ABSTRACT
In this study, tibial shaft fracture has been treated with implants as numerically to investigate the stress behavior and the effect of plate material, position and length under pressure load. Plates of stainless steel, titanium alloy(Ti6Al4V), or CF-PEEK(CF50) were used to fix the tibial shaft comminuted fracture in different location and different working length. The maximum stress, the maximum micromotion of fracture and the stress shielding of cortex bone were analyzed. CF50 is more ideal biomechanical fixation material than traditional metal material for the treatment of tibial shaft comminuted fractures. In the treatment of tibial shaft comminuted fracture, lateral position and with relatively long working length of the plate have the advantages in micromotion, stress and stress shielding rate of the fracture end.
Subject(s)
Humans , Biomechanical Phenomena , Bone Plates , Finite Element Analysis , Fracture Fixation, Internal , Fractures, Comminuted/surgery , Tibial Fractures/surgeryABSTRACT
For implantable medical devices, traditional mechanical property testing is achieved by mechanical testing devices, while such method is lack of pertinence during sampling of series of products, and also time consuming during experimental testing. With the complete development of finite element analysis (FEA) techniques, introducing FEA to quality supervision and inspection will become a scientific method for saving resources and time, and also improve the pertinence. In this study, the creditability of FEA in application of highest risk sample selection, failure analysis of marketed products and auxiliary optimization of fatigue test testing was verified through case study and experimental testing. The feasibility of FEA during implants inspection was illustrated. In order to ensure the accuracy and reliability of FEA in the application of implants inspection, the essentials of establishing related finite element standards were proposed.
ABSTRACT
Objective To investigate the wear mechanism of artificial hip joints and the criteria for wear life definition, analyze the causes of abnormal wear and the clinical manifestations of wear failure, establish the reasoning route of failure incidents. Methods The wear process and early factors on abnormal wear in artificial hip joints were studied through elastohydrodynamic lubrication computation and finite element analysis; the service life of artificial hip joints was determined through establishing criteria for wear life definition; the clinical manifestations of wear failure were introduced and classified through wear-osteolysis morphological matrix; the reasoning logic of failure incidents was established through clinical investigation. Results The minimal synovium thickness and contact stress between the femoral head and the acetabular cup were calculated, and the effect of relevant parameters was studied as theoretical references for wear analysis; the criteria on wear life definition of artificial hip joints were proposed, namely the mechanistic failure due to geometric change in artificial hip joints and the biological failure due to osteolysis; nine kinds of clinical manifestation for wear failure were found; the reasoning route for failure incidents was presented. Conclusions Primary wear process in artificial hip joints includes boundary and mixed friction, adhesive, ploughing and third-body wear; surface quality, fit clearance between the acetabular cup and the femoral head, and roundness have great impact on early abnormal wear; normal mechanistic life of metal-UHMWPE artificial hip joint can reach 40 years, but its maximum biological life is no more than 10-15 years, which is the constraint of prosthesis life today; the diversity of clinical manifestations for wear failure is the morphological Results of mechanical wear and osteolysis, which is helpful for the reasoning route of failure incidents.
ABSTRACT
Objective To propose a detailed method on the diagnosis of dislocation failure by studying the mechanism of mechanical failure and causes of dislocation occurrence after the total hip arthroplasty (THA). Methods The correlation between dislocation failure and clinical situation, product design and patients was analyzed by establishing the dislocation model to study the biomechanical mechanism of dislocation procedure. Results The reasoning route for dislocation analysis after THA was proposed and the visual hip prosthesis motion analysis software was developed and validated. Conclusions Case study on dislocation failure after THA shows that the proposed method and developed software can judge the cause of dislocation incidence in detail, and determine the relationship between implanting position for the hip prosthesis and dislocation incidence. Meanwhile, it can find the best implanting position before operation and analyze the risk of dislocation incidence, which will be helpful for the prosthesis design.