Degenerative changes of the interface membrane as a possible reason for prosthesis loosening.

OBJECTIVE The aim of the present study was to perform a comparative evaluation of septic and aseptic interface membranes, assessing histological features, inflammatory infiltrate, and expression of inflammatory cytokines. METHODS Septic and aseptic interface membranes from 102 patients were examined by histology, histochemistry, and immunohistochemistry (tissue arrays). The cell subpopulations were characterized by quantification of CD3, CD4, CD8, CD20, and CD163 positive cells. Additionally, a semiquantitative evaluation of inflammatory cytokines (TNFalpha, TGF-beta1, IL-1, IL-6, CRP, MMP-1, MMP-6) was performed to complete the analysis of inflammatory infiltrates. RESULTS The histological analysis revealed three different types of aseptic interface membranes: wear particle, degenerative, and mixed type. The expression of inflammatory molecules did not differ between septic and wear particle interface membranes. Significantly lower expression of cytokines, MMPs and CRP was observed, however, in degenerative interface membranes compared to other types. No expression of TNFalpha was observed in the degenerative interface membranes. Over 88% of patients with degenerative interface membranes had had a clinical record of osteoarthritis. CONCLUSION Aseptic interface membranes were represented by wear particle, degenerative and mixed type. The expression of inflammatory factors in wear particle type is similar to this in septic membranes and can contribute to the bone destruction and prosthesis loosening. These factors seem not to play a major role in the degenerative membranes.