1977 Volume 68 Issue 3 Pages 249-257
As one of the fundamental researches for the development of microexplosion lithotripsy, chemical component, density, hardness, compressive strength, tensile strength and the modulus of elasticity were measured on 66 dry urinary calculi. The results are as follows:
1) Chemical component was not so different from that of former reports.
2) Density was from 0.97g/ml to 1.75g/ml.
3) Hardness was from 12.5 HRF to 102.5 HRF.
4) Compressive strength was from 19.0kg/cm2 to 176.0kg/cm2.
5) Tensile strength was from 0.8kg/cm2 to 34.3kg/cm2.
6) A direct proportion was observed between the compressive and the tensile strength of calculi.
7) The modulus of elastisity was 5.4×108 dyne/cm2 to 88.0×108 dyne/cm2.
8) Almost no correlation was observed between the strength of calculi and their chemical component. Laminated calculi, however, were weaker than non-laminated one in most cases.
9) Urinary calculi could be classified into two groups according to their strength at the border of 65kg/cm2 in compressive strength and of 15kg/cm2 in tensile strength by dry sample. Approximately 80-90% of all calculi might belong to the “low strength calculus” group of which strength was under the borderline and the remaining 10-20% might belong to the “high strength calculus” group of which strength was over the borderline.
10) From these results obtained by dry samples, it became evident that two kinds of calculus model should be prepared for the experiment of lithotripsy: the “low strength calculus model” of which strength was approximately 65kg/cm2 in compressive and 15kg/cm2 in tensile and the “high strength calculus model” of which strength was approximately 180kg/cm2 in compressive and 35kg/cm2 in tensile.
