Microhardness measurements of renal calculi: regional differences and effects of microstructure.

Journal Article (Journal Article)

Microhardnesses of five types of renal calculi: calcium apatite (82.5%)/magnesium ammonium phosphate hydrogen (10%)/calcium oxalate monohydrate (7.5%); calcium apatite (95%)/calcium oxalate monohydrate (5%); magnesium ammonium phosphate hydrogen (90%)/calcium apatite (10%); calcium oxalate monohydrate (85%)/calcium apatite (15%); and cystine (100%) were measured. Using Knoop and Vickers indenters the effects of chemical composition and microstructure on the microhardness measurement were assessed. Calcium oxalate monohydrate, magnesium ammonium phosphate hydrogen, and cystine stones, without apparent structure pattern, showed neither regional nor directional differences in their microhardness. In contrast, calcium apatite stones, with distinctly concentric laminae structure, showed regional variations which were correlated with the chemical composition of stone constituents. Scanning electron microscopy of the indenter impressions were taken to help in interpreting the directional dependence in Knoop hardness measurements with respect to the microstructure of the calculi. Vickers measurements showed the crystalline stones were isotropic within a layer. Combined results of Knoop and Vickers measurements indicate that the anisotropic Knoop hardness readings seen in the laminated regions were structural but not material-based. Implications of the results for the fragmentation of renal calculi in extracorporeal shock wave lithotripsy are discussed.

Full Text

Duke Authors

Cited Authors

  • Zhong, P; Chuong, CJ; Goolsby, RD; Preminger, GM

Published Date

  • September 1992

Published In

Volume / Issue

  • 26 / 9

Start / End Page

  • 1117 - 1130

PubMed ID

  • 1429761

International Standard Serial Number (ISSN)

  • 0021-9304

Digital Object Identifier (DOI)

  • 10.1002/jbm.820260902


  • eng

Conference Location

  • United States