Creating a Statistical Shape Model of the Patella
The patella is designed to transmit enormous amounts of force from the quadricep muscle to the lower leg. When a patient needs a total knee replacement, the patellar implant must rise to the occasion and provide the same high impact service. Unfortunately, when the patellar implant fails, the implications for the patient are catastrophic. It is imperative to understand the correct surgical techniques and implant shapes to use to prevent patellar implant failure. One way to do this is to create a statistical shape model (SSM) of the patella so patellar shapes can be "randomly generated" to be used in finite element analysis and other simulation software. Sample patellas to use in the statistical modeling were created as stl files from cadaver CT scans, then important landmarks on the bone were identified to later be used to position it in the correct coordinate system. After that, MATLAB script was adapted to morph all the sample patellas to one "template" one. Then, this template patella could be stretched or manipulated in ways that modeled the normal range of geometry captured by the large sample size of original patellas.