Problems of bone - orthopaedic implant interactions

The paper presents main aspects of modern orthopaedic implants design and operation. Influence of implant shape and especially stiffness characteristics and stress distribution on the surface of implant, which is in direct contact with bone, are presented. As the second factor influence of implant shape on the bone remodelling processes in the macro and micro scale was analyzed. Main distribution of general bone density as well as distribution of cancellous bone trabecules in the presence of implant is analyzed. Finally, new type of surface layer (including technology of layer manufacturing) was developed. DOI: 10.17489/biohun/2008/1/4

Determination of Stent Load Conditions in New Zealand White Rabbit Urethra

Background: Frequency of urethral stenosis makes it necessary to develop new innovative methods of treating this disease. This pathology most often occurs in men and manifests itself in painful urination, reduced urine flow, or total urinary retention. This is a condition that requires immediate medical intervention. Methods: Experimental tests were carried out on a rabbit in order to determine the changes of pressure in the urethra system and to estimate the velocity of urine flow. For this purpose, a measuring system was proposed to measure the pressure of a fluid-filled urethra. A fluoroscope was used to observe the deformability of the bladder and urethra canal. Results: Based on these tests, the range of changes in the urethra tube diameter, the pressures inside the system, and the flow velocity during micturition were determined. Conclusions: The presented studies allowed determining the behavior of the urethra under the conditions of urinary filling. The fluid-filled bladder and urethra increased their dimensions significantly. Such large changes require that the stents used for the treatment of urethral stenosis should not have a fixed diameter but should adapt to changing urethral dimensions