Patellar height ratios in children: an interobserver study of three methods.

Several indices for patellar height measurement have been described to relate patellofemoral instability and maltracking. No known study has proved interobserver reliability of these indices when applied to growing knees. This study included comparisons of three of these indices: Caton-Deschamps, Blackburne-Peel, and Koshino. Three observers measured patellar height on 36 lateral radiographs of children's knees. The best interobserver agreement was achieved by the Caton-Deschamps method, a simple, reliable, and reproducible index that is not affected by skeletal maturation.