O3471 POSTOPERATIVE MIGRATION OF CEMENTLESS TITANIUM HIP-STEMS. CLINICAL STUDY WITH ROENTGEN STEREOMETRIC ANALYSIS (RSA)

Abstract

Aims: The purpose of this study was to evaluate primary stability and the time of bony þxation of two different designed cementless titanium hip stems. Therefore we designed a prospective clinical study with high precision RSA and close follow up periods (3, 6,12, 24, 52, 104 weeks). Methods: One stem was a Ç straight stem È (BICONTACT, Aesculap AG, Germany) with a rough pure Titanium surface in the upper part for proximal þxation. The second stem (Image, Smith& Nephew, Germany) was anatomically shaped with additional HA coating. 34 IMAGE stems and 20 BICONTACT stems with RSA markers were implanted. Mean age in both groups was 64 years. In September 2002, 28 patients (14 X BICONTACT and 16 X IMAGE) were followed for more than 1 year and 12 patients (6 X BICONTACT and 6 X IMAGE) for more than 2 years. Results: Subsidence was predominantly observed between the postoperative control and the 6 weeks follow up. (IMAGE 0.83mm, BICONTACT 0,60mm) and decreased up to 12 weeks (IMAGE 0.05mm, BICONTACT 0,29mm). After 12 weeks both stems were stabilized (12–24 weeks: IMAGE 0.05mm, BICONTACT 0.06mm; 6 months -1 year: IMAGE 0.05mm, BICONTACT 0.04mm. Between 1 and 2 years subsidence for the IMAGE stem was 0.05mm compared to 0.16mm in the Bicontact group. Overall subsidence of the IMAGE stem during the þrst year was 0.96mm compared to 0.97mm for the BICONTACT stem. Conclusions: Titanium cementless hip stems with a rough proximal titanium surface or HA coating showed a sufþcient primary and mid-term stability. Bony þxation is achieved between 6 and 12 weeks. No statistical differences were found between both stems.