Paper #II-3

ANALYSIS OF BONE SUPPORT OF CEMENTLESS ACETABULAR CUPS USING COMPUTED TOMOGRAPHY

James L. Howard, MD

London, ON

Co-Authors

AJ Hui

DW Holdsworth

RB Bourne

Introduction

The initial stability and long-term survivorship of cementless acetabular cups is partially dependent on bone-prosthesis contact patterns. Presently there is no imaging modality that can accurately assess these contact patterns. The purpose of this study was to determine the amount and distribution of bone-prosthesis contact for three acetabular component designs using a novel image analysis technique.

Methods

Eighteen cadaveric hemipelvis specimens were randomly assigned to receive a hemispherical cup, a dual geometry cup, or a spiked cup. An experienced team prepared the specimens and implanted the acetabular cups. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was performed using custom-developed imaging software.

Results

The mean amount of cup contact was 48.6 % in the hemisphere group, 31.9 % in the dual geometry group, and 35.1 % in the spiked group (ANOVA p 0.05). A comparison between the groups for amount and distribution of contact was performed.

Discussion and Conclusion

This study outlines a novel CT analysis technique to evaluate bone-prosthesis contact for cementless acetabular cups. The hemisphere, dual geometry, and spiked designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone prosthesis contact.