[Histological and ultrastructural characteristics of interface membrane around aseptically loosened prostheses].

OBJECTIVE

To investigate the effect of wear particles on prosthetic loosening by analyzing the histological and ultrastructural characteristics of interface membrane around aseptically loosened prostheses.

METHODS

Slices of interface membranes around aseptically loosened hip prostheses of 51 cases were stained with HE, Safranin O-Briliant green and CD68 Mab immunohistochemical technique respectively. The histological structure of the membranes and the kinds of wear particles and their distribution characters were observed. The size of particles and the number of CD68 positive cells were measured. Ultrastructure of cells in the membrane and the characters and size of the particles phagocytozed by M phi were also observed and measured.

RESULTS

Interface membrane consisted of fibromatrix, fibroblasts, M phi[CD68 positive, occupying (23 +/- 5)% (x +/- s)], and foreign body giant cells. In the membranes at the site of osteolysis, great amount of UHMWPE particles, PMMA particles and Ti alloy or CoCr alloy particles collected at the side attaching to the implant and caused chronic foreign body inflammatory reaction. Most of the particles outside M phi were less than 15 microns while that inside M phi were less than 1 micron. Different kinds of wear particles could exist in the lysosomes of one M phi. No particles but cartilage-like tisses appeared in the membranes at the site without osteolysis.

CONCLUSION

Wear particles in the interface membrane have relations with osteolysis and fibrous tissue proliferation at bone-implant interface, which plays an important role in aseptic loosening.