Patella Position in the Normal Knee Joint

A method for deriving a more convenient expression of patella position than those currently in use is described. Lateral radiographs of 114 normal knees were measured and the diagonal length of the patella was compared with the length of the ligamentum patellae. It was found that both measurements were approximately equal and that normal variation did not exceed 20%. The ratio of the patella to the patellar ligament may therefore be used as an index of patella height.