Figure 3

Electron microscope analysis of cartilage mineralization. FE-SEM analysis in combination with EDX was performed on a subset of 20 consecutive specimens out of the total 80. All areas of mineralization identified by DCR were proven to be calcium phosphate aggregates using this technique. The FE-SEM studies detected one nearly amorphous (A, C) and one idiomorphic mineral (B, D) phase with different chemical compositions. The two mineral phases contained calcium-phosphate ratios similar to BCP (A, C) and CPPD crystals (B, D). BCP crystals were found in all patients, CPPD crystals additionally in two patients. Panel A show a cartilage specimen with apatite calcification at 15× magnification; panel C the same specimen at 500× magnification. Panel B (15×) shows a patient with CPPD crystals. In panel D (500× magnification), the typical rhomboid CPPD crystals (arrow) are visible.