The vertical position of the patella estimated by four radiographic measurements

The methods of Insall and Salvati, Blackburne and Peel, Caton and Laurin of assessing the vertical position of the patella, were applied on 200 normal knees. The indices for Insall and Salvati's, and Blackburne and Peel's methods were 1.07 +/- 0.25 and 0.78 +/- 0.19 respectively, independent of sex and flexion of the knee. The measurements for Caton's index were 0.95 +/- 0.24 and 0.88 +/- 0.22 at kneeflexions of 45 degrees and 90 degrees. Laurin's method was insufficient as it showed 50% of the patellas to be high riding. The different methods were compared. The technique of Insall and Salvati was a reliable and applicable method, and is therefore recommended for routine use.