Understanding Patellofemoral Pain with Maltracking in the Presence of Joint Laxity: Complete 3D In Vivo Patellofemoral and Tibiofemoral Kinematics

Patellofemoral pain is widely accepted as one of the most common pathologies involving the knee, yet the etiology of this pain is still an open debate. Generalized joint laxity has been associated with patellofemoral pain, but is not often discussed as a potential source of patellar maltracking. Thus, the objective of this study was to compare the comptete 6 degree of freedom patellofemoral and tibiofemoral kinematics from a group of patients diagnosed with patellofernoral pain syndrome and maltracking to those from an asymtomatic population. The following null hypotheses were tested: kinematic alterations in patellotemoral maltracking are limited to the axial plane; knee joint kinematics are the same in maltrackers with and without generalized joint laxity (defined by a clinical diagnosis of Ehlers Danlos Syndrome); and no correlations exist between tibiotemoral and patellofemoral kinematics or within patellofemoral kinematics. This study demonstrated that alterations in patellofemoral kinematics, associated with patellofemoral pain, are not limited to the axial plane, minimal correlations exist between patellofemoral and tibiofemoral kinematics, and distinct subgroups likely exist within the general population of maltrackers. Being able to identify subgroups correctly within the omnibus diagnosis of patellar maltracking is a crucial step in correctly defining the pathophysiology and the eventual of these patients. (C) 2008 Orthopaedic Research Society. *Published by Wiley Periodicals, Inc. J Orthop Res 27:561-570, 2009