Ossification of the phalanges of the foot and its relationship to peak height velocity and the calcaneal system

PURPOSE: There are multiple skeletal maturity grading systems, but none of them utilizes the phalanges of the foot. To minimize radiation, it would be ideal if one could assess the skeletal maturity of a foot based on bones seen on routine foot radiographs, if guided growth is being considered as a treatment option. We developed a system that correlates changes of the appearance of the foot phalanges to peak height velocity (PHV) and the recently described calcaneal apophyseal ossification grading system. METHODS: We selected 94 children from the Bolton-Brush study, each with consecutive radiographs from age ten to 15 years old. Using the anteroposterior view, we analyzed the ossification patterns of the phalanges and developed a six-stage system. We then determined the PHV for each subject and defined its relationship with our system. Our system was then compared with the previously established calcaneal system. RESULTS: We calculated an Intraclass correlation coefficient (ICC) range of 0.957 to 0.985 with a mean of 0.975 and interclass reliability coefficient of 0.993 indicating that this method is reliable and consistent. Our system showed no significant difference between gender with respect to PHV, which makes it a reliable surrogate for determining bone age in paediatric and adolescent patients. CONCLUSIONS: Our system has a strong association with the calcaneal system. It is a simple six-stage system that is reliable and correlated more strongly with PHV than chronological age. The system requires knowledge of the ossification markers used for each stage but is easily used in a clinical setting.