Association between regional heterogeneity in the mid-facial bone micro-architecture and increased fragility along Le Fort lines.

Abstract

Le Fort lines have traditionally been considered as zones of weakness in the mid-facial skeleton although the structural basis of increased bone fragility at these sites has not yet been investigated. Considering recent findings of occlusal loading-related regional heterogeneity in the mid-facial bone micro-architecture, the aim of this study was to explore whether such heterogeneity in cortical and cancellous bone micro-architecture may contribute to increased fragility at Le Fort fracture sites. Twenty-five cortical and thirteen cancellous bone specimens were harvested from a dry skull and analyzed by micro-CT. Specimens were classified into Le Fort or Non-Le Fort groups based on their location in the mid-facial skeleton. Cortical bone along Le Fort lines showed tendencies toward lower thickness (1.5±0.63 vs 1.75±0.79; P=.39) and greater porosity (11.48±5.67 vs 10.28±5.28; P=.59). A significant difference was detected in the trabecular degree of anisotropy which was higher in cancellous bone from Le Fort fracture sites (2.14±0.69 vs 1.58±0.34; P=.02). Regional heterogeneity in cortical bone micro-architecture could not fully explain increased fragility of the mid-facial skeleton at the Le Fort lines. However, regional differences in trabecular bone anisotropy may contribute to increased bone fragility.