Midterm Outcome of the Plasma Cup in Total Hip Arthroplasty

One hundred and twenty eight primary total hip arthroplasties (THA) in 104 patients were reviewed to assess mid-term survivorship and clinical outcome of the ‘Plasma’ cup. Outcome was evaluated clinically, radiographically, and by self-administered questionnaires. Patient mean age at surgery was 51 years, and 52 THAs (41%) were performed for secondary arthritis. Prior to surgery the median Merle D’Aubigne score was 8. At 59 (standard deviation 18) months this score had improved to 17, and the median Harris hip score was 85. The mean annual polyethylene wear rate was 0.14mm/year. There were no instances of aseptic loosening but 2 cups had small, focal osteolytic lesions at the site of screw holes. Three cups were revised, two for recurrent dislocations, and one for infection. Cup survivorship at 5 years was 97% (Kaplan-Meier).This data suggests that the Plasma cup performs well in the mid-term and may be used safely in a young population with a high incidence of secondary osteoarthritis.