Calcium pyrophosphate dihydrate crystal formation in model hydrogels.

Using powder x-ray diffraction analysis, we studied calcium pyrophosphate crystal formation in silica and gelatin gels was well as in comparable aqueous solutions. We demonstrated that the physiological salts, monoclinic and triclinic calcium pyrophosphate dihydrate can be formed in gels and that gels do affect the type of crystals formed from ions in solution. These observations support our hypothesis that calcium pyrophosphate dihydrate crystal deposition in joints is regulated by the physical chemical gel state of the connective tissue matrix.