98 patients undergoing total hip arthroplasty due to osteoarthritis or rheumatoid arthritis were randomized to receive either solid-backed or cluster-hole acetabular cups. The purpose of this study was to determine and compare the effects of either component on incidence of osteolysis, cup migration, reoperation rate and functional outcome. Radiographs, computer tomography (CT) scans, Oxford Hip Scores and SF-12 assessments were assessed over 5-year follow-up. The results of this study observed no significant difference in any of the specified outcomes when comparing the two types of acetabular components.