Some clinical observations in problems of soft tissue calcification

Calcification of the organic matrix of bone, enamel, dentine, and epiphyseal cartilage occurs normally in the human body. Abnormal or heterotopic sites of calcium deposition are not infrequently encountered. These deposits may be in the form of bone, or they may be a collection of calcium phosphate (apatite) crystals in an amorphous organic matrix (Robinson). Even though the exact mechanisms by which these abnormal calcific deposits are formed are not well understood, their relationship to certain disease processes has long been recognized. The obvious defects in our knowledge of the production mechanisms for heterotopic calcification and bone formation have made it impossible to rationally apply prophylactic methods in these problems and have limited the development of therapeutic measures. Included in this lack of knowledge is the mechanism by which calcium is transformed from the soluble phase in the circulating blood to the solid or crystalline phase found in calcifications in