Search

BACKGROUND: With social progress, the incidence rate of knee osteoarthritis is getting higher and higher in the face of the rapidly developing aging problem in the social population, and the number of total knee replacement operations is gradually increasing. OBJECTIVE: To study the relationship between prosthesis size and stress shielding by improving the tibial prosthesis base. METHODS: A female patient with severe knee osteoarthritis was selected. Based on Mimics, through extracting the bone structure of the knee joint and simulating the total knee replacement surgery, osteotomy, positioning, and implantation operations were carried out to establish the geometric modeling of the total knee replacement prosthesis (including the femoral prosthesis, tibial bracket, and tibial pad), and improve the design of the tibial prosthesis base, analyze the effect of different tibial prosthesis bases on stress shielding of surrounding bone tissue. RESULTS AND CONCLUSION: (1) Compared with single-stem tibial intramedullary stem prosthesis, the design of four-post tibial intramedullary stem prosthesis created a certain degree of stress shielding around the short stem. However, compared with a thicker single long stem, this stress shielding effect was significantly reduced, and the load was evenly distributed among the four short stems, so there was no stress concentration at the bottom of the pile. (2) The design with a rectangular hole in the middle not only provided relatively good stability, but also helped to reduce stress shielding of cancellous bone to a certain extent, with a reduction rate of 77.5%. (3) Compared with a single-stem tibial intramedullary stem prosthesis, both the four-post tibial intramedullary stem prosthesis and the four-post tibial intramedullary stem prosthesis with a hole in the middle have good stability, which can reduce stress shielding to a certain extent without causing stress concentration, providing theoretical guidance for the design of the tibial intramedullary stem. [ABSTRACT FROM AUTHOR]

Knee osteoarthritis (OA), also known as degenerative arthritis, is a disease characterized by irreversible changes in the cartilage and bones comprising the joints, resulting in pain, impaired function, and deformity. Furthermore, independent of natural aging, the rate of change in joint cartilage has increased in recent years, which is mainly attributed to environmental factors. The rising incidence of knee-related disorders emphasizes the importance of analyzing the morphology and kinematics of knee structure. This study introduces a knee measurement system designed to replicate the motions of knee using 3D-printing technology, providing insights into knee mechanics with OA level. The research explores the stages of OA using the Kellgren–Lawrence (KL) grade scale, highlighting the variations in the force applied to the knee bone according to movement. The developed knee-simulation system, utilizing the four-bar-link theory, presents a novel approach to studying OA levels 0 to 4. As OA progresses, the cartilage deteriorates, affecting the movement of OA. The OA-based knee measurement system that incorporates soft tissues and skeletons can assist in developing a personalized diagnostic approach for knee disease. This will also help to enhance surgical effectiveness by facilitating the creation of personalized prosthetic joints for individual patients and offering a customized surgical simulation. [ABSTRACT FROM AUTHOR]

Abstract Ti15Mo alloy has been regarded as one of the most potential biomedical materials due to its excellent performance. However, the low hardness and poor wear resistance of titanium alloy limit the further application. Therefore, high temperature solid carburising technology was performed on the surface of Ti15Mo alloys to prepare titanium carbide (TiC) coating with graphene (G) as the carburising agent. The microstructure, mechanical properties, and tribological properties of TiC coating under different lubricants were investigated. Results showed that TiC coating was closely bonded to the titanium substrate. The maximum thickness of TiC coating treated with 1150°C was approximately 184.02 μm, and the microhardness of alloys treated with 1100°C can achieve 1221.5 HV. All modified Ti15Mo alloys showed improved tribological performance compared to the original samples. The wear mechanisms of modified Ti15Mo alloys were abrasive wear and adhesive wear under the SBF lubricant, and the TiC coating was slightly peeled off. The overall friction coefficient and wear rate under 25% calf serum lubricant were lower than the SBF lubricant, and surface scratches were almost absent, and slight abrasive wear and adhesive wear occurred on the surface.

Abstract Objective Ni-Ti memory alloys are unusual materials for hard-tissue replacement because of their unique superelasticity, good biocompatibility, high strength, low specific gravity, low magnetism, wear resistance, corrosion resistance and fatigue resistance. The current study aims to evaluate its mechanical properties and provide biomechanical basis for the clinical application of the prosthesis. Methods Ten adult metacarpophalangeal joint specimens were randomly divided into a prosthesis group (n = 5, underwent metacarpophalangeal joint prosthesis) and a control group (n = 5, underwent sham operation). Firstly, the axial compression strength was tested with BOSE material testing machine to evaluate its biomechanical strength. Secondly, these specimens were tested for strain changes using BOSE material testing machine and GOM non-contact optical strain measurement system to evaluate the stress changes. Thirdly, fatigue test was performed between groups. Lastly, the mechanical wear of the metacarpophalangeal joint prosthesis was tested with ETK5510 material testing machine to study its mechanical properties. Results Axial compression stiffness in the prosthesis group was greater than that in the control group in terms of 30 ° and 60 ° flexion positions (P 0.05). In the fatigue wear test, the mean mass loss in the prosthesis group’s prosthesis was 17.2 mg and 17.619 mm3, respectively. The mean volume wear rate was 0.12%. There was no statistically significant difference in the maximum pull-out force of the metacarpal, phalangeal, and polymer polyethylene pads between the prosthesis group and the control group specimens. Conclusions Ni-Ti memory alloy metacarpophalangeal joint prosthesis conforms to the biomechanical characteristics of metacarpophalangeal joints without implants, and the fatigue strength can fully meet the needs of metacarpophalangeal joint activities after joint replacement.

Ti15Mo alloy has been regarded as one of the most potential biomedical materials due to its excellent performance. However, the low hardness and poor wear resistance of titanium alloy limit the further application. Therefore, high temperature solid carburising technology was performed on the surface of Ti15Mo alloys to prepare titanium carbide (TiC) coating with graphene (G) as the carburising agent. The microstructure, mechanical properties, and tribological properties of TiC coating under different lubricants were investigated. Results showed that TiC coating was closely bonded to the titanium substrate. The maximum thickness of TiC coating treated with 1150°C was approximately 184.02 μm, and the microhardness of alloys treated with 1100°C can achieve 1221.5 HV. All modified Ti15Mo alloys showed improved tribological performance compared to the original samples. The wear mechanisms of modified Ti15Mo alloys were abrasive wear and adhesive wear under the SBF lubricant, and the TiC coating was slightly peeled off. The overall friction coefficient and wear rate under 25% calf serum lubricant were lower than the SBF lubricant, and surface scratches were almost absent, and slight abrasive wear and adhesive wear occurred on the surface. [ABSTRACT FROM AUTHOR]

In this study, we have innovatively proposed a method of in-situ synthesized TiC hard phase to improve the surface mechanical properties of artificial joint materials (Ti6Al4V). In order to explore the optimum graphene oxide (GO) addition, GO/Ti6Al4V composite powders with different proportions (0, 0.5, 1.0, and 1.5 wt.%) were prepared. The homogeneously dispersed GO/Ti6Al4V composite powder was prepared on Ti6Al4V substrate by laser cladding technology. The microstructure, phase composition, and mechanical behavior of GO/Ti6Al4V composite coatings were studied by scanning electron microscope (SEM), optical microscope (OM), energy dispersive spectrometer (EDS), tribometer, hardness tester, and surface profiler. The results showed that the addition of GO could significantly improve the mechanical properties of TC4 substrate. During the preparation of the coating, the grain size of in-situ TiC phase was nanoscale and was distributed between acicular martensite, which played a critical role in enhancing the mechanical properties of the coating. The TiC phase distributed between acicular martensite refine the grain size of α ′ phase and improve the cutting resistance of the coating. Nevertheless, excessive GO decreased the fluidity of the molten pool, and micro holes tended to generate in the coating, which had a negative impact on the mechanical properties of the coating. At the GO content of 0.5 wt.%, the microhardness of the GO/Ti6Al4V coating was 1.325 times that of pure Ti6Al4V. Under the friction environment of simulated body fluid solution, the average friction coefficient was approximately 0.307 and the wear rate decreased to 3.5 × 10−7 mm3/N · m. Graphical abstract [ABSTRACT FROM AUTHOR]

Objective: Ni-Ti memory alloys are unusual materials for hard-tissue replacement because of their unique superelasticity, good biocompatibility, high strength, low specific gravity, low magnetism, wear resistance, corrosion resistance and fatigue resistance. The current study aims to evaluate its mechanical properties and provide biomechanical basis for the clinical application of the prosthesis. Methods: Ten adult metacarpophalangeal joint specimens were randomly divided into a prosthesis group (n = 5, underwent metacarpophalangeal joint prosthesis) and a control group (n = 5, underwent sham operation). Firstly, the axial compression strength was tested with BOSE material testing machine to evaluate its biomechanical strength. Secondly, these specimens were tested for strain changes using BOSE material testing machine and GOM non-contact optical strain measurement system to evaluate the stress changes. Thirdly, fatigue test was performed between groups. Lastly, the mechanical wear of the metacarpophalangeal joint prosthesis was tested with ETK5510 material testing machine to study its mechanical properties. Results: Axial compression stiffness in the prosthesis group was greater than that in the control group in terms of 30 ° and 60 ° flexion positions (P < 0.05). There was no statistically significant difference between two groups with regards to axial compression stiffness and stress change test (P > 0.05). In the fatigue wear test, the mean mass loss in the prosthesis group's prosthesis was 17.2 mg and 17.619 mm3, respectively. The mean volume wear rate was 0.12%. There was no statistically significant difference in the maximum pull-out force of the metacarpal, phalangeal, and polymer polyethylene pads between the prosthesis group and the control group specimens. Conclusions: Ni-Ti memory alloy metacarpophalangeal joint prosthesis conforms to the biomechanical characteristics of metacarpophalangeal joints without implants, and the fatigue strength can fully meet the needs of metacarpophalangeal joint activities after joint replacement. [ABSTRACT FROM AUTHOR]

Knee osteoarthritis (OA), also known as degenerative arthritis, is a disease characterized by irreversible changes in the cartilage and bones comprising the joints, resulting in pain, impaired function, and deformity. Furthermore, independent of natural aging, the rate of change in joint cartilage has increased in recent years, which is mainly attributed to environmental factors. The rising incidence of knee-related disorders emphasizes the importance of analyzing the morphology and kinematics of knee structure. This study introduces a knee measurement system designed to replicate the motions of knee using 3D-printing technology, providing insights into knee mechanics with OA level. The research explores the stages of OA using the Kellgren–Lawrence (KL) grade scale, highlighting the variations in the force applied to the knee bone according to movement. The developed knee-simulation system, utilizing the four-bar-link theory, presents a novel approach to studying OA levels 0 to 4. As OA progresses, the cartilage deteriorates, affecting the movement of OA. The OA-based knee measurement system that incorporates soft tissues and skeletons can assist in developing a personalized diagnostic approach for knee disease. This will also help to enhance surgical effectiveness by facilitating the creation of personalized prosthetic joints for individual patients and offering a customized surgical simulation.

Osteolysis of prosthesis caused by wear debris is one of the key factors leading to clinical failure of artificial joints. In order to understand the friction， wear and debris characteristics of prosthesis materials and optimize the tribological design of prosthesis， the most commonly used cobalt chromium molybdenum-ultra-high molecular weight polyethylene (CoCrMo-UHMWPE) pair was selected as artificial joint， and neonatal bovine serum solution was used as the lubricant. Subsequently， a 50，000 reciprocating sliding wear experiment was carried out under the point-to-surface contact stresses of 22， 35， 48 and 60 MPa， respectively. The friction coefficient， wear amount and wear morphology of the CoCrMo-UHMWPE pair were studied by multi-functional friction and wear testing machine， metallographic microscope， scanning electron microscope and other instruments， and then its friction and wear characteristics were characterized. Furthermore， the quantity，size， morphology and distribution characteristics of wear debris were studied by acid decomposition method. Results showed that the contact stress had a significant effect on the friction， wear and wear debris characteristics of the CoCrMo-UHMWPE pair. With the gradual increase of contact stress， the friction coefficient of CoCrMo-UHMWPE pair changed little but had a downward trend， the wear amount increased significantly and presented a certain linear relationship， and the wear morphology also showed more serious furrows and scratches. In terms of wear debris characteristics， the increase of contact stress led to a significantly increase of the number of wear debris with a size smaller than 5 μm，but the total amount of wear debris first increased and then decreased. Besides， the typical morphology of wear debris was mainly blocky， accompanied by a small amount of spherical and flaky wear debris of smaller sizes.

The joint capsule removal after artificial joint replacement surgery have led to improper lubrication, causing the pair to wear out quickly and reducing the joint lifespan. In this paper, laser processing and chemical corrosion were used to prepare a hexagonal convex texture on the surface of titanium alloy (Ti6Al4V). After etching and laser polishing, SEM images indicated the presence of secondary micro-nano textures in the grooves around the hexagonal texture, and the formation of anatase oxides on the surface, resulting in an increase of the surface energy and a very small contact angle (CA). The surfaces' CA increases with the texture ratio, and the surface is super-hydrophilic when the texture ratio is less than 0.84. Furthermore, the effect of texture parameters and directions are studied by using UHMWPE and Ti6Al4V as friction pairs and simulated body fluid as lubricant. The COF is 0.068 with 0.84 area ratio, which is 51.4% lower than the original surface. The wear rate of UHMWPE on the textured surface decreases by 74.5% after two hours of tribological testing. In addition, high speed camera images and calculation results proved that creating grooves can promote fluid distribution on the textured surface. The surface texture on titanium alloy results in a significant COF and wear reduction, extending the service life of artificial joints. [ABSTRACT FROM AUTHOR]

Polyether-ether-ketone (PEEK) has been proposed as a biocompatible artificial joint material. Wear particles, generated by friction between artificial joints, lead to bone resorption, aseptic loosening, and ultimately, joint failure. The size and morphology of wear particles contain information of friction and wear. Aim to obtain the wear mechanism of PEEK under different loads, this study separated PEEK debris and investigated the mechanism of wear debris and the relationship between wear mechanism and PEEK-debris morphology. An experiment was carried out with a pin-on-plate testing apparatus under different load conditions, with PEEK sliding against XLPE under saline lubrication. A method of isolating PEEK and XLPE debris from 0.9% normal saline at the same time was investigated by low-speed centrifugation. The morphologies of worn surface and wear debris were obtained based on scanning electron microscopy. The results showed that the maximum friction coefficient and minimum wear loss were 0.115 and 0.223 mg at the load of 50 N. The friction coefficient decreased and the wear loss increased with the load increase. This debris-isolation method can effectively isolate PEEK and XLPE particles larger than 200 nm in diameter. More than 96% wear PEEK particles range from 0.1 µm to 10 μm. Compared with the debris generated under the lower load condition, 0.8% more large wear particles with irregular shapes were found at a load of 150 N. The morphology of wear particles is consistent with the wear mechanism. [ABSTRACT FROM AUTHOR]

The service life of artificial joints has gradually failed to meet the needs of patients. Herein, the synergistic lubrication and antioxidant efficacies of graphene oxide (GO) and fullerenol (Fol) as biological lubricant additives for artificial joints were investigated. The lubrication mechanisms of biological lubricant containing GO and Fol at the friction interface of artificial joints were then revealed. Tribological tests showed that the average friction coefficients of Al2O3–Ti6Al4V pairs and Ti6Al4V–UHMWPE pairs for artificial joints could be reduced by 30% and 22%, respectively, when GO and Fol were used as biological lubricant additives simultaneously. The lubrication mechanism showed that some incommensurate sliding contact surfaces could be formed between the GO nanosheets and spherical Fol at the interface, which reduced the interaction forces of friction pairs. The maximum scavenging rates of •OH and DPPH free radicals by the biological lubricant containing GO and Fol were 35% and 45%, respectively, showing a good antioxidant efficacy of the biological lubricant. This can be attributed to the GO and Fol scavenging free radicals through electron transfer and hydrogen transfer. This study provides a theoretical basis for the development and application of carbon nanomaterials as biological lubricant additives for artificial joints in the future. [ABSTRACT FROM AUTHOR]

The level of joint laxity, which is an indicator of accurate diagnosis for musculoskeletal conditions is manually determined by a physician. Studying joint laxity via artificial joints is an efficient and economical way to improve patient experience and joint proficiency. However, most of study focus on the joint geometry but are inadequate with regard to the tailored mechanical properties of soft tissues. On the basis of collagen fibril deformation, this study proposes bioinspired 3D fibers braided from polyethene multifilament for the reproduction of the controlled nonlinear behavior of ligaments and tendons. Four braided bands are designed, all showing biological behaviors. Two knot-based bands exhibit large toe strains of 10.98% and 5.33% but low linear modulus of 239.84 MPa and 826.05 MPa. The other two bands without knots exhibit lower toe strains of 1.61% and 1.52% but high linear modulus of 2605.27 MPa and 2050.74 MPa. Empirical formulas for braiding parameters (wales and courses) and mechanical properties are expressed to provide a theoretical basis for the mimicry of different tissues in the human body by artificial joints. All parameters have significant effects on the linear region of the load-displacement curve of a fiber due to braided structure, while changing the number of wales facilitates a major contribution to the toe region. A biofidelic human knee has been successfully reconstructed by using bioinspired 3D braided fibers. This study demonstrates that the nonlinear mechanical properties of soft tissues can be replicated by bioinspired 3D braided fibers, further yielding the design of more biomechanically realistic artificial joints.

BACKGROUND: At present, dexamethasone is widely used in hip and knee arthroplasties to reduce postoperative pain, nausea and vomiting, and speed up the recovery of patients. However, domestic and foreign studies on the role of dexamethasone in the perioperative period of unicondylar arthroplasty have not been reported. OBJECTIVE: To investigate the effect of intravenous dexamethasone on the perioperative period of unicondylar arthroplasty. METHODS: Sixty-nine knee osteoarthritis patients who underwent primary unicondylar arthroplasty in Department of Orthopedics, The First Affiliated Hospital of Soochow University from January 2020 to May 2021 were randomly divided into two groups. Patients in the trial group (n=35) were given dexamethasone 8 mg intravenously before skin incision. Patients in the control group (n=34) were given an equal volume of normal saline intravenously. Before surgery and 1, 2, and 3 days after surgery, the visual analogue scale scores of the patients at rest and walking were evaluated; the occurrences of nausea and vomiting at the corresponding time points after the surgery were recorded. Before surgery and 1 and 3 days after surgery, leukocyte count and C-reactive protein value were detected. The postoperative follow-up was conducted for 3 months to record the presence of complications such as wound infection, joint prosthesis infection, peptic ulcer bleeding and so on. RESULTS AND CONCLUSION: (1) The visual analogue scale scores of pain in the trial group were significantly lower than those in the control group when walking on the 1st and 2nd day after the operation and resting on the 1st day after the operation (P < 0.05). (2) The incidence of nausea and vomiting at 0-6 and 6-24 hours after operation was significantly lower in the trial group than that of the control group (P < 0.05). (3) The leukocyte count and C-reactive protein value were significantly lower in the trial group than those of the control group on the 1st postoperative day (P < 0.05). (4) The patients in the two groups were followed up for 3 months without complications such as wound infection, joint prosthesis infection, or peptic ulcer bleeding. (5) The results suggest that intravenous injection of dexamethasone used during unicondylar arthroplasty can effectively relieve early postoperative pain, reduce postoperative nausea and vomiting, inhibit early inflammation, and is beneficial for patient recovery. [ABSTRACT FROM AUTHOR]

Artificial joints are exposed to loads on a daily basis. Loads on the bone through the artificial joint and the joint's sliding surface shear force may cause implant fixation failure, fatigue fractures, wear of the bearing and foreign body reactions. Artificial joints can experience sudden internal damage, which can be fatal if it occurs during activities performed at high altitudes or in water. The standard design hip prosthesis has a metal femoral stem. Most stem fractures are caused at the proximal one third of the stem by fatigue due to repetitive loading. Femoral stem neck fractures can also occur. To eliminate in vivo prosthesis failures, safety performance preclinical studies evaluate stem body and neck breakage. However, the development of new femoral stems via prototyping and fatigue test verification would require excessive time and money. Therefore, evaluation methods based on numerical analyses, such as finite element analysis (FEA), have been introduced to simulate tests on actual machines. Fatigue strength design verification using FEA can efficiently identify a design that can pass International Organization for Standardization fatigue tests. FEA may also aid with composite implant development by enabling efficient preclinical testing to prove safety using minimal actual fatigue testing. Once a biological safety study of a composite material is performed, a clinical trial can prove its clinical efficacy and safety and device regulatory approval can be requested. This review was created based on a translation of the Japanese review written in the Japanese Journal of Artificial Organs in 2020 (Vol. 49, No. 3, pp. 195–198), with adding some additional contents and references. [ABSTRACT FROM AUTHOR]

Hydroxyapatite (HA) coatings have been widely used for improving the bone-implant interface (BII) bonding of the artificial joint prostheses. However, the incidence of prosthetic revisions due to aseptic loosening remains high. Porous materials, including three-dimensional (3D) printing, can reduce the elastic modulus and improve osseointegration at the BII. In our previous study, we identified a porous material with a sintered bionic trabecular structure with in vitro and in vivo bio-safety as well as in vivo mechanical safety. This study aimed to compare the difference in osseointegration ability of the different porous materials and HA-coated titanium alloy in the BII. We fabricated sintered bionic trabecular porous titanium acetabular cups, 3D-printed porous titanium acetabular cups, and HA-coated titanium alloy acetabular cups for producing a hip prosthesis suitable for beagle dogs. Subsequently, the imaging and histomorphological analysis of the three materials under mechanical loading in animals was performed (at months 1, 3, and 6). The results suggested that both sintered bionic porous titanium alloy and 3D-printed titanium alloy exhibited superior performances in promoting osseointegration at the BII than the HA-coated titanium alloy. In particular, the sintered bionic porous titanium alloy exhibited a favorable bone ingrowth performance at an early stage (month 1). A comparison of the two porous titanium alloys suggested that the sintered bionic porous titanium alloys exhibit superior bone in growth properties and osseointegration ability. Overall, our findings provide an experimental basis for the clinical application of sintered bionic trabecular porous titanium alloys.

The level of joint laxity, which is an indicator of accurate diagnosis for musculoskeletal conditions is manually determined by a physician. Studying joint laxity via artificial joints is an efficient and economical way to improve patient experience and joint proficiency. However, most of study focus on the joint geometry but are inadequate with regard to the tailored mechanical properties of soft tissues. On the basis of collagen fibril deformation, this study proposes bioinspired 3D fibers braided from polyethene multifilament for the reproduction of the controlled nonlinear behavior of ligaments and tendons. Four braided bands are designed, all showing biological behaviors. Two knot-based bands exhibit large toe strains of 10.98% and 5.33% but low linear modulus of 239.84 MPa and 826.05 MPa. The other two bands without knots exhibit lower toe strains of 1.61% and 1.52% but high linear modulus of 2605.27 MPa and 2050.74 MPa. Empirical formulas for braiding parameters (wales and courses) and mechanical properties are expressed to provide a theoretical basis for the mimicry of different tissues in the human body by artificial joints. All parameters have significant effects on the linear region of the load-displacement curve of a fiber due to braided structure, while changing the number of wales facilitates a major contribution to the toe region. A biofidelic human knee has been successfully reconstructed by using bioinspired 3D braided fibers. This study demonstrates that the nonlinear mechanical properties of soft tissues can be replicated by bioinspired 3D braided fibers, further yielding the design of more biomechanically realistic artificial joints. [ABSTRACT FROM AUTHOR]

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: For complex knee osteoarthritis, traditional surgical instruments for osteotomy positioning technology can easily lead to poor placement of artificial total knee arthroplasty prostheses. Personalized three-dimensional printed osteotomy guide plate can achieve accurate osteotomy and prosthesis placement. OBJECTIVE: To investigate the early clinical effects of total knee arthroplasty with personalized three-dimensional printed osteotomy guide plates in the treatment of advanced knee osteoarthritis with femoral deformities. METHODS: Thirty-one patients with severe knee osteoarthritis combined with femoral deformity admitted to the Fifth Affiliated Hospital of Guangzhou Medical University from June 2016 to May 2020 were enrolled in the study. There were 14 males and 17 females, which aged 54-88 years old. A personalized three-dimensional printed osteotomy guide plate was used to assist in total knee arthroplasty surgery. Imaging measurement was conducted before treatment and at 3 days after treatment, to measure the included angle between femur and tibia mechanical axis, posterior condylar angle, patella transverse axis-femoral transepicondylar axis angle. American Hospital of Special Surgery score, Visual Analogue Scale score and range of motion of the knee joint were measured and assessed before and at 6 and 12 months after treatment. RESULTS AND CONCLUSION: All the 31 patients were followed up for more than 12 months, and no adverse advents related to implant materials occurred during the trial and follow-up. At 3 days after treatment, the included angles between the femur and tibia mechanical axis, posterior condylar angle, and patella transverse axis-femoral transepicondylar axis angles were lower than those before treatment in all the patients (all P=0.000). At 6 and 12 months after treatment, the American Hospital of Special Surgery score and the range of motion of the knee were higher than those before treatment in all the patients (P < 0.05), while the Visual Analogue Scale scores were lower than those before treatment (P < 0.05). Therefore, total knee arthroplasty with the assistance of three-dimensional printed personalized osteotomy guide plates can relieve joint pain, improve joint function, restore lower limb force lines and femoral rotation alignment, and improve patellar trajectory in patients with advanced knee osteoarthritis combined with femoral deformities. [ABSTRACT FROM AUTHOR]

BACKGROUND: Surface treatment technology has been widely used in biomedical field, which can effectively improve the friction and wear properties of artificial joints materials. OBJECTIVE: Taking the friction and wear performance of artificial joints as the research object, to summarize the application and development of surface texture technology and surface coating technology in the friction and wear performance of artificial joints in recent years. METHODS: Studies on the surface treatment technology, friction and wear performance of artificial joints were searched by computer on ScienceDirect, SpringerLink, EBSCO, Web of Science and other databases. The retrieval words were “artificial joints, friction, wear, surface treatment/surface modification”, and the retrieval time was from March 2000 to June 2020. RESULTS AND CONCLUSION: Surface treatment technology is mainly divided into surface texture technology and surface coating technology. Surface texture technology will affect the microstructure of artificial joints, so as to optimize the performance of artificial joints. However, not all texture structures can improve the friction and wear performance of artificial joints. When the initial roughness value of the surface texture structure is too large, it will inhibit the hydrodynamic effect of the texture structure and weaken the friction and lubrication performance. Surface coating technology will affect the surface performance of artificial joints, thus increasing the service life of artificial joints [ABSTRACT FROM AUTHOR]

The service life of artificial joints has gradually failed to meet the needs of patients. Herein, the synergistic lubrication and antioxidant efficacies of graphene oxide (GO) and fullerenol (Fol) as biological lubricant additives for artificial joints were investigated. The lubrication mechanisms of biological lubricant containing GO and Fol at the friction interface of artificial joints were then revealed. Tribological tests showed that the average friction coefficients of Al2O3–Ti6Al4V pairs and Ti6Al4V–UHMWPE pairs for artificial joints could be reduced by 30% and 22%, respectively, when GO and Fol were used as biological lubricant additives simultaneously. The lubrication mechanism showed that some incommensurate sliding contact surfaces could be formed between the GO nanosheets and spherical Fol at the interface, which reduced the interaction forces of friction pairs. The maximum scavenging rates of •OH and DPPH free radicals by the biological lubricant containing GO and Fol were 35% and 45%, respectively, showing a good antioxidant efficacy of the biological lubricant. This can be attributed to the GO and Fol scavenging free radicals through electron transfer and hydrogen transfer. This study provides a theoretical basis for the development and application of carbon nanomaterials as biological lubricant additives for artificial joints in the future.

Copyright of Lubrication Engineering (0254-0150) is the property of Editorial Office of LUBRICATION ENGINEERING and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

BACKGROUND: Myocardial infarction is one of the catastrophic complications after total joint arthroplasty. However, the risk factors and predictive model have not been reported in previous research after total joint arthroplasty. OBJECTIVE: To study the incidence and risk factors of myocardial infarction after total joint arthroplasty, and develop a nomogram for predicting the myocardial infarction after total joint arthroplasty. METHODS: We retrospectively reviewed the data of 5 746 patients who underwent total hip arthroplasty or total knee arthroplasty in the Affiliated Hospital of Qingdao university and the People’s Hospital of Xixiu District between September 2013 and July 2017. The baseline characteristic, preoperative comorbidities, preoperative examinations, operative data, other hospital information and follow-up data were collected, recorded and were used to analyze the risk factors of myocardial infarction. In addition, a nomogram was developed based on the independent risk factors for predicting the myocardial infarction after total joint arthroplasty, and receiver operating characteristic curve and calibration curve were used to evaluate the nomogram. RESULTS AND CONCLUSION: Forty-eight patients affected myocardial infarction within 14 days after total joint arthroplasty, and the incidence of myocardial infarction was 0.8%. Multivariate Logistic analysis indicated that age-adjusted Charlson Comorbidity Index, anesthesia type and atrial fibrillation were independent risk factors for postoperative myocardial infarction (P < 0.05). The risk of myocardial infarction in patients with age-adjusted Charlson Comorbidity Index ≥ 5 was higher than patients with age-adjusted Charlson Comorbidity Index < 5. The risk of myocardial infarction in patients receiving general anesthesia was higher than that of patients receiving epidural/lumber anesthesia. The risk of myocardial infarction in patients combined with atrial fibrillation was higher than that in patients without it. Receiver operating characteristic curve showed that the nomogram has a high degree of discrimination (AUC=0.730, 95%CI: 0.661-0.799), and the calibration curve showed that the model had a high degree of calibration. A predictive model based on age-adjusted Charlson Comorbidity Index, anesthesia type and atrial fibrillation can accurately predict the myocardial infarction following total joint arthroplasty. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to evaluate the effect of the metal artifact reduction (MAR) method on quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT) to reveal the usefulness of MAR in patients with metal implants. Methods: We performed a phantom experiment simulating patients with artificial hip prostheses using SPECT/CT equipped with the iterative MAR (iMAR). The phantom was filled with Tc-99m solution (29.5 kBq/mL). For the CT scan conditions, tube current time products were applied to obtain volume CT dose indexes (CTDIvols) of 1.4, 2.8, and 5.6 mGy. Six types of quantitative SPECT images were reconstructed using data from different doses of CT processed with and without iMAR for CT attenuation correction. Thirty circular regions of interest (ROIs) were placed in each of the dark-band artifact areas, the white-streak artifact areas, and the non-artifact areas. We calculated radioactivity concentrations from quantitative SPECT images with and without iMAR to evaluate the quantitative accuracy. The differences of the effect of iMAR with different CT doses were also evaluated. Results: The results obtained using CT data with a CTDIvol of 2.8 mGy are described below. For quantitative SPECT data without iMAR, we observed the underestimation of radioactivity concentration in the dark-band artifact areas and overestimation in the white-streak artifact areas. We observed quantification errors ranging from − 41.1% to + 20.0% without iMAR, depending on the ROI localization. When iMAR was used, these errors were reduced to a range of − 22.8% to + 14.2%. The mean absolute error from the true value in the artifact regions was also significantly reduced from 4.00 to 1.74 kBq/mL. In the non-artifact areas, the radioactivity concentrations obtained from the quantitative SPECT data with and without iMAR were equivalent to the true value and did not differ significantly between the two conditions. Similar results were observed for procedures with CTDIvols of 1.4 and 5.6 mGy. Conclusions: This study indicated that iMAR could improve the quantitative accuracy of SPECT/CT independent of the CT dose. iMAR can serve as a practicable technique for quantitative SPECT/CT in patients with metal implants. [ABSTRACT FROM AUTHOR]

BACKGROUND: Most of the domestic and foreign literatures reported the mid-term and long-term effects of the unicompartmental knee arthroplasty of the mobile bearing, but few reported the mid-term and long-term clinical effects of the unicompartmental knee arthroplasty of the fixed bearing. Simultaneously, most of the studies did not analyze the knee function recovery and the lower limb force line change at different time points after the fixed bearing unicompartmental knee arthroplasty, and also ignored the follow-up of the patients’ self-feeling after the unicompartmental knee arthroplasty. OBJECTIVE: To explore the mid-term clinical effect of fixed bearing unicompartmental knee arthroplasty in the treatment of medial compartment osteoarthritis of knee joint and to observe the change of force line of lower limbs. METHODS: From January 2014 to January 2015, a retrospective analysis was made of the data of 66 patients diagnosed as osteoarthritis of the medial compartment of the knee in the Department of Arthritis, Foshan Hospital of Traditional Chinese Medicine. According to the inclusion and exclusion criteria, 66 patients were included, including 18 males and 48 females, aged (62.36±16.33) years. The American Knee Society knee score and the hospital for special surgery knee score were used to assess the knee function before and 1, 3 and 5 years after the operation. Visual analogue scale score was utilized to evaluate the severity of knee. Forgotten joint score was used to assess the subjective feeling of prosthesis after unicompartmental knee arthroplasty. Hip-knee-ankle angle and tibiofemoral angle were measured using X-ray films before treatment and at follow-up to evaluate the force line of weight-bearing lower limbs. RESULTS AND CONCLUSION: (1) The postoperative follow-up time was 5-6 years, averagely 5.5 years. The incision healed in the first stage. There was no early complication such as joint infection or lower extremity deep vein thrombosis, and there was no prosthesis loosening, dislocation or other diseases of the contralateral compartment and patellofemoral joint. (2) The American Knee Society knee score clinical score, American Knee Society knee score function score, hospital for special surgery knee score, knee motion range and visual analogue scale score were lower at 1, 3 and 5 years after operation than those before treatment (P < 0.05). The American Knee Society knee score clinical score, American Knee Society knee score function score, knee motion range and visual analogue scale score at 3 and 5 years after operation were significantly lower than those at 1 year after operation (P < 0.05). There was no significant difference in American Knee Society knee score clinical score, American Knee Society knee score function score, knee motion range and visual analogue scale score between 3 and 5 years postoperatively (P > 0.05). (3) Forgotten joint score was higher at 3 and 5 years after treatment than that at 1 year after treatment (P < 0.05); and there was no significant difference between 3 and 5 years postoperatively (P > 0.05). (4) Hip-knee-ankle angle and tibiofemoral angle were significantly improved after treatment in all patients compared with those before treatment (P < 0.05). There was no significant difference in hip-knee-ankle angle and tibiofemoral angle at 1, 3 and 5 years postoperatively (P > 0.05). (5) The results show that the mid-term clinical effect of unicompartmental knee arthroplasty with fixed bearing is satisfactory, and the degree of self-prosthesis is high. After treatment, the force line of lower limbs was improved, and there was no significant change in the 5-year follow-up. [ABSTRACT FROM AUTHOR]

There is a global tendency to rejuvenate joint diseases, and serious diseases such as arthrosis and arthritis develop in 90% of people over 55 years of age. They are accompanied by degradation of cartilage, joint deformities and persistent pain, which leads to limited mobility and a significant deterioration in the quality of life of patients. For the treatment of these diseases in the late stages, depending on the indications, various methods are used, the most radical of which are methods of joint arthroplasty and, in particular, total arthroplasty. Currently, total arthroplasty is one of the most effective and high-quality surgical operations at the relevant medical indications. However, complications may also arise after it, leading, inter alia, to the need for repeated surgical intervention. In order to minimize the likelihood of complications, the artificial joints used in total arthroplasty and the technology of their fabrication are constantly being improved, which leads to the emergence of new designs and methods for their integration with living tissues. At the same time, at the moment, the improvement of traditional designs and production technologies has almost reached the top of their art, and their further improvements can be insignificantly or are associated with the use of the most up-to-day technologies, allowing for friction couples with low tribological properties to provide for them high ones, for example, gradient increase hardness in the couple titanium alloy on titanium alloy. This paper presents the current state of traditional technical means and technologies for joint arthroplasty. The main attention is paid to the analysis of the latest technologies in the field of joint arthroplasty, such as osseointegration of artificial joints, the improvement of materials with the property of osteoimmunomodulation, the improvement of joint arthroplasty technologies based on the modeling of dynamic osteosynthesis, as well as the identification of possible unconventional designs of artificial joints that contribute to these technologies, predictive assessment of areas for technologies improvement.

Wear has been considered as a major issue for ball and socket artificial discs. This paper studies the effects of ball radius and radial clearance of the artificial disc on the von Mises stresses. Different material combinations, used in artificial discs, are compared. FEA simulation using Solidworks has been conducted for different disk geometries. The highest von Mises stress was 714MPa for 10mm radius metal against metal design. The lowest von Mises stress was 14.8MPa for 16mm radius of the UHMWPE/CoCr material combination, which exhibited the lowest von Mises stresses for all the radii of the ball and socket articulation. Considering radial clearance, the lowest von Mises stress was 14.8MPa for 0.015mm clearance of the UHMWPE/CoCr combination. The highest von Mises stress of 100.8MPa with a radial clearance of 0.25mm was recorded for the same combination. There is a strong relation between the von Mises stress and the geometry of the ball and socket of the artificial disc. [ABSTRACT FROM AUTHOR]

Introduction: We aimed to explore the risk factors for periprosthetic joint infection (PJI) after primary artificial hip and knee joint replacements by performing a case-control study. Methodology: The clinical data of patients receiving primary hip and knee joint replacements were retrospectively analyzed. The case group included 96 patients who suffered from PJI, comprising 42 cases of hip joint replacement and 54 cases of knee joint replacement. Another 192 patients who received joint replacement at the ratio of 1:2 in the same period and did not suffer from PJI were selected as the control group. Differences between the two groups were compared in regard to etiology, pathogen, blood type, urine culture, body mass index (BMI), surgical time, intraoperative blood loss, postoperative 1st day and total drainage volumes, length of hospitalization stay, and history of surgery at the affected sites. Results: Gram-positive bacteria were the main pathogens for PJI. The most common infection after hip joint replacement was caused by Staphylococcus epidermidis, which accounted for 38.10%, while Staphylococcus aureus was mainly responsible for the infection of knee joint (40.74%). High BMI, long surgical time, large postoperative drainage volume, long hospitalization stay, history of surgery at incisions, previous use of immunosuppressants, preoperative hypoproteinemia and superficial infection were independent risk factors (p < 0.05). Conclusions: PJI after primary replacement was mainly caused by gram-positive bacteria, and patients with high BMI, long surgical time, large postoperative drainage volume, long hospitalization stay, history of surgery at incisions, previous use of immunosuppressants, preoperative hypoproteinemia and superficial infection were more vulnerable. [ABSTRACT FROM AUTHOR]

BACKGROUND: Three-dimensional (3D) printing technology is a new rapid prototyping technology, which has been initially applied in orthopedics, especially in the clinical application of hip replacement surgery. OBJECTIVE: To summarize the application status, existing problems and future development direction of 3D printing technology in hip arthroplasty. METHODS: The relevant articles published between January 2000 and March 2019 were retrieved from PubMed, CNKI and WanFang databases. The keywords were "3D printing, rapid prototyping, additive manufacturing, computer aided, computer-assisted, hip, hip replacement, hip arthroplasty, revision hip arthroplasty" in English and Chinese, respectively. Initially, 1833 articles were retrieved, and finally 105 eligible articles were included for result analysis in accordance with the inclusion and exclusion criteria. RESULTS AND CONCLUSION: (1) In the clinical application of hip replacement surgery, 3D printing technology is mainly used to make anatomical models for clinical teaching or preoperative plan, patient-specific surgical guides, customized implants or prostheses. (2) The advantages of 3D printing technology can make up for the deficiency of traditional treatment, and n can help to optimize the surgical plan, shorten the operation time, decrease the bleeding, reduce postoperative complications, improve the accuracy of surgery and clinical results. (3) Individualized treatment with 3D printing technology will become a new direction in hip arthroplasty. [ABSTRACT FROM AUTHOR]

BACKGROUND: Polyetheretherketone (PEEK) and its composites have a unique set of properties, and 3D printing technology can customize personalized implants according to the patient's condition, and the effective combination of the two plays a significant role in the field of bone repair. OBJECTIVE: To summarize the application status of PEEK and its composite combined with 3D printing technology in the field of bone repair, and to further predict the application prospects of the effective combination of the two. METHODS: CNKI, PubMed, and Web of Science databases were retrieved with the search terms "PEEK, PEEK composites, bone defect repair, PEEK implants, PEEK 3D printing, prosthodontics" in English and Chinese, respectively, for the articles published from April 1995 to April 2019. Totally 147 articles were searched, and finally 51 eligible articles were enrolled for review in accordance with the inclusion and exclusion criteria. RESULTS AND CONCLUSION: Biologically active materials and the particles or fibers with improved mechanical properties were introduced into the PEEK matrix to prepare its composite. 3D printing technology was used to precisely customize implants that are highly matched to the patient's defect. The implants with good biocompatibility, bioactivity, and mechanical properties exhibited good therapeutic effects in the repair of skull, jaw, spine, lumbar vertebra, artificial joint and oral defects. They improved patient satisfaction after treatment. This article summarized the application of PEEK, its composite and 3D printing technology in the repair of various bone defects, and expressed its views on the application and prospect of personalized PEEK implants or prostheses prepared with 3D printing technology. [ABSTRACT FROM AUTHOR]

BACKGROUND: Total hip arthroplasty is the ultimate treatment for adult developmental dysplasia of the hip in the late stage of disease. However, due to the complicated anatomical variation of developmental dysplasia of the hip patients, the traditional total hip arthroplasty faces great challenges. OBJECTIVE: To explore the effectiveness and safety of three-dimensional(3 D) printing technology-assistedtotal hip arthroplasty in the treatment of developmental dysplasia of the hip. METHODS: Twenty patients with developmental dysplasia of the hip, who underwent primary total hip arthroplasty in Department of Orthopedics, Central Hospital Affiliated to Shenyang Medical College from January 2016 to June 2018, were randomly divided into two groups. The 10 patients in the 3 D printing group underwent total hip arthroplasty assisted by 3 D printing technology, and 10 patients in the traditional operation group underwent traditional total hip arthroplasty. The operation time, blood loss, occurrence of complication, visual analog scale score and Harris hip joint function score before and 6 months after operation were recorded. RESULTS AND CONCLUSION:(1) Compared with the traditional operation group, the operation time and blood loss in the 3 D printing group were significantly shortened, with significant differences(P=0.000).(2) Visual analog scale score and Harris hip joint function score were significantly higher at 6 months after operation than that before operation in both groups(P=0.000).(3) There was no significant difference in visual analog scale score and Harris hip joint function score between the two groups 6 months after operation(P > 0.05).(4) No complication occurred in both groups.(5) These results indicate that both 3 D printing technology-assisted total hip arthroplasty and traditional total hip arthroplasty can achieve good clinical effects in the treatment of developmental dysplasia of the hip, but 3 D printing technology combined with total hip arthroplasty has shorter operation time and less blood loss. [ABSTRACT FROM AUTHOR]

The relationship between the wear behaviour of an ultra-high-molecular-weight polyethylene (GUR1050) pin and surface profile of a Co-28Cr-6Mo alloy (ASTM F-75) disc was investigated. Tribological tests have been performed by pin-on-disc wear testing machine with multi-directional pathways, obtaining the influence of micro slurry-jet erosion (MSE) processed Co–Cr–Mo alloy. The specific wear and the wear particles have been investigated. It was elucidated that the Co–Cr–Mo alloy surface processed by MSE influenced the specific wear rate of polyethylene; however, the morphological aspect of polyethylene wear particles was not drastically changed. The wear particles isolated from the lubricating liquid were added to a culture medium, and human monocyte-derived macrophages were incubated by using an upright/inverted method. The production of TNF-α and IL-6 seemed to have a correlation with the amount of wear particles added, however, the influence of particle size on the production of TNF-α and IL-6 was not obvious. This means that the improvements for the incubation method, i.e. upright/inverted method, need further investigation for the accurate analysis.

Through the effective application of Essential Principles of Safety and Performance of Medical Devices and IVD Medical Devices (EP), to continuously improve the corresponding management tools to ensure the safety and effectiveness of medical device in the quality management system, risk management system, evaluation of safety and effectiveness for the supervision departments and manufacturers. The current status of the application of EP and the application issues are analyzed in the study. Take artificial joint products for example, the idea of using EP in quality management system, risk management system and evaluation of safety and effectiveness is investigated, and several thoughts are proposed. Supervision departments should strengthen the unified understanding of EP, develop requirements according to the classification of medical device，and refine specific execution requirements.

BACKGROUND: Compared with the traditional posterolateral approach, the SuperCap approach for the treatment of femoral neck fractures has the advantageous of short incision, less damage to the soft tissue around the hip joint during the operation, no need for dislocation, and the patients can do postoperative functional exercise more early. OBJECTIVE: To compare the short-term clinical outcomes of minimally invasive SuperCap approach and posterolateral approach. METHODS: A total of 48 cases from October 2016 to April 2018 were collected, including 24 cases of SuperCap approach(SuperCap group) and 24 cases of conventional approach(conventional group). Operation time, length of incision, intraoperative blood loss, postoperative blood transfusion, postoperative hospital stay and complications were recorded in both groups. The hip joint function was evaluated before surgery and 1, 3, 5, 7, 14, 30, 90, and 180 days after surgery by the use of Visual Analogue Scale and HHS. The time up and go test, timed stair climb test, and short performance physical battery test were conducted at 3, 5, 7, 14, 30, 90, and 180 days after surgery. RESULTS AND CONCLUSION:(1) The length of incision in the SuperCap group was shorter than that in the conventional group(P < 0.05). There was no significant difference in the operation time, intraoperative blood loss, postoperative blood transfusion and postoperative hospital stay between the two groups(P > 0.05).(2) One case suffered from deep vein thrombosis in the SuperCap group and two cases suffered from deep vein thrombosis in the conventional group. No complications such as infection, dislocation, prosthesis loosening, sciatic nerve injury and paralysis occurred in the two groups.(3) The Visual Analogue Scale scores of the SuperCap group were lower than that of the conventional group(P < 0.05). The HHS scores at 1, 3 and 5 days after operation were higher in the SuperCap group than in the conventional group(P < 0.05). There was no difference in above scores at the other time points between the two groups(P > 0.05).(4)The results of the time up and go test on the 5 th day after operation in the SuperCap group were better than that in the conventional group(P < 0.05). The results of the timed stair climb test on the 14 th and 30 th days after operation were better in the SuperCap group than that in the conventional group(P < 0.05). The results of the short performance physical battery test within 30 days after operation were better in the SuperCap group than that of the conventional group(P < 0.05).(5) The results showed that compared with the traditional approach, SuperCap approach has the advantages of short incision, small intraoperative soft tissue injury, rapid recovery of hip joint function, light pain, and good coordination of hip muscles. [ABSTRACT FROM AUTHOR]

BACKGROUND: Periprosthetic joint infection is a serious and catastrophic complication after joint arthroplasty. For asymptomatic bacteriuria, during perioperative period of joint arthroplasty, many doctors choose oral antibiotics. However, the previous research on whether asymptomatic bacteriuria will cause periprosthetic joint infection has no consensus, and the effect of antibiotics is unknown. OBJECTIVE: To investigate whether asymptomatic bacteriuria is a risk factor for periprosthetic joint infection and whether antibiotic treatment is effective by meta-analysis. METHODS: Through systematic research based on computer of major foreign and Chinese databases, such as PubMed, Ovid, Cochrane Library, EMBASE, CNKI, WanFang, VIP, and CMB databases, and manual research, literature traceability was performed. The articles concerning the effect of asymptomatic bacteriuria on the prognosis of joint arthroplasty published before May 2018 was searched. Literature screening, quality evaluation and data extraction were performed according to the Cochrane system, and analysis was undergone on Review Manager 5.3 software. RESULTS AND CONCLUSION: (1) Nine articles were enrolled, involving 29 844 cases of joint arthroplasty, including 2 366 cases of asymptomatic bacteriuria. (2) Periprosthetic joint infection had a significantly higher incidence in the asymptomatic bacteriuria group than that in the non-asymptomatic bacteriuria group (OR=3.15, 95%CI: 1.23-8.02, P=0.02). (3) Seven in the nine articles reported the use of antibiotics for treating perioperative asymptomatic bacteriuria, and there was no significant difference in the incidence of periprosthetic joint infection between two groups (OR=1.64, 95%CI: 0.84-3.23, P=0.15). (4) To conclude, the occurrence of asymptomatic bacteriuria in the perioperative period of joint arthroplasty is a risk factor for periprosthetic joint infection, and the use of antibiotics for asymptomatic bacteriuria does not change the incidence of periprosthetic joint infection. [ABSTRACT FROM AUTHOR]

• Liposomes with increasing carbon chain length reveal excellent lubrication. • The bilayers weaken the stability of vesicles and exhibit increased friction. • Lipid complexes led to the formation of a remarkable boundary lubrication layer. • Lipid complexes can efficiently improve the lubrication properties of liposomes. Achievement of efficient biolubrication is essential for the design of artificial joints with long lifetimes. This study examines the frictional behaviors and adsorption structures of liposomes and liposome complexes with biocompatible polymers to reveal the underlying lubrication mechanisms between biomimetic bearing surfaces of polyetheretherketone (PEEK) and silicon nitride (Si 3 N 4). The liposomes with increasing carbon chain lengths exhibit the remarkable lubrication capabilities that correlate strongly with the structural integrity of small unilamellar vesicles adsorbed on the Si 3 N 4 surfaces, while the bilayer structures weaken the stability of vesicles against rupture and cause the increase of friction. The synergistic interaction of liposomes and biocompatible negative-charged polymer leads to the formation of a boundary–lubricating layer with high-density liposome–polymer complex structures that can efficiently improve the lubrication properties of liposomes. Our findings might have implications for future biolubrication investigations on biocompatible liposome–polymer complexes applicable to artificial joints at the specified macroscale conditions. [ABSTRACT FROM AUTHOR]

Abstract The artificial joints would go through serious wear after implantation surgery due to the poor lubrication of the body fluid, and the biomimetic lubricants directly injected in vitro is easy to be absorbed by human tissues, and after a period of time, it will lose its lubrication effect. However, the composite hydrogel with slow-release lubrication effect provides a new way for the lubrication of artificial joints. In this study, Graphene oxide/Poly(ethylene glycol) (GO/PEG) composites were prepared to improve the artificial joint lubrication, and through wrapped in the Chitosan/Sodium glycerophosphate (CS/GP) hydrogel, the GO/PEG lubricant will be released under the squeezing action, thus to prolong the service time of biomimetic lubricants. The friction experimental results showed that GO/PEG had better lubrication effect, and the average friction coefficient of the slow-release solution was below 0.03, especially with the pressure increasing. GO, PEG and small molecule GP in the slow-release solution through hydrogen-bond interaction might form a particular structure, which led to the good lubricating effect. The experiments of cell and acute toxicity in vivo showed that GO and its composite hydrogel had good biocompatibility. Graphical abstract Graphene oxide (GO), Poly(ethylene glycol) (PEG) and small molecule Sodium glycerophosphate (GP) in the slow-release solution through hydrogen bonds effect may form a particular structure, which leads to the good lubrication effect. Fig. 11 The mechanism of slow-release GO, PEG, CS and GP from GO/PEG/CS/GP gel. Unlabelled Image Highlights • We adopt higher concentration of GP on the GO/PEG/CS sol to get the GO/PEG/CS/GP gel. • The treatment method of hydrogel slow-release lubrication could prevent the GO/PEG lubricant from being diluted by body fluid. • GO, PEG and GP in the slow-release solution through hydrogen-bond interaction may form a particular structure, which led to the good lubricating effect. [ABSTRACT FROM AUTHOR]

Abstract Background The large-scale clinical problem caused by unacceptable tribological behaviour of certain large diameter metal-on-metal prosthetic hips has directed attention to adverse condition testing. High metal-on-metal wear is connected with adverse reaction to metal debris. Friction is important because high friction may be associated with high wear, risk the fixation of the cup, and cause detrimental heating of periprosthetic tissues. Methods A friction measurement system was added to a multidirectional, established hip joint wear simulator, and its functionality was evaluated. In preliminary tests, a 50 mm diameter metal-on-metal prosthesis was tested in an optimal acetabular cup inclination angle (48°) and in a steep angle (70°) using a normal peak load (2 kN) and an increased peak load (3 kN). The test length was 100 h. Long-term adverse condition tests of 3 million cycles were run for three 52 mm metal-on-metal prostheses. The lubricant was diluted calf serum at 37 °C. Findings In the 100 h tests, metal-on-metal frictional torque was not highly sensitive to the angle, load and serum degradation, and it was close to that of a conventional 28 mm prosthesis with a polyethylene cup, mostly below 5 Nm. However, a manyfold higher frictional torque (10 to 20 Nm) was observed in long-term metal-on-metal tests with substantial wear. Interpretation To obtain a realistic prediction of the frictional behaviour of a hip design, long-term, multidirectional wear tests are necessary. The friction should preferably be measured during the wear test. In addition to normal conditions, adverse condition testing is strongly recommended. Highlights • Single-axis friction measurement hip joint simulators cannot produce realistic wear. • Friction should be measured in conditions similar to those of the wear test. • Friction measurement was added to an established, multidirectional hip simulator. • High metal-on-metal wear resulted in friction manyfold to that of unworn prostheses. • For a realistic view of frictional behaviour a multidirectional wear test is needed. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract To overcome the drawbacks of the UV grafting method, an alternative, thermal grafting process is suggested. The uniform and geometry-independent grafting of zwitterionic polymers on curved cross-linked polyethylene (CLPE), which is used in artificial hip joints, surface was successfully achieved. Poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(2-(methacryloyloxy)ethyl)dimethyl(3-sulfopropyl)ammonium hydroxide) (PMEDSAH) were grafted on the CLPE by two methods: a UV-based process and a thermal process. The thermal method yielded zwitterionic surfaces with similar hydrophilicities and graft layer thicknesses to those prepared via the UV grafting method. The X-ray photoelectron spectra and surface zeta potential results showed that the PMPC and PMEDSAH layers were successfully grafted onto the CLPE surface. In addition, 3-D confocal microscopy, as well as friction and wear volume tests, confirmed that there was a significant decrease in the friction coefficient and wear, which indicates that the thermal grafting method can successfully substitute the UV grafting method. The thermally grafted polymer showed uniform graft layer thickness on the curved CLPE surface, whereas the UV-grafted polymer showed a geometry-dependent heterogeneous graft layer thickness. Thus, we confirmed that the thermal grafting method is advantageous for the preparation of uniform grafting layers on artificial joint surfaces with complicated shapes. Statement of Significance Formation of uniform grafting thickness of the zwitterionic polymers on the implant materials is a very important issue in the field of biomaterials. In this study, a thermal grafting process was developed for the formation of the uniform grafting thickness of the zwitterionic polymers on the curved cross-linked polyethylene (CLPE) surface used in artificial hip-joint. This method yielded zwitterionized CLPE surfaces with similar hydrophilicities and friction coefficient to those prepared via the UV grafting method which has been widely used process to modify the implant surfaces. Furthermore, the thermally grafted CLPE surface showed geometry-independent uniform grafting thickness on the curved CLPE surface while UV-grafted one showed uneven grafting thickness. This grafting method could help the development of complex, personalized, and biocompatible artificial liner surfaces. [ABSTRACT FROM AUTHOR]

High-precision machining is required for manufacturing hyper-hemispherical artificial joints made of difficult-to-cut metals such as cobalt-chromium (Co-Cr) alloys to provide wear resistance in the human body. The hyper-hemisphere of Co-Cr alloys is finished by curve generator machining, in which the rotation axes of the cutter and workpiece intersect each other at the center of the sphere to be machined. This paper presents a kinematic model to simulate the shape and surface topography on hyper-hemispheres with the cutter loci in curve generator machining. The kinematic model was validated with a cutting test, in which the surface profiles were measured around the pole and equator of the sphere. Simulations were performed to study the cutting process and surface finish. The appropriate cutting parameters were determined to improve the surface finish based on a kinematic simulation. A smooth surface was obtained when small inclinations of the workpiece, large nose radii of the cutter, low workpiece rotation speeds, and non-integer ratios of the tool spindle speed to the workpiece rotation speed were employed. The effects of the setting errors, such as the mounting error of the cutter and alignment error of the spindle and workpiece axes, were estimated via the kinematic simulation. It was found that the surface topography and radius of the sphere depended on the setting errors. The radius and center of the spherical shape were different from those of an ideal sphere by an error in the X-axis in the global coordinate system. The oval shape was caused by an error in the Y-axis. An error in the Z-axis affected the radius of the machined sphere. [ABSTRACT FROM AUTHOR]

Ultra-high molecular weight polyethylene (UHMWPE) wear particles from artificial joints induce osteolysis and the subsequent loosening of implants. Studies have reported that particles in the size range of 0.1–10 μm are the most biologically active in macrophage immune response. To develop prosthetic joints with greater longevity and durability, it is crucial to understand the deleterious effects of wear particles. In this study, to evaluate the effects of particle size on the activities of human monocyte-derived macrophages (HMDMs), seven differently sized particles of polymethylmethacrylate (PMMA), in the range of 0.1–20 μm, were prepared. Viability and the secretion of cytokines were evaluated after phagocytosis of each size particles by HMDMs. Differences in the viability of HMDMs after phagocytosis of particles sized 0.16–9.6 μm were statistically significant. Proinflammatory cytokine production of both tumor necrosis factor-α and interleukin-6 by HMDMs was strongly induced by 0.8 μm PMMA particles. Consistent with the fact that macrophages are known to respond to pathogens measuring approximately 1.0 μm in size, in this study, PMMA particles measuring 0.8 μm in size induced an immune response. This work provides fundamental data for the designing of surface profiles of prosthetic joints, Which may expect the lower incidence of immune response.

Poly (vinyl alcohol) (PVA) hydrogel with high water content is the candidate material for artificial cartilage. PVA hydrogels prepared by freeze-thawing (FT) method (PVA-FT gel), cast-drying (CD) method (PVA-CD gel) and hybrid method of FT and CD (PVA-hybrid gel) were developed and their friction and wear behaviors were evaluated. Sliding pairs of a cobalt-chromium-molybdenum alloy or alumina ceramic ball and a PVA hydrogel plate were tested in reciprocating friction test. Ultra-pure water and simulated synovial fluid were used as lubricants for friction test. PVA-FT gel showed high friction and severe wear in ultra-pure water. Friction coefficient of PVA-CD gel in ultra-pure water was quite low such as about 0.005, but scratches were observed on the surface of PVA-CD gel. PVA-hybrid gel lubricated in ultra-pure water showed low friction such as 0.004, and intact surface structure of PVA-hybrid gel remained after friction test. Simulated synovial fluid contributed to the improvement of lubrication property of all PVA hydrogels and PVA-hybrid gel showed the lowest friction coefficient such as 0.003 and minimum wear. These results indicated that PVA-hybrid gel has a great potential as the material for artificial joint.

Artificial joint surface coating is a hot issue in the interdisciplinary fields of manufacturing, materials and biomedicine. Due to the complex surface characteristics of artificial joints, there are some problems with efficiency and precision in automatic cladding path planning for coating fabrication. In this study, a path planning method for a laser cladding robot for artificial joints surface was proposed. The key of this method was the topological reconstruction of the artificial joint surface. On the basis of the topological relation, a set of parallel planes were used to intersect the CAD model to generate a set of continuous, directed and equidistant surface transversals on the artificial joint surface. The arch height error method was used to extract robot interpolation points from surface transversal lines according to machining accuracy requirements. The coordinates and normal vectors of interpolation points were used to calculate the position and pose of the robot tool center point (TCP). To ensure that the laser beam was always perpendicular to the artificial joint surface, a novel laser cladding set-up with a robot was designed, of which the joint part clamped by a six-axis robot moved while the laser head was fixed on the workbench. The proposed methodology was validated with the planned path on the surface of an artificial acetabular cup using simulation and experimentation via an industrial NACHI robot. The results indicated that the path planning method based on topological reconstruction was feasible and more efficient than the traditional robot teaching method.