Understanding patellofemoral pain with maltracking in the presence of joint laxity: Complete 3D in vivo patellofemoral and tibiofemoral kinematics

Abstract

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 complete 6 degree of freedom patellofemoral and tibiofemoral kinematics from a group of patients diagnosed with patellofemoral pain syndrome and maltracking to those from an asymptomatic population. The following null hypotheses were tested: kinematic alterations in patellofemoral 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 tibiofemoral 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 treatment of these patients.

Q-angle and J-sign: Indicative of Maltracking Subgroups in Patellofemoral Pain

“…The slope of each variable was defined by the linear best fit of each with knee angle. The validity of using a linear best fit has been documented [39].…”

“…In one study, no differences were reported [25], yet in another, differences in the majority of the 3D PF displacements and rotations were reported [39]. This variability is likely the result of differences in measurement techniques, variables measured, and the presence of various types of maltracking patterns in the omnibus term of patellar maltracking [37,39]. For example, Schutzer et al [37] identified three distinct malalignment patterns in patients with PF pain: excessive lateral tilt, lateral subluxation, and lateral subluxation with tilt.…”

“…Numerous studies have compared PF alignment [1,14,22,24,26,31] and PF displacements/rotations [5,29,39,44,48] in patients diagnosed with PF pain with asymptomatic controls. These studies typically reported variations in PF alignment, displacements, and/or rotations between the two populations, but the results are inconsistent across studies.…”

“…These studies typically reported variations in PF alignment, displacements, and/or rotations between the two populations, but the results are inconsistent across studies. In one study, no differences were reported [25], yet in another, differences in the majority of the 3D PF displacements and rotations were reported [39]. This variability is likely the result of differences in measurement techniques, variables measured, and the presence of various types of maltracking patterns in the omnibus term of patellar maltracking [37,39].…”

“…As previous studies showed PF pain is associated with rotational and displacement variations in all three planes [39,48], these correlations were expanded to include all 12 PF motion parameters (the value of PF medial, superior, and anterior displacement along with PF flexion, medial tilt, and varus rotation and the slopes of each of these variables relative to knee angle). The secondary objective was to explore whether more than one maltracking pattern could be discriminated, based on PF displacements and rotations.…”