Editorial Commentary: Trochlear Dysplasia Is Difficult to Measure, No Matter How You Slice It

Trochlear dysplasia is one of the primary morphologic abnormalities associated with patellar instability. Although qualitative classifications based on trochlear shape such as the Dejour classification exist, radiographic measurements to quantify the severity of trochlear dysplasia are numerous and varied. Each measurement addresses a different element of the complex and wide-ranging presentations that exist along a spectrum of abnormalities in trochlear morphology, and the reported reliability of such measurements are mixed. Overall, our understanding of trochlear dysplasia continues to evolve, and the ability to quantify the morphology of the trochlea, as well as its influence on patellar stability, remains a work in progress. Future directions include developing improved 3-dimensional descriptions of trochlear anatomy, as well as standardizing measurement methods and image slice selection, to better evaluate trochlear morphology in the assessment of patellar instability.