Three-dimensional Analysis of Patellar Instability: A Review of Current Concepts.

Patellar instability presents diagnostic and treatment challenges despite advances in imaging and surgical techniques. Given the link between patellar instability and trochlear dysplasia, the key to understanding instability may lie in subtle morphological variations in the trochlea. Traditional 2-dimensional methods of understanding instability can suffer from issues of geometric alignment. As a result, 3-dimensional analysis has an emerging role in understanding the pathogenesis of patellar instability. One 3-dimensional metric, the entry point-transition point angle, is used to quantify the degree of lateralization of dysplastic trochlear grooves. This angle is measured on 3-dimensional reproductions of computed tomography scans and can be used for surgical decision-making in instability patients. Further research should investigate how to best incorporate 3-dimensional metrics in surgical decision-making.