Five to Seven Years Survival Analysis of a Modular Titanium Alloy Stem Primary Total Hip Replacement

Abstract

We report the results of a retrospective study of 94 primary total hip replacements with a modular implant (Howse II /Ultima) at a minimum of five years’ follow-up, performed since June 1991 to December 1993 for osteoarthritis of the hip. Twenty-one patients (22 THRs) had died and four patients were lost to follow-up. Mean Harris Hip score of 47 ± 8.7 (range 24–64) pre-operatively rose to 84.9 ± 21.5 (range 22–97). The survival rate of femoral stem in patients who had revisions for aseptic loosening was 91% and no stem was diagnosed as radiologically loose in the first five years of insertion. Using radiological criteria by Harris, three stems were definitely loose (3.2%), three were probably loose (3.2%) and two were possibly loose (2.1%). Survival rate of the Ultima cup for aseptic loosening in patients who had revisions was 87% at seven years. At the final follow-up, three sockets were definitely loose, four were probably loose and four more were possibly loose. Risk of failure of primary total hip replacements increased with increased weight (BMI of greater than 1.25 as compared to below 1.0 (p=0.04, chi test); in patients with osteonecrosis (p=0.048, chi test) and patients who were younger than 65 years of age (p=0.039, chi test). This study represented the outcome of Ultima hip arthroplasties performed by a variety of surgeons and included patients in all age groups and all aetiologies leading to osteoarthritis.