Experience of an anatomic femoral stem in a UK orthopaedic centre beyond 20 years of follow-up.

INTRODUCTION

Increasing interest in the use of anatomical stems has developed as the prevalence of periprosthetic fractures (PPFs) continues to increase. The primary aim of this study was to determine the long-term survivorship and PPF rate of an anatomical femoral stem in a single UK centre.

PATIENTS AND METHODS

Between 2000 and 2002, 94 consecutive THAs were performed using the 170 mm Lubinus SP II anatomical femoral stem in our institution. Patient demographics, operative details and clinical outcomes were collected prospectively in an arthroplasty database. Patient records and national radiographic archives were reviewed finally at a mean of 21.5 years (SD 0.7) following surgery to identify occurrence of subsequent revision surgery, dislocation or periprosthetic fracture.

RESULTS

Mean patient age at surgery was 65.8 years (SD 12.5, 34-88 years). There were 48 women (51%). Osteoarthritis was the operative indication in 88 patients (94%). Analysis of all-cause THA failure demonstrated a survivorship of 98.5% (95% confidence interval [CI], 98.0-99.3%) at 10 years and 96.7% (94.5-98.9%) at 21 years. The 20-year stem survival for aseptic loosening was 100% with no cases of significant lysis found (lucent line > 2 mm) and no stems required revision. Patient demographics did not appear to influence risk of revision (p > 0.05). There were 2 revisions in total (2 for acetabular loosening with original stems retained). There were no PPFs identified at mean 21.5 year follow-up and 5 dislocations (5%).

CONCLUSIONS

The Lubinus SP II 170 mm stem demonstrated excellent survivorship and negligible PPF rates over 20 years following primary THA.