Normal values of 3 methods to determine patellar height in children from 6 to 12 years

The aim of the study was to compare three methods for high-score measurement in children, Caton-Deschamps, Blackburne-Peel and Koshino-Sugimoto, to determine the normal value of each method in a group of normal children.

A cross-sectional study on knee x-rays of normal children. Three orthopaedic surgeons measured the Caton-Deschamps, Blackburne-Peel and Koshino-Sugimoto indices. Concordance was assessed using the intraclass correlation coefficient. For interobserver variability, the measurements of each observer for each index were compared and for intraobserver variability, the coefficient between the 2 measurements was calculated by the same observer at 2 different times.

140 knee X-rays divided into 4 age groups were obtained. For the Blackburne-Peel index, an average median of the 3 observers was obtained of 1.07 and with P5-P95 (0.76-1.60). For the Caton-Deschamps index, an average median of the three observers of 1.22 was obtained and with P5-P95 (0.91-1.70). For the Koshino-Sugimoto index, we obtained an average median of the 3 observers of 1.16 and with P5-P95 (0.99-1.36).

This study shows that the Koshino-Sugimoto index had the highest reliability, reproducibility and similarity in the population studied, both intra-observer and inter-observer. The other methods evaluated also had variability indices to be taken into account, but were inferior to the Koshino-Sugimoto index.