LONG TERM RESULTS OF THE HOFER IMHOF LUBRIMET METAL ON METAL ARTICULATION

Abstract

Aims: A polyethylene free, metal on metal acetabular system (Hofer-Imhof cup; Lubrimet metal on metal articulation made of CoCr-forge alloy) was designed in an effort to improve total hip arthroplasty longevity. This study was undertaken to review the clinical performance of this implant and to determine if acetabular loosening or revision and wear and osteolysis were prevalent.

The long term results (mean follow up period 110 months) are presented in this study.

Methods: In this prospective, randomized study a minimum of 90 months follow up results involving the first 100 implanted metal liner total hip arthroplasties are presented. The mean follow up was 110 months. Between April 1995 and November 1996 ninety-eight patients (100 hips) had a total hip replacement consisting of a titanium cementless self reaming, parabolic cup, a cementless titanium stem and the Lubrimet® metal on metal articulation.

Two acetabular and one femoral component had to be revised due to aseptic loosening without showing macroscopic evidence of metallosis and no histological evidence of excessive metal wear. One patient hat to be revised by a complete change of the total hip (acetabular component and stem) showing histologic evidence of a metal induced hyperergic immunologic reaction. One patient presented with a broken neck of the stem and had to be revised by stem exchange.

As a none device related orthopedic complication one acetabular component required revision surgery due to a periprosthetic fracture.

Conclusions: The long term results of the Hofer-Imhof Lubrimet®Metal-on-metal articulation are satisfying and so the system represented a viable alternative for total hip arthroplasty in younger higher demand patients in the past. Due to the possible development of a hyperergic immunologic reaction to the metal on metal articulation and the availibility of a ceramic on ceramic articulation we do not implant this liner anymore.