A CAD-CAM methodology to produce bone-remodelled composite femurs for preclinical investigations

V. Waide, L. Cristofolini, A. Toni

Research output: Contribution to journalArticlepeer-review

Abstract

Femoral bone remodelling, following total hip arthroplasty, is a clinically observed phenomenon attributed to the changed stress environment of the postoperative implanted hip. While this process cannot be avoided, there is concern as to its consequences on the long-term survival of hip joint replacements. Previous methods of studying remodelling, such as clinical or animal-based studies, or finite element analyses, have their limitations. The aim of this study is to develop experimental specimens incorporating bone resorption features typical of clinically successful implants. This work describes the use of computer aided design/manufacturing methods (CAD-CAM) to produce these specimens, based on modifying commercially available composite femurs. The procedures are investigated and verified for two different designs of cemented prostheses (Lubinus SPII and Müller Curved). Quantitative clinical data is used to define the remodelled geometry of a CAD model of the femur for each stem design. Composite femur specimens are machined using a three-axis milling machine, where each specimen can be accurately positioned using a custom-designed jig and a digitizer system. The accuracy of the process is assessed by analysing the deviation of the digitized premachined and postmachined surfaces of each specimen in relation to the CAD model. The results demonstrate that the procedure can be used for developing in vitro specimens with bone resorption features. These specimens are proposed as a useful tool for performing preclinical trials, such as load transfer or longevity/stability testing, with the advantage of modelling a long-term clinical situation, rather than solely analysing implanted femurs in an immediate postoperative state.

Original languageEnglish
Pages (from-to)459-470
Number of pages12
JournalProceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine
Volume215
Issue number5
DOIs
Publication statusPublished - 2001

Keywords

  • Bone remodelling
  • CAD
  • CAM
  • Cemented implants
  • Composite femurs

ASJC Scopus subject areas

  • Biomedical Engineering
  • Mechanical Engineering
  • Medicine(all)

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