The cement fixation of femoral hip arthroplasty implants

Student thesis: Doctoral Thesis

Abstract

Femoral hip arthroplasties are frequently fixed to the bone with a methylmethacrylate cement layer. Using polymeric stem replicas, we developed and validated, a CT based technique to quantify the three dimensional structure of the bone-cement-stem complex in vitro.
Despite numerous arguments supporting stems that are undersized, some French implants cemented line-to-line with the broach, perform very well in clinical practice. This is known as the "French Paradox" and was explored by quantifying the cement mantle surrounding undersized and line-to-line stems. These morphological data were used to create finite element analysis models to study the propagation of microcracks in the cement mantle and the rotational implant stability during cyclic loading.
Both, anatomic and straight stems can be cemented line-to-line or undersized. We investigated which factor was most influential for the structure of the cement mantle. In a literature review, we confronted experimental and clinical evidence on stem shape, broach-stem sizing and other design features of cemented stems to try to recognise concepts with proven long-term track records.
Interfacial defects between stem and cement can arise from cement shrinkage during polymerisation (interfacial porosity) or from air entrained along the stem during cementation (interfacial gaps). We quantified these interfacial gaps and used finite element analysis models to try to predict the effect of both types of defects on implant stability and crack propagation during cyclic loading.
Finally, the CT scan based technique developed to analyse cemented stems was adapted to quantify the cement-implant-bone complex of polymeric resurfacing heads. This technique offers new perspectives for research on the quality of the cement mantle in hip resurfacing.
Date of Award18 Mar 2008
Original languageEnglish
Awarding Institution
  • Vrije Universiteit Brussel
SupervisorPierre Casteleyn (Promotor), Christiaan Van Schravendijk (Jury), Christiane Van Den Branden (Jury), Filip Van hoenacker (Jury), Pierre Opdecam (Jury), Jean-Pierre Simon (Jury), Steffen Breusch (Jury), Frank Deconinck (Jury), Rudolf Geesink (Jury) & Roger Lemaire (Jury)

Keywords

  • Hip arthroplasty
  • Cement mantle
  • Computer tomography
  • Segmentation
  • Interfacial gap
  • Interfacial pore
  • Finite element analysis

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