3D reconstruction of the skeletal anatomy of the normal neonatal foot using 3D ultrasound.

Currently imaging plays a limited role in the assessment of the neonate with a foot deformity. The aim of this study was to establish a technique for examining the neonatal foot with three-dimensional ultrasound (3D US). 3D US was attempted on the normal feet of 20 infants (9 male, 11 female) under 6 weeks old (range 35-41 days). The data sets were obtained whilst the infants were feeding or asleep to minimize movement artefact. A high-resolution optically tracked freehand 3D US system (Diasus, 16 MHz transducer) was used with Stradx software to acquire and analyse the data sets. Manual segmentation of the non-ossified tarsi from the data sets was performed. Five infants were too restless to be examined. 107 data sets were recorded from 22 feet of the remaining 15 infants. 21 of the data sets were discarded due to movement artefact. 86 were suitable for manual segmentation. Surface interpolation of the segmented data sets produced surface rendered reconstructions illustrating the complex 3D anatomy of the foot. This new technique may offer a method of examining the deformed foot, e.g. congenital talipes equinovarus.