de Carvalho index (knee)

The de Carvalho index is used to measure patellar height and identify patella alta. Similar to the Caton-Deschamps index, it relies upon the length of the patellar articular surface and its distance from the tibia, reducing erroneous measurements in those with long patella bodies, as measured in the Insall-Salvati index.

Measurement

The de Carvalho index can be measured on a lateral radiograph or sagittal knee MRI. The original study performed measurements on lateral radiographs with the knee in 30º flexion ¹. 

F: the shortest distance between the tibial plateau and the most inferior aspect of the patellar articular surface

D: patellar articular surface length

de Carvalho index = F / D

Interpretation

• patella alta: > 1.11

See also

• Insall-Salvati index
• modified Insall-Salvati index
• Caton-Deschamps index
• Blackburne-Peel index