Biomechanical evaluation of the helica femoral implant system using traditional and modified techniques

Mark Dosch, Kei Hayashi, Tanya C. Garcia, Robert Weeren, Susan M Stover

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Objective: To determine the effect of implant placement on proximal femoral axial bone strains, implant subsidence, implant motion, and failure mechanical properties of Helica implants. Study Design: In vitro biomechanical study. Sample Population: Cadaveric canine femora (n=8 pairs). Methods: Femora instrumented with strain gauges and kinematic markers were cyclically loaded in axial compression before (intact femora) and after implantation with a Helica prosthesis that engaged only cancellous bone (traditional technique) or cancellous bone and lateral cortex (modified technique) to evaluate bone strains, subsidence, and motion; femora were then loaded to failure to evaluate failure mechanical properties. Results: After implantation, modified femoral prosthesis angle was 5% less than intact femora and 5.7% less than traditional implanted femora. Medial femoral bone strain was lower (P≤.05) for intact (-570μstrain) than modified (-790), but not (P=08) traditional (-700) implanted femora. High-load implant subsidence was present but small (-0.087mm) for the modified technique. Motion (traditional and modified) increased (P=05) during cyclic loading (-0.17 and -0.328mm) and failure (P=04) (-2.121 and -3.390mm); remaining yield and failure properties revealed no significant findings (P≤.05). Conclusions: The modified technique resulted in a smaller neck angle and minimal subsidence. Bone strain was minimally altered so stress shielding may be less compared to findings with traditional implants. Motion detected during cyclic and failure testing may lead to implant loosening in vivo.

Original languageEnglish (US)
Pages (from-to)867-876
Number of pages10
JournalVeterinary Surgery
Volume42
Issue number7
DOIs
StatePublished - Oct 2013

ASJC Scopus subject areas

  • veterinary(all)

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