Extensive localized bone resorption within the femur was observed after
four total hip replacements. The amount and location of the resorption
suggested the presence of infection or tumor, but there was no evidence of
either condition and the roentgenographic appearance differed from that
associated with a loose uncemented endoprosthesis or a grossly loose
femoral component of a total hip replacement. At reoperation the femoral
components were not rigidly fixed but were only slightly loose.
Histologically there were sheets of macrophages, a few giant cells, and
multiple small fragments of a birefringent material, but no inflammatory
cells. While the exact mechanism of this serious complication is unclear,
the findings suggest that a benign, non-inflammatory, adverse tissue
response can occur in relation to the femoral components of total hip
replacements that are not rigidly fixed. In all four hips, reimplantation
of a new total hip replacement was successful after follow-up of thirteen
to eighteen months.