Uncemented total hip replacements using the Mecron acetabular cup--a prospective study
Lim, H.H.; Hunt, D.M.
Annals of the Academy of Medicine Singapore 26(4): 459-464
1997
ISSN/ISBN: 0304-4602 PMID: 9395811 Document Number: 471221
The uncemented threaded cup gained some popularity over the past decade, firstly as a revision and then as a primary procedure. We elected to test the Mecron acetabular threaded cup system as a routine hip replacement. As there was no matched femoral component, we decided to use an uncemented femoral stem of the Ring system of the hip prosthesis. All patients were logged on to the study at the outset although this is not a controlled comparison with another system. Patients were assessed annually for up to 4-years at the time of reporting. There were 104 primary total hip replacements in 99 patients between 1987 and 1991. The mean follow-up for this report was 22.5 months (range 12 to 48 months). The mean age was 76.3 years (range 24 to 88 years) and the female to male sex ratio was 3.3:1. Within the study period, 5 hips required revision, all for acetabular loosening. Patients were assessed by the modified Harris score annually and 60.6% of the cases had an excellent or good short-term result. Poor results were observed in 18.3% of cases. Radiographic studies of the acetabular component were undertaken annually and measured. Migration and tilting of the acetabular cup was observed in all cases. Heterotropic bone formation occurred in 10 patients. As a result of these poor results, the prosthesis was abandoned in 1991. The cohort of patients continues to be followed. Failure of the Mecron acetabular cup in our series was mainly due to tilting and migration and not untwisting.