Spatial structure of talus trabeculae based on high resolution X-ray and micro-CT

Abstract

Objective: To study the specific alignment and structure of cancellous bone within the talus in order to understand the mechanism of force transmission within the bone and to provide some theoretical basis for the repositioning of talar fractures and the design of prostheses. Methods: In January 2020, a total of 40 adult talar bone specimens were scanned by Micro-CT in 20 pairs obtained from the Department of Orthopedics of Tianjin Hospital. The bone volume fraction, bone surface area fraction, trabecular thickness, number of trabeculae, trabecular pattern factor of the head, neck and body of the talus were calculated, and the differences in each parameter were compared between different parts of the same side and different sides of the same part, respectively. The talus was cut into 2 mm thick slices in the coronal, sagittal and horizontal planes using a hard tissue slicer, and the slices were then scanned using high-resolution X-rays to describe the bone structure. Results: There were no statistically significant differences between the medial and lateral talar and right and left side in lateral trabecular bone volume fraction, bone surface area fraction, trabecular thickness, trabecular number, trabecular pattern factors (all P>0.05). The number of trabeculae in the talar head, neck and body was 1.608±0.150, 1.639±0.142 and 1.749±0.159, respectively; trabecular thickness (μm) in the talar head, neck and body was 0.378±0.054, 0.370±0.053 and 0.331±0.062, respectively; and the trabecular pattern factors (mm-1) in the talar head, neck and body was -0.407±0.699, -0.478±0.848 and -1.029±0.851, respectively. There were significant differences between talar head, neck and the talar body trabeculae in terms of the number of trabeculae, trabecular thickness,trabecular pattern factor parameters(all P<0.05). The structure of the talar body trabeculae was found to consist of plate trabeculae arranged vertically parallel to each other in the coronal, sagittal and horizontal planes. The talar neck trabeculae were twisted, external-superior to internal-inferior reticular plate structure that travelled posteriorly and anteriorly, and the talar head trabeculae consisted of similarly parallel aligned semi-arc-shaped external-superior and internal-inferior trabeculae. Conclusion: The talar trabeculae are clearly directional and functional, so anatomical reduction should be achieved after the fracture; at the same time, the design of the talar prosthesis should take into account the stress distribution and direction of the prosthesis during walking and standing.