Abstract
We have experienced a case with metallosis after total hip replacement, caused by metal debris between a stem and a trochanter plate.
The left hip of a forty-seven year-old patient with aseptic necrosis of both femoral heads was replaced with a Muller-type prosthesis with a trochanter plate in 1979. After four years, left coxalgia started and the pain became severe. Consequently a revision arthroplasty was carried out with a Charnly-type prosthesis in 1985. During the operation the surface of the tissues around the prosthesis was found to be entirely black in color and histological findings showed marked deposits of metals (Co, Cr, and Ni) and foreign body reactions. The metal surface of the trochanter plate was worn out.
The trochanter plate setting on the cortex of the trochanteric region was designed to prevent sinking of the stem, but it has not been so effective in preventing this. Stem design has been recently improved to fit with maximum intramedullary contact and such a trochanter plate no longer seems to be worthwhile.
Metal debris produced by friction between the two metals can possibly result in looseness or a malignant tumor, and metal contact prosthesis should be avoided.
