Regional distribution of microvasculature within the canine femoral head: a study of plastinated tissue histology and 3D reconstruction.

Abstract

Background: Understanding the intraosseous vascularity of the femoral head is important for preserving its structural integrity and function. Disruptions in microcirculation can lead to osteonecrosis of the femoral head (ONFH). This anatomical study aimed to quantify the regional distribution of the microvessels within the trabecular bone of the femoral head.

Methods: Eleven beagles (five males, six females) were infused with intra-aortic radiopaque silicon, followed by micro-computed tomography imaging and 3D modelling using Avizo. EXAKT non-decalcified plastinated tissue histology of the proximal femur was performed and quantified using the Bioquant Osteo semi-automated histomorphometry with ImageJ. Vascular diameter, density, length density, and osteochondral parameters were calculated and compared within the subcortical and central zones of the femoral head in both sexes.

Results: A well-developed intraosseous microvascular network was identified within the trabecular struts, resembling Volkmann's canals and integrating into Haversian system at the subchondral compact bone. Dense capillary networks traversed both trabecular and cortical bone to supply articular cartilage. Subcortical microvasculature was denser, with thinner diameters and shorter lengths compared to the central zone. The middle part of the femoral head displayed higher subcortical vascular density compared to superior and inferior parts. Strong positive correlations were observed between the endocortical area, tissue area, mean cortical width, bone surface and trabecular spacing. A moderate negative correlation was found between quiescent surface and cartilage density. No significant sex differences were observed in vascularity or bone metrics.

Conclusion: Based on the spatial distribution of the microvasculature, the central zone serves as a conduit for primary intraosseous blood vessels, supplying the subcortical zone, including the cortex and articular cartilage. These findings establish baseline reference values for normal intraosseous microvessels and bone metrics in canine anatomy, which can be utilized for diagnosing and treating osteochondral diseases.