Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Engineering Science

Program

Mechanical and Materials Engineering

Collaborative Specialization

Musculoskeletal Health Research

Supervisor

Johnson, James A

2nd Supervisor

Langohr, G Daniel G

Abstract

Radial head hemiarthroplasty design has been extensively studied with a focus on utilizing the geometrical characteristics of the native radial dish as a guide of implant placement and design. Although implant design has been studied, optimal radial head implant fixation technique remains unknown. This thesis focused on the effect of stem fit on radiocapitellar contact mechanics, using both finite element and experimental bench-top approaches. Additionally, investigation into the impact of varus/valgus malalignment of the radial head in both the native state and following hemiarthroplasty was conducted. It was found that loose fitting a smooth stem axisymmetric radial head implant through over reaming between 2 to 3 mm provided the greatest improvement in contact mechanics, which included contact area, threshold area, and average contact pressure. Additionally, the work in this thesis indicated that over reaming of 3 mm following malalignment into varus and valgus positions may help to preserve the remaining native capitellar cartilage.

Summary for Lay Audience

Radial head hemiarthroplasty design has been extensively studied with a focus on utilizing the geometrical characteristics of the native radial dish as a guide of implant placement and design. Although implant design has been studied, optimal radial head implant fixation technique remains unknown. This thesis focused on the effect of stem fit on radiocapitellar contact mechanics, using both finite element and experimental bench-top approaches. Additionally, investigation into the impact of varus/valgus malalignment of the radial head in both the native state and following hemiarthroplasty was conducted. It was found that loose fitting a smooth stem axisymmetric radial head implant through over reaming between 2 to 3 mm provided the greatest improvement in contact mechanics, which included contact area, threshold area, and average contact pressure. Additionally, the work in this thesis indicated that over reaming of 3 mm following malalignment into varus and valgus positions may help to preserve the remaining native capitellar cartilage.

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