Anatomic variations of the knee extensor mechanism may result in predisposition to maltracking or instability of the patella and quadriceps mechanism. In addition to these anatomic variations, individuals may subject their knees to a wide variety of activities and stresses. Each case of patellofemoral dysfunction, which may range from only anterior knee pain to patellar dislocation, must be considered individually. In the presence of maltracking or patellar instability that is recalcitrant to rehabilitation, there is no single structure which can be surgically altered, repaired, or reconstructed in each case to expect a satisfactory result. The purpose of this article is to describe recent work on the anatomy and biomechanics of the patellofemoral joint to aid the reader in understanding, assessing, and determining the method of treatment most likely to result in improvement in symptoms associated with patellofemoral dysfunction.