Quadriceps forces and patellar motion in the anatomical model of the patellofemoral joint

The effects of quadriceps muscle loading on three-dimensional patellar movements were studied in vitro with three patterns of muscle loading according to anatomical, mathematical and Q-angle models. Loading of the quadriceps based on the mathematical model resulted in more lateral patellar deviation, 0.5 ± 0.6 cm in 0°, and 0.6 ± 0.9 cm in 15° of knee flexion, than those of the other two models (P < 0.05). Loading based on the anatomical model resulted in more lateral patellar tilt, 2.0 ± 2.3° in 15°, and 1.3 ± 2.1° in 30° of knee flexion than the other two models (P < 0.05). The Q-angle model kept a neutral patellar position and was considered to be better than the anatomical or the mathematical model for the patellofemoral study using cadaver knees.