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Los Angeles, CA, United States

Sangiorgio S.N.,Md Orthopaedic Research Center | Longjohn D.B.,University of Southern California | Dorr L.D.,The Dorr Arthritis Institute at Good Samaritan Hospital | Ebramzadeh E.,Md Orthopaedic Research Center
Journal of Biomechanics | Year: 2011

In this study, the in vitro fixation of four otherwise identical double-tapered stem-types, varying only in surface finish (polished or matte) and proximal stem geometry (with or without flanges) were compared under two conditions. First, four specimens of each stem type were tested with initially bonded stem-cement interfaces, representing early post-operative conditions. Then, simulating conditions a few weeks to months later, stems were implanted in unused synthetic femurs, with a thin layer coating the stem to prevent stem-cement adhesion. Per-cycle motions were measured at both cement interfaces throughout loading. Overall, surface finish had the smallest relative effect on fixation compared to flanges. Flanges increased axial fixation by 22 γm per-cycle, regardless of surface finish (P=0.01). Further, all stems moved under dynamic load at the stem-cement interface during the first few cycles of loading, even without a thin film. The results indicate that flanges have a greater effect on fixation than surface finish, and therefore adverse findings about matte surfaces should not necessarily apply to all double-tapered stems. Specifically, dorsal flanges enhance the stability of a tapered cemented femoral stem, regardless of surface finish. © 2010 Elsevier Ltd.


Billi F.,Md Orthopaedic Research Center | Campbell P.,Md Orthopaedic Research Center
Journal of Applied Biomaterials and Biomechanics | Year: 2010

Metal-on-metal (M-M) joint replacement has raised concerns about the long-term effects of metal wear debris and corrosion products. This review summarizes the current concepts in biological reactivity to metal wear particles, ions, and corrosion products. Attention is focused on Co-Cr-Mo alloy since it is the most diffused and discussed material in arthroplasty. © Società Italiana Biomateriali.

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