Characterization Of Wear Debris Research Articles

Isolation and characterisation of wear debris surrounding failed total ankle replacements.

Aseptic loosening and osteolysis continue to be a short- to mid-term problem for total ankle replacement (TAR) devices. The production of wear particles may contribute to poor performance, but their characteristics are not well understood. This study aimed to determine the chemical composition, size and morphology of wear particles surrounding failed TARs. A recently developed wear particle isolation method capable of isolating both high- and low-density materials was applied to 20 retrieved periprosthetic tissue samples from 15 failed TARs of three different brands. Isolated particles were imaged using ultra-high-resolution imaging and characterised manually to determine their chemical composition, size, and morphology. Six different materials were identified, which included: UHMWPE, calcium phosphate (CaP), cobalt chromium alloy (CoCr), commercially pure titanium, titanium alloy and stainless steel. Eighteen of the 20 samples contained three or more different wear particle material types. In addition to sub-micron UHMWPE particles, which were present in all samples, elongated micron-sized shards of CaP and flakes of CoCr were commonly isolated from tissues surrounding AES TARs. The mixed particles identified in this study demonstrate the existence of a complex periprosthetic environment surrounding TAR devices. The presence of such particles suggests that early failure of devices may be due in part to the multifaceted biological cascade that ensues after particle release. This study could be used to support the validation of clinically-relevant wear simulator testing, pre-clinical assessment of fixation wear and biological response studies to improve the performance of next generation ankle replacement devices. STATEMENT OF SIGNIFICANCE: Total ankle replacement devices do not perform as well as total hip and knee replacements, which is in part due to the relatively poor scientific understanding of how they fail. The excessive production of certain types of wear debris is known to contribute to joint replacement failure. This is the first study to successfully isolate and characterise high- and low-density wear particles from tissues collected from patients with a failed total ankle replacement. This article includes the chemical composition and characteristics of the wear debris generated by ankle devices, all of which may affect their performance. This research provides clinically relevant reference values and images to support the development of pre-clinical testing for future total ankle replacement designs.

Isolation and Characterisation of Wear Debris Surrounding Failed Total Ankle Replacements

Isolation and Characterisation of Wear Debris Surrounding Failed Total Ankle Replacements

Study on Wear Debris Characterization of Polycarbonate Urethane (PCU) as a Bearing of Artificial Hip Joint

As with all artificial joints, wear debris is of particular concern due to its effect on both implant life and the in vivo biological reactions that can occur. The purpose of the research is to study debris characterization of PCU. Wear particle is produced from testing the PCU material using a pin on disc wear tester within 50000 cycles. This study showed that the PCU wear debris gotten from the simulator had various different shapes, including laminar and spherical types. The morphology of worn surface and wear debris analysis showed that wear mechanism of PCU were fatigue wear. Thus we conclude that PCU is expected to be a lifetime implantation of artificial joint.

Experimental investigation on the effect of misalignment on the wear failure for spline couplings

The teeth of misaligned spline couplings used in power transmission parts of helicopter and aero-engine often suffer serious abnormal wear faults during service. Through the self-made spline coupling test rig, the mechanism of misalignment on the spline coupling wear was explored. The tooth contact domain of the spline coupling with shaft misalignment is close to the addendum, and the tooth contact domain of the spline coupling with angle misalignment is mainly concentrated on the side of the tooth end. The edge contact effect becomes more serious as the amount of misalignment increases, resulting in abnormal wear at specific positions on the tooth surface. The presence of misalignment increases the vibration intensity of the spline coupling based vibration signal monitoring, which will increase the wear of the teeth. In addition, the difference in system vibration response of different misalignment types can be used to identify the misalignment failure mode of the spline coupling. It can be inferred from the characterization of wear debris that fretting wear is the cause of the failure of the misaligned spline coupling. Tooth modification, surface strengthening modification and lubrication design are necessary as potential solutions to improve the wear resistance of misaligned spline couplings.

Study on biocompatibility, tribological property and wear debris characterization of ultra-low-wear polyethylene as artificial joint materials.

Ultra-low-wear polyethylene (ULWPE) is a new type polyethylene made by experts who are from China petrochemical research institute, which is easy to process and implant. Preliminary test showed it was more resistant to wear than that of Ultra-high-molecular weight polyethylene (UHMWPE). The purpose of the research is to study biocompatibility, bio-tribological properties and debris characterization of ULWPE. Cytotoxicity test, hemolysis test, acute/chronic toxicity and muscular implantation test were conducted according to national standard GB/T-16886/ISO-10993 for evaluation requirements of medical surgical implants. We obtained that this novel material had good biocompatibility and biological safety. The wear performance of ULWPE and UHMWPE was evaluated in a pin-on-disc (POD) wear tester within two million cycles and a knee wear simulator within six million cycles. We found that the ULWPE was higher abrasion resistance than the UHMWPE, the wear rate of ULWPE by POD test and knee wear simulator was 0.4 mg/106cycles and (16.9 ± 1.8)mg/106cycles respectively, while that of UHMWPE was 1.8 mg/106cycles and (24.6 ± 2.4)mg/106cycles. The morphology of wear debris is also an important factor to evaluate artificial joint materials, this study showed that the ULWPE wear debris gotten from the simulator had various different shapes, including spherical, block, tear, etc. The morphology of worn surface and wear debris analysis showed that wear mechanisms of ULWPE were adhesion wear, abrasive wear and fatigue wear and other wear forms, which were consistent with that of UHMWPE. Thus we conclude that ULWPE is expected to be a lifetime implantation of artificial joint.

Characterization of wear debris released from alumina-on-alumina hip prostheses: Analysis of retrieved femoral heads and peri-prosthetic tissues

We analyzed by SEM three alumina-on-alumina femoral heads obtained from three patients who underwent revision for an aseptic loosening of the acetabular component. In parallel, the peri-prosthetic tissues were analyzed histologically in search of wear debris coming from the ceramic. Stripe wears, abrasive streaks, craters, and areas with extensive biomaterial removal were evidenced on the three femoral heads by SEM. In the altered area, the structure of the ceramic composed of minute polyhedric grains packed together was evidenced. In the peri-prosthetic tissues, the alumina particles were present in different forms: larges particles appeared transparent and birefringent, small particles engulfed by the macrophages had a light brown tint and were not birefringent. Large particles corresponded to the grains observed by SEM. EDS microanalysis confirmed the presence of aluminum oxide in these particles. Alumina debris are difficult to identify microscopically due to their pleomorphism.

Characterization of wear debris from metal‐on‐metal hip implants during normal wear versus edge‐loading conditions

Advantages of second-generation metal-on-metal (MoM) hip implants include low volumetric wear rates and the release of nanosized wear particles that are chemically inert and readily cleared from local tissue. In some patients, edge loading conditions occur, which result in higher volumetric wear. The objective of this study was to characterize the size, morphology, and chemistry of wear particles released from MoM hip implants during normal (40° angle) and edge-loading (65° angle with microseparation) conditions. The mean primary particle size by volume under normal wear was 35 nm (range: 9-152 nm) compared with 95 nm (range: 6-573 nm) under edge-loading conditions. Hydrodynamic diameter analysis by volume showed that particles from normal wear were in the nano- (<100 nm) to submicron (<1000 nm) size range, whereas edge-loading conditions generated particles that ranged from <100 nm up to 3000-6000 nm in size. Particles isolated from normal wear were primarily chromium (98.5%) and round to oval in shape. Edge-loading conditions generated more elongated particles (4.5%) (aspect ratio ≥ 2.5) and more CoCr alloy particles (9.3%) compared with normal wear conditions (1.3% CoCr particles). By total mass, edge-loading particles contained approximately 640-fold more cobalt than normal wear particles. Our findings suggest that high wear conditions are a potential risk factor for adverse local tissue effects in MoM patients who experience edge loading. This study is the first to characterize both the physical and chemical characteristics of MoM wear particles collected under normal and edge-loading conditions. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 986-996, 2018.

Seal wear debris characterization for predictive maintenance

It has been estimated that at least 30% of the maintenance expenditures of large refineries and chemical plants are spent on pump repairs. In turn, each dollar spent on pump repairs contains a 60 or 70 cents outlay for mechanical seals. Seal failure reduction is therefore a priority assignment for mechanical technical service personnel in the petrochemical industry. In general, careful examination is possible only if the entire failed seal is available. However, this specific circumstance is very rare. It was, therefore, in this particular research to propose a preliminary assessment through a systematic statistical design of experimental studies of the NBR rubber debris inspection for sliding wear: namely adhesion, abrasion, after acid attack and swelled NBR rubber specimens that point to further clues and lead to the root causes of most mechanical seal problems. A series of tests were conducted with NBR rubber specimens vs cast iron wheel. NBR rubber wear particles were systematically studied in a particular block-on-ring tribosystem to assess wear products both worn surfaces and wear debris morphology. Specifically, NBR wear debris morphology obtained through an optical microscope was used to classify NBR wear debris in conjunction with their generating wear modes/mechanisms. Implementation of such results from this particular work is a basic foundation in the study of the seal wear process and essential in the evaluation of the deterioration state of this specific tribosystem. Study of seal wear particles can then be applied for predictive maintenance.

Characterization of wear-debris group in on-line visual ferrographic images

Wear-debris characterization using ferrography, which is of importance in machine condition monitoring and fault diagnosis, remains a challenge. The newly developed on-line visual ferrograph can provide digital wear-debris images and perform on-line analysis during wear monitoring. In this article, image projection transformation was utilized for extracting the overall characteristics of the wear-debris chains according to the fundamental feature of wear-debris arraying along the horizontal direction. Moreover, Full Binary Tree Based Image Division was also proposed to analyse the regional features on different scales in on-line visual ferrographic images. Several descriptive parameters including thinning ratio, chain length and chain width were proposed. In the experiments, four types of images with different wear-debris groups were compared and a group of time-sequence on-line visual ferrographic images of an inline four-cylinder gasoline engine was studied. It is found that more comprehensive wear information can be acquired through the proposed multi-parameter description method. Meanwhile, the image projection transformation method extracts macrocharacteristics of images rapidly and efficiently and the thinning ratio measures wear-debris width in an intuitive way.

Wear Debris Characterization and Corresponding Biological Response: Artificial Hip and Knee Joints.

Wear debris, of deferent sizes, shapes and quantities, generated in artificial hip and knees is largely confined to the bone and joint interface. This debris interacts with periprosthetic tissue and may cause aseptic loosening. The purpose of this review is to summarize and collate findings of the recent demonstrations on debris characterization and their biological response that influences the occurrence in implant migration. A systematic review of peer-reviewed literature is performed, based on inclusion and exclusion criteria addressing mainly debris isolation, characterization, and biologic responses. Results show that debris characterization largely depends on their appropriate and accurate isolation protocol. The particles are found to be non-uniform in size and non-homogeneously distributed into the periprosthetic tissues. In addition, the sizes, shapes, and volumes of the particles are influenced by the types of joints, bearing geometry, material combination, and lubricant. Phagocytosis of wear debris is size dependent; high doses of submicron-sized particles induce significant level of secretion of bone resorbing factors. However, articles on wear debris from engineered surfaces (patterned and coated) are lacking. The findings suggest considering debris morphology as an important parameter to evaluate joint simulator and newly developed implant materials.

Watershed-Based Morphological Separation of Wear Debris Chains for On-Line Ferrograph Analysis

Separation and characterization of wear debris from ferrograph images are demanded for on-line analysis. However, particle overlapping issue associated with wear debris chains has markedly limited this technique due to the difficulty in effectively segmenting individual particles from the chains. To solve this bottleneck problem, studies were conducted in this paper to establish a practical method for wear debris separation for on-line analysis. Two conventional watershed approaches were attempted. Accordingly, distance-based transformation had a problem with oversegmentation, which led to overcounting of wear debris. Another method, by integrating the ultimate corrosion and condition expansion (UCCE), introduced boundary-offset errors that unavoidably affected the boundary identification between particles, while varying the corrosion scales and adopting a low-pass filtering method improved the UCCE with satisfactory results. Finally, together with a termination criterion, an automatic identification process was applied with real on-line wear debris images sampled from a mineral scraper gearbox. With the satisfactory separation result, several parameters for characterization were extracted and some statistics were constructed to obtain an overall evaluation of existing particles. The proposed method shows a promising prospect in on-line wear monitoring with deep insight into wear mechanism.

Characterization of polyethylene wear particle: The impact of methodology

Due to the prevalence of problems caused by wear particles, the reduced durability of total joint replacements is well documented. The characterization of wear debris enables the size and morphology of these wear particles to be measured and provides an assessment of the biological response in vivo. However, the impact of different methodologies of particle analysis is not yet clear. Hence, the aim of this investigation was to analyze the influence of different particle characterization methods performed by three research centers within the scope of a “round robin test”. To obtain knowledge about possible pitfalls, single steps of the particle characterization process (storage, pore size of the filter, coating durations by gold sputtering and scanning electron microscopy (SEM) magnification) were analyzed. The round robin test showed significant differences between the research groups, especially for the morphology of the particles. The SEM magnification was identified as having the greatest influence on the size and shape of the particles, followed by the storage conditions of the wear particle containing lubricant. Gold sputter coating and filter pore size also exhibit significant effects. However, even though they are statistically significant, it should be emphasized that the differences are small. In conclusion, particle characterization is a complex analytical method with a multiplicity of influencing factors. It becomes apparent that a comparison of wear particle results between different research groups is challenging.

Characterization of wear debris in total elbow arthroplasty

The purpose of this study was to evaluate wear debris in periprosthetic tissues at the time of revision total elbow arthroplasty. Polyethylene, metallic, and bone cement debris were characterized, and the tissue response was quantified. Capsular and medullary tissue samples were collected during revision surgery. Polyethylene debris was characterized by scanning electron microscopy after tissue digestion. The concentrations of metal and cement debris were quantified by inductively coupled plasma mass spectrometry. Tissue response was graded with a semiquantitative histologic method. Polyethylene particle size varied from the submicron range to over 100 μm. The mean diameter ranged from 0.6 μm to about 1 μm. Particles in the synovial tissues were larger and less abundant than those in tissues from the medullary canal. Cement, titanium alloy, and low levels of cobalt-chrome debris were also present, with cement predominating over metal debris. Histiocyte response was associated with small polyethylene particles (0.5-2 μm), and giant cells were associated with large polyethylene particles (>2 μm). Histiocyte scores positively correlated with the polyethylene particle number and the presence of metal. We have shown that periprosthetic tissues of total elbow patients who have undergone revision for loosening and osteolysis contain polyethylene, cement, and metal debris. Although the polyethylene particles were of a size and shape that have been previously shown to result in activation of phagocytic cells, osteolysis after total elbow arthroplasty is a multimodal process. Because of the presence of multiple wear particle sources, a cause-and-effect relationship between polyethylene debris and osteolysis cannot be established with certainty.

An In Vitro Assessment of Wear Particulate Generated From NUBAC

In vitro biotribological wear particulate investigation. To characterize poly-ether-ether-ketone (PEEK)-OPTIMA wear particulate generated from a series of wear tests used to evaluate the wear resistance and long-term biodurability of NUBAC, a PEEK-on-PEEK articulating nucleus replacement device, and compare with wear particulate associated with hip and knee total joint arthroplasties. The use of PEEK in spinal arthroplasty represents a unique application of this material. Clinically, osteolysis, osteolytic changes, and adverse reactions to metal ions have been documented in spinal arthroplasty. Therefore, it is critically important to analyze the PEEK wear particulate to evaluate its resultant biologic reactivity. Historically, scanning electron microscopy (SEM) has been used for wear debris characterization. Light scattering, specifically laser diffraction, has also been successfully used. The combined use of both techniques may provide a more comprehensive analysis than either method alone. Proteinacious serum containing PEEK wear debris generated from four groups of devices from separate wear tests underwent enzymatic and acid digestion. The particulate was analyzed using laser diffraction in duplicate, followed by SEM analysis. Laser diffraction analysis demonstrated a relatively large mean particle diameter on the basis of particle volume (16.5-40.0 µm) as compared with particle number (0.9-2.2 µm). For all groups, more than 50% of debris was larger than 5.0 µm. SEM analysis revealed a mean particle size consistent with the number-based laser diffraction results. The morphology of the wear particulate appeared to be similar for all the groups analyzed. The analysis of the particles generated from an articulating PEEK-on-PEEK nucleus replacement device shows debris within size ranges typical of other total joint arthroplasty implants, with relatively round morphology, along with the results suggesting a reduced particle load. These attributes tend to diminish the potential of these PEEK particles to elicit an inflammatory response.

Wear Behaviour and Wear Debris Characterization of UHMWPE on Alumina Ceramic, Stainless Steel, CoCrMo and Ti6Al4V Hip Prostheses in a Hip Joint Simulator

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.

On the ferro-graphic characterisation of wear debris in tribological system by grey fixed weight clustering

Both characterisation of wear debris and identification of wear debris from lubricating oils and greases in the tribological systems were investigated in the present paper. The characterisation system to describe wear debris morphology was erected based on the identification parameters of wear debris in the ferro-graphic system. Four characterisation parameters were analysed, including colour, surface texture, shape and size of wear debris. By using grey fixed weight clustering method, six kinds of wear debris were recognised, i.e., normal wear debris, ball particles, cutting debris, sever sliding debris, debris of Fe2O3 and Fe3O4, which is helpful to pre-diagnose the fault type of machinery.

Metal wear particles: What we know, what we do not know, and why

The importance of wear particle characterization for orthopaedic implants has long been established in the hip and knee arthroplasty literature. With the increasing use of motion preservation implants in the spine, the characterization of wear debris, particularly metallic nature, is gaining importance. An accurate morphological analysis of wear particles provides for both a complete characterization of the biocompatibility of the implant material and its wear products, and an in-depth understanding of the wear mechanisms, ion release, and associated corrosive activity related to the wear particles. In this paper, we present an overview of the most commonly-used published protocols for the isolation and characterization of metal wear particles, and highlight the limitations and uncertainties inherent to metal particle analysis.

Numerical surface characterization of wear debris from artificial joints using atomic force microscopy

Study on surface features of wear particles generated in wear process provides an insight into the progress of material failure of artificial joints. It is very important to quantify the surface features of wear particles in three dimensions. In this study, a new approach using atomic force microscopy was proposed to carry out 3D numerical surface characterization of wear debris generated from artificial joints. Atomic force microscopy combined with image processing techniques was used to acquire appropriate 3D images of wear debris. Computerized image analysis techniques were then used to quantify surface texture features of wear debris such as surface roughness parameters and surface texture index. The method developed from the present study was found to be feasible to quantity the surface characterization of nano- and micro-sized wear debris generated from artificial joints.

Comparison of periprosthetic tissue digestion methods for ultra‐high molecular weight polyethylene wear debris extraction

There is considerable interest in characterization of wear debris from polyethylene (UHMWPE) bearing components used in total joint replacement. To isolate UHMWPE wear debris, tissue samples must be excised from regions adjacent to revised UHMWPE implant components, followed by exposure to one of many available tissue digestion methods. Numerous studies demonstrate successful digestion, but the relative efficiency of each method is not clear. The purpose of this study was to evaluate a variety of conditions for tissue digestion to provide a quantitative comparison of methods. Porcine and human hip tissues were exposed for 24 h to basic, acidic or enzymatic agents, filtered and digestion efficiency calculated based on the percentage of initial to final tissue weight. Of the conditions tested, 5 M NaOH, 5 M KOH, 15 M KOH or 15.8 M HNO(3) yielded the most complete porcine hip tissue digestion (<1% residual tissue weight; p < 0.05). Proteinase K and Liberase Blendzyme 3 did not effectively digest tissue in a 24 h period. Similar to results from the porcine dataset, human tissues digestion was most efficient using 5 M NaOH, 5 M KOH or 15.8 M HNO(3) (<1% residual tissue weight; p < 0.05). To verify that particle surface modifications did not occur after prolonged reagent exposure, GUR415 and Ceridust 3715 particles were immersed in each solution for 24 h. Overall, this study provides a framework for thorough and efficient digestive methods for UHMWPE wear debris extraction.

Alumina-on-Alumina Articulation in Total Hip Arthroplasty: From Bench-side to Bedside

Alumina-on-alumina total hip arthroplasty has been used for 32 years in Europe. The theoretical advantages of this combination are represented by its remarkable sliding characteristics, its very low wear debris generation, and its improved fracture toughness. These advantages are achieved if the material is properly processed with high density, high purity, and small grains. The authors summarize the results obtained with the alumina-on-alumina combination concerning in vitro and in vivo wear behavior with special emphasis on wear debris characterization and quantification and histological tissue examinations. Alumina-on-alumina seems to be one of the best choices in young and active patients provided that sound socket fixation is maintained in the long term.