Intermediate-term results with the Mecron screw cup acetabulum--a follow-up study

Abstract

The short term result of the cementless implanted titan screw cups (type Mec-Ring) has been very encouraging. The study was aimed to show the survival rate in the middle term. The survival rate of 111 implanted acetabular titan screw cups (type Mec-Ring) was determined in a retrospective study. 85 patients (= 76.5%) could be followed up after 6.7 years (5-8.5 years). 38 Implants had to be removed during the follow up period (34.2%). Taking into account the radiologic loosening in addition 22 cups were defined as failure (19.8%). Overall 36 (32.4%) cups showed excellent or good clinical results with 85 points according to the Harris-Hip-Score. 15 of the 22 radiologic loose implants showed only little or no pain. Considering the removed implants the probability of survival is 69% after 7 years. Defining the radiologic loose implants as failure the survival rate is 54%. X-rays have to be taken frequently to determine bone loosening early with subsequent revision operation. The survival rate is to low compared to other types of fixation. Therefore acetabular titan screw cups (type Mec-Ring) should not be used any more.