Aim: To determine the incidence of periacetabular osteolysis in an uncemented, press-fit, one-piece, titanium plasma spray backed acetabular cup used in conjunction with a cemented or uncemented femoral component followed for 10 years.

Method: Patients undergoing primary total hip arthroplasty in 1989 were reviewed and new radiographs obtained. These were compared with the initial post-operative radiographs and the presence of osteolysis in the three zones of Delee and Charnley were recorded.

Results: Of 57 patients, 14 were deceased at the time of follow-up and nine were lost to follow-up. Ten patients had undergone revision for problems related to the femoral stem. There was only one possible case of periacetabular osteolysis seen in this series. In this case the lytic lesion was seen on the early post-operative radiograph and did not change in 10 years, and thus may not have been osteolysis.

Conclusions: The reported incidence of periacetabular osteolysis with two-piece cups varies between 30 and 50%. Thus, this cup has an extremely low possible osteolysis incidence. This study raises the wisdom of the continued use of two piece cups of any design.