The purpose of this study was to assess the correlation between patellar shape and knee pain and to determine the effectiveness of quadriceps setting exercise for the relief of knee pain. The lateral radiographs of the 34 patients with knee pain and 44 control group were analyzed with respect to patellar shape by computing the ratio of patellar length to the length of the articular surface(morphology ratio). The 34 patients performed quadriceps setting exercise daily for 12 months.

Pain disability index was scored by patients at the beginning and at the end of the 12-month exercise. Three types of patellae were established by morphology ratio. A significantly larger portion of type II and type III patellae was found in patients with knee pain. After 12-month quadriceps setting exercise significant decrement of pain disability index was noted. In conclusion patellar shape in the sagittal plane can provide useful information to the clinician about patients with knee pain.