a perfect circle as the component is slowly rotated. The Talyrond measures a single profile to an accuracy of 30 nm and up to 72,000 data points per revolution. The air spindle has a radial accuracy of <0.02 μm and the Talymin gauge a minimum resolution of 12 nm. Individual roundness profiles can be stitched together to build up 3D cylinder maps, allowing 3D pictures of sections of explanted hip components to be generated. COORDINATE MEASURING MACHINE. Co-ordinate measuring machines (CMMs) have been widely used in manufacturing quality and research departments for a number of years and the CMM is recognised as a powerful and important tool capable of ascertaining geometric data from a component. The CMM used in this study was a Zeiss Prismo CMM (Carl Zeiss Ltd., Rugby, UK) with a probing error of 0.7 μm. Components are securely held in a chuck fixture arrangement and the dimensions of the component in the portion of the bearing that is unworn is ascertained through measurement. The initial measurements are used to produce a reverse engineered 3D CAD surface which represents the component ‘pre-wear’ surface. The surface of the component is then scanned and the deviation from this pre-wear surface is mapped. The maximum linear wear and wear volume are then calculated directly. DISCUSSION. The main advantage of CMM and Talyrond is that they are available in most metrology and measurement rooms. The CMM is a particularly versatile machine and can be used to measure any orthopaedic components. There is a need to develop a suitable Standard for both machines detailing a protocol to measure explanted hip and quantify the wear. A study is underway to measure a set of explanted hip components to allow a detailed comparison between of measurements between the Talyrond and CMM. The result of this study will be included in the paper. CONCLUSIONS. The CMM and Talyrond are both instruments suited to measuring wear of explanted hips. A full evaluation of the systems and the development of robust measurement protocol and standard would be advantageous to the orthopaedic industry

Objectives

Several genome-wide association studies (GWAS) of bone mineral density (BMD) have successfully identified multiple susceptibility genes, yet isolated susceptibility genes are often difficult to interpret biologically. The aim of this study was to unravel the genetic background of BMD at pathway level, by integrating BMD GWAS data with genome-wide expression quantitative trait loci (eQTLs) and methylation quantitative trait loci (meQTLs) data

Objectives

Microindentation has the potential to measure the stiffness of an individual patient’s bone. Bone stiffness plays a crucial role in the press-fit stability of orthopaedic implants. Arming surgeons with accurate bone stiffness information may reduce surgical complications including periprosthetic fractures. The question addressed with this systematic review is whether microindentation can accurately measure cortical bone stiffness.

Objectives

Effects of insulin-like growth factor 1 (IGF1), fibroblast growth factor 2 (FGF2) and bone morphogenetic protein 2 (BMP2) on the expression of genes involved in the proliferation and differentiation of osteoblasts in culture were analysed. The best sequence of growth factor addition that induces expansion of cells before their differentiation was sought.

The peer review process for the evaluation of manuscripts for publication needs to be better understood by the orthopaedic community. Improving the degree of transparency surrounding the review process and educating orthopaedic surgeons on how to improve their manuscripts for submission will help improve both the review procedure and resultant feedback, with an increase in the quality of the subsequent publications. This article seeks to clarify the peer review process and suggest simple ways in which the quality of submissions can be improved to maximise publication success.

Cite this article: Bone Joint Res 2013;2:245–7.

Objective

To study the effect of hyaluronic acid (HA) on local anaesthetic chondrotoxicity in vitro.