A Technique to Determine Coordinates of the Patellar Entry Point and Transition Point of the Patellofemoral Joint Using Computed Tomography Scans

Patellas of patellofemoral instability patients typically have more lateral entry points into their proximal trochleas. They also generally have more shallow or convex proximal trochlear grooves, leading to trochlear transition points where the grooves straighten distally. In this technique article, we describe a method using standardized imaging software and computed tomography scans to measure coordinates of the entry point and transition point and show its reliability across numerous knees and raters. This method will increase understanding of the proximal trochleas of patellofemoral instability and arthritis patients, thereby helping to guide optimal treatment.