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An Automated System for Design and analysis of Total Hip Implants
A method of Modeling the Proximal Endosteal Canal Using 3-D CT Data
Mark A. Manasas - 1999
Introduction
Following case shows the outline of a study that was performed to develop a hip prosthesis ideal for the Asian market. There are three big steps in reaching the final design :
- Select the information
- Treatment of that information
- Creating the new design
Selection of the information
What do we need ?
In order to be able to make the proper design of the implants, we need to know what structures and references are important. Following entities where defined:
- Sphere fit to femoral head
- Line tagged to Greater Trochanter
- Cylinder fit to Canal Axis
- Surface fit to Endosteal Canal
- Line tagged to Lesser Trochanter
By exporting the above objects, they had all information needed for the statistics and the future design.
A segmentation protocol was set up to make the processing the same for all cases. To determine the threshold in a unique way, a rule was formulated. The necessary editing steps were also described.
Like this, different operators can achieve the same result. This is important for the statistics afterwards, because there should be no influence of the operator.
Perform Statistics
The picture shows an example of average curves created on each section during average femur template creation for a random group of femora.
Make new design
The picture shows the cross sections of average femur templates.
The input for making the new design of implants is ready. Different ranges have been determined to have a range suitable for the Asian market.
The picture shows three average femur templates for 12mm distal diameter distal canal: 3D result in different directions.