Table 1.

Patellar height ratios and their values for classification of a patella norma, alta and infera

Method	Alta	Norma	Infera
Blackburne-Peel	> 1.0	0.8-1.0	< 0.8
Insall-Salvati	> 1.0	0.75-0.99	< 0.75
Caton-Deschamps	> 1.2	0.8-1.2	< 0.8
Linclau	> 1.2	0.9-1.2	< 0.9
Labelle-Laurin	See footnote	See footnote	See footnote

For Labelle-Laurin, a patella alta is defined when the proximal patella pole is beyond the tangent of the ventral cortical line; a patella norma is defined when the tangent of the ventral cortical line contacts exactly the proximal patellar pole; a patella infera is defined if the distance between the proximal patellar pole and the tangent of the ventral cortical line exceeds 5 mm