Morphometric Analysis of the Canal System of Cortical Bone: An Experimental Study in the Rabbit Femur Carried Out with Standard Histology and Micro‐CT

Abstract

SummaryThe osteonal pattern of cortical bone is gradually built around the intracortical vessels by the progression of the cutting cones (secondary remodelling); therefore, the central canal size can be used as index of the remodelling activity. An experimental model in the rabbit femur was used to investigate, through central canal morphometry and frequency distribution analysis, the remodelling activity, comparing the middle of the diaphysis (mid-shaft) with the extremity (distal-shaft) and at the same level sectors and layers of the cortex in transversal sections. The study documented a higher density of canals in the mid-shaft than in the distal-shaft and a higher remodelling in the distal-shaft. There were no significant differences between dorsal, ventral, medial and lateral sectors at both midshaft and distal-shaft levels, while the number of canals was higher in the sub-periosteal layers than in the sub-endosteal. A lower threshold of 40 lm 2 was observed in the central canal area. Sealed osteons in the midshaft were 22.43% of the total number of osteons of the central canal area between 40 and 200 lm 2 and 0.44% of those of the distal-shaft. Micro-CT allowed a 3D reconstruction of the vascular canal system, which confirmed the branched network pattern rather than the trim architecture of the traditional representation. Some aspects like the lower threshold of the central canal size and the sealed osteons documented the plasticity of the system and its capacity for adaptation to changes in the haemodynamic conditions.

A comparison of the microarchitecture of lower limb long bones between some animal models and humans: a review

“…In addition, a similar osteon arrangement was found in the sheep radius where osteons are slightly twisted orientated from the bone axis and in the dog femur where osteons are orientated in a helical way around the bone shaft in a clockwise direction in the right femur, and in the same pattern but counter clockwise in the left femur (Cohen and Harris 1958;Mohsin et al 2002). Table 2 shows the values of Haversian canal density in the cortex of the femur at different anatomical Pazzaglia et al 2010 locations in humans and rabbits, depending on sex and age. Haversian canal density in the femoral middle shaft in rabbits is higher than in the distal shaft, which is accordant with the fact that the presence of blood vessels in the middle shaft is higher than in the distal shaft (Pazzaglia et al 2008(Pazzaglia et al , 2010.…”

“…The diameter of the Haversian canal in rabbit femur in two different studies by Martiniakova et al (2008) and Pazzaglia et al (2010) are closely matched despite the differences in age of the tested animals ( Table 1). The primate genus Rhesus has osteon and Haversian canal diameters most similar to humans (Table 1), probably because of genetic similarity and similar demands during locomotion.…”

“…Canal openings on the endosteal surface in the middle shaft have an oval shape and diameters of between 30 µm and 1000 µm (Pazzaglia et al 2009). Five different shapes of canals were found in rabbit femoral cortical bone: cylindrical 39.2%, conical with proximal openings 9.4%, conical with distal openings 35.1%, elliptical 12.2% and hyperbolic 4.1% (Pazzaglia et al 2010). Cooper et al (2006) reported that cylindrical canals are located in primary osteons and in secondary osteons with lamelar apposition.…”

“…Table 2 shows the values of Haversian canal density in the cortex of the femur at different anatomical Pazzaglia et al 2010 locations in humans and rabbits, depending on sex and age. Haversian canal density in the femoral middle shaft in rabbits is higher than in the distal shaft, which is accordant with the fact that the presence of blood vessels in the middle shaft is higher than in the distal shaft (Pazzaglia et al 2008(Pazzaglia et al , 2010. Additionaly, Haversian canal density is significantly higher in the subperiosteal than the subendosteal part of the cortex which is probably the result of intensive remodelling in the subperiosteal area (Pazzaglia et al 2010).…”

“…Recently, however, great progress has been made in this field (Hert et al 1994;Bagi et al 1997;Ardizzoni 2001;Sugawara et al 2005;Tromp et al 2006;Cooper et al 2007;Mavropoulos et al 2007;Martiniakova et al 2008;Britz et al 2009;Pazzaglia et al 2010;Schneider et al 2010). Nevertheless, only a few papers comparing bone microarchitecture between animal models and humans have been published so far (Jowsey 1966;Bagi et al 1997;Pearce et al 2007).…”