Patellofemoral Tracking Resulting From Decreased Activation Of The Vastus Medialis Muscle
Patellofemoral pain is one of the most frequent knee conditions seen by sports medicine providers. Dysfunctional tracking of the patella is thought to be a cause. The purpose of this project was to determine if reduced maximal strength of the vastus medialis would cause muscle forces in a model to increase laterally directed patellar forces or torsion.
2 participants completed 5 maximum effort jumps and landings. Models were made in Matlab to calculate torques required to produce the given motion. The model was altered to reduce the force producing capability of the vastus medialis. The patellar tendon force was calculated for decreased amounts of normal force producing capabilities. Paired T-tests were utilized.
The reduced maximum force producing capabilities of the vastus medialis decreased its estimated muscle force and increased the vastus lateralis muscle force in order to create enough torque to produce the movement. Peak patellar mediolateral forces were decreased by 0.5% from the 100% condition to the 50% condition while peak patellar torsion was decreased by 4.9%.
The expected effects of decreased vastus medialis strength were produced by the models. This resulted in small decreases in laterally direct patellar forces and somewhat larger decreases in patellar torsions.