Comparison of the peak and the loading rate of the knee abduction moment of women with and without patellofemoral pain during stair descent

Abstract

Patellofemoral pain (PFP) is characterized as peri- or retropatellar pain of insidious onset and exacerbated by activities that increase joint stress between the patella and the femoral condyle. It has a high occurrence in the young adult population, in which women are at higher risk of developing it. Several studies were performed to identify which are the biomechanical alterations responsible for the development of this disorder, however, the etiology remains unclear. Some studies have suggested that higher knee abduction moments can generate increased patellofemoral reaction forces and therefore cause the PFP. On the other hand, recently, it started to be speculated that the speed at which the abduction moment is applied also may influence the development of PFP. However, such a conjecture remains speculative and needs further investigation. Therefore, the objective of this study is to compare the peak and the loading rate of the knee abduction moment of women with and without DFP during stair descent. 15 women with and without DFP will be recruited for this study. kinetic and kinematic analysis will be performed during stair descent by means of a 9 camera system (Vicon Motion Systems Inc, USA) using 37 markers placed on established anatomical landmarks and a platform coupled to the staircase (Bertec Corporation, Columbus, OH). All statistical analyzes will be conducted in SPSS 18.0. Comparisons between groups will be performed by independent t test or Mann-Whitney test and the relationship between variables will be verified by the Pearson or Spearman correlation test, depending on the data distribution.