No difference in early cellular response of the pseudo-synovial membrane after total hip arthroplasty: Comparison of 3 combinations of bearing materials

Background Wear-resistant bearing materials may hypothetically reduce chronic inflammation in the pseudosynovial membrane as compared to less wear-resistant bearing materials such as polyethylene. We assessed the foreign body response in the pseudosynovial membrane in vivo after total hip replacement.Methods 37 patients from a larger prospective randomized trial of 225 patients had biopsies taken arthroscopically from the artificial hip joint (i.e. the pseudosynovial membrane) 1 year after insertion of the implant. All patients had an identical hip prosthesis (Bimetric-RingLoc) except for the bearing materials, which consisted of polyethylene on zirconia, CoCr on CoCr, or alumina on alumina.Histological quantification was performed on 2-μm-thick semi-thin plastic sections or paraffin sections by point counting technique to compare the volume fraction of macrophages, granulomas and endothelial cells in biopsies of the pseudosynovial membrane.Results The median macrophage volume fractions for polyethylene-o...