Abstract
Aims: In vitro studies have demonstrated that phagocytosed metal wear particles can lead to osteolysis by osteoclast activation. While others have reported massive metallosis with no loosening of the implant. The incidence of metallosis has remained uncertain so far. The purpose of this prospective study was to assess the incidence of metallosis and explore the correlation between metallosis and the time to revision of total hip replacements, getting additional information of the role of metallosis in aseptic loosening.
Materials and Methods: 72 patients underwent revision of total hip arthroplasty at the authors department from 01/01/2001 to 31/12/2002. All of them were examined for metallosis macroscopically and biopsy was taken from the interfacial membrane for histological analysis. Two subgroups were created from revisions of both cemented and uncemented prostheses. First group was composed of cases if metallosis was either visible during the surgery or high amount of metal particles were found by histology (high-grade metallosis). The other group consisted of cases if metallosis was not visible intraoperatively and only a few metal particles were described by histology (low-grade metallosis). The survivorships of the prostheses were assessed by Kaplan-Meyer statistic analysis.
Results: High-grade metallosis could be detected in 10/42 revisions of cemented (23.8%), and in 12/30 cases of uncemented prostheses(40%). The time from implantation to revision was 88(36–144) months when metal-losis could be observed vs. 122(41–360) months in cases with no metallosis in the cemented group. However there was not significant difference in survival rate of the uncemented prostheses between the metallotic and non-metallotic groups. If only very few metal particles were found, high amount of polyethylene particles were described by histology.
Conclusion: The incidence of high-grade metallosis was higher around uncemented prostheses. The time to revision of cemented prostheses was significantly less if high-grade metallosis was found. Hence it seems like metallosis can have effect on aseptic loosening of cemented prostheses by the large number of metal particles which can make the progress of osteolysis faster resulting in shorter survivorship of the implant. If no high-grade metallosis, but a lot of polyethylene wear were found, then those particles could have the same inductive effect on aseptic loosening.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
