Analysis of the hip torque and kinematics of the femur and rearfoot considering the ascending and descending theories as causal factors of patellofemoral pain

Abstract

Patellofemoral pain (PFP) is most frequently diagnosed in women. PFP is characterized as anterior, peri or retropatellar pain that is aggravated by activities that increase knee flexion, such as stair climbing. The main factor responsible for PFP development is increase stress in the patellofemoral joint (PFJ) which is related to excessive femoral internal rotation. However, there is no agreement with regard to which factors would be responsible for poor femoral motor control. Changes in hip (descending theory) and rearfoot (ascending theory) could be the cause of excessive femoral movement in the transversal plane. Moreover, it is difficult to transpose these biomechanical findings for clinical practice. Therefore, the aim of this study is to investigate the torque of the hip muscles and femoral/ rearfoot kinematics in women with and without PFP to elucidate which theory (ascending or descending) present more relationship with PFP. Therefore, will be performed (i) comparisons between isokinetic torque of the hip muscles and comparisons of the joint angles of the femur and rearfoot eversion in women with and without PFP; (ii) correlations between ascending/descending theories and femoral internal rotation angles; and (iii) correlations between variables and functional tests (step down and forward step down) and investigate whether the kinematic and kinetic changes are able to predict the results of functional tests. Women with PFP (PFP group) and pain-free (control group) will be selected, and then, will perform an experimental protocol consisting of 2 stages, on different days: kinetic and kinematic analysis. Initially, participants will perform a muscle torque test with an isokinetic dynamometer. Kinematic analysis will be performed in another day and participants will perform 5 stair climbing movements in an experimental set up composed by 9 cameras for captation of femur and rearfoot eversion joint angles. It is expected that the findings of this study will present a decrease in the isokinetic torque of hip muscles and increase femoral internal rotation and rearfoot eversion in women with PFP. Furthermore, it is believed that at least one of these theories (ascending and descending) will be strongly correlated with femoral internal rotation in women with PFP. Regarding to functional tests, it is expected that there is correlation between at least one variable analyzed with at least one of the tests, and also that the kinematic and kinetic changes possibly found to be able to predict the outcomes of functional tests. (AU)