Bone reaction to uncemented threaded polyethylene acetabular components.

One hundred and eighty-one cementless total hip arthroplasties with threaded polyethylene acetabular components, carried out between 1980 and 1981, have been reviewed retrospectively. Discrepancy between the complaints of the patients with loose components and destruction of acetabular bone led to the development of a four stage radiological grading system which would enable loosening to be anticipated in routine cases. There was a high percentage of loosening (33%) in our series and direct bone-polyethylene contact gave rise to severe granulomatous reactions around the implants. Strict radiological follow up and early revision surgery is indicated in this type of arthroplasty.