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 ca lcific periarthritis. Methods. Thirty-six specimens from 34 patients who had acute inflammation a cid roentgenographically recognized calcification in soft tissue were analy zed. Twenty-three patients with calcific tendinitis in the shoulder and 11 with calcific periarthritis at other sites were included. We prepared 2 kin ds of samples from each specimen: a dried sample (washed and dried calcific deposit), and a sample heated to 1000 degreesC. All were analyzed by X-ray diffraction, Raman spectroscopy, infrared absorption spectroscopy, and X-r ay fluorescence spectrometry for calcium and phosphorus molar ratio. Synthe tic HAP was used as the control in each analysis. Results. The X-ray diffraction patterns of all dried samples were similar t o those of HAP and carbonate apatite. We found no diffraction patterns of O CP or TCP. However. an OH- group at 3570cm(-1) was observed with Raman spec troscopy for samples heated to 1000 degreesC and synthetic HAP, but not for the dried samples. Infrared absorption spectroscopy also confirmed an OH- group for samples heated to 1000 degreesC and synthetic HAP, and confirmed that dried samples contained carbonate. Conclusion, Calcium deposits are composed of carbonate apatite. HAP, OCP, a nd TCP were not identified in any deposits.