Histological predictors of unsatisfactory regeneration of nasal bones

The nasal bones are key elements in the architecture of the back and outer contour of the nose. The protruding position of the nasal bones relative to other bones of the facial skeleton makes them vulnerable to various injuries. Even decades after the injury, radiological diagnostic methods can reveal signs of fractures and surgical interventions on the nasal bones. This fact, along with the high frequency of nasal injuries, highlights the need to study the causes of limited regeneration of nasal bones. A similar pattern is observed in the flat bones of the cranial vault, which, like the nasal bones, are formed through intramembranous ossification, which suggests the presence of common mechanisms underlying limited reparative regeneration.

Purpose: To identify the histological features of nasal bones caused by intramembranous osteogenesis, which serve as predictors of their unsatisfactory regeneration.

Materials and methods: The study was performed on nasal bone fragments obtained during reduction rhinoplasty in 10 middle-aged patients with rhinocyphosis and rhinocypholordosis. Samples were subjected to standard histological processing with hematoxylin and eosin staining, according to Van Gieson and Picro-Mallory. Morphometric analysis was performed.

Results and discussion: Histological examination of the nasal bones revealed the following features: the absence of spongy bone tissue, significant depletion of the periosteum by blood vessels in combination with the absence of the cambial layer, as well as insufficient blood supply to the compact bone substance. The above-mentioned morphological features of the nasal bones lead to a shortage of specialized niches where mesenchymal stem and osteoprogenitor cells are localized, which are the main sources of bone tissue regeneration. In the compact substance, thinning and resorption of the outer shingles of bone plates is noted, and the preservation of haversov systems of early generations. All of the above also indicates a weak level of bone remodulation of the nasal bones in postnatal osteogenesis. The main place preserving the cellular osteoprogenitor potential, on the side of the nasal bridge, is the nasal suture.

Conclusion: The intramembranous type of osteogenesis, leading to specific histoarchitectonics of bone tissue, determines the unsatisfactory regeneration of nasal bones.