[Can samples from the cups of Weller endoprosthesis be the basis for analysis of the degree of biomaterial crystallinity under the influence of external factors?]. / Czy próbki pobrane z panewek endoprotez Wellera moga byc podstawa analizy zmian stopnia krystalicznosci biomaterialu pod wplywem czynników zewnetrznych?

The paper is a thesis verification. The thesis stated that samples from cups of Weller endoprosthesis can be the basis of biomaterial crystallinity analysis under the influence of external factors. Cup segments were deformed and exposed to X-rays. Basing on thermoanalytic analysis the authors prove that the cups (completely transformed and sterilized) cannot be used as research material, to be tested by application of external factors, to assess polyurethane morphology. An alternative reliable method has been proposed: direct investigation of the material used for cup production. These conclusions were reached as result of research done with a differential scanning calorimeter (heat-flux type) DCS 30 in Mettler TA-4000 thermoanalytic system.

[Mechanical durability characteristics of polyethylene cup in total hip arthroplasty]. / Mechaniczne uwarunkowania trwalosci polietylenowej panewki w calkowitej endoprotezoplastyce stawu biodrowego.

The paper presents an analysis of the processes that determine the durability of the polyethylene cup of the Weller total hip prosthesis. Mechanisms of wear of the polyethylene cup have been presented. It has been inferred that the process of loosening of the polyethylene cup is a combination of plastic deformation, tribologic wear, fracture and changes of the polyethylene structure. All these occurrences are connected with reaction of bone tissue to stress and polyethylene debris.

[Experimental in vitro investigations of hardness changes in hip prosthesis polyethylene cups caused by x-rays and aging]. / Badania doswiadczalne in vitro zmian twardosci polietylenowych panewek endoprotez pod wplywem starzenia i oddzialywania promieni rentgenowskich.

The aim of this paper was to determine the influence of X-rays and ageing on the mechanical properties of polyethylene cups of Weller type hip prostheses. Polyethylene cups produced in the period between 1987 and 1992 were investigated. Some of the cups were exposed to a radiation dose exceeding greatly the average dose used in a routine X-ray examination. Polyethylene cups produced in different years and those subjected to "artificial ageing" (long-term exposure to high temperature) were examined. Brinell's method was used to assess the hardness of polyethylene. The results of this study indicate that both exposure to X-rays and ageing lead to hardening of the cups. This may in turn cause cup fractures--a potential source of complications following hip replacement procedures.

[Computer stimulation of stress distribution in finite element models of the normal femur and after Weller, Centrament, Parhofer-Mönch type prosthesis implantation]. / Komputerowa symulacja rozkladów naprezen w modelach kosci udowej prawidlowej oraz po implantacji trzpieni typu Weller, Centrament i Parhofer-Mönch.

The paper presents an example of application of computerized analysis in the evaluation of the biomechanical reactions of the bone tissue after total hip replacement. Finite element models of the normal femur and femurs after Weller, Centrament and Parchofer-Monch type hip prosthesis implantation were constructed. Basing on these models, a comparative analysis of the stress patterns in all femurs was performed according to Pauwels' method. This study showed that total hip replacement leads to a redistribution and diminution of stress in the bone tissue, because of material disconformity of the prosthesis. The authors believe that the evolving virtual analytic tools used in simulations will in the future play a major role in reconstructive surgery.

[Comparative evaluation of stress patterns in models of the normal hip joint and after implantation of the Parhofer-Mönch type hip prosthesis]. / Porównawcza ocena rozkladów naprezen w modelach panewki stawu biodrowego prawidlowego i po endoprotezoplastyce Parhofera-Möncha.

The paper presents a comparative appraisal of stress patterns of the normal acetabulum of the hip joint and after implantation of a Parhofer-Monch type prosthesis based on a computer simulation analysis. Three-dimensional physical models were constructed basing on finite element methods and loaded according to Pauwels' scheme with a force R = 2878 N. Mathematical analysis was performed on a computer equipped with a Pentium II processor, using professional software written for theory of elasticity problem solving. Equipotential stress patterns were designated according to Hubers' hypothesis. A redistribution and decrease in stress values in the bone directly around the acetabular component of the prosthesis was noted.

[An attempt to assess the effect of stress in the femoral bone after implantation of the Weller endoprosthesis on changes within bone tissue in correlation with densitometry examination]. / Próba oceny wplywu stanu wytezenia w kosci udowej po implantacji endoprotezy typu Weller na zmiany zachodzace w tkance kostnej w korelacji z badaniem densytometrycznym.

The paper presents comparative analysis of stress distribution, determined by finite elements method in normal femoral bone and one after Weller total hip replacement, with Gruen zones in consideration. An attempt to correlate an effort and bone tissue state has been made. The results of computer simulation have been compared with results of densitometry. It was found, that alloplasty unloads bone tissue along the stem and particularly around trochanteric area. Dual energy X-ray densitometry performed 7 days, 6 and 12 months after surgery revealed decreased BMC and BMD values in all analyzed zones. The greatest decrease was noted in zone 7.1 and 6.