Long-Term Results of Total Hip Arthroplasty with RM Classic Cups

Abstract

Relevance. The RM Classic monoblock titanium-coated polyethylene cup is widely used in the total hip arthroplasty. However, so far in Russia there has been no analysis of follow-up over 10 years for a limited number of patients in a single hospital. The aim of the study was to evaluate the long-term outcomes of total hip replacement with RM Classic acetabular component. Materials and Methods. The outcomes of 328 total hip arthroplasties (289 patients operated in the period from 1997 to 2007) with RM Classic cups were evaluated in a monocentral retrospective clinical study. The average follow-up period was 14.4 years. Revision procedure due to aseptic loosening, polyethylene wear or osteolysis was considered as the end point of the study. Results. 9 revisions during the short and medium follow-up periods (up to 10 years) were associated with malpositioning of RM Classic components and errors in surgical technique. The indications for later revision THA (19 cases) were polyethylene wear and aseptic loosening. Only in one case they were combined with pelvic bone osteolysis with the formation of III a defect according to W.G. Paprosky classification. Within 15 years the Kaplan-Meier survivorship of RM Classic cup was 92.5%. There was a statistically significant difference of the survival curves in the ceramic-on-poly against metal-on-poly bearings: 94.9% and 79.4%, respectively. The average Harris Hip Score was 88.6. Conclusion. RM Classic uncemented monoblock cup has proven its high efficiency and survival in 15 years follow-up period and over.

Keywords

• total hip arthroplasty
• uncemented monoblock titanium-coated polyethylene cup
• long-term survivorship of the acetabular components