A comparative study on medium-term results of cementless acetabular components with metal-on-metal and metal-on-polyethylene articulations

Abstract

The purpose of this study was to evaluate the medium-term clinical and radiological outcomes of two metal-backed acetabular cups with metal-on-metal and metal-on-polyethylene joint couples, in patients unselected for age. Seventy-five metal-on-polyethylene CLS expansion cups were implanted in 70 patients and 66 metal-on-metal Fitek cups were implanted in 65 patients. The average age at surgery in the two groups was 63 years (range, 25 to 72 years) and 58 years (range, 32 to 68 years), respectively. Data regarding 64 of 75 CLS cups (85%) and 58 of 66 Fitek cups (88%) were collected at a minimum 36-month and maximum 144-month follow-up. The Harris hip score showed excellent results in 86% of the CLS cups, good results in 7%, and fair results in 7%. No poor results were recorded. For metal-on-metal acetabular components, excellent results were recorded in 84% of the cups, good results in 8%, fair results in 5%, and poor results in 3%. Fifty-five patients with 57 of 64 CLS cups (89%) and 50 patients with 51 of 58 Fitek cups (88%) were fully satisfied with their prosthesis. No acetabular reconstructions were revised for aseptic loosening. No radiolucent lines greater than 2 mm were observed, either about CLS or Fitek cups, and low incidence of osteolysis and polyethylene wear was noted in metal-on-polyethylene articulations. Post-operative three-phase bone scanning was obtained in 51 patients and this examination did not show increased uptake in blood pool or bone phase indicating aseptic loosening of CLS and Fitek cups. In conclusion, we found similar rates of excellent and good results using two acetabular components with different bearing surfaces, in patients of unselected age. Therefore, the less expensive implant should be selected for total hip arthroplasty in elderly or low-demand patients.