The inflammatory response to particulate wear debris in total hip arthroplasty.

OBJECTIVE

To identify the cell types and patterns of cell distribution associated with particulate wear debris in the membranes of patients who undergo revision of hip arthroplasty.

DESIGN

Case series.

SETTING

Three university-affiliated hospitals.

PATIENTS

Twenty-nine patients who underwent revision of a hip arthroplasty for reasons other than infection. Eight patients were excluded because loosening of the prosthesis was found to be associated with infection, leaving 21 patients, 18 with aseptic loosening and 3 with recurrent dislocation.

INTERVENTION

Retrieval of inflammatory membranes from loosened total hip prostheses.

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

None of the tissue cultures grew any organisms. All membranes contained T cells and macrophages, but B cells were present in only three patients at a low level. Particulate debris, surrounded by macrophages and foreign-body giant cells, was present in all membranes. Three histologic patterns were noted: type I--mostly fibrous tissue with cells and macrophages widely scattered through membrane (3 membranes); type II--fibrous membrane with a significant number of T cells, macrophages and foreign-body giant cells and well-defined foreign-body granulomas (7 membranes); type III--diffusely scattered T cells, ill-defined granulomas, "foamy" macrophages and fewer foreign-body giant cells than in type II (11 membranes).

CONCLUSIONS

These findings document the key cellular elements involved in cell-mediated immunity in association with particulate wear debris in aseptically loosened total hip arthroplasty membranes. T-cell amplification of the innate macrophage inflammatory reaction to particulate debris may play a role in the mechanism of particle clearance.