Tarsal shape, size, and articulating surface morphology in adolescent surgically treated clubfoot and their contralateral normal foot

Despite the inability of radiographic measurements to quantify the 3-dimensional (3D) shape and size of the hindfoot bones affected by the clubfoot pathology, radiographs continue to be used to evaluate treatment efficacy. Advancements in imaging and image analysis allow new quantitative insights to be obtained into bone shape and size. Therefore, this study sought to quantify and compare the 3D size, shape, and articulating surface morphology of the tibia, talus, calcaneus, navicular, and cuboid bones in the adolescent surgically treated unilateral clubfoot and the contralateral normal foot. Anatomic measurements were obtained by geometrically modeling 3D reconstructed magnetic resonance images of the hindfoot tarsals in the feet of 7 adolescents (mean age, 13.0 ± 2.8 years). The results showed that the tarsal bones in the surgically treated clubfoot were smaller in volume (20%-36%) and smaller in surface area (16%-28%) than those in the contralateral normal foot. Correspondingly, the size and shape of the articulating surfaces of these bones in the surgically treated clubfoot were also smaller and flatter than those in the contralateral normal foot. Specifically, the mean talar articular surface area was 25% to 40% smaller, the mean talar-tibiotalar articular surface length was 26% smaller, the mean tibiotalar articular surface length difference was 78% smaller, and the mean navicular "flattening index" was 86% larger in the surgically treated clubfoot. These data offer an objective standard that will advance the knowledge of the clubfoot pathology and aid treatment efficacy evaluation.