A finite element study of the effect of diametral interface gaps on the contact areas and pressures in uncemented cylindrical femoral total hip components

Timothy Harrigan, William H. Harris

Research output: Contribution to journalArticle

Abstract

Uncemented femoral total hip components rely entirely on contact with the prepared femur for their initial fixation. The contact areas and stresses between a straight tubular bone and a metal cylindrical prosthesis 12.5 cm long and 13 mm in diameter were calculated in a finite element model which includes uniform diametral gaps varying from 20 to 500 μm, using transverse loads from 100 to 2000 N. Frictionless three-dimensional contact elements were used between the bone and the prosthesis. Contact stresses were high and irregular in all cases, and the contact areas were small. Two regions of contact were apparent for lower loads and larger gaps. A third region of contact occurred near the distal tip of the implant at higher loads. This region of contact markedly increased the contact stresses at the distal tip of the prosthesis. A 20 μm overlap between bone and implant was modelled to assess a slight interference fit. The contact stress distribution in this case was markedly different from the stress distribution with a 20 μm diametral gap. The data collectively indicates that gaps of less than 20 μm between bone and implant can substantially change contact stress distributions.

Original languageEnglish (US)
Pages (from-to)87-91
Number of pages5
JournalJournal of Biomechanics
Volume24
Issue number1
DOIs
StatePublished - Jan 1 1991
Externally publishedYes

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Thigh
Hip
Bone
Prostheses and Implants
Stress concentration
Pressure
Bone and Bones
Femur
Metals

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation

Cite this

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abstract = "Uncemented femoral total hip components rely entirely on contact with the prepared femur for their initial fixation. The contact areas and stresses between a straight tubular bone and a metal cylindrical prosthesis 12.5 cm long and 13 mm in diameter were calculated in a finite element model which includes uniform diametral gaps varying from 20 to 500 μm, using transverse loads from 100 to 2000 N. Frictionless three-dimensional contact elements were used between the bone and the prosthesis. Contact stresses were high and irregular in all cases, and the contact areas were small. Two regions of contact were apparent for lower loads and larger gaps. A third region of contact occurred near the distal tip of the implant at higher loads. This region of contact markedly increased the contact stresses at the distal tip of the prosthesis. A 20 μm overlap between bone and implant was modelled to assess a slight interference fit. The contact stress distribution in this case was markedly different from the stress distribution with a 20 μm diametral gap. The data collectively indicates that gaps of less than 20 μm between bone and implant can substantially change contact stress distributions.",
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N2 - Uncemented femoral total hip components rely entirely on contact with the prepared femur for their initial fixation. The contact areas and stresses between a straight tubular bone and a metal cylindrical prosthesis 12.5 cm long and 13 mm in diameter were calculated in a finite element model which includes uniform diametral gaps varying from 20 to 500 μm, using transverse loads from 100 to 2000 N. Frictionless three-dimensional contact elements were used between the bone and the prosthesis. Contact stresses were high and irregular in all cases, and the contact areas were small. Two regions of contact were apparent for lower loads and larger gaps. A third region of contact occurred near the distal tip of the implant at higher loads. This region of contact markedly increased the contact stresses at the distal tip of the prosthesis. A 20 μm overlap between bone and implant was modelled to assess a slight interference fit. The contact stress distribution in this case was markedly different from the stress distribution with a 20 μm diametral gap. The data collectively indicates that gaps of less than 20 μm between bone and implant can substantially change contact stress distributions.

AB - Uncemented femoral total hip components rely entirely on contact with the prepared femur for their initial fixation. The contact areas and stresses between a straight tubular bone and a metal cylindrical prosthesis 12.5 cm long and 13 mm in diameter were calculated in a finite element model which includes uniform diametral gaps varying from 20 to 500 μm, using transverse loads from 100 to 2000 N. Frictionless three-dimensional contact elements were used between the bone and the prosthesis. Contact stresses were high and irregular in all cases, and the contact areas were small. Two regions of contact were apparent for lower loads and larger gaps. A third region of contact occurred near the distal tip of the implant at higher loads. This region of contact markedly increased the contact stresses at the distal tip of the prosthesis. A 20 μm overlap between bone and implant was modelled to assess a slight interference fit. The contact stress distribution in this case was markedly different from the stress distribution with a 20 μm diametral gap. The data collectively indicates that gaps of less than 20 μm between bone and implant can substantially change contact stress distributions.

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