SEVENTEEN-YEAR SURVIVORSHIPS OF THE ALLOCLASSIC™ FEMORAL TAPER IN PRIMARY TOTAL HIP ARTHROPLASTY

Abstract

Introduction: Aim of this study was to provide survivor-ship analysis of the cementless Zweymüller, then Alloclassic flat-wedge femoral titanium alloy taper used in primary THA.

Material and Methods: Of 1128 consecutive 1ary THAs (paired with a grit-basted threaded cup in 93%) performed over the 01/1986–12/2008 period and prospectively followed-up, 31 were all-cemented (2.7%), 74 were hybrid reconstructions (6.6%) and 1023 were fully cementless (90.7%). A total of 1034 cementless tapers (72 “Hochgezogen” and 962 “Alloclassic-SL” implants) were implanted.

Results: Considering the unavoidable learning curve, first author complication rates (526 consecutive 1ary THAs) were acceptable with fracture ; femur, 0.5%: greater-trochanter, 0.8% ; subsidence > 2mm, 3.4% ; varus position 14.3% ; and osteolysis, 0.9%. Of the 1034 uncemented tapers, 19 were revised for: deep infection (7), recurrent dislocation (4), intra-operative or late fractures (4), unexplained pain (3, none loose at revision) and 1 for aseptic loosening (due to metallic head sleeve impingement). Overall femoral revision burden was 1.8% (< 0.1% per year) and survivorship with revision “for any reason” and “for aseptic loosening” was 94.2% and 99.5% % at 17 years, respectively. Currently, main reason for revision is related to osteolysis due to wear of conventional polyethylene liners.

Conclusion. In a general orthopaedic population and in a regular setting, the Alloclassic SL-stem, our everyday femoral component, was forgiving and reliable for more than 20 years. We can reasonably expect an outstanding outcome in the future due to improved surgical skill, hard bearings (Metasul, 1994), slimmer neck and “Offset” options (2004).