Peri-articular reactions to microscopic erosion of silicone-polymer implants. Light- and scanning...

Two patients are described who underwent implantation of silicone-polymer prostheses: one for an arthroplasty of the left great toe after a bunionectomy, and another for replacement of fractured trapezoid bone of the left wrist. Each patient developed unexplained severe pain at the sites of surgery at 3 and 7 months postoperatively. On removal of the implants and adjacent tissues, there was a microscopic foreign-body reaction to amorphous material in the subsynovial connective tissue. Although both prostheses were grossly intact, scanning electron microscopy revealed multiple erosions on their surfaces. Energy-dispersive x-ray analysis of foreign material in the paraffin-embedded sections revealed a peak for silicon. These two cases indicate that clinically significant pathological reaction may occur as early as 3 months after silicone-polymer implantation and that energy-dispersive x-ray analysis of excised tissue is a useful and specific diagnostic procedure.