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 .
A prospective study of the migration of two acetabular components
Summary Fifty-nine PCA cups and 61 hydroxyapatite-coated RM cups were included in a prospect i ve r and omised study with a mean follow up of 5.2 years . Clinical evaluation revealed better results with the RM cup . Radiological criteria of loosening could be applied only with considerable restrictions as different parameters were assessed : progressively loosened beads in PCA cups and faded contour in RM cups . Migration was measured by a computer assisted method ( EBRA ) . PCA cups showed significantly more longitudinal migration 2 years after operation and subsequently . High migration values correlated with a limp . Loosening as defined by migration was of clinical relevance , could be measured early and predicted the survival rate . RésuméCinquante-neuf  cotyles PCA et 61 cotyles RM , recouverts d'hydroxyapatite  , ont été rassemblés dans une étude prospect i ve r and omisée . La durée d'observation moyenne est de 5,2 ans . L'évaluation clinique , douleur , mobilité , marche , est en faveur du cotyle RM . Les critères radiologiques d'instabilité sont difficiles à apprécier , d'autant qu'il faut évaluer des paramètres différents : fragments progressivement libérés dans les cotyles PCA et irrégularités des contours dans les cotyles RM . Le déplacement a été étudié selon une nouvelle technique computérisée EBRA . Les cotyles PCA ont présenté une migration appréciable , surtout longitudinale , dès la 2ème année post-opératoire et ultérieurement une migration moyenne de 0,6 mm à 5 ans . Il existe une corrélation entre les déplacements importants et la boiterie . L'instabilité cotyloïdienne définie par le déplacement semble correspondre au résultat clinique , même à un stade précoce
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 .