Mechanism of stone formation.

This article reviews the physical principles involved in urolithiasis. For urinary stones to form, crystals must form first and they then should be retained in the urinary tract. These phenomena require the interaction between the forces of saturation, crystal inhibition, crystal nucleation, growth aggregation, and retention, which all occur in a complex solution. In the latter part of the article the authors review the relevance of these physical principles in the lithogenesis of the most common urinary stones.