[2 new methods for determination of the height of patella]

A short review of the literature on various methods of determining the height of the patella in the sagittal plane is given. These methods are critically appraised. Two new measuring techniques based on other well-known ones are presented which have a number of advantages over those currently used. The accuracy of the two methods is about the same. The new patellar height angle is recommended. Both methods use the distal end of the femur as a reference and depend on the degree of bending of the knee on lateral films. Since, for technical reasons, a standardized lateral view, e.g., with 30 degrees flexion, is not feasible, both methods require a conversion table which indicates the knee-bending angle to within 5 degrees. In order to differentiate better between a knee cap at normal height and a patellar dystopia an intermediate or transition zone is stipulated. Measuring of the height of the patella requires more knowledge and experience than is generally realized. There is still no really convincing and absolutely reliable measuring method.