Comparison of the volumetric composition of lamellar bone and the woven bone of calluses

Abstract

Woven tissue is mainly present in the bone callus, formed very rapidly either after a fracture or in distraction processes. This high formation speed is probably responsible for its disorganized microstructure and this, in turn, for its low stiffness. Nonetheless, the singular volumetric composition of this tissue may also play a key role in its mechanical properties. The volumetric composition of woven tissue extracted from the bone transport callus of sheep was investigated and compared with that of the lamellar tissue extracted from the cortical shell of the same bone. Significant differences were found in the mineral and water contents, but they can be due to the different ages of both tissues, which affects the mineral/water ratio. However, the content in organic phase remains more or less constant throughout the mineralization process and has proven to be a good variable to measure the different composition of both tissues, being that content significantly higher in woven tissue. This may be linked to the abnormally high concentration of osteocytes in this tissue, which is likely a consequence of the more abundant presence of osteoblasts secreting osteoid and burying other osteoblasts, which then differentiate into osteocytes. This would explain the high formation rate of woven tissue, useful to recover the short-term stability of the bone. Nonetheless, the more abundant presence of organic phase prevents the woven tissue from reaching a stiffness similar to that of lamellar tissue in the long term, when it is fully mineralized.

Evolution of relaxation properties of callus tissue during bone transport

“…This fact would lead to a quick relaxation of stresses. As time passes, the mineral phase becomes more and more present, 15 so hindering water from flowing and slowing down relaxation, but making the tissue stiffer.…”

Anatomical characteristics of the alveolar process and basal bone that have an effect on socket healing

“…12,30 The woven bone eventfully occupies the entire socket, but it is a highly disorganized tissue, with no load-bearing property and, consequently, it needs the protection of the socket walls to prevent interrupted blood supply. 32,34,35 Concomitantly, the hard tissue walls of the socket, mainly bundle bone, are gradually resorbed. 2,15 The inflammatory and proliferative phases of the socket healing process are now complete.…”

“…Constant and rich blood supply will bring in the area calcium and phosphate, that are fundamental components for hydroxyapatite (Ca 10 [PO 4 ] 6 [OH] 2 ) assemble 12,30 . The woven bone eventfully occupies the entire socket, but it is a highly disorganized tissue, with no load‐bearing property and, consequently, it needs the protection of the socket walls to prevent interrupted blood supply 32,34,35 . Concomitantly, the hard tissue walls of the socket, mainly bundle bone, are gradually resorbed 2,15 .…”

Current State of Bone Adhesives—Necessities and Hurdles

“…A third cell type (osteocytes) participates in bone remodeling by operating the process in response to external pressures. These cells receive and provide information by sensing mechanical stresses and transfer the information via biochemical signals, such as sonic hedgehog [59,60]. Osteocytes are interconnected to each other via long cytoplasmic extensions that occupy tiny canals (canaliculi) serving as the exchange pathway of nutrients and cellular wastes [61].…”