DEVELOPMENT OF A MODEL FOR ASSESSMENT OF BIOMATERIAL ENCRUSTATION IN THE UPPER URINARY-TRACT

A need exists for ureteral stent materials capable of preventing or re ducing encrustation. The aim of this study, therefore, was to develop an in vitro model producing biomaterial encrustation similar to that o n stents in vivo. Three models were designed and evaluated. Polyuretha ne stent sections were immersed in human urine (37 degrees C, 5% CO2): (1) with and (2) without crushed human kidney stone and (3) in an art ificial urine (37 degrees C, 5% CO2). Encrustation of similar composit ion, as determined by infrared spectroscopy, X-ray diffraction and ene rgy dispersive X-ray analysis, formed on stent materials in vivo, in a rtificial urine and in human urine with crushed kidney stone. Magnesiu m ammonium phosphate (struvite) and calcium phosphate (hydroxyapatite) predominated in all encrustations. The reproducibility and ease of us e of the artificial urine model provided optimum encrustation assessme nt of materials presently used in ureteral stents and evaluation of no vel biomaterials.