Calcification properties of saline-filled breast implants.

Three patients requested explantation of their saline-filled breast implants. Bilateral calcification had occurred in all six implants. Four of the implants were manufactured by McGhan Corporation (Santa Barbara, Calif.), and two, by the Simaplast Company (Toulon, France). All implants had been inserted in the subglandular plane and had been in place for 7 to 23 years. At the time of explantation, patients were 32, 34, and 44 years old. Calcification on the surface of the implants and capsules was analyzed. Implant surface calcification was clinically evident on all six implants, appearing as ivory-colored, tenaciously adherent deposits, only on the anterior surface of the implant. Capsular calcification, which was observed only microscopically, was characterized by poorly organized, irregularly shaped, calcified agglomerates; this calcification also occurred only on the anterior surface of the capsule, adjacent to the area of calcification on the implant. Ultrastructural analysis of scrapings from the implant surface showed large, electron-dense aggregates of crystals, with individual crystals measuring approximately 40 x 10 x 10 nm. In contrast, capsular calcification was characterized by two patterns of deposition, spherulitic aggregates of needle-shaped crystals and areas of metaplastic bone. The individual crystals were approximately 40 x 10 x 10 nm. Energy-dispersive x-ray spectroscopy of specimens from the areas of calcification on the implant and capsule surfaces demonstrated calcium and phosphorus. Electron diffraction of crystals from the implant and capsule surfaces demonstrated the D-spacings characteristic of calcium apatite. There were many differences between the calcification properties of these six saline implants and those of silicone gel implants. For example, mineralization has not been observed on the surface of gel implants, but in these saline implants it occurred primarily on the implant surface. Also, capsular calcification has been observed clinically in gel implants across the surface of the capsule (except at the site of attachment of a Dacron patch), but in this study it was observed only microscopically and was located on the anterior surface of the capsule, adjacent to the area of calcification on the implant. In addition, crystals 100 times larger than those observed on the six saline implant capsules have been observed on the surface of gel implant capsules. A model is presented to explain the mechanism of calcification associated with breast implants and to explain the observed differences between saline-filled and gel-filled implants.