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

Langohr, G. Daniel

2nd Supervisor

Johnson, James

Co-Supervisor

Abstract

Radial head arthroplasty is commonly used to treat comminuted radial head fractures to restore elbow stability and function. Implant design has focused on the contact mechanics of the radial head articular dish; however, a comprehensive examination of radial head morphology is lacking. This thesis focused on the quantification of the radial head dish size, depth and curvature, and the landing and side profiles. The correlations among these features and how they may be reflected in axisymmetric implant designs was studied. The contact mechanics of the proposed optimized radial head implants were assessed using finite element analysis to quantify their peak contact pressures and contact areas with the distal humerus. Results showed that a morphologically driven implant design reduced the peak contact pressures by 30% and slightly improved the mean contact area by 6% compared to a commercial implant. Modifications to traditional axisymmetric implant designs may result in improved clinical outcomes.

Summary for Lay Audience

Radial head implants are commonly used to treat severely fractured radial heads to restore elbow stability and loading capabilities. Current implant designs focus on just one feature of the radial head, however, a comprehensive analysis of the entire shape of the radial head is lacking. A previous study reported that modifying the shape of an elliptical implant design improved the implant’s effectiveness, although no work had been done to implement this into a more commonly used circular design. Although patient outcomes are adequate after radial head replacement, premature cartilage wear and arthritis are common due to abnormal contact between the implant and the native elbow anatomy. Optimizing radial head implant design could lead to improved contact mechanics and better long-term patient outcomes.

This thesis focused on quantifying the key features of the native radial head that contribute to its effective contact. The correlations among these key features and how they might be reflected in an optimized circular implant design was studied. It was found that these features should not be proportionally scaled as implant size increases, and also that current circular implants are not generally representative of the radials head’s native morphology.

This thesis compared the joint contact of a current circular radial head implant design to an optimized circular design, derived from the key features studied of the native radial head. Using computer modeling, it was found that an optimized circular radial head implant reduced peak contact pressures by nearly 30% and slightly increased the contact area by 6% compared to a commonly used circular design. These results are promising and indicate that the optimized implants may improve long-term patient outcomes.

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Available for download on Sunday, December 20, 2026

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