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Tyrimo aktualumas. Klubo sąnario endoprotezavimo operacija – tai viena iš labiausiai kliniškai sėkmingų ir veiksmingų duodanti ilgalaikius rezultatus siekiant sumažinti skausmą, pagerinti funkciją ir gyvenimo kokybę pacientams sergantiems klubo sąnario ligomis (Ferrata et al., 2011). Tyrimo objektas: kineziterapijos efektyvumas šlaunies sąnarių amplitudei, šlaunies raumenų jėgai, skausmui ir funkciniam mobilumui, pacientams po klubo sąnario endoprotezavimo. Tyrimo tikslas - įvertinti kineziterapijos poveikį klubo sąnario judesių amplitudei, šlaunies raumenų jėgai, skausmui ir savarankiškumui po klubo sąnario endoprotezavimo. Tyrimo uždaviniai: 1) įvertinti endoprotezuotos kojos šlaunies judesių amplitudės kitimą taikant kineziterapiją; 2) įvertinti endoprotezuotos kojos šlaunies raumenų jėgos kitimą taikant kineziterapiją; 3) įvertinti endoprotezuotos kojos skausmo kitimą taikant kineziterapiją; 4) įvertinti funkcinio mobilumo kitimą taikant kineziterapiją. Hipotezė: kinezitrepijos taikymas bus efektyvesnis pacientams, kuriems endoprotezavimo operacija atlikta dėl šlaunikaulio kaklelio lūžio, nei pacientams, kuriems operacija atlikta dėl koksartrozės. Išvados: 1. Po kineziterapijos procedūrų, endoprotezuotos kojos šlaunies lenkimo amplitudė statistiškai reikšmingai daugiau padidėjo pacientams, kuriems operacija buvo atlikta dėl koksartrozės. 2. Po kineziterapijos procedūrų, endoprotezuotos kojos šlaunies lekiamųjų raumenų jėga statsitiškai reikšmingai daugiau... [toliau žr. visą tekstą] / Importance of the study: Hip joint replacement – one of the most common and clinically successful procedures, which provides longterm results, in order to reduce pain, increase life quality in patients with hip joint diseases (Ferrata et al., 2011). Object of study: physiotherapy effectiveness on hip range of motion, hip muscle strength, pain and functional mobility in patients after hip replacement. Goal of the study: to assess physiotherapy influence to hip joint range of motion, hip muscle strength, pain and functional mobility after hip joint replacement. Aims of the study: 1) To assess hip range of motion after hip replacement applying physiotherapy; 2) To assess hip muscle strength after hip replacement applying physiotherapy; 3) To assess hip pain changes after hip replacement applying physiotherapy; 4) To assess functional mobility changes after hip replacement applying physiotherapy Hypothesis: physiotherapy will be more affective on patients who have had hip replacement after hip column fracture than for patients who have had hip replacement because of coxarthrosis. Conclusions: 1. After physiotherapy on patients who have had hip replacement, hip range of motion statistically significant improved on patients who have had surgery after coxarthrosis. 2. After physiotherapy on patients who have had hip replacement, hip muscle strength statistically significant improved on patients who have had surgery after hip column fracture. 3. After physiotherapy on... [to full text]

Surfaces exposed to wear always transform and typically a layer of new structure and composition is formed. This layer, often called tribofilm, changes the friction and wear properties. Tribofilms formed on ceramic surfaces may consist of products from chemical reactions between the materials in contact and the environment or consist of compacted wear debris. In this thesis, focus has been to understand the friction and wear mechanisms of ceramic surfaces, as well as acquiring knowledge about the properties of the new surfaces created during wear. Ultimately, this understanding can be used to develop ceramic systems offering high or low friction, while the material loss in both cases should be minimised. Such ceramics could improve numerous tribological systems and applications, out of which ultrasonic motors, low-friction ceramic coatings and hip joint replacements have been treated in this thesis. Friction and wear tests, and subsequently various surface analyses have been essential for the knowledge about the friction, wear and tribofilm formation.  For ultrasonic motors of the studied type, the highest driving force is achieved when the friction is high between the alumina components in the friction drive system. The highest friction was here accomplished with a thick tribofilm on the surfaces. The formation of such tribofilms was favoured by dry conditions, and using an initially rough surface, which increased the initial generation of wear debris. In a detailed investigation of the importance of microtopography on tribofilm formation and friction behaviour, a low-friction, PVD coating of TaC/a-C was studied. This coating showed a very low, stable friction. High sensitivity to the microtopography was demonstrated, smooth coating exhibited a faster build-up of a dense tribofilm of fine ground material on the counter steel surface and subsequently a faster running in and friction decrease.  The life span for total hip joint replacements can be prolonged by minimising the wear particles that cause inflammation and subsequent implant loosening. In this work coatings of amorphous/nanocrystalline silicon nitride have shown low wear rate, and hence produce a minimum of wear particles. Furthermore, these particles that are expected to resorb in vivo. This system therefore has potential to reduce problems with inflammation and osteolysis connected to wear particles.

This diploma thesis deals with an experimental analysis of lubrication of total hip joint replacement using fluorescence microscopy, focusing on so-called soft bearing pairs. Experiments were realized using a hip joint simulator, which was modified and refined for fluorescence microscopy. The aim of this diploma thesis was to determine the effect of the individual components of the synovial fluid on the lubrication mechanisms. For this purpose, different model fluids were designed to represent the composition of proteins and other synovial fluid constituents to elucidate the effect of albumin, -globulin and hyaluronic acid on the resulting lubrication performance. The experiments were separate into two categories different in type of load, dynamic (representative walking) and combined (representing standing with short walk). The experimental results were time-dependent fluorescence intensity values, representing dimensionless film thickness parameters. The values were recorded on the graphs and supplemented with fluorescence images taken during the characteristic sections of the measurements. The measured data was subsequently confronted with previously published articles. It was found that the dominant constituent responsible form film thickness is albumin, while -globulin and hyaluronic acid forms thin stable layer enhancing adsorption ability of albumin which contributes to increase of film thickness eventually.

This project attempts to quantify the integrity of the fixation of total hip arthro- T plasties (THAs) by observing vibration signal features. The aim of this thesis is, therefore, to find the signal differences between firm and loose prosthesis. These difference will be expressed in different transformed domains with the expectation that a certain domain will provide superior results. Once the signal differences have been determined they will be examined for their ability to quantify the looseness. Initially, a new definition of progressive, femoral component loosening was created, based on the application of mechanical fit, involving four general conditions. In order of increasing looseness the conditions (with their equivalent engineering associations) are listed as, firm (adherence), firm (interference), micro-loose (transition) and macro-loose (clearance). These conditions were then used to aid in the development and evaluation of a simple mathematical model based on an ordinary differential equation. Several possible parameters well suited to quantification such as gap displacement, cement/interface stiffness and apparent mass were the identified from the model. In addition, the development of this model provided a solution to the problem of unifying early and late loosening mentioned in the literature by Li et al. in 1995 and 1996. This unification permitted early (micro loose) and late (macro loose) loosening to be quantified, if necessary, with the same parameter. The quantification problem was posed as a detection problem by utilising a varying amplitude input. A set of detection techniques were developed to detect the quantity of a critical value, in this case a force. The detection techniques include deviation measures of the instantaneous frequency of the impulse response of the system (accuracy of 100%), linearity of the systems response to Gaussian input (total accuracy of 97.9% over all realisations) and observed resonant frequency linearity with respect to displacement magnitude (accuracy of 100%). Note, that as these techniques were developed with the model in mind their simulated performance was, therefore, considerably high. This critical value found by the detector was then fed into the model and a quantified output was calculated. The quantification techniques using the critical value approach include, ramped amplitude input resonant analysis (experimental accuracy of 94%) and ramped amplitude input stochastic analysis (experimental accuracy of 90%). These techniques were based on analysing the response of the system in the time-frequency domain and with respect to its short-time statistical moments to a ramping amplitude input force, respectively. In addition, other mechanically sound forms of analysis, were then applied to the output of the nonlinear model with the aim of quantifying the looseness or the integrity of fixation of the THA. The cement/interface stiffness and apparent mass techniques, inspired by the work of Chung et.al. in 1979, attempt to assess the integrity of fixation of the THA by tracking the mechanical behaviour of the components of the THA, using the frequency and magnitude of the raw transducer data. This technique has been developed fron the theory of Chung etal but with a differing perspective and provides accuracies of 82% in experimentation and 71% in simulation for the apparent mass and interface stiffness techniques, respectively. Theses techniques do not quantify all forms of clinical loosening, as clinical loosening can exist in many different forms, but they do quantify mechanical loosening or the mechanical functionality of the femoral component through related parameters that observe reduction in mechanical mass, stiffness and the amount of rattle generated by a select ghap betweent he bone/cement or prosthesis/cement interface. This form of mechanical loosening in currently extremely difficult to detect using radiographs. It is envisaged that a vibration test be used in conjunction with radiographs to provide a more complete picture of the integrity of fixation of the THA.