Knee is a middle joint in lower extremity and has relationship with hip joint and ankle joint alignment. Therefore the knee joint alignment is very important in aspect of biomechanically. Knee joint alignment depend upon patellar stability. Instability of the patellofemoral articulation, in the form of patellar subluxation or dislocation may be associated with a number of factors. Normal range of patellofemoral angle is very different by the reporter and by the gender also.