Evaluation of patellar shape in the sagittal plane. A clinical analysis.

A prospective study of 564 patients was performed to assess the correlation between patellar shape as seen on a lateral radiograph and 1) patellar pain and 2) the radiologic determination of patellar height. A classification of patellar shape was developed based on the ratio of the patellar length to the length of the articular surface. Three classification types were established, including the "long-nosed," "Cyrano" type. Patients were placed into one of two groups based on the presence or absence of patellar pain. Lateral radiographs were evaluated for patellar height using two published indices. A significantly larger portion of Type II and Type III patellae was found in patients with patellar pain. Moreover, accepted measures of patellar height have to be used with caution in the presence of unusual patellar shapes.