THE INFLAMMATORY RESPONSE TO PARTICULATE WEAR DEBRIS IN TOTAL HIP-ARTHROPLASTY

OBJECTIVE: To identify the cell types and patterns of cell distributio n associated with particulate wear debris in the membranes of patients who undergo revision of hip arthroplasty. DESIGN: Case series. SETTIN G: Three university-affiliated hospitals. PATIENTS: Twenty-nine patien ts who underwent revision of a hip arthroplasty for reasons other than infection. Eight patients were excluded because loosening of the pros thesis was found to be associated with infection, leaving 21 patients, 18 with aseptic loosening and 3 with recurrent dislocation. INTERVENT ION: Retrieval of inflammatory membranes from loosened total hip prost heses. MAIN OUTCOME MEASURES: Results of aerobic and anaerobic tissue cultures, number of macrophages, T cells and B cells, and presence and histologic pattern of particulate debris in the membranes. RESULTS: N one of the tissue cultures grew any organisms. All membranes contained T cells and macrophages, but B cells were present in only three patie nts at a low level. Particulate debris, surrounded by macrophages and foreign-body giant cells, was present in all membranes. Three histolog ic patterns were noted: type I mostly fibrous tissue with cells and ma crophages widely scattered through membrane (3 membranes); type LT - f ibrous membrane with a significant number of T cells, macrophages and foreign-body giant cells and well-defined foreign-body granulomas (7 m embranes); type III - diffusely scattered T cells, ill-defined granulo mas, ''foamy'' macrophages anti fewer foreign-body giant cells than in type LI (11 membranes). CONCLUSIONS: These findings document the key cellular elements involved in cell-mediated immunity in association wi th particulate wear debris in aseptically loosened total hip arthropla sty membranes. T-cell amplification of the innate macrophage inflammat ory reaction to particulate debris may play a role in the mechanism of particle clearance.