Establishing Baseline Radiological Metrics of the Talus and Calcaneus: A Retrospective Analysis of Computed Tomography Imaging in an Irish Cohort

Introduction The subtalar joint anatomy is complex and heterogeneity in its morphology creates unique challenges for foot and ankle surgeons. Anatomical metrics used for prosthesis design are well established. However, there is a paucity of literature quantifying foot and ankle measurement techniques and metrics used for prosthesis design. The aim of this study was to document reproducible measurement techniques and quantify talar and calcaneal metrics in a sample of Irish patients on computed tomography imaging to aid in the design of a novel hindfoot plate. Methods A retrospective analysis of consecutive foot and ankle computed tomography images performed at our institution was undertaken. Five measurements were performed on each foot and ankle image. Statistical analysis was performed to identify if a correlation existed between measurements. Results Sixty-four CTs met the inclusion criteria. Talar body height 27.1 mm (SD 2.17 mm), talar neck width 32.7 mm (3.16 mm), talar head height 25.41 (SD 2.16 mm), lateral process to posterior talus 23.6 (2.64 mm), calcaneal height 43.8 mm (SD 3.9 mm). A positive correlation was identified between all measurements. Conclusion This study identified that there was a low degree of heterogeneity in talar and calcaneal measurements in an Irish cohort. Furthermore, the metrics used in this study will provide valuable information for the preliminary design of a novel hindfoot plate.