[Critical study of patella alta. I. Comparison of results of methods for measuring patellar height in 100 control subjects].

The vertical patellar position is a function of patellar tendon length. Various easily-performed radiological techniques can be used to establish indices which define patellar height. 200 measurements were carried out on 100 control subjects who were free of knee joint pathology, and the various techniques were subsequently compared. Insall's index which is calculated as patellar tendon length over patellar length appears to be the most convenient measurement to use. When it is difficult to precisely determine the patellar tendon's lower insertion on the tuberosity of the tibia, Caton's or Blackburne and Peel's indices are preferable. Blummensaat's line does not seem to be dependable in view of the variations which were observed.