Fig. 4
From: Increased lower limb length ratio in patients with patellar instability
Patellar height measurement methods. a Insall–Salvati ratio: Ratio of the length of the patellar tendon (A) (measured from the distal pole of the patella to the tibial tuberosity) to the diagonal length of the patella (B) (measured from the distal pole to the proximal pole of the patella). b Blackburne–Peel ratio: Ratio of the height of the distal pole of the patellar articular surface above a tibial plateau line (A) to the articular surface length of the patella (B). c Caton–Deschamps ratio: the distance between the distal point of the patellar articular surface and the anterosuperior border of the tibia (A) divided by the length of the articular surface of the patella (B). d Modified Insall–Salvati ratio: Ratio of the distance between the distal end of the articular surface of the patella and the patellar tendon insertion on the tibia (A) to the length of the articular surface of the patella (B)