Papers by Keyword: Prosthesis

Abstract: Over the past decade, noninvasive brain-computer interfaces (BCIs) leveraging electroencephalography(EEG) to decode gait intention have matured from proof-of-concept studies to nearclinicalimplementations. We systematically reviewed 55 studies (January 2015-April 2024) usingPRISMA guidelines, focusing on neurophysiological markers (MRCPs, ERD/ERS, high-γ), signalprocessing pipelines (artifact suppression, time-frequency transforms), machine-learning classifiers(CSP-SVM, ERD SVM), and deep-learning frameworks (spatio-spectral CNNs, LSTM RNNs). Acrossstudies, median classification accuracy rose from 75% (2015-2018) to 87% (2021-2024), while detectionlatency fell below 200ms. Innovations include enhancing intention detection with emotionevokingmusic stimuli (up to early ERD and improved accuracy), decoding pediatric gait kinematicswith state-space models (r = 0.71 hip, 0.59 knee), and session-to-session transfer learning withoutrecalibration (≤4% performance drop). Challenges remain in artifact mitigation, small sample sizes,and limited multi-centre trials. We propose open, standardized datasets, transfer-learning pipelines,and larger clinical validations to accelerate translation.

Abstract: Low mechanical behaviors of natural fibres in the reinforcement of polymer composites have remain an issue of concern. This study is aimed at investigating the effect of NaOH treatment on the mechanical properties of plantain fiber for the transtibial prosthetic sockets made of polyester resin. Plantain fiber was extracted from the plantain bast using water retting techniques. The fibres were modified using alkaline treatment method of 5 – 25% for variable time of 30 to 150 minutes. It was optimized using 3-level Factorial design (3-LCD) of response surface methodology based on tensile properties of treated fibres. The polyester composites of plantain and glass fibers were prepared using hand-layup techniques. Instron Universal testing machine-3369 model was used to determine the tensile and impact properties of fibers and polyester composites. Rockwell hardness tester-RBHT/S-39 model was used to determine the hardness property. The optimum process conditions of 5 % NaOH for 119 minutes improved plantain fiber tensile strength, modulus, strain, energy, and extension by improved by 102.03, 208.07, 9.70, 210.52 and 205.73 %, respectively. The ultimate tensile strength and modulus was obtained at 10 and 12.5% fiber loading. The hardness and impact strength of NaOH modified unsaturated polyester composites was marginally more than 3.51 and 10.69% of glass fiber reinforced unsaturated composites, respectively, at 12.5% fiber loading. FTIR analysis revealed the improvement in mechanical properties. Thus, NaOH modified plantain fiber unsaturated polyester composites serves as a better alternative for making transtibial prosthetic socket.

Abstract: Osseointegration prosthesis is a directly implanted fixation in the bone for limb amputees. It has been used as an excellent alternative for amputees experiencing difficulties from the use of a traditional socket type prosthesis. A novel implant used for implanted prosthetics is designed and it depended on polymer as a primary material to increase bone osseointegration. As an alternative to the metallic material on the interface with the bone. The design consists of several parts and relies on thread to increase installation. This research aims to overcome the problems of loss implantation by using new designs for fixations. Evaluated this design by FEA (Finite element analysis) in different load cases to obtain the distribution of stress and force reaction when the implant displacement was applied. The polymeric part was designed in two shapes, each shape relies on a different size of threaded to verify the change of fixation with the threaded. As for the metal part, two cases were used, the first case, stainless steel 316L, and the second case titanium metal to reach the best stress distribution in this design.

Abstract: The knee at times undergoes a surgical process to substitute the weight-bearing surfaces of the knee joint. This procedure relieves the pain and disability around the knee joint. This research paper studied the knee arthroplasty, also referred to as knee replacement. This work was aided with computer vision for visual and accuracy. Autodesk fusion 360 and the stl files were used to generate cemented, posterior stabilised knee prosthesis and imported into the COMSOL Multiphysics software. Then, the three-dimensional models of the total knee arthroplasty (TKA) prosthetic structure are produced. The prosthetic components are modelled as linear isotropic elastic materials. Finite element (FE) simulations using COMSOL Multiphysics on a CAD model of a knee are effectuated to show the effect of several loads and strains on the knee. FE analysis of the model indicates that the orthotropic model depicts a more realistic stress distribution of the knee as it reveals the detailed anatomy of the entire knee structure. The computational results of this work displayed a fair agreement with experimental information from the literature.

Abstract: The human knee is a complex joint (the largest joint of the human body). During the different daily activities, this joint is exposed to significant loads and movements, may in some cases exceed the limit of the mechanical capacities of its components, which shows that the pathologies are quite numerous at the level of the human knee and the treatment sometimes requires surgery to either repair or implant (implant total knee prosthesis). As we know very well, the success of a total knee implant is highly dependent on the initial stability of the femoral or tibial implant and the integration of femur and tibia bone tissue with these implants in the long term. Due to the optimal distribution of mechanical stresses in the surrounding bone. It is for this reason that the search for reasonable solutions to compensate the damaged knee prosthesis and reduce the stresses in the cortical bone and spongy has become a very important research axis. In this regard, we have proposed three models of prosthesis knee joint from available literature and study the distribution of Von-Mises stresses and strains in the differents composents of knee prosthesis, know the total displacement between the model intact and model artificial of knee, 3D modeling software Solidworks 2016 is used for 3D modeling of knee prosthesis and finite element analysis software ANSYS 16.2 is used for numerical estimation of von-Mises stresses and strains. We find in this study that the maximum stresses and strains of Von Mises at the level of the tibia and tibial bone decrease, that is to say that the cement and the elastomer play a very important role in the absorption of the stresses and their minimization. On the other hand, the four knee prostheses (Model I (Ti6Al4V), Model II (CoCrMo), Model III (316L SS), Model IV (ZrO₂)) implanted by elastomer contribute significantly to the reduction of stresses in the patella bone compared to the Intact Model. In general, both models of the knee prosthesis and reinforced by a stress reduction system (cement, elastomer) gave a lower stress level in the tibia and tibial bone of a normal person compared to a healthy model. The results obtained provide a theoretical basis for choosing an appropriate surgical model.

Abstract: The purpose of this study is to develop computational mathematical models for virtual prototyping of an actuation system from an exoskeleton human knee joint. These models are a part of the virtual and experimental prototype of a mechatronic system for locomotion rehabilitation in case of disabled persons. Experimental tests were performed on a group of persons without locomotion deficiencies. The obtained database was used to develop geometrical kinematic synthesis of the exoskeleton actuation mechanisms for knee’s joint and also ankle.

Abstract: Various ball and socket-type designs of cervical artificial discs are in use or under investigation. All these disc designs claim to restore the normal kinematics of the cervical spine. In this study, we are interested in the cervical prosthesis, which concerns the most sensitive part of the human body, given the movements generated by the head. The goal of this work is to minimize the constraints by numerical shape optimization in the prodisc-C cervical spine prosthesis in order to improve performance and bio-functionality as well as patient relief. Prodisc-C cervical spine prosthesis consists of two cobalt chromium alloy plates and a fixed nucleus. Ultra-high molecular weight polyethylene, on each plate there is a keel to stabilize the prosthesis; this prosthesis allows thee degrees of freedom in rotation. To achieve this goal, a static study was carried out to determine the constraint concentrations on the different components of the prosthesis. Based on the biomechanical behaviour of the spine discs, we totally fixed the lower metal plate; a vertical load of 73.6 N to simulate the weight of the head was applied to the superior metallic endplate. After a static study on this prosthesis, using a finite element model, we noticed that the concentration of the Von-Mises stress is concentrated on the peripheral edge core and the concave articulating surface of the superior metallic endplate the numerical. We use the module optimization for 3D SolidWorks for optimize our design, based on the criteria of minimizing stress value. Shape optimization concluded to minimize the equivalent stress value on both joint surface (concave and convex) from 11.3 MPa to 9.1MPa corresponding to a percentage decrease of 19.4% from the original geometry. We conclude that despite the fact that maximum Von Mises stresses are higher in the case of the dynamic load, remains that they are weak. Which is an advantage for the durability of the prosthesis and-also for the bone, because a low stress concentration on the prosthesis will reduce stress concentration generated by the implant on the bone, therefore its risk of fracture reduces.

Abstract: In high speed machining, to dynamically control the mechanical behaviour of the materials, it is essential to control temperature, stress and strain by appropriate speed, feed and depth of cut. In the present work, to predict the mechanical behaviour of Ti6Al4V and 316L steel bio-materials an explicit dynamic analysis with different cutting speeds was carried out. Orthogonal cutting of 316L steel and Ti6Al4V materials with 720 m/min, 900 m/min and 1200 m/min cutting speeds was performed, and the distribution of stress and temperature was investigated using Jonson-Cook material model. Additionally, the work aimed at determining the effect of cutting speed on work piece temperature, when cutting is carried out continuously. From the investigation, it was found that, while machining Ti6Al4V material, for the increase in cutting speed there was increase in tool-chip interface temperature. Specifically, this could found till the cutting speed 900 m/min. But, there was a decrease in tool-chip interface temperature for the increase in speed from 900 m/min to 1200 m/min. Similarly for 316L steel, the tool-chip interface temperature increased when increasing the cutting speed till 900 m/min. But reduction in temperature from 650 °C to 500 °C for steel and 1028 °C to 990 °C for Ti6Al4V were found, when the cutting speed increased from 900 m/min to 1200 m/min. The study can be used to conclude, at what temperature range the adoption of material with controlled shape and geometry is possible for potential applications like, prosthetic design and surgical instruments prior to fabrications.

Abstract: In this work, pre-sintered zirconia ZrO₂(Y₂O₃) ceramics were characterized aiming its acceptance in standard ISO 6872:2015 (Dentistry-Ceramic Materials). Pre-sintered zirconia blocks were sintered at 1450oC, 1500oC, 1530oC or 1600oC. Sintered samples were sanded, polished and characterized by relative density, crystalline phase, microstructure, hardness, fracture toughness, bending strength, translucence and dilatometry. The results indicated that the ceramic studied presents hardness superior to 1200HV, fracture toughness of 8MPa.m^1/2 and bending strength superior to 900MPa. Zirconia sintered at temperature of 1600oC, presented exaggerated grain growth which reduces the material toughness. With the porosity decreasing and the grain growth increasing it happens the increase of translucence, but the mechanical aspects must be analyzed carefully, in order to establish zirconia reliability for using it in dental prostheses.

Abstract: Cervical disc herniations represent the most frequent cervical-level pathology in patients aged 40 and above. Symptoms usually include C6-C7 radiculopathy, which has a prevalence of 3.3/1000 individuals. There still is a debate on whether any gender is more frequently affected, as some authors report women are more frequently affected [2, 3] while others claim both genders are equally affected. Ever since the 1950s the standard treatment for such patients was represented by Anterior Cervical Discectomy and Fusion (ACDF), however, concern for the development of adjacent level degeneration after the fusion of mobile vertebral segments has increased the interest in developing new dynamic disc prostheses designed to mimic the functions and natural motion of the spine. The purpose of this paper is to summarize, in a comprehensive literature-review-type article, the existing data regarding the ProDisc-C spinal implant within the OVID, SCOPUS and MEDLINE databases while at the same time presenting the personal experience of the authors using the above-mentioned implant.