Analysis of calcium deposits in calcific periarthritis.

OBJECTIVE

To determine if hydroxyapatite (HAP), octacalcuim phosphate (OCP), or tricalcium phosphate (TCP) can be found in the calcium deposits in calcific periarthritis.

METHODS

Thirty-six specimens from 34 patients who had acute inflammation and roentgenographically recognized calcification in soft tissue were analyzed. Twenty-three patients with calcific tendinitis in the shoulder and 11 with calcific periarthritis at other sites were included. We prepared 2 kinds of samples from each specimen; a dried sample (washed and dried calcific deposit), and a sample heated to 1,000 degrees C. All were analyzed by X-ray diffraction, Raman spectroscopy, infrared absorption spectroscopy, and X-ray fluorescence spectrometry for calcium and phosphorus molar ratio. Synthetic HAP was used as the control in each analysis.

RESULTS

The X-ray diffraction patterns of all dried samples were similar to those of HAP and carbonate apatite. We found no diffraction patterns of OCP or TCP. However, an OH- group at 3570cm(-1) was observed with Raman spectroscopy for samples heated to 1,000 degrees C and synthetic HAP, but not for the dried samples. Infrared absorption spectroscopy also confirmed an OH- group for samples heated to 1,000 degrees C and synthetic HAP, and confirmed that dried samples contained carbonate.

CONCLUSION

Calcium deposits are composed of carbonate apatite. HAP, OCP, and TCP were not identified in any deposits.