Comparison of Exercise Therapies for Patellofemoral Pain

Patellofemoral Pain (PFP) is a common knee problem, primarily affecting adolescents and young adults. PFP is characterised by significant retropatellar and/or peripatellar pain and impairment of function and quality of daily life. Exercise therapy is unequivocally recommended as a core component of the management of PFP. Different exercise types (e.g. quadriceps strengthening, hip strengthening and functional/neuromuscular exercises) have been investigated, with knee and hip strengthening exercises as the most common and recommended types. These exercises approaches produce similar small to moderate effects on pain and physical function. However, the PFP population is very heterogeneous and "one-size-fits-all"-approaches presumably are sub-optimal because the heterogeneity is ignored. The heterogeneity probably explains the overall limited beneficial effects of exercise, and the lack of differences in direct comparisons of different exercise types. In that sense, it is not unlikely that certain patient characteristics may predict outcome success of either a hip training program or a training program that focus on the quadriceps but this remains to be shown. This study has two aims: 1. To assess the comparative effectiveness of two different exercise programs (Quadricep Exercise \[QE\] vs. Hip Exercise \[HE\]) on self-reported pain and function in individuals with PFP. 2. To explore candidate patient characteristics that predict differential responses to the two exercise programs (QE vs HE) on self-reported pain and physical function in individuals with PFP. According to the study aims we pursue the following hypothesis: \- QE and HE have equivalent efficacy on self-reported pain after 12 weeks of treatment in patients with PFP. The second study aim is to explore possible candidate patient characteristics that may associate with differential outcomes. As this is exploratory, the pursuit of this aim is hypothesis-free.