Quantifying the effects of an optimised physical training programme in pre-season: does order matter?

The quadriceps angle (q-angle) is a measurement intended to predict the quadriceps forces acting on the patellofemoral joint and has therefore been considered relevant in the clinical examination of patellofemoral pain syndrome (PFPS). There is no standardized description of how to perform an accurate measurement, which may be why research has failed to reach consensus about the relevance of q-angle measurements in individuals with PFPS. The purpose of the study was to compare measurements between standard goniometry, conventional radiography and three-dimensional kinematics in two different projection planes, in supine and standing positions, in 17 women with PFPS and 17 matched controls. In general, the q-angle did not differ between groups, except for the goniometer measurement. There was a main effect of measurement showing that all measurements were generally different from one another. Three-dimensional kinematics showed that the largest q-angle was located in a plane set at an angle relative to the frontal plane. The present study suggests that the q-angle estimation is dependent on measurement method and that the largest q-angle may not be found in the frontal plane. This may have relevance for estimation of the lateral force pulling on the patella.