May the force be with you: understanding how patellofemoral joint reaction force compares across different activities and physical interventions – a systematic review and meta-analysis

Review written by Tom Goom info

Key Points

  1. This systematic review examined patellofemoral joint reaction force (PFJRF) during various activities and exercises as well as following physical interventions.
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Patellofemoral joint reaction force (PFJRF) is created by the tension in the quadriceps and patella tendon which drives the patella against the trochlear surface of the femur. It can increase due to greater quadriceps muscle force or increased knee flexion. In theory an increase in joint forces may influence symptoms in patellofemoral pain (PFP) so it is helpful for us to understand which activities may influence PFJRF.

This systematic review sought to examine PFJRF in daily activities, exercises and interventions, and to compare healthy individuals with those with PFP or osteoarthritis (OA).

Patellofemoral joint reaction force can increase due to greater quadriceps muscle force or increased knee flexion.
We could aim to decrease patellofemoral joint reaction forces in running by increasing the step rate to reduce patellofemoral load.


  • A comprehensive search strategy was used to identify relevant studies in key electronic databases. This was conducted in January 2019 and updated in November 2020. The reference list of these papers was then used to identity further research.
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