The knee joint is very complex in terms of degrees of mobility and for normal biomechanics it is necessary for all the anatomical structures at this level to be within physiological limits. Problems can be caused by a number of risk factors such as age, sex, weight, or local risk factors such as patellar changes represented by patela alta or patella baja, which can lead to instability of the lower limb. Risk factors that may influence the development and progression of knee osteoarthritis have been evaluated. Changes in patellar position in relation to knee osteoarthritis were also studied. A group of 377 patients hospitalized for unilateral or bilateral knee pain with instability were included in the study. 239 of the 377 starting group presented knee osteoarthritis, constituting the study group. The risk factors analyzed were age, patient sex, BMI, weight status, anatomical changes in position of the patella (patella alta and patella baja), COBB angle and spine deviation. The results indicated that obesity, anatomical changes in the position of the patella, (patella alta), COBB angle and spine deviations represent significant risk factors in the onset of knee osteoarthritis.