Is the RM- Uncemented Coated Acetabular Cup a Reliable Component in Total Hip Replacement?

Abstract

From August 1987 to the Ist of March 1993 1,477 RM.-isoelastic, uncemented cup components (257 HA, 1,220 Titanium coated) were inserted for T.H.R., matched with the RM- isoelastic and isotitan stem components. At a 4 year mean follow-up (7-1 years) 1,302 cups were clinically and radiographically assessed; 6.2% of cups could not be controlled, because at follow-up time the patients had died; 5.6% could not be traced. All the cups were fixed with 3.2 mm peripheral screws (mean number of screws: 6). The cups more than 60 mm in diameter were fixed with 2 additional cancellous (6.5 mm) screws. The Charnley score is: - 9 - (97.5%) - 8- (2.43%); 1 cup was removed because of infection (0.07%); 3 cups were revised because of malposition and reinserted in proper position. The results with a similar number of RM.-uncoated cups, fixed with only one or two screws from 1979 to 1985, at a mean 4 year follow-up were: 7% revision and 9% impending loosening. Even bone reaction at the bone-cup interface signifies no osteolisis, neither around the cup nor around the screws. The satisfactory clinical results suggest to proceed with the use of this cup