Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Science

Program

Surgery

Supervisor

Athwal, G

2nd Supervisor

Johnson, J

3rd Supervisor

Langohr, D

Abstract

The humeral head osteotomy influences shoulder arthroplasty component height, version and neck shaft angle and therefore outcomes. The purpose of this study is to develop and utilize navigation to execute the osteotomy.

3D printed models were used to develop a navigation technique, and then to execute planned osteotomies. Free hand, fixed angle guide, patient specific guides, and real time navigation osteotomies were completed. The height, neck shaft angle and version were recorded. Also collected, were the planes of the guides once they were placed.

Navigation had significantly less error from the planned osteotomy in neck shaft angle versus all other groups and for version compared to free hand and fixed angle guides. Patient specific guides had statistically less error from planned version compared to the fixed angle guides. There were no statistical differences in cut height across groups. There was no difference in planned, guide placement and completed osteotomy parameters.

Summary for Lay Audience

The rates of shoulder replacement are increasing, and projected to continue to do so. Both anatomic and reverse shoulder replacement rely on replacement of the proximal humerus. The humeral head cut influences the component height, its version and neck shaft angle. These parameters all influence outcomes of shoulder replacement. Little, however, has been done to evaluate these humeral head cuts. The purpose of this study is to develop navigation for the proximal humerus and use real time navigation to execute the cut.

3D printed models of 10 humeral specimen were created. These models were used to mark anatomic points and tracings in development of a proximal humerus navigation technique. These same models were then used to execute preoperatively planned head cuts. Four different cut methods were trialed; free hand, fixed angle guide, patient specific guides, and real time navigation. The cut height, neck shaft angle and version were recorded for all. Also collected, were the planes of the fixed angle and patient specific guides once they were placed. This was done to evaluate the accuracy in placing them, and their relation to the subsequent cut plane.

Our navigation error was minimized to 2.5 mm in estimating a superior point on the humerus. Navigation guided cuts had statistically significant less error from preoperatively planned cuts in neck shaft angle compared to all other groups. Navigated cuts also had statistically less error for achieving planned version compared to free hand and fixed angle guide cuts. Patient specific guides had statistically less error in achieving the preoperatively planned version compared to the fixed angle guides. There were no statistical differences in cut height across our four groups. There were no statistical differences in the version, neck shaft angle or cut height when comparing preoperatively planned osteotomy, guide placement and subsequent osteotomy with the use of guide, for both fixed angle and patient specific guides. Further research and utilization of navigation and patient specific guides may further improve shoulder arthroplasty.

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