kojos protezo gamybos paklaidų ir tampriųjų deformacijų įtakos eisenos tolygumui tyrimas

Abstract

GENERAL CHARACTERISTIC OF THE DISSERTATION Topicality of the problem Prosthesis in orthopaedic technique are constructions that act as leg function reproduction and for external normal view of the leg. It is a technique giving a possibility to adapt to the society and live a full-fledged life, when one or another limb is lost. By the data, declared by the world health society, people with a disability include 10 % of all world population, among them people over 80 years old. More and more orthopaedic techniques are produced in Lithuania at present. The production, manufactured in our country keeps in step with world design and quality in foreign countries and they are 5–6 times cheaper. The main aim of the designers and constructors of orthopaedic techniques is to design and produce functional and high quality lower limbs prosthesis and apparatus. In the meantime, the same as abroad, in Lithuania the production processes of the prosthesis are automated but not so much to ensure a good quality of the prosthesis. Sometimes it is very hard to make prosthesis of adequate size to a patient that prosthesis implicitly fits just to the patient. Also, it is very hard to adjust it, ensuring the same length as the residual limb which should precisely correspond to the lost limb of the changeable loads chains of the prosthesis periodically are deformed during walking. In other words, the length of the prosthesis changes during gait. Thus, it is very important to set the limits of the changing prosthesis length. Errors, which appear during the production of the prosthesis, and elastic deformations of the prosthesis links have a direct influence on the disabled human gait smoothness and the position of the mass centre. When the prosthesis is inaccurate, a human feels bad, pain appears in different parts of the body, especially in the back in the trunk area and pelvis. Scoliosis could possibly develop, as the position of the mass centre changes and different deformations appear as the forces of the mass centre and reaction start to act. Aims and tasks of the research The aim of the research is the leg prosthesis of a human, whose gait smoothness is influenced by the leg prosthesis manufacturing errors and elastic deformations of the materials. The main tasks are as follows: • to set the requirements, that would ensure the human gait smoothness, which would reduce fatigue and increase working capacity of the disabled, without increasing the production costs. • To evaluate anthropometrical parameters of the disabled person and to determine permissible variations of the manufacturing and assembly errors and elastic deformations of the leg prosthesis links. • To analyse the influence of the manufacturing errors and elastic deformations on the disabled human gait smoothness and to set possibilities of their inter-compensation. • To develop engineering methodology to calculate leg prosthesis manufacturing and assembly errors. Scientific novelty The theory of the disabled human’s gait has been developed, by adding: • Linear and non-linear statically unsolvable mathematical models, used to determine the main rational parameters of the leg prosthesis, influencing the disabled human gait unsmooth ness, and approximate methods to solve them. • Possibilities of inter-compensation of manufacturing errors and elastic deformations of the leg prosthesis links, analytical dependences of their quantitative evaluation and a balance of the leg prosthesis elastic deformations. • Analytical interdependence of the human’s anthropometrical parameters, permissible variations of the leg prosthesis manufacturing errors and elastic deformations and gait smoothness. Methodology of research – analytical, numerical, computing and experimental methods are used in this dissertation. The system of modern camera with three dimensional view and SIMIVidback software were used for the experiments. ANSYS software was applied to numerical analysis. 10 people of age from 20 to 40 and 6 people with a prosthetic leg of age from 20 to 30 were invited for the experimental research. The right leg and prosthesis were elongated by sticking the pads to a tread. Practical value The permissible values of total errors of the leg prosthesis, correlating them with leg links, stump and receiver contact deformation, have been determined by evaluating anthropometrical data of the human. Possibilities of inter-compensation of total errors and elastic deformations have been analysed. Inter-dependence of total errors, elastic deformations and leg tarsus distortion angle has been defined. Methodology to calculate the parameters regulating the quality of the disabled human gait has been developed and ensuring the smoothness of the human gait, fatigue reduction and working capacity increase, without increasing labour expenditures and the prime cost of the product permissible values of the parameters that set up the quality of the disabled human gait have been set. Defended prepositions • The research results on the possibilities to reduce leg prosthesis manufacturing errors, elastic deformations and the interdependence of the human’s anthropometrical parameters and their hazardous influence on the disabled human gait. • The dependence of the disabled human gait quality on manufacturing errors and prosthesis links elastic deformations, and analytical dependence of anthropometrical parameters and the ways to solve them. • Methodology to determine the leg prosthesis manufacturing errors and rational values of elastic deformations, their possibilities of inter-compensation and practical application. The scope of the scientific work The scientific work consists of the general characteristic of the dissertation, 5 chapters, conclusions, list of literature, and addenda. The total scope of the dissertation is 95 pages, 66 pictures, 6 tables.