Resurfacing hip arthroplasty. Classification of loosening and the role of prosthesis wear particles.

Abstract

Operative grading of loosening and histologic examination of the periprosthetic tissues and the femoral and acetabular bone-cement interfaces were undertaken in 72 revised resurfacing hip arthroplasties. By correlating the degree of macroscopic and microscopic loosening at the bone-cement interface, a classification of the stages of loosening at the bone-cement interface was devised. Examination of the femoral bone-cement interface of solidly fixed prosthesis components has demonstrated the presence of polyethylene wear particles and a macrophage response at the interface prior to loosening. This suggests that wear particles may migrate along bone-cement interfaces that are both macroscopically and microscopically solid, and emphasizes the important role of wear particles in prosthesis loosening.