Artificial Knee Joint Research Articles

212 人工膝関節の屈曲に関わる形状的要因に関する検討

212 人工膝関節の屈曲に関わる形状的要因に関する検討

502 人工膝関節摩耗予防のためのポリエチレングリコール混合潤滑剤の機能評価(GS 計測)

502 人工膝関節摩耗予防のためのポリエチレングリコール混合潤滑剤の機能評価(GS 計測)

A bio-inspired condylar knee joint for knee prosthetics

This paper presents a novel bio-inspired condylar prosthetic knee joint developed at the University of Bristol. The bio-inspired condylar joint mimics the structure and biomechanics of the human knee joint. The joint contains an inverted parallelogram four-bar mechanism combined with a cam mechanism. The joint has a favourable mechanical advantage compared with a hinge joint. The joint is also compact and robust. An adultsized prototype joint has been designed and tested. The prototype joint contains a long cable for the ligaments with a mechanism for adjusting preload. Compared with other prosthetic joints, the condylar joint has the advantages that it is simple and closely mimics human biomechanics. This paper presents the design of the new artifi cial knee joint and some of the test results. The joint can be used in artifi cial legs and also for knee implants. A rapid prototyping procedure is also presented that enables a custom-sized prosthetic knee joint to be made very quickly and from just a few key dimensions. This process has the potential to improve the quality of surgical implants.

Optimal Coefficient of Friction on Artificial Knee Joint Contact Surfaces

Wear generated by the presence of frictiononknee joint contact surfaces can cause debris, which may lead to failure of the artificial knee joint. In this study, the effects of friction coefficients occur on the knee joint contact surfaces were examined by Finite Element (FE) method. The knee joint was modelled to represent the contact surfaces between femur, meniscus and tibia. The measured angle from 0° to 15° was applied to analyze contact stresses for normal walking condition. It was found that the position angle of the knee joint at 10°offers the maximum value of contact pressure and shear compared to other knee joint position angles.Therefore, further examination was carried out and the FE results showed thattheoptimal friction coefficient was within the range of 0.1 and 0.15.

Design and Development of an EMG Driven Microcontroller Based Prosthetic Leg

Over the past years prosthetic legs have become much improved although complex. However their costs are high and are not within the reach of most people in the Third World. Low-cost fixed prostheses are available in the Third world countries of Asia and Africa, but these offer very basic movement with unnatural gait; climbing stairs gets quite difficult. The prosthesis being worked upon in the present work are for amputees with legs removed above the knee, and would offer a limited rotational movement of the knee joint under voluntary control of the wearer, driven by the EMG signals extracted from thigh muscles. The aim is to make it at a low cost, may be at a cost slightly higher than the passive ones, but allowing a better gait in walking, and in climbing stairs. An initial work was done in this direction by our extended group earlier; the present work gives further improvements. This involves redesigning of the motor and the gear system and that of the electronic circuitry for processing the EMG signals extracted from thigh muscles, interfacing the output to the microcontroller, rotating the motor in two directions thereby accomplishing the movement of the knee joint. The motor, geared down, is mounted horizontally and a pulley system drives the artificial knee joint. When complete, this will benefit a large number of handicapped people in the Third World. DOI: http://dx.doi.org/10.3329/bjmp.v4i1.14695 Bangladesh Journal of Medical Physics Vol.4 No.1 2011 107-114

Understanding of Healthcare Design

Healthcare industry scope grows quickly due to the serious aging problems and the concerns towards health and well-being life increasing continuity. The peoples’ recognition towards healthcare is not limited on the life extending; they pay more attention to how to ensure and develop normal functioning of a living organism, how to enjoy the whole process and so on. Therefore, the demand for ealth-related products and services increases. Recently, many domestic, foreign enterprises and related research institutes do a lot of researches about healthcare and healthcare design, but the data or research about overall understanding of healthcare-related classification and different design methods to be used in the each healthcare part is not enough and clear, so the basic study to help understanding healthcare and healthcare design, with the diverse social issues and developing trends as the base, is very necessary. In this study, classified the healthcare field by existing activities and issues about healthcare, and analysis each part develop and design direction, as well as design method. And took two examples to explain the healthcare design more clearly, one is healthy city design which is design for public healthy people and the other is case study about new mass customization service process model for the artificial knee joint, which is the case study design for unhealthy people by applying with service design method.From the two case study we could see the relationship between service design. The study for healthcare design is only a starting, under the interventions of multidisciplinary, the study are and study method of healthcare design will be more diversification. By importing service design method into the healthcare design industry could form a completely circle and improve the quality of healthcare industry.

Finite Element Simulation of the Artificial Knee-Joints of Similar Type Pairing

The stress relationship between several pairings was studied through the contrastive contact analysis between the artifical knee-joints of the same type pairing and similar type pairing in different angles and conditions to expand the application of the existing artifical knee-joints. The result shows that, the maximal equivalent stresses of the artifical knee-joints of similar type pairing are more than those of the artifical knee-joints of the same type pairing generally. The law is especially clear in conditions of larger force. In conditions of walking on the flat ground and climbing the stairs, the stress growths between 4/3 pairing and 3/3 pairing are the largest in 10° , they are 18.3% and 14.5% respectively; the stress growths between 3/2.5 pairing and 3/3 pairing are the largest in 20° , they are 13.4% and 15% respectively.

Service Life Study of the Artificial Knee-Joints of Crossed Pairing

The stress relationship between the artifical knee-joints of the same pairing and crossed pairing was studied by the contrastive contact analysis of finite element simulation in different angles and conditions. The service lives of the artifical knee-joints of different pairing were studied based on the above result and Archard wear design calculation theory to expand the application of existing artificial knee-joints. The result shows that, the maximal contact stresses of the artifical knee-joints of crossed pairing are more than those of the artifical knee-joints of the same pairing, and the more different pairing types are, the more obvious stress growths are. The service life of the artifical knee-joint of 3/3 pairing is 28.42 years, and the service lives of 3/2.5 pairing and 3/4 pairing are 27.08 years and 25.76 years respectively.

Strain-induced martensitic transformation near twin boundaries in a biomedical Co–Cr–Mo alloy with negative stacking fault energy

Biomedical Co–Cr–Mo (CCM) alloys have been commonly used for artificial hip and knee joint prostheses, but a need to improve their biomedical inertness and wear resistance has become widely recognized. The mechanical behavior of CCM alloys is dominated by strain-induced martensitic transformation (SIMT), which causes crack initiation during plastic deformation but dramatically enhances the wear resistance in practical use. To develop more reliable CCM alloys it is essential to clarify the factors affecting the occurrence of SIMT. In the present study we have focused on the effect of annealing twin boundaries (ATBs) on SIMT behavior. We have analyzed in detail the substructures near a parallel pair of ATBs after deformation under a stress preferential for slip parallel to the ATBs. Preferential formation of ε-hexagonal close-packed (HCP) phase at ATBs in metastable γ-face-centered cubic (FCC) phase was found by both scanning electron microscopy with electron backscattered diffraction (EBSD) analysis and transmission electron microscopy (TEM). High resolution TEM images indicated that thickening of the ε-HCP phase does not proceed regularly on every second atomic plane, which would form perfect ε-phase HCP structure, but irregularly leaving a high density of stacking faults. Furthermore, the thickness of the ε-HCP phase was found to be different at ATBs on the two sides of the twin. The difference was attributed to the internal stress due to strain incompatibility at the ATBs on the basis of residual stress analysis by the EBSD–Wilkinson method and phase-field simulation of solute segregation at ATBs.

Low Strain Rate Upset Forging of Preformed CoCrMo Powder Alloy for Load Bearing Application: A Review

CoCrMo alloy are known to be widely applied as biomedical implant materials. They have been used for artificial hip and knee joints because of their excellent corrosion and wear resistances as well as good mechanical properties and biocompatibility. Although as-cast or annealed CoCrMo alloys are frequently subjected to practical use, there are possibilities to exhibit insufficient mechanical properties due to coarse microstructure and solidification defects that often lead to premature failure of implants. Therefore, the review suggested that an improvement of tensile properties as well as fatigue properties shall be made for further mechanical reliability by applying low strain rate upset forging. Grain-structure or grain-flow optimization is a sufficient area to be studied to produce parts with enhanced mechanical properties, impact strength, and fatigue endurance limits. Forgings deliver strengths were the most needed while maintaining a good balance of 3-demensional properties. By optimizing grain-flow characteristics during the forging process, we should be able to tailor the directional strength, which permits forging to meet the requirements of the parts with the desired configurations.

J024046 PS型人工膝関節におけるコンポーネント間のインピンジメント評価([J024-04]関節メカニクスの評価と解析)

Impingement problem of femoral component and polyethylene insert after total knee arthroplasty (TKA) has been recently brought to light by contact pressure analysis using the knee joint simulator. Therefore, adequate motion analysis is important for estimating the impingement between components and improving postoperative exercise. The purpose of this paper is to analyze the impingement of TKA components during stair claiming activity in vivo. Ten patients with posterior-stabilized (PS) TKA were examined in stair claiming activity. The 3-D position and orientation of the implant components were determined using image matching technique. The 6-DOF of each component was able to be reproduced on 3-D CAD. Kinetic relation between the femoral component and polyethylene insert was calculated, and then the impingent was analyzed. In the result, impingement of the femoral intercondylar notch and anterior aspect of the tibial post was observed in extension of stair claiming activity. This study helps the surgeon be more aware about impingement between components under some conditions and is useful to improve the design of artificial knee joint.

Relationship between quality of life and coping style in patients accepted artificial total knee joint replacement

Objective To understand the present situation of the quality of life and coping style in elderly patients with total knee replacement surgery for more than a year,and analyze its correlation.Methods A questionnaire survey was conducted,General Self-set Questionnaire,health status questionnaire (SF-36) and simplified coping style questionnaire (SCSQ) were used to investigate 160 cases of arthroplasty patients.And 120 health patients were selected as the control group during the same period.Results The score of life quality in patients with artificial total knee replacement was significantly lower than that in the control group [(61.37 ±6.18) vs (79.13 ±4.84)],with significant difference (t =-26.063,P =0.000).Patients with negative coping style score (20.80 ± 5.88) was higher than that in the control group(16.89 ± 2.71),and the difference was statistically significant (t=6.765,P =0.000).Positive coping style was positively correlated with the social functioning,general health,mental health and quality of life score (r =0.214,0.165,0.164,0.268,respectively; P ＜ 0.05); Negative coping style was negatively correlated with the social functioning,general health,vitality,the physiological function (r =-0.205,-0.205,-0.227,-0.261,-0.358,respectively;P ＜ 0.01).Conclusions Quality of life is low in patients with total knee replacement,and the quality of life is correlated with the coping style,so it is necessary to take corresponding nursing interventions to guide the patients to adopt a positive coping style,and provide the necessary social support so as to improve their quality of Key words: Quality of life; Osteoarthritis; Artificial total knee arthroplasty; Coping style

Review: Tribological behavior of polyethylene-based nanocomposites

Thermoplastics polyethylene (PE) materials, such as high density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE), are widely used as bearing materials in industrial applications. UHMWPE, with its superior wear resistance and low-friction surface properties, has also been applied successfully as a key material in artificial knee and hip joint replacements. However, the wear debris generated during the joint motions could cause osteolysis and loosening of the implant, contributing to the main cause for joint revision. Many attempts have been made to improve the wear resistance of PE materials in order to elongate the material’s service life. Various nano-fillers, including carbon nanofibers, carbon nanotubes, nano-alumina, and nano-montmorillonite, have been applied as ideal reinforcing components to modify the tribological properties of PE. This article reviews the current status of research in tribological studies of PE-based nanocomposites, mainly UHMWPE and HDPE nanocomposites, including the types of nano-fillers, fabrication methods, and tribological characterization approaches. The dependence of tribological properties of those nanocomposites on the concentrations and modifications of nano-fillers, and other tribological parameters is summarized; the different wear mechanisms are reviewed. New research directions in this field are proposed.

Multicriteria Synthesis of a Polycentric Knee Prosthesis For Transfemoral Amputees

Abstract— In one of the prosthesis designs for lower limb transfemoral amputations artificial knee joints with polycentric mechanisms are used. Such prostheses are characterized by high stability during the stance phase of the movement. The existing variety of polycentric mechanisms indicates the possibility of finding the optimal prosthesis design satisfying several quality criteria.In this paper we present a multicriteria method for the synthesis of the artifical polycentric knee mechanism based on the uniform systematic study of the design parameters space and on the analysis of Pareto optimal solutions. Keywords— Optimalcriteria, polycentric knee, prosthesis, synthesis,transfemoral amputee.I. I NTRODUCTION OR a long period of time mankind has attempted to create artificial devices (prostheses) capable to replace as fully as possible natural human organs lost or damaged due to various reasons. First of all such devices were created to restore motor functions lost due to loss of the lower limbs. On one side, this problem seemed the most simple on a technical level, on the other side - the restoration of motor activity allows a person to carry out vital actions even with quite simple devices. The obvious drawbacks of such devices have stimulated the search for new, more sophisticated designs that could improve the quality of life for amputees. However, despite the huge technological progress made to date in this area, lower limb prostheses are still not correspond to biological analogues from different points of view [1]. Lower limb prostheses for transfemoral amputations differ by the kind of thigh and shank joint (single-axis and polycentric) and by the control methods [2].Single-axis prostheses have a fixed center of rotation of the hip relative to shank, are relatively inexpensive and with high accuracy simulate the motion of the knee. However, these prostheses have low functionality and are not sufficiently stable during the stance phase.In the polycentric prostheses position of the instant center of rotation (ICR) continuously changes with changing of the angle of knee flexion.

Wear of knee prostheses

This paper describes how three different unique design solutions for artificial knee joints each provide extremely low wear and the potential for a 50-year osteolysis-free lifetime in high-demand patients. Each of the three low-wearing prosthetic design solutions provides a different and distinctive functional solution for the patient and surgeon.

HiL simulation for testing joint stability after total knee arthroplasty

Instability of total knee replacements (TKRs) remains one of the most prevalent complications after total knee arthroplasty. Especially the actual event of instability involving complex interactions between implant components and soft tissue structures is not well understood. Therefore, the purpose of this work is to introduce a novel approach for testing TKRs with respect to stability of the artificial knee joint based on a mechatronic hardware-in-the-loop (HiL) test system. The mechanical test setup is composed of an industrial robot with a compliant support for the endoprosthesis to be tested. It interacts with a biomechanical multibody model consisting of all relevant body parts of the lower extremity incorporating ligament structures of the knee joint. According to the movement angles and reaction forces/torque provided by the multibody model, the robot rotates and loads the femoral component with respect to the tibial component. The resulting position and loading of the femoral component are measured and fed back into the model, thus closing the control loop for HiL simulations. The functional principle of the HiL simulation is proven by simulating a passive flexion movement of a bicondylar, posterior cruciate ligament retaining TKR using the described biomechanical multibody model.

Rationale analysis of human artificial knee replacements

Artificial knee replacement is a surgical operation in which the defective knee joint surfaces are replaced completely with an artificial joint. Total knee replacement (TKR), also referred to as total knee arthroplasty (TKA), is a surgical procedure where worn, diseased, or damaged surfaces of a knee joint are removed and replaced with artificial surfaces. The current investigation deals with one of the most important parameters in controlling the life span of the artificial knee, which is the thickness of the polyethylene layer of Tibia Tray of artificial knee joint. Three different thickness of polyethylene layers (8, 9, and 10mm) are available at hospitals assembled with similar identical tibia trays. This makes knee surgeons confused as to which polyethylene layer thickness to choose. It was found that the strength of polyethylene and the strength of cement constituents of the artificial knee are increased with polyethylene layer thickness.

Preliminary Studies for Validation of a Novel Sensor Fiber to Measure Forces in Artificial Knee Ligaments

Even though modern ski bindings can prevent tibia fractures they are still unable to reliably protect the knee. Attempts are therefore made to develop mechatronic concepts to implement additional release criteria. In order to systematically test and optimize such new bindings an artificial instrumented knee joint is currently being constructed at our Institute. A major challenge in this development is to measure the tension forces in the artificial ligaments. To provide this demanding measuring, a novel sensor fiber made of silicon rubber and filled with carbon black was used, which alters its electrical conductivity due to elongation. The fiber itself was either bonded or sewn on the synthetic ligament (LARS, Corin Group PLC, UK). To check the linearity, reproducibility and accuracy of the new measurement unit, tensile tests have been conducted using a similar method as proposed by another study on sensor fibers. As a result, the tests revealed good quality of the developed measurement application, showing minimal variance and high reproducibility. Thus it turned out to be a reliable and appropriate tool to record forces in a uniaxial direction making it an interesting device not only in our application but generally as a method to measure tension in sports apparel and other fabrics.

The Effect of Flexion Angle and Sagittal Radius on Femorotibial Contact Stresses

The artificial knee joint need to satisfy and meet certain design requirements in addition to being biocompatible. These being the design of the flexion angle and sagittal radius of the prosthetic knee for specific activities such as walking and exercising. Day to day physical activities do result in generating frequent contacts between the femur and tibia leading to stresses at the interface of the femorotibial joint. These stresses on exceeding certain limit do result in damage of the tibia which acts as bearing surface carrying loads during each of the knee activity. Hence, prediction and minimization of the stresses at the knee interfaces is the key issue to ensure high performance knee joints. In the light of the above, the stresses at the knee interfaces are computed using commercially available FEA software (ANSYS 10). The three dimensional model was developed using PRO E software for sagittal radius of 40, 50 and 60 mm. The flexion angles considered are 0, 20 and 40 degrees. A load of 500N was considered. It is observed that the stress intensity increases with increase in flexion angle and sagittal radius for all the material combinations of the prosthetic knee joint. Further, alumina ceramic femur and polyethylene chopped carbon fiber composite tibia exhibits the least stress levels at all the studied sagittal radius and flexion angles.

The Finite Element Analysis of Standard Knee Prosthesis

The research uses the finite element software ANSYS to analyze the stress of the standard artificial knee joint, particularly the contact stress between the femoral condyle and the ultra-high molecular weight polyethylene (UHMWPE) meniscus. When analyze the stress of the standard artificial knee joint in the case that knee joint unbend (bend 0°) and bend 10°and 20°, the lower surface of the proximal tibia maintains completely constraints and we apply the corresponding constraints and surface load with the actual situation.Finally calculate the stress distribution of the artificial knee joint. The analysis results were compared with the stress of the normal knee joint to further improve the design of the artificial knee joint.