We all see people with patellofemoral pain. Some of those cases may have responded to orthotic therapy. Some studies show that the effects on frontal plane kinematics are minimal (1 degree); this doesn’t mean it didn’t work, or this amount is not clinically significant. So why do they help? Perhaps it is a “timing” issue and the knee abduction moment.
“Our results are consistent with a 2003 study by Mundermann et al that compared the effects of custom orthoses (with posting, molding, or a combination of both) to flat inserts. For each orthotic condition, these authors reported a significant delay in the timing of the peak knee abduction moment. This finding may be related to the aforementioned clinical effects, as delaying the peak knee abduction moment would effectively decrease the rate of loading at the knee joint. The rate of loading has been previously implicated as a possible contributing factor in running-related overuse injuries, as runners with a history of injury have demonstrated a higher rate of loading of the vertical ground reaction force than runners with no history of running-related injury.”
This is an interesting take. If you have a few moments, give it a read: