Lateral Cuneiform Ossification and Tibialis Anterior Tendon Width in Children Ages 3 to 6: Implications for Interference Screw Fixation of Tibialis Anterior Tendon Transfers in Children

Background: While the transfer of the tibialis anterior tendon (TAT) to the lateral cuneiform (LC) following serial casting has been used for nearly 60 years to treat relapsed clubfoot deformity, modern methods of tendon fixation remain largely unstudied. Interference screw fixation represents an alternative strategy that obviates concerns of plantar foot skin pressure-induced necrosis and proper tendon tensioning associated with button suspensory fixation. A better understanding of LC morphology in young children is a necessary first step in assessing the viability of this fixation technique. Therefore, the purpose of this investigation is to define LC morphology and TAT width in children aged 3 to 6 years. Methods: A retrospective radiographic review of 40 healthy pediatric feet aged 3 to 6 years who had either magnetic resonance imaging or computed tomography scans was performed at a single pediatric hospital. The length, width, and height of only the ossified portion of the LC were measured digitally using sagittal, coronal, and axial imaging. In addition, the maximal cross-sectional diameter of the TAT was measured at the level of the tibiotalar joint. Results: The average ossified LC width ranged from 8.5 mm in the 3-year-old cohort to 10.3 mm in 6-year-old children. Analysis of variance testing revealed no statistically significant difference in width between age groups. Average ossified LC length ranged from 13.5 mm in the 3-year-old cohort to 18.3 mm in 6-year-old children with statistically significant increases in age groups separated by 2 or more years. Significant differences in LC height, volume, and TAT diameter were demonstrated after analysis of variance testing. The TAT to ossified LC width ratio ranged from 44% to 53% across age groups. Conclusions: The dimensions of the LC ossification center are large enough to allow interference screw fixation in children 3 to 6 years of age. Further studies are needed to investigate interference screw fixation performance in the pediatric clubfoot population. Level of Evidence: Level IV.