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Numerical analysis of wear particles from non-arthritic and osteoarthritic human knee joints

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Abstract

Wear processes occur in synovial joints and as a result wear particles are produced. Preliminary work has shown that the shape of these particles might be related to joint diseases. Samples of knee joint synovial fluid were collected from thirty patients and analysed for wear particles. The condition of the patients' joints selected for the study ranged from healthy to severely osteoarthritic. Populations of particles were extracted from synovial fluid samples by ferrography and analysed in a scanning electron microscope (SEM). The SEM particle images were then processed by a computer and analysed numerically. Numerical particle shape descriptors, such as the boundary fractal dimension, shape factor, convexity and elongation were calculated. A non-parametric Mann-Whitney-Wilcoxon rank test and multiple comparison test performed on the knee joint particle populations demonstrated that there are clear differences in the particle slope between these populations, i.e. that there is a direct relationship between wear particle shape and joint condition. The results obtained indicate that the particle shape can be used as an indicator of the synovial joint condition, i.e. in the diagnosis and prognosis of joint diseases.

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... During OA process, the integrity of cartilage is suffering a continuous loss, accompanied with abrasion and fissure reaching down to the deep and calcified cartilage region. Accordingly, OA severity could be defined into grades 1 to 3 based on the loss of total cartilage thickness [1,11,12]. ...
... Wear debris, the by-products of the above wear process, contains valuable information in its surface topography and mechanical properties for assisting in the understanding of OA mechanisms and wear features. For example, it has been revealed, from previous qualitative studies [12][13][14][15], that particles generated in a healthy joint normally have a lamellar shape. Generation and detection of chunky or osseous fragments indicate that the wear condition deteriorates into calcified or subchondral regions. ...
... The wear particles analysis technique using numerical descriptors has been recognized as an objective and non-destructive approach for OA assessment. However, due to the restrictions of the microscopy techniques used, conventional boundary morphologies have been mainly investigated based two-dimensional (2D) information acquired using Scanning Electronic Microscopy (SEM) [12][13][14][15]24]. However, standard SEM is not a suitable facility for obtaining appropriate surface data for 3D surface analysis due to a number of factors including its 2D nature, sample preparation requirement prior to imaging, and surface dehydration and resulted artefacts in the imaging process. ...
Article
Full-text available
In the wear and tear process of synovial joints, wear particles generated and released from articular cartilage within the joints have surface topography and mechanical property which can be used to reveal wear conditions. Three-dimensional (3D) particle images acquired using laser scanning confocal microscopy (LSCM) contain appropriate surface information for quantitatively characterizing the surface morphology and changes to seek a further understanding of the wear process and wear features. This paper presents a new attempt on the 3D numerical characterisation of wear particle surfaces using the field and feature parameter sets which are defined in ISO/FDIS 25178-2. Based on the innovative pattern recognition capability, the feature parameters are, for the first time, employed for quantitative analysis of wear debris surface textures. Through performing parameter classification, ANOVA analysis and correlation analysis, typical changing trends of the surface transformation of the wear particles along with the severity of wear conditions and osteoarthritis (OA) have been observed. Moreover, the feature parameters have shown a significant sensitivity with the wear particle surfaces texture evolution under OA development. A correlation analysis of the numerical analysis results of cartilage surface texture variations and that of their wear particles has been conducted in this study. Key surface descriptors have been determined. Further research is needed to verify the above outcomes using clinic samples.
... 7,9 Studies of extracted synovial fluid from healthy and osteoarthritic human knees have observed changes in cartilage particle number and physical descriptors such as size and roughness correlated with grade of disease. 10,11 In lapine, canine, and equine in vivo studies, injection of cartilage particles into the knee joint led to rapid development of synovitis followed by gradual onset of fibrotic synovium thickening and decreased cartilage thickness, similar to traditional animal models of OA such as ACL transection or meniscal release. [12][13][14] Our group has also demonstrated that small CWP (<10 µm diameter) both attach to the cell membrane and are phagocytosed, and stimulate proteinase activity, cellular proliferation, collagen synthesis, and nitric oxide production in bovine FLS monolayer cultures. ...
... Once cartilage begins to degrade, the release of wear particles into the synovial fluid and their attachment to the synovial intima. 8,10,11 Unlike chemical mediators commonly associated with the disease such as pro-inflammatory cytokines, the cellular response to this physical factor of the OA environment has not been widely studied. The present work demonstrates that JOURNAL OF ORTHOPAEDIC RESEARCH ® SEPTEMBER 2019 treatment of FLS monolayers with CWP increased proliferation and release of pro-inflammatory mediators, chemokines, cytokines, and MMPs. ...
... Previous work has characterized CWP from human synovial fluid aspirates that range in size from 5-100 µm diameter, 24 and correlate varying shape and surface properties to OA disease stage. 10,11,25 The present work employed a Coulter Counter to isolate and characterize a well-defined distribution of relatively small particles generated by manual abrasion, that represented the lower end of this physiologic range. Previous work in the juvenile bovine model has shown that this size particle interacts directly with FLS by both attachments to the cell surface and phagocytosis. ...
Article
The synovium plays a key role in the development of osteoarthritis, as evidenced by pathological changes to the tissue observed in both early and late stages of the disease. One such change is the attachment of cartilage wear particles to the synovial intima. While this phenomenon has been well observed clinically, little is known of the biological effects that such particles have on resident cells in the synovium. The present work investigates the hypothesis that cartilage wear particles elicit a pro‐inflammatory response in diseased and healthy human fibroblast‐like synoviocytes, like that induced by key cytokines in osteoarthritis. Fibroblast‐like synoviocytes from 15 osteoarthritic human donors and a subset of 3 non‐osteoarthritic donors were exposed to cartilage wear particles, interleukin‐1α or tumor necrosis factor‐α for 6 days and analyzed for proliferation, matrix production, and release of pro‐inflammatory mediators and degradative enzymes. Wear particles significantly increased proliferation and release of nitric oxide, interleukin‐6 and ‐8, and matrix metalloproteinase‐9, ‐10, and ‐13 in osteoarthritic synoviocytes, mirroring the effects of both cytokines, with similar trends in non‐osteoarthritic cells. These results suggest that cartilage wear particles are a relevant physical factor in the osteoarthritic environment, perpetuating the pro‐inflammatory and pro‐degradative cascade by modulating synoviocyte behavior at early and late stages of the disease. Future work points to therapeutic strategies for slowing disease progression that target cell‐particle interactions. This article is protected by copyright. All rights reserved.
... In this study the following particle boundary parameters were calculated: area, convex area, filled area, perimeter, external perimeter, length, breadth, width, equivalent diameter, form factor, external form factor, roundness, convexity, aspect ratio, elongation and fractal dimension. A detailed description of the particle image analysis method used in this study can be found in [13][14][15][16]. In total, 269 wear particles collected during the experiments were imaged and analysed in this work. ...
... However, the trend observed is that as the wear damage becomes progressively worse, the wear particles originating from the deeper layers of articu- lar cartilage tend to be smaller and more irregular. This is consistent with the trend observed for wear particles harvested from osteoarthritic joints, i.e. as the severity of the disease increased the size of the particles became smaller and more irregular [16,18]. The length and boundary fractal dimension exhibited similar trends, i.e. particles from injected joints exhibited higher boundary fractal dimension than particles from non-injected joints and in general particles from injected joints appeared to be longer than particles from non-injected joints. ...
... This indicates a more complex and irregular wear particle boundaries for injected joints. This was also consistent with the trend observed for wear particles from human osteoarthritic joints (grade 1-3) which exhibited higher boundary fractal dimensions than wear particles from healthy, non-osteoarthritic joints [16,18]. Elongation, in general, was also greater for injected than non-injected joints. ...
Article
The surface of articular cartilage is covered with a superficial layer of high phospholipids concentration. The lubrication and hydrophobic properties of this layer appear to play an important role in synovial joint functioning. In this work it has been hypothesised that removal of the cartilage surface lipid layer is the key factor in the onset of osteoarthritis (OA). The aim of this research was to prove that destruction of the lipid layer accelerates wear and osteoarthritic damage. Special wear experiments have been conducted on intact sheep joints, aiming to compare ‘naturally worn’ joints and joints injected with lipid solvent prior to wear tests. Microscopic analysis has shown greatly accelerated osteoarthritic damage to the articular cartilage of lipid depleted joints. Wear particles extracted from synovial fluid have also been examined, with quantitative computer analysis confirming the above result and also demonstrating a direct correlation between lipid depleted sheep joints and osteoarthritic human joints.
... Ferrograhy is used to prepare wear particles found in human and sheep knee joints [4,38,82]. Initially, ferrography is an industrial approach which is used to separate ferrous debris from the lubricant. The main principle of ferrography is based on the magnetic precipitation of particles from suspension. ...
... Available electron microscopes, such as SEM and environmental scanning electron microscopy (ESEM), are used for investigations of wear particles. For example, SEM was used to obtain surface shape information of human wear particles [82]. To be imaged by SEM, wear particles need to be coated, which may alter their surface topography. ...
... The reported size of wear particles found in normal and osteoarthritic human knee joints ranges from 0.54 mm to 286.3 μm [82]. The mean size of wear particles in osteoarthritic joints is larger than that in the healthy joint. ...
Article
Full-text available
Wear occurs in natural knee joints and plays a pivotal factor in causing articular cartilage degradation in osteoarthritis (OA) processes. Wear particles are produced in the wear process and get involved in inflammation of human knees. This review presents progresses in the mechanical and surface morphological studies of articular cartilages, wear particles analysis techniques for wear studies and investigations of human knee synovial fluid in wear of human knees. Future work is also included for further understanding of OA symptoms and their relations which may shed light on OA causes.
... A few wear tests were made using human cartilage [18][19][20][21]. Wear of whole hip joints with no fluid environment using a pendulum device [18] or impact loading of cartilage specimens by a flat stainless steel plate [19] resulted in visible damage to the cartilage surface, but with no quantitative estimate on the wear. ...
... Wear of whole hip joints with no fluid environment using a pendulum device [18] or impact loading of cartilage specimens by a flat stainless steel plate [19] resulted in visible damage to the cartilage surface, but with no quantitative estimate on the wear. Wear particles found in synovial fluid samples, extracted from arthritic and non-arthritic human knee joints, were analyzed [20]. A relation was found between the shape of the wear particles and the degree of osteoarthritis in the tested joints, which can be used to detect the progress of osteoarthritis in synovial joints. ...
Article
Osteoarthritis (OA) is a disease of joints, affecting a large number of people worldwide. One of the symptoms of OA is wear of articular cartilage; it is thought that among other factors this may be due to failure of lubrication. Injection of bio-lubricants into a joint may remedy this problem. Wear of cartilage and its prevention is a focus of much interest. The present paper describes wear tests performed using human cartilage on cartilage under various working conditions. Several techniques assessing wear are described, such as changes in surface morphology using optical profilometry and variation in the content of collagen and proteoglycans (PG) in the lubricating solution. Of all these techniques the PG content analysis was found to be the most efficient one.
... Fractals have been used to describe morphology of wear debris by Berthier et al. (1988), Kirk et al. (1991), Zhang et al. (1997) and Wrona (2003. There have been attempts to automate the analysis of wear particles, see, Xu and Luxmoore (1997), Podsiadlo et al. (1997 ). Laser scanning microscopy has been applied to obtain threedimensional images of wear particles and to surface roughness analysis of a single wear particle by. ...
... For example, in bearings, in fretting processes and in prostheses of human joints, wear particles are always present inside the contact region. Wear debris in the prostheses of human joints may be responsible serious illnesses (Podsiadlo et al., 1997Podsiadlo et al., , 1998 Tipper et al., 2001). @BULLET Analysis of wear debris is an important indicator in fault diagnosis of machines and mechanisms. ...
Article
Wear appears as gradual removal of a material from contacting and rubbing surfaces of solids during their relative sliding. The mechanism of wear involves formation of debris particles. The particles have small sizes and different shapes. The wear debris can be "rolled over" into cy-lindrical, spherical and needle-like particles. Particles are detached from rubbing surfaces and they form a more or less continuous interfacial lay-er. They transmit forces, moments and displacements (translational and rotational) at the contact interface. The presence of wear debris between sliding surfaces affects frictional and wear behaviour significantly. Con-stitutive relations characterize quasi-solid, quasi-fluid and granular-like behaviour of wear particles. In the paper, two constitutive models of we-ar debris are discussed: (a) material continuum, (b) granular medium. The continuum models are formulated for a micropolar thermoelastic material, micropolar fluid and thermo-viscous fluid.
... As the by-products of articular cartilages in the wear process, wear particles carry rich information on knee joint conditions and could potentially be used for the diagnosis and/or 4 prognosis of OA severities. Wear particles found in normal and osteoarthritc human knee joints range from 0.54 µm [9] to 286.3 µm [10] in size. When OA progresses, the wear rate increases, with more and larger wear particles produced. ...
... The size of human wear particles in osteoarthritic synovial fluid spreads wider than that in a normal joint [9]. Particles found in healthy knee joints are smooth and thin [11], while those found in diseased knee joints tend to be irregular and chunky [10]. These existing observations demonstrate that the wear particles reveal joint conditions and their changes. ...
Article
Although wear particles are the by-products of wear processes in knee joints and carry rich information about the processes and wear conditions, wear debris generated in human knee joints has not been well studied. The purpose of this study was to develop methodologies for investigating the nano-mechanical properties and nano-surface topographies of wear particles found in human knee synovial fluid, and their correlation with those of human cartilages in osteoarthritis (OA) progression. To fulfil the purpose, atomic force microscopy (AFM) was used to study wear particles and human knee articular cartilages in a fluid mode and at a nanometer scale. Young’s moduli of wear debris and human cartilages were examined and compared. Image processing and numerical analysis techniques were established to quantitatively characterise the surface topographies of wear debris. The preliminary results demonstrated that the mechanical property and quantitative surface features of the wear particles were successfully studied by using the established methods. This study provided evidence that the nano-scaled surface textures and nano-mechanical property of the wear particles alter with increasing OA grade, and that there is the need for further evaluation of correlations between wear particles and human cartilages, and the effectiveness of analysing wear particles for revealing nano-mechanical and structural changes in the knee joint conditions.
... onal purification steps using saline and hyaluronidase were employed for successful analysis. 180 It was demonstrated that using this technique, improved diagnosis of arthritis might be possible basedon the examination of separated particles. To identify the particles, ferrograms may be inspected by light microscopy methods, SEM and X-ray analysis.In 1997, Podsiadlo et al.employed SEM to study particles extracted from synovial fluid samples by ferrography and to examine how they might be related to the severity of OA. 181 Significant differences were found between the numerical descriptors calculated for wear particles from healthy and osteoarthritic knee joints (the boundary fractal dimension, shape fact ...
Article
Full-text available
Clinically, osteoarthritis (OA) is characterised by joint pain, stiffness after immobility, limitation of movement and, in many cases, the presence of basic calcium phosphate (BCP) crystals in the joint fluid. The detection of BCP crystals in the synovial fluid of patients with OA is fraught with challenges due to the submicroscopic size of BCP, the complex nature of the matrix in which they are found and the fact that other crystals can co-exist with them in cases of mixed pathology. Routine analysis of joint crystals still relies almost exclusively on the use of optical microscopy, which has limited applicability for BCP crystal identification due to limited resolution and the inherent subjectivity of the technique. The purpose of this Critical Review is to present an overview of some of the main analytical tools employed in the detection of BCP to date and the potential of emerging technologies such as atomic force microscopy (AFM) and Raman microspectroscopy for this purpose.
... Under healthy conditions, human joint performance is facilitated by low-friction articular cartilage bearing surfaces, which are conforming and self-regenerating [1][2][3][4]. When natural joints are severely damaged, e.g. ...
Article
Full-text available
The effect of sliding friction on the size of yielding region in the ultra high molecular weight polyethylene asperity in contact with metal was investigated. The main objective of this work was to gain an understanding of wear particle generation mechanism from the two-dimensional finite element model. To assess the influence of the parameters of interest, different friction coefficients and loading conditions were used in the numerical simulations. Results from the finite element analysis show that the increase of the yielding region is strongly influenced by the friction coefficient and the rise in the tangential force, which is related to the generation of wear particles. Finite element wear particle generation model, based on strain discontinuities, was therefore proposed. The results obtained in this study can lead to the development of an accurate finite element particle generation model that would be of use in the assessment of an artificial implant performance and their development.
... When characterizing wear particles particle boundary and surface morphology need to be described. Numerous shape descriptors, such as aspect ratio, shape factor, convexity, roundness, boundary-curvature-based Fourier descriptors and boundary fractal dimension, are commonly used to describe a particle boundary [1][2][3][4][5][6][7][8][9]. Various problems associated with calculations of boundary fractal dimension have been identified and resolved [10][11][12], so that the complexity of particle boundary can now be reliably described [12]. ...
Article
Wear particles and surfaces are three-dimensional (3-D) objects and their numerical characterization and classification is still largely an unresolved problem. Usually a set of various parameters is employed to describe the surface topography. These parameters are of limited use, especially when dealing with anisotropic surfaces. To solve this problem a modified Hurst orientation transform (HOT) method has been developed and applied to characterize the surface anisotropy. However, despite the apparent success this method does not yet provide a full description of the surface topography. It is known that complex structures observed in nature can be described and modeled by a combination of simple mathematical rules. It is therefore reasonable to assume that, in principle, it should also be possible to describe any surface by a set of such rules. The problem is in finding those rules. For this purpose, a modified partitioned iterated function system (PIFS) was developed and applied to encode the 3-D surface topography information, i.e. to obtain full description of surface topography of wear particles and surfaces. Importantly, PIFS information gained from individual wear particles or surfaces allows to classify them in groups which are characteristic to a particular failure type. This, in turn, allows to ascribe an ‘unclassified’ particle or surface to a particular group/category which is characteristic to a specific failure type or wear mechanism. This forms the basis of a system, which when fully developed, would allow an automated recognition of particles and surface morphologies without the need for experts. The system then can be developed further to include diagnosis of the type of failure. In this paper an overview of recent advances and developments in the characterization, classification and recognition of wear particles and surfaces is presented.
... Several feasibility studies used analytical ferrography in the fields of life sciences and medicine already in the 1980s. These included erythrocyte and white blood cell separation (20)(21)(22)(23), bacterial tracking (22)(23)(24), and monitoring the wear of either natural diarthrodial joints (25)(26)(27)(28)(29)(30)(31)(32)(33)(34) or artificial joints (25,26,29,35). In those studies, Er 31 was the magnetizing agent. ...
Article
Background: The epidermal growth factor receptor (EGFR) is overexpressed in carcinoma. In some cases, including in colorectal cancer, it is used as a therapeutic target. Bio-Ferrography is a non-destructive method for isolating magnetized cells and tissues from a fluid onto a glass slide based on their interaction with an external, strong and focused magnetic field.Methods: Here, we implement Bio-Ferrography to separate EGFR positive cancer cells from EGFR negative non-cancer cells, mixed at a ratio of 1 to 1 × 106, from either PBS or human whole blood (HWB). Incubation of the cells with an anti-EGFR antibody and magnetic microbeads coupled to a secondary antibody was used to magnetize the target cells prior to the ferrographic analysis.Results: A procedure was developed for “a proof of concept” isolation. Recovery values as high as 78% for 1 mL PBS, and 53% for 1 mL HWB, with a limit of detection (LOD) of 30 and 100 target cells, respectively, were achieved.Conclusions: These capture efficiency values are considered significant and therefore warrant further study on isolation of real circulating tumor cells (CTCs) from blood samples of patients, aiming at early diagnosis of EGFR overexpressing tumor types. This article is protected by copyright. All rights reserved.
... Apart from taking out wear simulation test to evaluate wear resistance of hip prostheses, we always analyze the wear debris to assess the wear state in hip joint components and the possible biological response of removed materials. It has been shown that the wear debris shape is closely related to wear severity of wear occurring in joints [7] and to severity of osteoarthritis in human joints [8]. ...
Article
Ultra-high molecular-weight polyethylene (UHMWPE) has been used in total hip replacement for the last three decades. Despite the advancements in prosthesis design, the wear of UHMWPE remains a serious clinical problem; the release of wear debris may induce osteolysis and implant loosening. Understanding of wear behavior and wear debris morphology of the polyethylene is essential to improve the reliability of hip joint implants. The investigation in this paper carried out wear simulation tests of UHMWPE on Al2O3, 316L stainless steel, CoCrMo alloy and Ti6Al4V alloy, respectively. The lubrication of plasma solution and bovine serum solution was presented in wear tests. The effect of motion and loading on the wear behavior and wear debris morphology, and the influence of femoral head material and assembly style were studied in order to obtain a better understanding of the morphology of ultra-high molecular weight polyethylene wear particles. It is shown that the wear of UHMWPE acetabular cups against metal femoral heads was significantly higher than that against ceramic heads. The presence of protein in lubricant increases the wear of UHMWPE acetabular cups on Al2O3 heads. The wear rates of UHMWPE in multi-directional motion are approximately 2.5 times of those in uni-directional motion. The size distribution range of the UHMWPE debris particles for all head materials varies from submicron particles up to several hundreds micron. The size distribution range of wear debris particles is not directly related to wear resistance of UHMWPE, but significantly influenced by wear mechanisms. The UHMWPE debris particles produced in hip wear simulation tests are classified as round debris, flake-like debris and stick debris, which are closely related to the primary mechanisms of abrasive wear, adhesive wear and fatigue wear.
... Several feasibility studies used analytical ferrography in the fields of life sciences and medicine already in the 1980s. These included erythrocyte and white blood cell separation (20)(21)(22)(23), bacterial tracking (22)(23)(24), and monitoring the wear of either natural diarthrodial joints (25)(26)(27)(28)(29)(30)(31)(32)(33)(34) or artificial joints (25,26,29,35). In those studies, Er 31 was the magnetizing agent. ...
Article
The epidermal growth factor receptor (EGFR) is overexpressed in carcinoma. In some cases, including in colorectal cancer, it is used as a therapeutic target. Bio-Ferrography is a nondestructive method for isolating magnetized cells and tissues from a fluid onto a glass slide based on their interaction with an external, strong, and focused magnetic field. Here, we implement Bio-Ferrography to separate EGFR-positive cancer cells from EGFR-negative noncancer cells, mixed at a ratio of 1 to 1 × 10(6) , from either phosphate-buffered saline or human whole blood. Incubation of the cells with an anti-EGFR antibody and magnetic microbeads coupled to a secondary antibody was used to magnetize the target cells prior to the ferrographic analysis. A procedure was developed for "a proof of concept" isolation. Recovery values as high as 78% for 1 mL phosphate-buffered saline, and 53% for 1 mL human whole blood, with a limit-of-detection of 30 and 100 target cells, respectively, were achieved. These capture efficiency values are considered significant and, therefore, warrant further study on isolation of real circulating tumor cells from blood samples of patients, aiming at early diagnosis of EGFR-overexpressing tumor types. © 2014 International Clinical Cytometry Society. © 2014 Clinical Cytometry Society.
... It was reported previously [1][2][3][4][5][6] that the size and shape of the solid particles (crystals and wearing particles) in synovial fluid were related with knee joint disease to some extent, but up to now there has been no systematic research performed to give information on how the size and shape as well as the properties of the solid particles are correlated with the types of knee joint disease. On the other hand, in the previous researches, the size and shape of the solid particles were measured by using either a scanning electron microscope (SEM) or a transmission electron microscope (TEM). ...
Article
The shape and size of solid particles and their distribution in synovial fluid were observed and determined as functions of knee joint diseases by using a multi-dimensional microscope. The results show that there is a close correlation between them, so that the measurement of the parameters might offer a reliable method for diagnosing joint diseases at an early stage and their prognosis.
... Human joints operate by low-friction articular cartilage bearing surfaces, which are conforming and self-regenerating [1][2][3]. When natural joints are severely damaged, e.g. ...
Article
Knee and hip joint replacement implants involve a sliding contact between the femoral component and the tibial or acetabular component immersed in body fluids, thus making the metallic parts susceptible to tribocorrosion. Micro-motions occur at points of fixation leading to debris and ion release by fretting corrosion. β-Titanium alloys are potential biomaterials for joint prostheses due to their biocompatibility and compatibility with the mechanical properties of bone. The biotribocorrosion behavior of Ti-29Nb-13Ta-4.6Zr was studied in Hank's balanced salt solution at open circuit potential and at an applied potential in the passive region. Reciprocating sliding tribocorrosion tests were carried out against technical grade ultra high molecular weight polyethylene, while fretting corrosion tests were carried out against alumina. The wear of the alloy is insignificant when sliding against polyethylene. However, depassivation does take place, but the tested alloy showed an ability to recover its passive state during sliding. The abrasivity of the alloy depends on the electrochemical conditions of the contact, while the wear of polyethylene proceeds through third body formation and material transfer. Under fretting corrosion conditions recovery of the passive state was also achieved. In a fretting contact wear of the alloy proceeds through plastic deformation of the bulk material and wear resistance depends on the electrochemical conditions.
... e l s e v i e r . c o m / l o c a t e / a c t a b i o m a t bility studies have demonstrated its applicability to the study of arthritic human and sheep joints14151617181920. Ferrography was found to be very sensitive in monitoring articular erosion, with a resolution much greater than that of arthroscopy [15]. ...
Article
Millions of people are stricken with the degenerative joint disease known as osteoarthritis. Osteoarthritis is associated with biochemical and mechanical processes, and is characterized by loss of articular cartilage and hypertrophy of bone. As cartilage and bone particles are released into the synovial fluid, a variety of biomarkers have been suggested for the analysis of this fluid. Here we have developed a method for isolating bone and cartilage wear particles suspended in the synovial fluid of the hip, knee and ankle joints of humans, based on specific magnetization of collagens I and II. Bio-ferrography is used to capture the particles on glass slides, allowing microscopic, chemical and statistical analyses. The relations between the level of the disease and the number, dimensions, shape and chemical composition of the particles were established. The method, which was found to be sensitive and reliable, can easily be extended to other applications, such as diagnosis of cancer and infectious diseases, determination of the efficacy of drugs or optimization of implants.
... Normal human joint performance is facilitated by low-friction articular cartilage bearing surfaces, which are conforming and self-regenerating [1][2][3][4]. Severely damage of natural joints, e.g. due to osteoarthritis, they are often replaced by artificial implants. ...
Article
Full-text available
The effect of micromotion on the shear shielding and size of yielding region in the bone asperity in contact with metal of femoral stem was investigated. The main objective of this work was to gain an understanding of bone wear particleformation mechanism from the two-dimensional finite element model of cementless femoral stem type. To assess the influence of the parameters of interest, different friction coefficients and sliding distance (micromotion)were used in the numerical simulations. Results from the finite element analysis showed that the increase ofthe yielding region is strongly influenced by the rise in sliding distance (micromotion), which is related to the generation of bone wear particle formations. Finite element bone wearparticle formation model, based on strain discontinuities, was therefore proposed for further works. The results obtained in this study can lead to the development of an accurate finite element wearparticle formation mechanism model that would be of use in the assessment of an artificial implant performance and their development.
... Moreover, a set of outline sequences is defined as radius differences from the equal circle so that some analytical methods such as Fourier transform can be easily applied in a sequence 41,48,49 . Based on the fractal theory, a fractal dimension is obtained through measuring the perimeter of a debris outline with different step sizes, which is used to represent the outline feature [50][51][52][53][54][55][56][57][58] . In addition, surface texture is also an important morphological attribute [59][60][61][62][63] , so debris pictures are processed by grey level analysis 64 , 2D fast Fourier transform 65 , fractal dimension 66 , and pattern recognition 67 . ...
Article
Full-text available
Mechanical debris is an important product of friction wear, which is also a crucial approach to know the running status of a machine. Many studies have been conducted on mechanical debris in related fields such as tribology, instrument, and diagnosis. This paper presents a comprehensive review of these studies, which summarizes wear mechanisms (e.g., abrasive wear, fatigue wear, and adhesive wear) and debris features (e.g., concentration (number), size, morphology, and composition), analyzes detection methods principles (e.g., offline: spectrograph and ferrograph, and online: optical method, inductive method, resistive-capacitive method, and acoustic method), reviews developments of online inductive methods, and investigates the progress of debris-based diagnosis. Finally, several notable problems are discussed for further studies.
... The success of analytical ferrography in condition monitoring of engineering systems triggered few feasibility studies in the fields of life sciences and medicine, mainly in hip and knee joint applications, already in the 1980s [81]. These included erythrocyte and white blood cell separation [82][83][84][85], bacterial tracking [84][85][86] and monitoring the wear of either natural diarthrodial joints [81,[87][88][89][90][91][92][93][94][95][96] or artificial joints [87,88,91,97]. In those studies, Er 3+ was the magnetizing agent. ...
Article
Full-text available
Metallic biomaterials are used in medical devices in humans more than any other family of materials. The corrosion resistance of an implant material affects its functionality and durability and is a prime factor governing biocompatibility. The fundamental paradigm of metallic biomaterials, except biodegradable metals, has been “the more corrosion resistant, the more biocompatible.” The body environment is harsh and raises several challenges with respect to corrosion control. In this invited review paper, the body environment is analysed in detail and the possible effects of the corrosion of different biomaterials on biocompatibility are discussed. Then, the kinetics of corrosion, passivity, its breakdown and regeneration in vivo are conferred. Next, the mostly used metallic biomaterials and their corrosion performance are reviewed. These biomaterials include stainless steels, cobalt-chromium alloys, titanium and its alloys, Nitinol shape memory alloy, dental amalgams, gold, metallic glasses and biodegradable metals. Then, the principles of implant failure, retrieval and failure analysis are highlighted, followed by description of the most common corrosion processes in vivo. Finally, approaches to control the corrosion of metallic biomaterials are highlighted.
... Numerical descriptors would simplified manifold and would not require specialized expertise. Fractal methods also useful in characterizing the surface anisotropy and directionality [5]. ...
Conference Paper
Fractals can be very useful when applied to tribology. Fractal descriptions of wear particles require surface texture information to be processed. The morphology of wear particles depends on its surface characteristics. These characteristics are represented by fractal dimension derived from the boundary profile. In this paper, Fractal dimension is used to describe wear particles obtained from engine oil. This article compares different fractal methods to calculate fractal dimension for characterization of wear particles. This paper presents a review of progress and developments in fractal dimension computing methods as applied to characteristics the surface of wear particles. Some of Fractal dimension methods are structure walk method, box counting method etc.
... Ein Umbau des Prüfstandes mit Paralellogrammführung und reibungslosen Blattfederlagern wäre hier in Zukunft wünschenswert.Die Messung der Höhenabnahme des Knorpels soll an dieser Stelle kritisch diskutiert werden. Die Beschreibung von Verschleißerscheinungen am Knorpel wird in der Literatur in vivo sowie in vitro beschrieben[222,224,231,232,328] [227]. So beschreiben Oungoulian et al.[233] einen quantitativen Rückschluss auf den Verschleiß durch einen Abrieb-Partikel-Zähler. Die Konzentration von 4-Hydroxyprolin (einem Bestandteil des Kollagens) sowie die GAG-Konzentration im Schmiermittel der artikulierenden Proben sind quantitativ erfassbare Parameter zur Deskription von tribologischen Ereignissen[230]. ...
Thesis
Das grundlegende Ziel dieser Dissertation war es, Gelenkknorpel von jungen und alten porkinen Kniegelenken vor und nach einer tribologischen Belastung zu vergleichen. Hierfür wurde auf Kniegelenke aus dem örtlichen Schlachthof zurückgegriffen, der von 16 jungen (6 Monate) und 15 alten (5 Jahre) Schweinen stammte. Die folgenden Fragestellungen wurden hierbei untersucht: 1. Konnte an dem Gelenkknorpel Osteoarthrose nachgewiesen werden? Falls Osteoarthrose vorhanden gewesen sein sollte, wie stark war diese ausgeprägt? 2. Gab es einen statistisch belastbaren Unterschied zwischen dem Knorpelbelag der alten und jungen Schweine? 3. Konnte ein Unterschied im biomechanischen Verhalten nach einer tribologischen Belastung zwischen den jungen und alten Knorpelproben nachgewiesen werden? 4. Welchen Effekt auf der morphologischen Ebene hinterließ die tribologische Belastung an den Knorpelproben? Gab es einen Unterschied zwischen den jungen und alten Tieren im Hinblick auf diesen Effekt? Zur Beantwortung von 1. und 2. wurde unter Zuhilfenahme von radiologischen (Kellgren&Lawrence- Score), makroskopischen (ICRS-Score) und mikroskopischen (Little-Score) Bewertungskriterien der Knorpel beider Gruppen untersucht und verglichen. Hierbei konnte nachgewiesen werden, dass alte Kniegelenke osteoarthrotischen Veränderungen unterlagen und sich in allen drei Bewertungskriterien signifikant von jungen Kniegelenken unterscheiden. Im Anschluss (3.) wurde der Knorpel mit Hilfe eines tribologischen Prüfsystems - basierend auf dem Pin-on-Plate-Prinzip - getestet. Als Pin diente ein osteochondraler Zylinder aus der Femurkondyle, der sich oszillierend auf der korrespondierenden, quadratischen Plate aus dem Tibiaplateau bewegte. Mithilfe eines Höhenmessers wurde hierbei die kontinuierliche Abnahme der Knorpelhöhe der Proben während der 1108 Test-Zyklen (2,03 Stunden) andauernden Belastung gemessen. Hier konnte ebenfalls ein statistisch belastbarer Unterschied nachgewiesen werden. Im Mittel verloren junge Knorpelproben nach der tribologischen Belastung 0,86 mm und alte 0,50 mm an Knorpelhöhe. Eine negative Korrelation zwischen den Arthrose-Scores und der Höhenabnahme des Knorpels zeigte, dass je stärker der Knorpel von Osteoarthrose befallen war, er umso weniger an Höhe während der tribologischen Testung verlor. Für 4. wurde mit denselben makro- und mikroskopischen Bewertungskriterien der Effekt der Belastung auf die jeweilige Gruppe evaluiert und beide Gruppen miteinander verglichen. Der makro- sowie mikroskopisch erkennbare Effekt führte in beiden Gruppen zu einem signifikanten Anstieg des Scores im Vergleich zur Situation vor der Belastung. Auf der tibialen (Plate-) Seite war eine ausgeprägte Riefenbildung erkennbar, welche in der jungen Gruppe stärker zur Geltung kam. Ein eigener, adaptierter Score, bei dem der Fokus der mikroskopischen Veränderungen ausschließlich auf den durch die Reibeversuche verursachten Effekte auf der Oberfläche des Knorpels und nicht auf degenerativen Prozessen lag, konnte in der Situation nach Belastung kein Unterschied zwischen den beiden Gruppen feststellen. Die Ergebnisse dieser Dissertation lassen die Interpretation zu, dass arthrotischer Knorpel resistenter gegenüber mechanischen Beanspruchungen ist, als junger. Diskutiert werden sollte, inwieweit dem tribologischen Prüfsystem mit seiner Pin-on-Plate Konfiguration ein eventueller Einfluss auf die Ergebnisse zugeschrieben werden muss. Die vielversprechenden Ergebnisse dieser Dissertation sollten in weiterführenden Projekten verfolgt werden, da sie wichtige Charakterisierungen der Biomechanik des Knorpels liefern können.
Article
This paper provides a general overview of developments and progress in quantitative computer image analysis as applied to wear particle identification/classification technology, over the last two decades. Since many technical disciplines are involved in this ‘infant-stage’ technical area, an attempt is made to put into perspective mechanical failure prediction/diagnosis and prevention through quantitative wear particle morphological analysis. The problems experienced with applying conventional wear particle analysis methods in machinery condition monitoring, notably the employment of wear debris morphological diagnostic systems, revealed that it is not prudent to rely solely on human interpretation in the analysis of ‘filtergram’ slides. This has highlighted the need for improving the provision of ‘intelligent’ objective methods for performing this type of analysis. In this paper, some of the developments reported in the literature relating to progress made with wear particle image analysis are reported and examined as a basis for establishing improved methods of diagnostic analysis.
Article
Significant advances have recently been made in the numerical characterization of particle boundaries. However, progress in the numerical characterization of particle surfaces is slow. There are two fundamental issues associated with this problem; i.e., the acquisition of reliable three-dimensional (3-D) surface data and numerical description of the 3-D surface features. In this paper, the first issue is addressed while the second issue will be addressed in our next papers. Pairs of field emission scanning electron microscope (FESEM) stereo images of wear particles found in synovial joints have been acquired. A specially developed stereoscopy method was applied to the acquired FESEM images in order to obtain 3-D surface topography data of wear particles. The surface topography data obtained from the wear particles was then processed to produce: the range image, the contour map and the shaded image of a particle surface. The surface topography of wear particles was also shown in the colour stereo images. The results obtained in this study have clearly demonstrated that 3-D surface topography data of wear particles is very helpful in particle visualization and it can be used in numerical description of the surface.
Article
Wear particles are three-dimensional objects. Recent advances, accelerated by the application of computer technology, allow numerical characterization of particle shape in two dimensions. However, three-dimensional (3D) characterization of wear particle surface topography is still largely an unresolved problem. There are two issues associated with this problem, i.e., the acquisition of accurate wear particle surface topography data and the numerical description of 3D surface features. The usually small size of wear particles restricts the techniques that could be used to acquire accurate data from the particle surface. Surface profilometers, e.g., Talysurf, the instruments traditionally used in surface topography imaging, cannot be used because of the small size of particles. The limitation of an atomic force microscope is its relatively small vertical range, while the horizontal resolution of laser confocal or interferometric microscopes is too low to obtain accurate particle surface topography data. The application of a combination of SEM and stereoscopy techniques seems to alleviate this problem. 3D surface topography data obtained using this technique can be processed and presented in many different ways. The usefulness of various methods of surface data representation in visualization and numerical characterization of wear particle surfaces is discussed. One of the major difficulties associated with the characterization of surface topographies is the accurate description of surface spatial properties, i.e., their anisotropy and directionality. Recently, a specially modified Hurst Orientation Transform (HOT), to suit wear particle surface data, has been developed and applied to characterize the surface topography of particles. The Hurst coefficients are related to fractal dimensions and are a measure of surface roughness, i.e., a rougher surface is represented by lower Hurst coefficients. It was found that the modified HOT can be applied to reveal the surface anisotropy of wear particles. Although none of the other methods developed so far allow such a thorough characterization of wear particle surfaces as does the modified HOT, this method still does not provide a full description of the surface topography. Therefore, it appears that a totally different approach is needed in order to make a fundamental breakthrough in the characterization of wear particle surfaces. Since many of the complex structures observed in nature can be described and modelled by a combination of simple mathematical rules, it may be possible to describe the surface of a particle by a set of such rules. In our first attempt, a Partitioned Iterated Function System (PIFS) was applied to encode the wear particle surface topography information. This information can then be used to calculate the relevant surface descriptors. In this paper, an overview of recent advances and developments in the numerical characterization of wear particle surfaces is presented.
Article
As a result of wear in the synovial joint, cartilaginous and osseous wear particles are produced. Previous research has shown that wear-particle shape may be correlated with joint disease status. In addition, phospholipids, present naturally in the joint, have been implicated as major contributors to joint lubrication. This study aimed to investigate the effect of phospholipids, as surface-active boundary lubricants, on the wear characteristics of the synovial joint by the application of numerical shape descriptors to cartilage wear particles. Artificially worn, lipid-depleted, sheep knee joints were injected with two concentrations of the phospholipid dipalmitoyl phosphatidylcholine (L-DPPC) and worn further in a mechanical rig. Particles were harvested from the joint, extracted from solution by ferrography, and analyzed in a field-emission scanning electron microscope (FESEM). After binary processing, the particle images were numerically analyzed for shape parameters such as boundary fractal dimension, shape factor, convexity, elongation and area. The condylar surfaces were also extracted and viewed in their hydrated state in an environmental scanning electron microscope (ESEM). The results of numerical particle analysis indicate that a synthetic solution of L-DPPC in propylene glycol may have a significant effect on the wear characteristics of synovial joints. Statistically significant differences between pre- and post-lubricated particles for convexity, elongation and formfactor have been found for 35 mg/ml L-DPPC and synovial fluid. In addition, similar trends for synovial fluid and the phospholipid solutions were noted for the boundary fractal dimension and curl. Particles have been of similar shape and morphology as described in the literature. The condyle surface morphology observed was characteristic of worn articular cartilage.
Article
Articular cartilage is an extremely complex material; it exhibits unique properties, unmatched by man-made materials. It is widely thought that articular cartilage plays a major role in controlling both the lubrication and, more importantly, wear of synovial joints. Degenerative joint diseases, such as osteoarthritis, are thought to be related to the wear of articular cartilage. As the wear rate accelerates, the cartilage is completely worn away, leading to direct bone-to-bone contact, eventually requiring joint replacement surgery. Intensive research has been focused on the lubrication properties of synovial joints, while their wear characteristics and mechanisms still remain poorly researched.In this paper, preliminary results obtained from wear studies conducted on articular cartilage samples are described and discussed. Sheep knee joints were worn in a joint simulator for different periods of time. Two criteria, i.e. changes in surface morphology and in wear particle morphology, were used in wear assessment. The worn joints were compared to control (unworn) joints to determine the changes occurring. The surface morphology of articular cartilage was imaged using both scanning electron microscopy (SEM) and environmental SEM, with surface damage found to increase as the duration of wear tests increased. Environmental scanning electron microscopy (ESEM) has allowed the true surface of articular cartilage to be imaged in its natural state, without the need for fixation. ESEM imaging has revealed a surface layer that lies on top of the collagen matrix. The function of this surface layer is found to be disrupted by wear. Wear particles were also collected and characterised using numerical descriptors. The wear particles were observed to change shape and size as wear progresses.
Chapter
Volume 18 addresses friction and wear from a systems perspective, while providing a detailed understanding of why it occurs and how to control it. It explains the basic theory of friction and wear, and offers valuable insight on the forces, mechanisms, and interactions that are involved. It examines common wear scenarios, including wear by particles or fluids, rolling-contact wear, sliding wear, impact wear, and both chemical and environmentally assisted wear. It also covers operational wear, addressing several cases, including tool and die wear, bearing wear, engine wear, turbine wear, pump wear, and seal wear. In addition, the volume provides information on lubricants and lubrication, coatings, surface treatments and modifications, and the tribology of irons and steels, cobalt-base alloys, titanium, aluminum alloys and composites, cemented carbides, ceramics, polymers, and polymer composites. It also introduces the topic of condition monitoring, addressing wear particle analysis, vibroacoustic monitoring, and motor current signature analysis. For information on the print version of Volume 18, ISBN 978-1-62708-141-2, follow this link.
Article
Total knee arthroplasty introduces foreign materials into the body that are intended to withstand significant biological and mechanical stresses while maintaining biocompatibility. Unfortunately many arthroplasty patients experience inflammation and pain, presumably due to wear debris that dislodges from the artificial joint over time. The failure mechanisms of prosthetic devices and the chemical make-up of the associated wear debris are presently unclear. In this study, we use x-ray photoelectron spectroscopy and Raman microscopy to identify the chemical composition of the wear debris. Knee synovial fluid was aspirated from seven different prosthetics patients and centrifuged, resulting in small deposits of wear debris. Our analysis identifies oxidized titanium in five of the seven sets of samples, indicating femoral component wear and potentially back-side wear of the tibial base plates of the prosthetics. Furthermore, samples with large percentages of titanium also contain sodium, whereas the others contain chlorine. This may indicate differences in the chemical composition of synovial fluid under different inflammatory conditions. Copyright © 2005 John Wiley & Sons, Ltd.
Article
Quantitative measurements of cartilage wear have been challenging, with no method having yet emerged as a standard. This study tested the hypothesis that latest-generation particle analyzers are capable of detecting cartilage wear debris generated during in vitro loading experiments that last 24 h or less, by producing measurable content significantly above background noise levels otherwise undetectable through standard biochemical assays. Immature bovine cartilage disks (4 mm diameter, 1.3 mm thick) were tested against glass using reciprocal sliding under unconfined compression creep for 24 h. Control groups were used to assess various sources of contamination. Results demonstrated that cartilage samples subjected to frictional loading produced particulate volume significantly higher than background noise and contamination levels at all tested time points (1, 2, 6, and 24 h, p < 0.042). The particle counter was able to detect very small levels of wear (less than 0.02% of the tissue sample by volume), whereas no significant differences were observed in biochemical assays for collagen or glycosaminoglycans among any of the groups or time points. These findings confirm that latest-generation particle analyzers are capable of detecting very low wear levels in cartilage experiments conducted over a period no greater than 24 h.
Article
Of the many approaches used to characterize the complex nature of wear particle boundaries, the boundary fractal dimension has often been shown to be particularly useful. Accurate calculation of the fractal dimension can, however, be limited by a problem of variation in step length, the difficulties associated with line fitting into the Richardson plot and the fact that the dimension is sensitive to image noise and focusing. In this paper, the performance of three boundary fractal methods; i.e., the exact ‘hand and dividers’, the fractal analysis by estimation-normalized approach, and the fast Hamblin-Stachowiak method; was evaluated on artificial shapes and wear particle images. The most accurate method for calculating the fractal dimension from a particle boundary was selected. The sensitivity of these methods to image noise and focusing was also examined.
Article
Osteoarthritis (OA), the most prevalent form of arthritis, is a degenerative joint disease affecting millions of people worldwide. The overall aims of the project were: (i) to gain a better understanding of the wear processes occurring in human joints during a walking process, particularly in relation to osteoarthritic degeneration and (ii) to develop effective, minimally intrusive tools to assess OA activity and progression. Based on existing developments, this project, using three-dimensional numerical descriptors, further investigated correlation between the cartilage surface subjected and particle generated in the walking process. This is a critical step in developing and utilizing wear particle analysis techniques for OA assessment. With further study and development along with this study, it is possible to develop better diagnostic and prognostic procedures for clinic OA assessment using wear debris analysis techniques.
Article
In this work, the tribocorrosion behavior of Ti–12.5Mo, Ti–13Nb–13Zr and Ti–29Nb–13Ta–4.6Zr β titanium alloys which are candidate biomaterials for joint prostheses is studied against ultra high molecular weight polyethylene in Hank's balanced salt solution. Ti–6Al–4Fe α+β titanium alloy is also tested for comparison. Experiments were carried out at open circuit potential and at a passive applied potential using a pin-on-flat reciprocating sliding tribo-electrochemical apparatus. The potential, anodic current and friction coefficient were measured in situ as a function of time. The β alloys exhibited a tendency to repassivate during sliding at passive and open circuit potential. The predominant wear mechanism of the metal-polyethylene pairs was 3 body wear, exhibited by the transfer of polyethylene to all titanium alloys. Polyethylene showed a comparatively low wear against β titanium alloys. The effect of the addition of synovial fluid constituents, namely bovine serum albumin, hyaluronic acid and dipalmitoyphosphatidylcholine on the tribocorrosion of Ti–29Nb–13Ta–4.6Zr alloy was also studied. The presence of additives affected the friction coefficient, induced an increase of the wear volume, and a modification of the dominant wear mechanism which was identified as abrasion without transfer of polyethylene.
Article
Cartilage wear particles are released into the synovial fluid by mechanical and chemical degradation of the articular surfaces during osteoarthritis and attach to the synovial membrane. Accumulation of wear particles could alter key tissue-level mechanical properties of the synovium, hindering its characteristically low-friction interactions with underlying articular surfaces in the synovial joint. The present study employs a custom loading device to further the characterization of native synovium friction properties, while investigating the hypothesis that attachment of cartilage wear particles increases friction coefficient. Juvenile bovine synovium demonstrated characteristically low friction coefficients in sliding contact with glass, in agreement with historical measurements. Friction coefficient increased with higher normal load in saline, while lubrication with native synovial fluid maintained low friction coefficients at higher loads. Cartilage wear particles generated from juvenile bovine cartilage attached directly to synovium explants in static culture, with incorporation onto the tissue denoted by cell migration onto the particle surface. In dilute synovial fluid mimicking the decreased lubricating properties during osteoarthritis, wear particle attachment significantly increased friction coefficient against glass, and native cartilage and synovium. In addition to providing a novel characterization of synovial joint tribology this work highlights a potential mechanism for cartilage wear particles to perpetuate the degradative environment of osteoarthritis by modulating tissue-level properties of the synovium that could impact macroscopic wear as well as mechanical stimuli transmitted to resident cells.
Conference Paper
As a common joint disease often caused by wear and tear and particularly common for aged people, osteoarthritis (OA) occurs with articular cartilage deterioration and wear particle generation. Current clinical OA diagnosis approaches are mainly based on qualitative evaluation of orthopaedists. This not only brings heavy cost to community healthcare, but can also limit the required service to OA patients in regional areas. In this paper, based on our previous work on the numerical analysis of cartilage and wear particles, an expert system has been established for automatic OA diagnosis using both cartilage and wear particle analysis methods. The developed system supported vector machine (SVM) to obtain cartilage and wear particle data and applied a statistical classification method for an OA assessment. This was a first time that wear particle analysis technique was integrated into an OA diagnosis system. Internal evaluations showed that the correct OA degree recognition rates were 80% and 72% based on the cartilage and particle analysis results, respectively. This paper presents the background information, how the system was developed, and the approach used to deal with inconsistent results from cartilage and wear debris analysis. The proposed framework has demonstrated that it is feasible to develop an automatic and objective OA diagnosis system for future clinic applications.
Chapter
Here, we summarize the principles of tribology and demonstrate the importance of wear particle analysis in condition monitoring. The principles of Ferrography, a technique that was originally developed for condition monitoring of engineering systems, are explained. A new modification of this technique, known as Bio-Ferrography, is reviewed and its application in magnetic isolation of target cells or tissues is demonstrated. Routes for magnetic labeling of biological matter and synthetic polymers are also presented. The hip and knee natural joints are discussed, along with osteoarthritis-their most common noninflammatory disorder. The use of Ferrography and Bio-Ferrography for isolating bone and cartilage particles from the synovial fluids in osteoarthritic joints is reviewed. Artificial joints and the use of Ferrography and Bio-Ferrography for monitoring their wear, either during the development stage or during service, are also reviewed. The concept of soft bearing materials is presented. © 2012 Springer Science+Business Media New York. All rights are reserved.
Article
Objective: To analyze the CD4+CD25+Foxp3+ regulatory T cell (Treg) contents in peripheral blood and synovial fluid of patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and investigate the potential role of Treg in RA. Methods: The peripheral blood samples of 36 patients with RA, 30 patients with OA and 33 healthy volunteers were collected using blood collection tube with negative pressure, and the synovial fluid of patients with RA and OA by routine articulus puncturation, then determined for CD4+CD25+Foxp3+ Treg content. Results: CD4 +CD25+Foxp3+ Treg content in peripheral blood of patients with RA was significantly lower than those of patients with OA and those of healthy volunteers (P < 0.05). However, the CD4+CD25 +Foxp3+ Treg in peripheral blood of patients with OA showed no significant difference with that of healthy volunteers (P > 0.05). The CD4+CD25+ Foxp3+ Treg content in synovial fluid of patients with RA was significantly higher than that with OA(P < 0.01). Both the CD4+CD25+ Foxp3+ Treg contents in synovial fluid of patients with RA and OA were significantly higher than those in peripheral blood of the same groups (P < 0.01). Conclusion: A decreased negative regulation of CD4+CD25+Foxp3 + Treg was observed in the patients with RA, which might be an indispensable factor for disease. However, it was more likely to be a secondary action after inflammation in synovial fluid.
Article
β Titanium alloys are potential biomaterials for joint prostheses due to their biocompatibility and increased compatibility with the mechanical properties of bone. Knee and hip joints involve a sliding contact between the femoral head and the accetabular cup thus making the metallic components susceptible to tribocorrosion. Micro-motions occur at the fixation between the implant stem and the bone leading to debris and ion release by fretting-corrosion. Ti-29Nb-13Ta-4.6Zr was tested in Hank's balanced salt solution at open circuit potential and at an applied potential in the passive region at 37°C. Reciprocating tribocorrosion tests were carried out against technical grade ultra high molecular weight polyethylene (UHMWPE), while fretting-corrosion tests were carried out against alumina. Under tribocorrosion conditions, the wear of the alloy is insignificant when sliding against polyethylene. Additionally, the tested alloy showed the ability to recover its passive state during sliding. The abrasivity of the alloy depends on the electrochemical conditions in the contact, while the wear of polyethylene proceeds through 3 rd body formation and material transfer. Under fretting-corrosion conditions no recovery of passive state was possible due to the increased contact pressure. The wear resistance of the alloy was found to be dependent on the electrochemical conditions in the contact.
Article
This paper gives an overview of the progress which has been made in surface metrology over the past ten years. It updates the surface classification system, and discusses the practical and theoretical reasons for the technological shifts which have occurred. This includes the use of surfaces with predetermined features as an alternative to traditional machined surfaces, and the move from simple to freeform shapes. The paper discusses technological shifts in association, filtration, numeric parametric techniques, fractals associated with function and standardisation. Many examples are given in order to contextualise the significance of these technological changes. This paper should help to predict the direction of future developments in surface metrology, and therefore emphasise its importance in functional applications in advanced manufacture.
Article
Many images are not easily segmented by thresholding into separate features and background, because the average brightness is not unique. Image processing can sometimes convert information in the original image into a form which does permit such thresholding. A parameter of particular interest for such purposes is the texture, which is often recognizable by human viewers as a distinguishing characteristic. Most texture operators use local neighborhood pixels to compute the range, variance, moments, etc., but these are often inadequate. The operator shown here calculates a local Hurst coefficient for each point by finding the range (max-min) as a function of radial distance and performing a linear least-squares fit. The values are assigned to each pixel to create a derived image which can be thresholded.
Is the fractal dimension, of a particle's projected boundary less than the fractal dimension of the sectioned boundary of the same particle? This question has been posed by several researchers, and Russ (1991) argues that it is less, using a computer simulation to validate this opinion. In this paper, a series of real metallic particles are examined as projections and sections, using techniques outlined in a previous paper by Hamblin and Stachowiak (1993). Isotropic and anisotropic particles are examined, and in almost every case a substantial decrease in dimension was found when viewed as a projection. The appearance of bimodal Richardson plots is questioned with respect to assigning 'textural' and 'structural' fractal dimensions.
Article
An analysis of wear particles extracted from synovial fluid from osteoarthritic and rheumatoid human knee joints and asymptomatic sheep knee joints is presented in this paper. It is shown that analysis of particle morphology can provide information about the cause and progression of joint diseases which are complex and still remain poorly understood. The aim of this paper is to differentiate between populations of wear particles obtained from asymptomatic sheep knee joints and human knee joints afflicted with osteoarthritis and rheumatoid arthritis. The particles were extracted from synovial fluid by a ferrography technique and were examined using a scanning electron microscope (SEM), with the resulting SEM images analysed numerically by computer. The boundary fractal dimension and aspect ratio were then calculated for each particle used in the analysis. Finally, a statistical comparison between wear particle populations was conducted using the Wilcoxon rank test with results indicating that there are clear differences between the populations of particles obtained from the healthy and diseased joints. The advantage of the technique presented is that the analysis of wear particles is objective, consistent and furthermore it can be automated.
Article
This paper considers the use of rank sums from a combined ranking of k independent samples in order to decide which populations differ. Such a procedure is suggested as a convenient alternative to making separate rankings for each pair of samples, and the two methods are compared. Asymptotic use of the normal tables is given and the treatment of ties is discussed. A numerical example is given.
Article
Human synovial fluid often contains small cartilaginous "wear particles." Previous in vitro experiments have indicated the potential involvement of these particles in the pathophysiology of arthritis. To determine whether this potential is realized under the conditions existing within joints, standard suspensions of lapine articular cartilage were injected intraarticularly into the knee joints of rabbits. Thrice-weekly injections of 1 mg allogenic cartilage produced an inflammatory arthritis, accompanied by a marked cellular effusion, in all rabbits within 5 months. The synovium became hyperplastic, discolored, and infiltrated with mononuclear inflammatory cells. Embedded particles of the injected material were seen in histologic preparations of these synovia. Organ cultures of such synovia produced 4 to 5 times more collagenase, plasminogen activator, "Pz-peptidase," neutral and acid azocaseinase, and beta-glucuronidase than did cultures of synovia from control knees injected with saline. Furthermore, the articular cartilage of knees injected with cartilaginous particles showed elevated intrinsic collagenolytic activity. Histologic examination of the articular cartilage revealed an attendant loss of metachromasy, resulting in friability, pitting, and discoloring of the cartilage. Preliminary immunoassays failed to demonstrate a systemic immune response to the injected material.
Article
Cytologic analysis of filtered synovial lavage was compared with the independent arthroscopic findings in 70 patients with knee pain secondary to injury. Correlation existed between the arthroscopic evaluation of the articular surfaces and the presence of cartilaginous fragments and their microscopic features. Study of the filtered lavage was carried out without knowledge of the patient's clinical status or arthroscopic findings. Patients with unblemished articular surfaces and normal menisci demonstrated essentially no fragments in the synovial lavage. Minimal fibrillation of the articular surface with normal menisci was associated with few cartilage fragments per sample. Patients with moderate to severe fibrillation of the articular surface requiring a surface altering procedure, demonstrated significantly more fragments per sample. Chondrocyte nuclei were visible in these fragments, often arranged in multicellular clusters. Isolated lesions of the meniscus were associated with cartilage fragments that did not contain chondrocyte nuclei. Microscopic analysis of synovial lavage may serve as a useful diagnostic adjunct in the evaluation of the painful knee and the study of the pathogenic role of cartilage fragments is osteoarthrosis.
Article
Ferrography is a technique for analysing wear by means of the magnetic separation of wear particles. To evaluate its application in human joints, the results of the ferrographic analysis of saline washings of symptomatic human knees were compared with the results of the arthroscopic examination of the same knees. Ferrography was found to be an extremely sensitive monitor of articular erosion, with a resolution far greater than that of arthroscopy. This was particularly apparent with knees suffering from a torn anterior cruciate ligament: arthroscopy detected no damage to the cartilaginous surfaces whereas ferrography detected a substantial level of "microdamage". The spectrum of wear particles showed qualitative and quantitative alterations depending upon the condition of the knee. Ferrography thus holds much promise as a potential differential diagnostic technique of great sensitivity, with particular relevance to the very early changes which precede clinical symptoms. Study of wear particles is also justified by evidence indicating an active role in the pathophysiological progression of arthritis.
Article
Pair of sheep knee joints were used in the experiments. One of the joints was worn in a simulator over different periods of time under carefully simulated physiological forces and kinematic cycles while the other, 'control joint', was kept intact for comparison. Wear particles were extracted from a synovial fluid from both the worn and unworn sheep joints by a ferrography technique and then examined in a scanning electron microscope (SEM). The shape of the particles was characterized by boundary fractal dimension, shape factor and convexity. The shape parameters obtained for particle populations were statistically compared using a Wilcoxon rank test. It has been found that subtle changes in the shape of the particle boundary occur during the wear process. Studying the changes in wear particle boundaries provides important information about the cause and progression of wear in synovial joints.
Ferrographic analysis of wear in human joints
  • Evans
Comparison of boundary fractal dimensions from projected and sectioned particle images: part I, technique evaluation
  • Hamblin
Median-sigma filter for SEM wear particle images
  • Podsiadlo
Cartilaginous debris in the injured human knee
  • Hotchkiss