Comparison of the results of cemented, porous-ingrowth, and threaded acetabular cup fixation. A meta-analysis of the orthopaedic literature.

A meta-analysis of the orthopaedic literature was performed to evaluate the clinical performance of cementless, threaded acetabular cups. The hypothesis for the study was that the clinical performance of the cementless, threaded acetabular cup is equivalent to that of the cemented and porous-ingrowth acetabular cups. Ninety-five articles were included in the study. There were 1,269 cases in the threaded cup group, 1,979 in the porous control group, and 10,230 in the cemented control group. The primary outcome variable tested was the rate of aseptic loosening of the acetabular components as measured by the revision rates following the index total hip arthroplasty procedure. Other measures of acetabular component loosening that were analyzed included clinical rating scores, pain scores, frequency of radiolucencies according to location and size, frequency of radiolucencies as a separately defined outcome variable, progressive radiolucencies, and component migration. The threaded cup group was found to have a significantly higher rate of revision, clinical and pain score failures, progressive radiolucencies and migrations when compared with the cemented and porous control groups (P < .05). Despite the many limitations of meta-analyses and the poor state of the orthopaedic literature database, this study provides a reasonable comparison of the clinical performance of threaded acetabular cups with that of cemented and porous-ingrowth acetabular cups.