In vitro testing of Al 2O 3–Nb composite for femoral head applications in total hip arthroplasty

Abstract

Alumina (Al 2O 3) bearings in total hip arthroplasty lead to low wear rates, but catastrophic failure of Al 2O 3 femoral heads, while rare, remains a concern. In the present work, a composite of Al 2O 3 and niobium (Nb) was tested in vitro for potential use as an alternative femoral head material in vivo. Dense composite laminates of Al 2O 3 and Nb were fabricated by hot pressing, and their microstructure and mechanical properties were evaluated. The flexural strength of Al 2O 3–Nb laminates in four-point loading was 720 ± 40 MPa, compared with a value of 460 ± 110 MPa for Al 2O 3. Scanning electron microscopy and X-ray diffraction showed a well-bonded interface between the Al 2O 3 and Nb without measurable formation of an interfacial reaction phase. The interfacial shear strength between Al 2O 3 and Nb, measured by a double-notched specimen test, was 290 ± 15 MPa. The feasibility of fabricating prototype femoral heads (32 mm in diameter), consisting of an Al 2O 3 surface layer (2–3 mm thick) and a Nb core, by hot pressing was shown. The composite femoral head combined the low wear of an Al 2O 3 articulating surface with the safety of a ductile metal femoral head.