A Three Dimensional Virtual System Used to Analyze the Normal and Prosthetic Joint of the Hip

Abstract

Treatment of hip pathology has evolved over the last two centuries, ranging from rudimentary surgical procedures to modern hip arthroplasty, with an explosion marked in the last 30 years, considered to be one of the most successful surgeries to date. Hip arthroplasty is a permanent challenge due to the desire to discover the "supreme prosthesis", for which competition is still open. Hip disorders requiring prosthesis show a change in articular morphology. Among the most common medical conditions that have as final therapeutic solution hip arthroplasty are: coxarthrosis, both primary and secondary, followed by traumatic conditions: femoral neck collapse and femoral neck pseudarthrosis, aseptic head necrosis femoral stage III, as well as rheumatic coxitis from rheumatoid arthritis, ankylosing spondylitis or juvenile art. Endoprosthetic arthroplasty can be defined as an intervention of reconstructive surgery with bone sacrifice and prosthetic replacement of the articular components. It is, in the end, an operation aimed at restoring joint mobility and normal functioning of the muscles, ligaments and other periarticular structures that control joint movement. The materials initially used (glass, metal, plastic) did not have the desired bone strength and integration capacity. It followed the development of cemented implants, obtaining different types of cement with better and better quality. Problems arising from cemented arthroplasty (decimation, involving prosthetic revision) have led to a parallel development of the design and materials used for uncured prostheses with the possibility of very good integration of prosthetic material into the bone, raising them to the top of preferences in recent years. Treatment of hip pathology has evolved over the last two centuries, ranging from rudimentary surgical procedures to modern hip arthroplasty, with an explosion marked in the last 30 years, considered to be one of the most successful surgeries to date. The purpose of this study was to obtain the three-dimensional models of the hip joint and the prosthesis for the use of these models for various analyzes and virtual experiments. At the end of the paper important conclusions were drawn based on the results obtained in the simulations using the finite element method.

An Experimental and Virtual Approach to Hip Revision Prostheses

“…The following simplifying assumptions were used in the analyses of the three orthopaedic systems: Knowing that orthopaedic cement, used in these orthopaedic prostheses, provides stability and fixation of the components, it was not geometrically modelled, and its behaviour was replaced with the use of bonded elements that practically provide cohesion of the elements between themselves [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ]; It is known that, during the human gait, the variation of the force occurring in the hip joint varies between values of 0 N and about 2300 N. We have considered that it is sufficient to use an equivalent force that has a linear variation between the values of 800 N (characteristic of the orthostatic position) and 2300 N (maximum value of the force during normal human gait [ 26 , 27 , 28 , 29 , 30 , 31 , 39 , 42 ]); For revision prostheses using a morcellated bone graft, the study was considered to be performed after complete osseointegration of the graft, when it acquires the appearance and properties of the trabecular bone [ 26 , 27 , 28 , 39 ]. …”

“…Knowing that orthopaedic cement, used in these orthopaedic prostheses, provides stability and fixation of the components, it was not geometrically modelled, and its behaviour was replaced with the use of bonded elements that practically provide cohesion of the elements between themselves [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 ];…”

“…It is known that, during the human gait, the variation of the force occurring in the hip joint varies between values of 0 N and about 2300 N. We have considered that it is sufficient to use an equivalent force that has a linear variation between the values of 800 N (characteristic of the orthostatic position) and 2300 N (maximum value of the force during normal human gait [ 26 , 27 , 28 , 29 , 30 , 31 , 39 , 42 ]);…”

“…For revision prostheses using a morcellated bone graft, the study was considered to be performed after complete osseointegration of the graft, when it acquires the appearance and properties of the trabecular bone [ 26 , 27 , 28 , 39 ].…”