Challenges in modeling total knee arthroplasty and total hip replacement

AbstractTotal knee arthroplasty and hip replacement are commonly used procedures in which an ailing knee or hip joint is replaced with a carefully engineered artificial joint. Multibody models of healthy knee and hip joints are used extensively to design artificial knee and joints. The quality of the replacement joint is thus intrinsically related to the quality of the multibody models. In this work, the quality of a kinematic knee model is assessed by comparing predicted knee kinematics to cadaveric knee kinematics under several patellar overstuffing conditions. In addition, the micro motion at the hip joint (between the femoral head and the acetabulum) under varying loads is experimentally measured using a cemented and a cementless cadaveric hip joint

Challenges in modeling total knee arthroplasty and total hip replacement

AbstractTotal knee arthroplasty and hip replacement are commonly used procedures in which an ailing knee or hip joint is replaced with a carefully engineered artificial joint. Multibody models of healthy knee and hip joints are used extensively to design artificial knee and joints. The quality of the replacement joint is thus intrinsically related to the quality of the multibody models. In this work, the quality of a kinematic knee model is assessed by comparing predicted knee kinematics to cadaveric knee kinematics under several patellar overstuffing conditions. In addition, the micro motion at the hip joint (between the femoral head and the acetabulum) under varying loads is experimentally measured using a cemented and a cementless cadaveric hip joint

Experimental and analytical validation of a modular acetabular prosthesis in total hip arthroplasty

A finite element model has been developed to predict in vivo micro motion between a modular acetabular cup and liner after cement less total hip arthroplasty. The purpose of this study is to experimentally validate the model. Six LVDT sensors were used to monitor the micromotion of the liner when subjected to loading conditions ranging from 250 N to 5000 N. Deformations at points of interest for both the experiment and FEM were compared. Results of the FEM with different coefficient of friction between the liner and the cup were investigated to correlate with the experimental results

Comparative study of locking neutralization plate construct versus tension band wiring with a cannulated screw for patella fractures: Experimental and finite element analysis

Transverse patella fractures, accounting for approximately 1% of Orthopedic injuries, pose intricate challenges due to their vital role in knee mechanics. This study aimed to compare the biomechanical performance of a construct, integrating cannulated screws and an anterior locking neutralization plate, with the conventional tension band wiring technique for treating these fractures. Experimental testing and Finite Element Analysis were employed to evaluate the constructs and gain profound insights into their mechanical behavior. Sixteen cadaveric knees were prepared, and transverse patella fractures were induced at the midpoints using a saw. The plate construct and tension band wire fixation were randomly assigned to the specimens. A cyclic test evaluated the implants' durability and stability, simulating knee movement during extension and flexion. Tensile testing assessed the implants' maximum failure force after cyclic testing, while Finite Element Analysis provided detailed insights into stress distribution and deformation patterns. Statistical analysis was exclusively performed for the experimental data. Results showed the plate enhanced stability with significantly lower deformation (0.09 ± 0.12 mm) compared to wire fixation (0.77 ± 0.54 mm) after 500 cycles (p = 0.004). In tensile testing, the construct also demonstrated higher failure resistance (1359 ± 21.53 N) than wire fixation (780.1 ± 22.62N) (p = 0.007). Finite Element Analysis highlighted distinct stress patterns, validating the construct's superiority. This research presents a promising treatment approach for transverse patella fractures with potential clinical impact and future research prospects. This study presents a promising advancement in addressing the intricate challenges of transverse patella fractures, with implications for refining clinical practice. The construct's improved stability and resistance to failure offer potential benefits in postoperative management and patient outcomes

Computer-aided design and mmanufacturing/ Amirouche

xviii, 538 hal.: ill.; 23 cm

An Electromagnetically-Actuated All-PDMS Valveless Micropump for Drug Delivery

This paper presents the fabrication process of a single-chamber planar valveless micropump driven by an external electromagnetic actuator. This micropump features a pair of micro diffuser and nozzle elements used to rectify the fluid flow, and an elastic magnetic membrane used to regulate the pressure in the enclosed fluid chamber. Polydimethylsiloxane (PDMS) is used as the main construction material of this proposed micropump, including the structural substrate and the planar actuation membrane embedded with a thin micro magnet. Both the Finite Element Method and experimental analysis are used to assess the PDMS-membrane actuation under the applied electromagnetic forces and characterize the pump performance at variable working conditions. The resonant frequency of this micropump is identified experimentally and de-ionized (DI) water is loaded to account for the coupling effects of the working fluid. The experimental data was used to demonstrate the reliability of flow rates and how it can be controlled by consistently adjusting the driving frequencies and currents. The proposed micropump is capable of delivering a maximum flow rate of 319.6 μL/min and a maximum hydrostatic backpressure of 950 Pa (9.5 cm H2O). The planar design feature of the pump allows for potential integration of the pump with other PDMS-based microfluidic systems for biomedical applications

Micropump for Drug Delivery

www.mdpi.com/journal/micromachine

Innovative Approach in the Development of Computer Assisted Algorithm for Spine Pedicle

Pedicle screws are typically used for fusion, percutaneous fixation, and means of gripping a spinal segment. The screws act as a rigid and stable anchor points to bridge and connect with a rod as part of a construct. The foundation of the fusion is directly related to the placement of these screws. Malposition of pedicle screws causes intraoperative complications such as pedicle fractures and dural lesions and is a contributing factor to fusion failure. Computer assisted spine surgery (CASS) and patient-specific drill templates were developed to reduce this failure rate, but the trajectory of the screws remains a decision driven by anatomical landmarks often not easily defined. Current data shows the need of a robust and reliable technique that prevents screw misplacement. Furthermore, there is a need to enhance screw insertion guides to overcome the distortion of anatomical landmarks, which is viewed as a limiting factor by current techniques. The objective of this study is to develop a method and mathematical lemmas that are fundamental to the development of computer algorithms for pedicle screw placement. Using the proposed methodology, we show how we can generate automated optimal safe screw insertion trajectories based on the identification of a set of intrinsic parameters. The results, obtained from the validation of the proposed method on two full thoracic segments, are similar to previous morphological studies. The simplicity of the method, being pedicle arch based, is applicable to vertebrae where landmarks are either not well defined, altered or distorted