Papers by Keyword: Knee Joint

Abstract: The knee joint transmission mechanism of quadruped robots usually adopts a fixed transmission ratio. Because the output torque of the knee joint fluctuates greatly during the support phase, a higher requirement is set for the torque output capability of knee joint actuator. Experimental data of multiple walking gaits was collected and parameters of the four-link transmission mechanism with strut structure for the knee joint were optimized using the complex method. In order to reduce the fluctuation of the output torque of the knee joint actuator, the knee joint is expected to maintain a higher transmission ratio at angles with higher torque output requirements. The optimization result shows that due to the limitations of the four-link mechanism, the knee joint has a larger transmission ratio at smaller angles and the maximum output torque angle, and a smaller transmission ratio at larger angles. During the support phase, the output torque of the knee joint actuator is significantly smoother, which can meet the use requirements to a certain extent.

Abstract: Understanding the complex biomechanical behaviour of the injured and meniscectomised knee joints is of utmost significance in various clinical circumstances. The objective of this study is to investigate the effects of bucket handle tears in the medial meniscus and subtotal medial meniscectomies on the biomechanical response of the knee joints belonging to multiple subjects. The three-dimensional (3D) finite element models of human knee joints including bones, cartilages, menisci, ligaments and tendons are developed from magnetic resonance images (MRI) of multiple healthy subjects. The knee joints are subjected to an axial compressive force, which corresponds to the force of the gait cycle for the full extension position of the knee joint. Three different conditions are compared: intact knee joints, knee joints with bucket handle tears in the medial meniscus and knee joints after subtotal meniscectomies. The bucket handle tear causes a considerable rise in the maximum principal stress at its tip compared to that at the same location in the intact meniscus. This would cause the total rupture of the meniscus resulting in cartilage damage. Subtotal meniscectomy causes a considerable reduction in the contact area along with a substantial increase in the contact pressure and maximum compressive stress in the cartilages in comparison with that in the intact knee. This could give rise to severe degenerative changes in the cartilage. The results of this study could help surgeons in making clinical decisions when managing patients with meniscal injuries.

Abstract: This study deals with evaluation of smart economic transfemral Prosthetic consist of a new design and manufacturing of knee joint and design and manufacture of a simple electronic circuit that is programmed to control the muscle pressure on the sensor during movement and transfer the voltage of force sensor after processing in microcontroller to the electric motor to flexion and extend the knee joint. A number of tests were carried out to evaluate the smart prosthetic. Gait cycle and EMG tests were performed on a patient with amputation above the knee in two cases, the first is when the patient is wearing the traditional limb and the second is when the patient is wearing the smart prosthetic. The results showed that the gait cycle during the wearing of the smart prosthetic is more acceptable, stable and balanced than the case of the traditional prosthetic wear. The results of EMG test showed that muscles need less effort during movement when wearing a smart limb and this indicates that the energy spent is less and thus provide comfort to the patient. The results of the finite element analysis (ANSYS 14.5) of the knee joint confirmed the strength of the joint and its ability to carry high weights for patients.

Abstract: A Knee-Ankle-Foot orthosis (KAFO) is used as a supportive device by individuals with lower limb disability. A type of KAFO that allows knee flexion-extension is prescribed for people who need knee stability in the transverse and frontal planes. In such an orthosis, mimicking the human knee motion is vital to avoid relative motion (called pistoning) between the limb and the orthosis. A four-bar mechanism, owing to its polycentric nature, simplicity and ease of fabrication can provide a customizable, biomimetic solution. This paper presents an improved and robust optimization approach to synthesize a four-bar mechanism to closely mimic the anatomical knee motion. The reference human knee centrode is obtained from literature. A genetic algorithm is used for optimal synthesis of the fourbar mechanism. Results show that the average error between the reference centrode and the centrode of the synthesized four-bar mechanism is very small (0.2 mm). Thus, the synthesized crossed four-bar linkage can reproduce better anthropomorphic characteristics of the knee joint. The methodology can be used for the design of customized orthotic knee joints for KAFOs and knee braces.

Abstract: The human knee joint is very critical and complex joint of human body which is responsible for our optimal daily functions. It consists of various bones – femur, tibia, patella, fibula, different ligaments, cartilages, menisci and muscles. FEM is a very useful tool for the analysis of knee joint and various knee replacement products. In the knee replacement surgery a proper understanding of knee joint biomechanics is essential. Because of certain limitations of experimental studies, FEM analysis process is playing a significance role for prominent understanding of knee biomechanics and produced an effective and impressive tool for total knee replacement (TKR/TKA) or partial knee replacement (PKR/PKA). The aim of this paper is to give a review on FEM analysis of human knee joint and knee prosthesis devices and how much adequate this method for these type of analysis.

Abstract: The paper presents research results of resistance to abrasive wear of titanium alloys: Ti6Al4V (commonly used) and Til3Nb13Zr (alloy of new generation) in association with polyethylene (UHMW-PE) predisposed for elements on pair of the knee endoprosthesis. The results were analysed from the point of possibility of an use of new generation titanium alloys as components of such implants. The tests of resistance to abrasive wear of selected kinematic pairs were conducted with the PT-3 tribometer in Ringer’s solution a constant load 2.0 kN, rotational speed of the rotating specimens (Ti13Nb13Zr and Ti6Al4V) 30 rev/min, and test duration 1 or 2 hrs.

Abstract: Mechanical properties of the structure of human body joint always is an important research topic of biomechanics, the biomechanics of the knee joint research, this article through the establishment of a complete dynamic model of the gait cycle of human knee joint of human lower limb gait has carried on the numerical analysis, simulated by dynamic mechanical parameters of the structure of the human body joint, three-dimensional finite element model for the knee joint, through calculation and analysis to determine the rule of the inside of the knee joint dynamic stress, strain, for the study of complex shapes and complex load and complex material of human body joint provide a research idea.

Abstract: The paper presents a complex three-dimensional model of the human knee joint, containing bones, ligaments, menisci, tibial and femoral cartilages. To investigate the role of the articular cartilage in the developing of the osteoarthritis, to analyze and simulate the biomechanical behavior of the human knee joint, a finite element analysis was performed. The non-linearities are due to the presence of the contact elements modeled between components surfaces and to the nonlinear properties of the cartilage, applying a load of 800 N and 1500 N, for 0o in flexion. The results show that misalignment (valgus variation) could damage the articular cartilage because they increase the stress magnitude, that progressively produce articular cartilage damage and it enhances the osteoarthritis phenomenon due to mechanical factors. The displacements and the Von Mises stress distributions on the cartilage and menisci for the virtual prototype, considering an angle of 10 degrees for valgus, are presented. The obtained values are comparable with the values obtained by other authors.

Abstract: The purpose of this paper is to introduce a new design of CPM training machine of recovery for knee joints which provides a constant-speed, translational and steady recover environment. A parallelogram mechanism and a magnetorheological fluid mechanism are used to ensure the patients not only to perform passive train in the earlier period after operation but also do active train in different stages without the influence of gravity compensation. The training machine makes the recover motion meet the physiology need of the joint motion after operation and has the applicable significance in medical practice.

Abstract: 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.