THE EFFECTS OF Q-ANGLES ON THE CONTACT BIOMECHANICS OF PATELLOFEMORAL JOINT

Abstract

METHODS The contact location, contact area and stress distribution of the patellofemoral joint were tested with the Fuji pressure sensitive film and the dyeing method in eight fresh human cadaver knee joints under the states of variety of Q-angles and knee flexion angles. The results indicated that, at physiological Q-angles, the patellofemoral contact location moved gradually from the inferior pole to the superior pole on the retropatellar articular surface. The contact area also enlarged with the increase of knee flexion angle, but the contact stress distribution kept uniform. The tendofemoral contact occurred after the knee flexion reached 80-90 degrees. These phenomena were important in protection of the articular cartilage from being damaged. As Q-angle increased or decreased, the contact location also diverged laterally or medially, the contact area did not change remarkably, but the contact stress distribution became uneven. CONCLUSIONS So the abnormal Q-angles should be thought as one of the potential pathogenic factors to patellofemoral joint disorders, which should be considered both in the procedure of patella realignment operation and in athlete selection.