Cortical bone has a higher strength in compression than in tension and is stronger in the longitudinal direction than in the transverse direction. For longitudinal loading, cortical bone is a tough material because it can absorb substantial energy before fracture.
What is cortical bone remodeling?
In cortical bone remodeling proceeds in tunnels with osteoclasts forming “cutting cones” removing damaged bone followed by refilling by osteoblasts in the “closing cone” occurring behind the osteoclasts .
Is cortical or trabecular bone stronger?
Cortical bone is stiffer and able to resist higher ultimate stresses than trabecular bone, but it is also more brittle [10,13,14]. Trabecular bone in vitro can withstand strains up to 30%, cortical bone fails with strains of only 2%.
What stimulates bone remodeling and strength?
The growth hormone/IGF-1 system stimulates both the bone-resorbing and bone-forming cells, but the dominant effect is on bone formation, thus resulting in an increase in bone mass. Thyroid hormones increase the energy production of all body cells, including bone cells.
Is cortical bone brittle?
Cortical bone is more brittle at high strain rates, and loading rate also has an effect on the accumulation of damage within bone tissue (2).
What is bone remodeling and why is it important?
Bone remodeling serves to adjust bone architecture to meet changing mechanical needs and it helps to repair microdamages in bone matrix preventing the accumulation of old bone. It also plays an important role in maintaining plasma calcium homeostasis. The regulation of bone remodeling is both systemic and local.
What is the purpose of cortical bone?
Cortical bone is the dense outer surface of bone that forms a protective layer around the internal cavity. This type of bone also known as compact bone makes up nearly 80% of skeletal mass and is imperative to body structure and weight bearing because of its high resistance to bending and torsion.
What triggers bone remodeling?
Bone remodeling is thought to be regulated by many factors including nutritional status, humoral factors, and biomechanical stress. However, the involvement of the autonomic nervous system, mainly the sympathetic nervous system (SNS), in the modulation of bone remodeling is beginning to receive more attention.
Why is cortical bone stronger than cancellous bone?
Cortical bone contributes about 80% of the weight of a human skeleton. It is much denser than cancellous bone, harder, stronger and stiffer. At the microscopic level, the structural arrangement of a cortical bone is different than cancellous. Compact bone consists of closely packed osteons or Haversian systems.
Which type of bone is stronger?
Long bones, however, are the most commonly loaded structures and therefore strongest load-bearing bones in the body, predominantly in the appendicular skeleton.
What is the difference between cortical bone and trabecular bone?
Trabecular bone has a large surface exposed to the bone marrow and blood flow, and the turnover is higher than in cortical bone . Resorption takes place along bone surfaces in the trabecular bone, whereas in the cortical bone, resorption tunnels through the bone itself.
How does exercise affect bone remodeling?
Because bone is living tissue, it changes over time in response to the forces placed upon it. When you exercise regularly, your bone adapts by building more bone and becoming denser. This improvement in bone requires good nutrition, including adequate calcium and Vitamin D.
What are the two main hormones that regulate bone remodeling?
PTH and PTHrP. PTH is a hormone synthesized and secreted by the parathyroid glands. The main function of PTH is to maintain blood calcium homeostasis. In addition, PTH regulates bone mass in an endocrine manner (52).
Why is bone remodeling important to fracture healing?
Remodeling is the final phase of bone healing. During this phase, solid bone continues to grow, and blood circulation improves at the fracture site.
What is the density of cortical bone?
The mass density of cortical bone ranges typically between 1.6 and 2 g.cm−3. The variations of mass density are due to a combination of variations of the bone volume fraction in a volume of interest (i.e., the bone is more or less porous) and the variations of the mass density of the extracellular mineralized matrix.
What is the range of typical intensity values for cortical and cancellous bone?
… the literature, depending on the measurement technique and parameters used, the source of bone and the structural variation in bone from the same source, a wide range of values has been reported for the compressive modulus of trabecular (0.12-1.1 GPa) and cortical bone (11.5-17 GPa) ( Table 2 ). …
What is measured by yield strength?
The yield strength is often used to determine the maximum allowable load in a mechanical component, since it represents the upper limit to forces that can be applied without producing permanent deformation.
What are characteristics of cortical bone?
Cortical bone is a dense tissue that contains less than 10% soft tissue. Cancellous or spongy bone is made up of trabecules shaped as plates or rods interspersed between bone marrow that represents more than 75% of the cancellous bone volume.
Does osteoporosis affect cortical bone?
With osteoporosis, there is reduced bone density and structure in the spongy bone, as well as thinning of the cortical bone. When your bones have thinned to the point that osteoporosis is diagnosed, the physical structure — and soundness — of your bones has changed. In particular: the cortical bone becomes thinner; and.
What is cortical bone made of?
Cortical bone is dense and solid and surrounds the marrow space, whereas trabecular bone is composed of a honeycomb-like network of trabecular plates and rods interspersed in the bone marrow compartment. Both cortical and trabecular bone are composed of osteons. Cortical osteons are called Haversian systems.
What two factors affect bone remodeling?
Bone growth factors affect the process of bone remodeling. These factors include insulin-like growth factors I and II, transforming growth factor beta, fibroblast growth factor, platelet-derived growth factor, and bone morphogenetic proteins. Bone volume is determined by the rates of bone formation and bone resorption.
What are the 4 stages of bone healing or remodeling?
ACTIVATION, RESORPTION, REVERSAL, FORMATION, and QUIESCENCE. The total process takes about 4 to 8 months, and occurs continually throughout our lives.
What happens if bone remodeling does not occur?
Failure to remodel bone can result in excessive microdamage burden, accumulation of advanced glycation end products (AGEs), and hypermineralization. Microdamage, left unrepaired, reduces the residual strength and stiffness of bone, and can lead to stress fractures.
What is cortical bone loss?
Bone is lost because remodelling becomes unbalanced after midlife. Most cortical bone loss occurs by intracortical, not endocortical remodelling. Each remodelling event removes more bone than deposited enlarging existing canals which eventually coalesce eroding and thinning the cortex from ‘within.
What is the word cortical mean?
Definition of cortical 1 : of, relating to, or consisting of cortex. 2 : involving or resulting from the action or condition of the cerebral cortex.