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Journal of Bone and Joint Surgery - British Volume, Vol 89-B, Issue 4,
549-556.
doi: 10.1302/0301-620X.89B4.18055 Copyright © 2007 by British Editorial Society of Bone and Joint Surgery The initial stability and contact mechanics of a press-fit resurfacing arthroplasty of the hipI. Udofia, PhD, Research Fellow1; F. Liu, PhD, Research Fellow1; Z. Jin, PhD, Professor of Computational Bioengineering1; P. Roberts, MA(Oxon), MB, FRCS, Consultant Orthopaedic Surgeon2; and P. Grigoris, MD, PhD, FRCS, Visiting Professor, Consultant Orthopaedic Surgeon3
1 Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK. Correspondence should be sent to Dr I. Udofia; e-mail: i.j.udofia{at}leeds.ac.uk
Finite element analysis was used to examine the initial stability after hip resurfacing and the effect of the procedure on the contact mechanics at the articulating surfaces. Models were created with the components positioned anatomically and loaded physiologically through major muscle forces. Total micromovement of less than 10 µm was predicted for the press-fit acetabular components models, much below the 50 µm limit required to encourage osseointegration. Relatively high compressive acetabular and contact stresses were observed in these models. The press-fit procedure showed a moderate influence on the contact mechanics at the bearing surfaces, but produced marked deformation of the acetabular components. No edge contact was predicted for the acetabular components studied. It is concluded that the frictional compressive stresses generated by the 1 mm to 2 mm interference-fit acetabular components, together with the minimal micromovement, would provide adequate stability for the implant, at least in the immediate post-operative situation.
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