The patellofemoral joint comprises the patella
and the femoral trochlea. The patella acts as
a lever and also increases the moment arm of
the patellofemoral joint, the quadriceps and
patellar tendons.8 Contact of the patella with
the femur is initiated at 20 degrees of flexion
and increases with further knee flexion,
reaching a maximum at 90 degrees.9
Stability of the patellofemoral joint
involves dynamic and static stabilizers (Figure
1), which control movement of the patella
within the trochlea, referred to as “patellar
tracking.” Patellar tracking can be altered
by imbalances in these stabilizing forces
affecting the distribution of forces along the