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Background: Ceramic-on-ceramic (COC) bearings in total hip arthroplasty (THA) have long been considered the coupling with the lowest overall wear. However, concerns about complications such as ceramic breakage and noise, combined with the improved performance of polyethylene, have limited its use in the United States. This postapproval follow-up reports long-term (10 years) results of Delta COC in THA patients primarily enrolled in an Investigational Device Exemption study. Methods: Patients received Delta COC THA in a prospective multicenter study with either 28-mm (N = 105 hips in 104 patients) or 36-mm (N = 81) articulations. Annual clinical and radiographic evaluations were performed for years 5 to 10, and study patients were asked about hip noises and reproducibility. Results: There have been 4 additional reports of noise in 4 patients (COC 28, n = 3; COC 36, n = 1). The cumulative incidence rate for squeaking or noise at 10 years is 5.9% for COC 28 and 13.5% for COC 36. There have been 2 additional reports of dislocation in 2 patients (COC 28, n = 1; COC 36, n = 1). The cumulative incidence rate for dislocation at 10 years is 3.7% for COC 28 and 3.5% for COC 36. At 10 years, there were greater than 40 hips available for follow-up. At mean 10-year follow-up, there were a total of 3 ceramic liner fractures, but none since the previous report. There were no revisions in the 28-mm cohort, and 2 revisions in the 36-mm cohort (1 for recurrent dislocation and 1 for pain and noise). Overall Kaplan-Meier survivorship was 95.96% at 10.5 years (28 mm: 97.68% at 10.2 years; 36 mm: 94.11% at 10.4 years.) Conclusions: At 10-year follow-up, we report excellent results in regard to survivorship, with one patient revised for pain with associated squeaking.

Organic radical monolayers (r-MLs) bonded to metal surfaces are potential materials for the development of molecular (spin)electronics. Typically, stable radicals bearing surface anchoring groups are used to generate r-MLs. Following a recent theoretical proposal based on a model system, we report the first experimental realization of a metal surface-induced r-ML, where a rationally chosen closed-shell precursor 3,5-dichloro-4-[bis(2,4,6-trichlorophenyl)methylen]cyclohexa-2,5-dien-1-one (1) transforms into a stable neutral open-shell species (1•) via chemisorption on the Ag(111) surface. X-ray photoelectron spectroscopy reveals that the >C═O group of 1 reacts with the surface, forming a C–O–Ag linkage that induces an electronic rearrangement that transforms 1 to 1•. We further show that surface reactivity is an important factor in this process whereby Au(111) is inert towards 1, whereas the Cu(111) surface leads to dehalogenation reactions. The radical nature of the Ag(111)-bound monolayer was further confirmed by angle-resolved photoelectron spectroscopy and electronic structure calculations, which provide evidence of the emergence of the singly occupied molecular orbital (SOMO) of 1•., This work was funded by ERC StG 2012-306826 e-GAMES, the European Regional Development Fund (ERDF) under the program Interreg V-A España-Francia-Andorra (contract no. EFA 194/16 TNSI), the Networking Research Center on Bioengineering, Biomaterials, and Nanomedicine (CIBERBBN), the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) through projects FANCY CTQ2016-80030-R, RTI2018-095460-B-I00 and MAT2016-78293-C6-2-R, the “Severo Ochoa” Programme for Centers of Excellence in R&D (SEV-2015-0496 and SEV-2017-0706), and the “Maria de Maeztu” program for Spanish Structures of Excellence (MDM-2017-0767). This research was also supported in part by Generalitat de Catalunya (grants 2017SGR13 and 2017SGR918). Computational time was provided by through grants from the Red Española de Supercomputacion. I.A. acknowledges the Spanish Ministerio de Educacion Cultura y Deporte for an FPU Ph.D. scholarship, and F.I. acknowledges additional support from a 2015 ICREA Academia Award. This research was also funded by the CERCA Programme/Generalitat de Catalunya. C.M. was supported by the Agency for Management of University and Research grants (AGAUR) of the Catalan government through the FP7 framework program of the European Commission under Marie Curie COFUND action 600385.

Background The ideal bearing surface for patients of avascular necrosis (AVN) undergoing total hip arthroplasty (THA) remains controversial. The purpose of this study is to evaluate the clinical outcomes, health-related quality of life (HRQL), and wear of the bearing surface between ceramic-on-ceramic (CoC) and ceramic-on-highly cross-linked polyethylene (CoXPE) THA for patients of AVN after midterm follow-up. Methods We performed a retrospective case-control analysis of 93 CoC and 77 CoXPE consecutive THAs for patients of AVN. The cases were followed at a minimum 5 years follow-up (average 7 years). Harris hip score (HHS) score and bearing-related complications were assessed. The health-related quality of life (HRQL) was assessed with the Short Form 36 (SF-36). Plain radiographs and computed tomography (CT) were used for radiographic evaluation. Results Both the CoC group and CoXPE group showed statistically significant improvements in HHS scores with no difference between the two bearing surfaces. There was no significant difference as for SF-36 at the latest follow-up between two groups, except for significant higher scores in the dimensions of general health in the CoC group (75.7 vs 64.7, P = 0.032). No radiographic evidence of osteolysis and loosening was present at the final follow-up. The mean wear rate of the CoC was 0.0096 mm/year and the CoXPE was 0.047 mm/year after evaluation with reconstructed CT. Conclusions CoC THAs acts as well as CoXPE THAs for patients with femoral head avascular necrosis after midterm follow-up. CoC bearing can significantly decrease the wearing rate than CoXPE bearing.

Promising results of total hip allowed to perform a hip replacement in younger and active patients. However, the results of arthroplasty in young populations are still not comparable with outcomes in patients of older age groups. The advent of new materials and further improvement of production technology is increasing interest in the use of alternative bearing surfaces, but to assess the effectiveness of each new implants needed long-term clinical studies. Use of any bearing surface has its own potential advantages and disadvantages that must be assessed in each case.

Formation of wear particles within total hip replacement is one of the main causes of its failure. In addition to improving the lubrication and wear resistance of materials used as bearing surfaces, understanding of wear particle distribution patterns within lubricants inside an implant gap could be used to improve design parameters and implants’ lifespan. In this study, the behaviours of biolubricants (with compositions similar to human joint synovial fluid) and suspended particles were investigated by micro-particle image velocimetry in curved mini channels under oscillatory Couette flow conditions. The studied biolubricants had shear-thinning viscoelastic characteristics. The authors found that increasing shear-thinning, elasticity or motion frequency levels did not affect the trend behaviours of biolubricant flows due to the low strain values of the experimental conditions applied. However, suspended particles formed strings along flow directions and exhibited cross-stream migration to channel walls. Motion frequency, fluid shear thinning and elasticity characteristics and channel dimensions strongly affected particle behaviours. Validerad;2018;Nivå 1;2018-08-16 (andbra)

Kluzná ložiska s naklápěcími segmenty se používají k ukládání točivých strojů s vysokou obvodovou rychlostí čepů hřídele. Ve výpočtech rotorové dynamiky se často zanedbává kmitání naklápěcích segmentů a síly přenášené ložiskem se linearizují. V příspěvku je představen výpočtový model respektující nelineární charakter sil v mazacím filmu, uložení segmentů a poddajnost segmentů i ložiskového tělesa. Model je schopen predikovat kmitání segmentů, kavitaci v mazivu a opotřebení kluzných ploch. Tato publikace byla podpořena projektem TE01020068 Technologické agentury ČR a projektem SGS-2016-038 Západočeské univerzity v Plzni. Tilting pad bearings can be found in rotating machinery with high circumferential speeds of journals. Vibrations of individual pads are usually neglected in rotordynamics simulations and hydrodynamic forces acting in oil films are often linearized. A computational model which respects non-linear properties of hydrodynamic forces, contact forces between the pads and a bearing housing, and deformations of the pads and the housing is introduced in this paper. The model can be used for the analysis of vibrational and tribological parameters including wear of bearing surfaces.

Adverse reactions to metal particle debris have been increasingly reported as a complication following large head metal-on-metal (MoM) hip arthroplasty. Elevated metal ion levels are a cause for concern. The aim of this study is to evaluate whether exposure to cobalt is associated with patient characteristics and symptoms of neuropathy, representing nervous system dysfunction. A cross-sectional study was conducted comparing patients with a MoM total hip arthroplasty and patients with a conventional hip arthroplasty. They received three questionnaires, one to assess neurotoxic complaints and two standardised self-administered questionnaires to identify symptoms that are suggestive of peripheral neuropathy. Current and historical data were available for whole blood cobalt levels in all patients. We analysed potential predictive factors for cobalt based on five different cut-off levels (0-2, 2-4, 4-10, 10-20, >20 µg/L). We performed 723 MoM total hip arthroplasties in 643 patients in our clinic. The response rate was 89%. Male-female ratio was 236/280, median age 63.6 years (30-72) with a mean follow-up of 50.6 months (20-86). We also sent the questionnaires to 98 patients in the control group. An increase in the incidence of reported symptoms was not consistent with higher serum cobalt levels. Female gender was the only consistent predictive factor for serum cobalt at different cobalt cut-off levels in the multivariate analysis. The study population did not show an increase in reported symptoms with elevated cobalt levels. Neurotoxic symptoms and whole blood cobalt levels did not show a consistent relationship with different dichotomised levels of cobalt exposure.

International audience; Neutron reflectivity has been used to investigate the effect of shear on the conformation of hydrogenated polystyrene chains end-grafted on a silicon wafer and covered by a deuterated polystyrene melt, in the grafting regime where the grafted chains at equilibrium extend in the bulk up to their radius of gyration. An experimental setup has been built to shear the samples above their glass transition temperature and then quench them rapidly after the shear. The flow-induced distorted conformation of the end-tethered chains was characterized by neutron reflectivity. We show that the effect of the shear is a decoupling between the grafted chains and the bulk chains which leads to a strong slip of the polymer melt at the solid interface.

The application of textured bearing surfaces results in a more complex lubricant flow pattern compared to smooth bearing surfaces. In order to capture the more complex flow pattern and possible inertia effects in the vicinity of the surface pockets, the NavierStokes equations should be used to model the flow between textured surfaces instead of the Reynolds equation. In this paper a multi-scale method is presented where the fluid flow in a single micro-scale texture unit cell is modelled using the NavierStokes equations, the results of which are then averaged to flow factors to be used in a novel texture averaged Reynolds equation on the macro-scale bearing level. Depending on the local flow conditions the non-linear inertia effects in the flow can either contribute or detract from the local load capacity of the lubricant film. Some results from the micro-scale calculations are presented, followed by the method developed to average these results to the macro-scale. The resulting flow-factors are presented and a load correction term is introduced. Although the method presented does not put restrictions to the texture dimensions, the texture unit cell dimensions are chosen equal to those in an experimental polymer water lubricated bearing. In a follow-up paper these results will be used to determine the efficiency of surface texturing in a lubricated journal bearing application. © 2010 Elsevier Ltd.

In view of the fact that the endo-prosthesis heads of human hip-joint are operated in extreme conditions, in respect of load, the selection of corresponding material and also increase of precision and quality of machining of spherical surfaces is rather topical task. In the submitted work are reviewed the problems connected with the definition of the influence degree of orientation of the sapphire crystal on its workability during the diamond grinding with the ring end. For conduct of investigations of workability of the sapphire crystal the method of low temperature precision grinding (LPG) was chosen elaborated at the Department of Mechanical Engineering of the Georgian Technical University as a version of progressive methods for grinding of hard and brittle non-metallic materials. On the basis of analysis of the existing kinematic schemes and technological processes of obtaining spherical surfaces the new more effective scheme has been suggested that provides the increase of precision of spherical surfaces. The essence of the scheme is in the selection of optimal ranges of the ratio of rotational speeds of the article and tool and in equal distribution of the article pressing to the grinding ring by the analog of the LPG method that is the pledge of exclusion of unequal wear of the abrasive tool, achievement and support of high precision of the work surface and by that the machining precision of the surface of incomplete surface., В виду того, что головки эндопротеза тазобедренного сустава человека эксплуатируются в экстремальных условиях, в отношении нагрузки, подбор соответствующего материала, а также повышение точности и качества обработки сферических поверхностей является весьма актуальной задачей. В представленной работе рассмотрены проблемы связанные с определением степени влияния ориентации кристалла сапфира на его обрабатываемость при алмазном шлифовании торцом круга и с разработкой перспективной, оригинальной схемы формообразования неполной сферической поверхности, в частности, сапфировой головки эндопротеза тазобедренного сустава человека., В зв’язку з тим, що головки ендопротеза тазостегнового суглоба людини експлуатуються в екстремальних умовах відносно навантаження, підбір відповідного матеріалу, а також підвищення точності і якості обробки сферичних поверхонь є досить актуальним завданням. У поданій роботі розглянуто проблеми, пов'язані з визначенням ступеня впливу орієнтації кристала сапфіра на його оброблюваність при алмазному шліфуванні торцем круга і з розробкою перспективної, оригінальної схеми формоутворення неповної сферичної поверхні, зокрема, сапфірової головки ендопротеза тазостегнового суглоба людини.

Background: Most literature in the field of total hip arthroplasty (THA) for fused hips, until date has reported the results of using metal on polyethylene and ceramic on polyethylene bearings. Results of THA using ceramic on ceramic (CoC) bearings in fused hips have not been published in literature. This study reports the results of cementless THA using CoC articulation perfomed in fused hips. Materials and Methods: Twenty-three patients (25 hips) with fused hips underwent conversion to THA using CoC bearings and were followed up for a mean 5.4 years. The conventional posterolateral approach was used in 15 hips, a modified two incision technique in 7 hips and a direct lateral approach with greater trochanteric osteotomy in 3 hips. Postoperatively, range of motion exercises were encouraged after 2-3 days of bed rest and subsequent gradual weight bearing using crutches was begun. Results: Mean Harris hip score improved from 42.4 to 84.2 and mean leg lengthening of 36.6 mm was achieved. In the average 5.4 years (range 2.8-9.1 years) followup there were no cases with osteolysis around acetabular cup and femoral stem. In this study, there was no case of ceramic fracture. There was one case of squeaking. Conclusion: This study suggests that cementless THA performed for fused hips with CoC bearings can provide good early clinical results.

В зв’язку з тим, що головки ендопротеза тазостегнового суглоба людини експлуатуються в екстремальних умовах відносно навантаження, підбір відповідного матеріалу, а також підвищення точності і якості обробки сферичних поверхонь є досить актуальним завданням. У поданій роботі розглянуто проблеми, пов'язані з визначенням ступеня впливу орієнтації кристала сапфіра на його оброблюваність при алмазному шліфуванні торцем круга і з розробкою перспективної, оригінальної схеми формоутворення неповної сферичної поверхні, зокрема, сапфірової головки ендопротеза тазостегнового суглоба людини. In view of the fact that the endo-prosthesis heads of human hip-joint are operated in extreme conditions, in respect of load, the selection of corresponding material and also increase of precision and quality of machining of spherical surfaces is rather topical task. In the submitted work are reviewed the problems connected with the definition of the influence degree of orientation of the sapphire crystal on its workability during the diamond grinding with the ring end. For conduct of investigations of workability of the sapphire crystal the method of low temperature precision grinding (LPG) was chosen elaborated at the Department of Mechanical Engineering of the Georgian Technical University as a version of progressive methods for grinding of hard and brittle non-metallic materials. On the basis of analysis of the existing kinematic schemes and technological processes of obtaining spherical surfaces the new more effective scheme has been suggested that provides the increase of precision of spherical surfaces. The essence of the scheme is in the selection of optimal ranges of the ratio of rotational speeds of the article and tool and in equal distribution of the article pressing to the grinding ring by the analog of the LPG method that is the pledge of exclusion of unequal wear of the abrasive tool, achievement and support of high precision of the work surface and by that the machining precision of the surface of incomplete surface. В виду того, что головки эндопротеза тазобедренного сустава человека эксплуатируются в экстремальных условиях, в отношении нагрузки, подбор соответствующего материала, а также повышение точности и качества обработки сферических поверхностей является весьма актуальной задачей. В представленной работе рассмотрены проблемы связанные с определением степени влияния ориентации кристалла сапфира на его обрабатываемость при алмазном шлифовании торцом круга и с разработкой перспективной, оригинальной схемы формообразования неполной сферической поверхности, в частности, сапфировой головки эндопротеза тазобедренного сустава человека.

The study of the aerodynamics of different configurations of aircraft with joined wing using panel-vortex method of symmetrical features (PANSIM). Performing the calculation and rating of the configurations aircraft with joined wing with a combination of different types of bearing surfaces.For each layout of the aircraft with joined wing was determined the effect relative impact of location and V-similarity angle the front wing on the transport aircraft efficiency and its corresponding prime aerodynamic lift coefficient value; on the maximum aerodynamic qualities and the corresponding optimal aerodynamic lift coefficient value.To select the optimal layout of aircraft with joined wing advisable to take the maximum transport efficiency values and maximum aerodynamic quality for distance between the front and rear wing aircraft.Due to the lack of information on the impact of combinations of bearing surfaces aircraft with joined wing on the aerodynamic performance and transport efficiency aircraft have been proposed recommendations of the aerodynamic design of aircraft with joined wing in which the aircraft will have a maximum range and flight duration.Detect the effect of the combinations of bearing surfaces aircraft with joined wing on the transport aircraft efficiency.Found rational construction layout construction solutions aircraft with joined wing., Исследуется аэродинамика различных компоновок летательных аппаратов с замкнутой пространственной системой крыльев с помощью панельно-вихревого метода симметричных особенностей (PANSIM). Выполняется расчет и оценка компоновок ЛА замкнутой пространственной схемы с различными типами соединения несущих поверхностей., Досліджується аеродинаміка різних компоновок літальних апаратів із замкненою просторовою системою крил за допомогою панельно-вихрового методу симетричних особливостей (PANSIM). Виконується розрахунок і оцінка компоновок ЛА замкненої просторової схеми з різними типами сполучення несучих поверхонь.

Досліджується аеродинаміка різних компоновок літальних апаратів із замкненою просторовою системою крил за допомогою панельно-вихрового методу симетричних особливостей (PANSIM). Виконується розрахунок і оцінка компоновок ЛА замкненої просторової схеми з різними типами сполучення несучих поверхонь. The study of the aerodynamics of different configurations of aircraft with joined wing using panel-vortex method of symmetrical features (PANSIM). Performing the calculation and rating of the configurations aircraft with joined wing with a combination of different types of bearing surfaces. For each layout of the aircraft with joined wing was determined the effect relative impact of location and V-similarity angle the front wing on the transport aircraft efficiency and its corresponding prime aerodynamic lift coefficient value; on the maximum aerodynamic qualities and the corresponding optimal aerodynamic lift coefficient value. To select the optimal layout of aircraft with joined wing advisable to take the maximum transport efficiency values and maximum aerodynamic quality for distance between the front and rear wing aircraft. Due to the lack of information on the impact of combinations of bearing surfaces aircraft with joined wing on the aerodynamic performance and transport efficiency aircraft have been proposed recommendations of the aerodynamic design of aircraft with joined wing in which the aircraft will have a maximum range and flight duration. Detect the effect of the combinations of bearing surfaces aircraft with joined wing on the transport aircraft efficiency. Found rational construction layout construction solutions aircraft with joined wing. Исследуется аэродинамика различных компоновок летательных аппаратов с замкнутой пространственной системой крыльев с помощью панельно-вихревого метода симметричных особенностей (PANSIM). Выполняется расчет и оценка компоновок ЛА замкнутой пространственной схемы с различными типами соединения несущих поверхностей.

We investigate the mechanical properties of ultra-thin layers of polystyrene/poly (2-vinylpyridine) (PS/P2VP) block copolymers by means of a Surface Forces Apparatus adapted to operate asa rheometer at the molecular level. Two systems are studied: ''brush/wall'' and ''brush/brush''. A comparison of the normal force curves shows that when brushes are compressed against each other, they contract rather than interpenetrate. Nanorheological experiments have been carried out on both systems but reliable measurements have been obtained only on the brush/wall system. The complex shear modulus, characterizing the confined medium, has been measured as a function of separation. Its distance dependence is compared with a scaling model describing the linear shear behaviour of a brush confined by a neutral surface.

Patients in need of total hip or knee arthroplasty are continuously getting younger which produce the need for bearing surfaces that can withstand both the high functional demand as well as the longevity of the patient. New developments are continuously flooding the market and the promotion of these products is directed towards patients themselves who, most of the time, will not have the necessary insight to choose the best possible product. Due to recent introduction into the market, these products all lack long-term independent clinical follow-up, but all have promising results in manufacturer-funded, short-term clinical trials and laboratory simulator trials. This leaves the surgeon with the dilemma of using new untested technology with potentially devastating results or keeping to the tried and trusted. Technological advances in bearing surfaces include modifications of known materials and the introduction of totally new materials, all in an attempt to find the perfect bearing coupling. This paper summarises the most important new developments in bearing surfaces and bearing couples in arthroplasty and puts emphasis on the dangers of using untested technology.

Purpose: The purpose of this paper is to describe the infrastructure of the total joint replacement registry of a large integrated healthcare system's and emphasize challenges associated with orthopedic device classification and evaluation. Conclusions: Clinically rich data from a registry with linkages to electronic health records and other administrative databases improve identification of exposures, outcomes, and patient subgroups in medical device evaluation. These various data sources facilitate refined adjustment for potential confounders such as hospital, surgeon, and patient factors and ensure comprehensive device performance evaluation within registries. Methods: Using a large integrated healthcare system innovative infrastructure including electronic health record data, administrative data sources, and registry data collection, we evaluated device choice and outcomes of total hip arthroplasty (THA). Devices were classified into type of bearing surface (alternative versus traditional). Multiple imputation was used to accommodate missing data, and a logistic regression model was applied to assess the impact of patient and surgeon factors on choice of bearing surface. A Cox regression model was used to evaluate risk of aseptic revision while controlling for surgeon, site, and patient characteristics. Adjusted cumulative probability-of-event curves were created, comparing survival of alternative against traditional bearings of devices, with aseptic revision as the outcome of interest. Results: The study sample consisted of 25 377 primary THAs with an average follow-up of 2.7 years. Choice of bearing surface varied by surgeon and patient characteristics. After adjusting for patient, surgeon, and hospital covariates, results showed that the risk of aseptic revision associated with alternative bearings did not differ significantly from traditional bearing surfaces (hazard ratio = 1.33; 95% confidence interval: 0.90, 1.98). Refereed/Peer-reviewed

The application of textured bearing surfaces results in a more complex lubricant flow pattern compared to smooth bearing surfaces. In order to capture the more complex flow pattern and possible inertia effects in the vicinity of the surface pockets, the NavierStokes equations should be used to model the flow between textured surfaces instead of the Reynolds equation. In this paper a multi-scale method is presented where the fluid flow in a single micro-scale texture unit cell is modelled using the NavierStokes equations, the results of which are then averaged to flow factors to be used in a novel texture averaged Reynolds equation on the macro-scale bearing level. Depending on the local flow conditions the non-linear inertia effects in the flow can either contribute or detract from the local load capacity of the lubricant film. Some results from the micro-scale calculations are presented, followed by the method developed to average these results to the macro-scale. The resulting flow-factors are presented and a load correction term is introduced. Although the method presented does not put restrictions to the texture dimensions, the texture unit cell dimensions are chosen equal to those in an experimental polymer water lubricated bearing. In a follow-up paper these results will be used to determine the efficiency of surface texturing in a lubricated journal bearing application. © 2010 Elsevier Ltd.

We investigate the mechanical properties of ultra-thin layers of polystyrene/poly (2-vinylpyridine) (PS/P2VP) block copolymers by means of a Surface Forces Apparatus adapted to operate asa rheometer at the molecular level. Two systems are studied: ''brush/wall'' and ''brush/brush''. A comparison of the normal force curves shows that when brushes are compressed against each other, they contract rather than interpenetrate. Nanorheological experiments have been carried out on both systems but reliable measurements have been obtained only on the brush/wall system. The complex shear modulus, characterizing the confined medium, has been measured as a function of separation. Its distance dependence is compared with a scaling model describing the linear shear behaviour of a brush confined by a neutral surface.

We investigate the mechanical properties of ultra-thin layers of polystyrene/poly (2-vinylpyridine) (PS/P2VP) block copolymers by means of a Surface Forces Apparatus adapted to operate asa rheometer at the molecular level. Two systems are studied: ''brush/wall'' and ''brush/brush''. A comparison of the normal force curves shows that when brushes are compressed against each other, they contract rather than interpenetrate. Nanorheological experiments have been carried out on both systems but reliable measurements have been obtained only on the brush/wall system. The complex shear modulus, characterizing the confined medium, has been measured as a function of separation. Its distance dependence is compared with a scaling model describing the linear shear behaviour of a brush confined by a neutral surface.