Results Best evidence analysis showed no difference in polyethylene wear rate , the frequency of cup migration , and aseptic loosening between monoblock and modular acetabular components .
No convincing evidence was found for the cl aim that lower frequencies of acetabular osteolysis are observed with the use of monoblock cups compared with modular uncemented cups .
Conclusions The purported benefits of monoblock cups were not substantiated by this systematic review of controlled studies in that polyethylene wear rates and frequencies of cup failure and acetabular osteolysis were similar to those observed with modular implants .
Background Monoblock acetabular components used in uncemented total hip arthroplasty ( THA ) have certain mechanical characteristics that potentially reduce acetabular osteolysis and polyethylene wear .
However , the degree to which they achieve this goal is not well documented .
Questions / purpose sThe purpose of this study was to use a systematic review of controlled trials to test the hypothesis that monoblock cups have superior ( 1 ) polyethylene wear rate ; ( 2 ) frequency of cup migration ; ( 3 ) frequency of acetabular osteolysis ; and ( 4 ) frequency of aseptic loosening compared with modular components used in uncemented THA .
Early migration predicts late aseptic failure of hip sockets.
We report a prospect i ve , stratified study of 60 PCA-cups and 60 RM-polyethylene cups which have been followed for a median time of 90 months , with annual radiography .  The radiological migration of cups was measured by the computer-assisted EBRA method . A number of threshold migration rates from 1 mm in the first year to 1 mm in five years have been assessed and related to clinical ly determined revision rates . A total of 28 cups showed a total migration of 1 mm or more within the first two years ; 13 of these cups have required revision and been exchanged . The survival curves of cups which had previously shown early migration were considerably different from those without early migration . For cups with a migration of less than 1 mm within the first two years the mean survival at 96 months was 0.96 + /- 0.02 ; for migrating cups , it was 0.63 + /- 0.11 ( log-rank test , p=0.0001 ; chi-square value=39.4 ) . Early migration is a good predictor for late loosening of hip sockets
Results Best evidence analysis showed no difference in polyethylene wear rate , the frequency of cup migration , and aseptic loosening between monoblock and modular acetabular components .
No convincing evidence was found for the cl aim that lower frequencies of acetabular osteolysis are observed with the use of monoblock cups compared with modular uncemented cups .
Conclusions The purported benefits of monoblock cups were not substantiated by this systematic review of controlled studies in that polyethylene wear rates and frequencies of cup failure and acetabular osteolysis were similar to those observed with modular implants .
Background Monoblock acetabular components used in uncemented total hip arthroplasty ( THA ) have certain mechanical characteristics that potentially reduce acetabular osteolysis and polyethylene wear .
However , the degree to which they achieve this goal is not well documented .
Questions / purpose sThe purpose of this study was to use a systematic review of controlled trials to test the hypothesis that monoblock cups have superior ( 1 ) polyethylene wear rate ; ( 2 ) frequency of cup migration ; ( 3 ) frequency of acetabular osteolysis ; and ( 4 ) frequency of aseptic loosening compared with modular components used in uncemented THA .