2.1 A semi-mechanistic bone remodeling theory As opposed to soft biological tissues, which can experience both appositional and interstitial growth, hard biological tissue can experience just appositional growth because of the nonexpendable nature of the bone matrix [16, 17, 2829]. The proposed regulatory process of spongy bone remodeling, as proposed by Huiskes et al. [1920], can be seen in Fig. 1. Bone remodeling is depicted as a coupled process of bone resorption and bone formation on the bone free surface. Osteoclasts are assumed to resorb bone stochastically, and osteocytes are suggested to act as SED rate sensing cells, and play a role in the regulation of bone remodeling. It is assumed that osteocytes locally sense the SED rate …show more content…
This two-dimensional model was a square domain of 1.52×1.52 mm2 and was divided into 38×38 rectangular four-node elements. Relative (or apparent) bone density (m) per element is considered to vary between 0.01 (no bone, just bone marrow), and 1.0 (no void, fully solid mineralized bone) (see Fig. 2). In this study, the criterion of m for separating bone matrix from bone marrow in the configuration was assumed to be 0.4. In order to apply external loads to our 2D computer model, the perimeter of the square domain was assumed to be surrounded by a band. The thickness of the band was one element, equal to 40 µm. This band did not participate in the bone remodeling process, and the load was applied at the edge of the bone model. In order to minimize the effect of stress shielding caused by continuous band corners, no external load was imposed on the corner of the band (see Fig. 2), and the material properties of the band were the same as those of a fully mineralized trabecular bone tissue, which were given a Young 's modulus of 5GPa and a Poisson ratio of 0.3. The structure was loaded by a sinusoidal stress, cycling between 0 and 2MPa, and at frequency of 1Hz [1920]. The semi-mechanistic bone remodelling theory assumed that the stimulus sensed by osteocytes is the maximal SED-rate during one loading cycle. It has been shown that the maximum SED-rate can be substituted by the SED value for some static load [3132]. Hence, the bone remodeling process can be evaluated by static finite element analysis. In this study, the SED value was calculated using a substitute static stress of 4MPa
However some of the basic bone functions include storing of crucial nutrients, minerals and lipids, producing red blood cells for the body, protect the organs such as heart, ribs and the brain, aide in movement and also to act as a buffer for pH. With the differences in all of the bones there are four things that remain the same in each bone, their cells. Bones are made up of four different cells; osteoblasts, osteoclasts, osteocytes and bone lining cells. Osteoblasts produce and secrete matrix proteins and then transport the minerals into the matrix. Osteoclasts are responsible for the breaking down of tissue. The osteoblasts and osteoclasts are both responsible for remodeling and rebuilding of bones as we grow and age. The production of osteoclasts for resorption is initiated by the hormone, the parathyroid hormone. Osteocytes are the mature versions of osteoblasts because they are trapped in the bone matrix they produced. The osteocytes that are trapped continue making bone to help with strength and the health of the bone matrix. The bone lining cells are found in the inactive bone surfaces which are typically found in
An osteoblast is a “baby” bone cell whose main job is to secrete osteoid which forms the hardened, or calcified, bone matrix. Osteocytes are formed from osteoblasts. Osteocytes are the mature bones cells that have been completely differentiated. They are found in the lacunae of hard bone and have a spider-like appearance due to their canaliculi. Osteoclasts are a different type of cell formed from the mesenchymal cells. These cells are not related to osteoblasts or osteocytes. Their job is to basically “eat” the bone to create cavities and other hallow spaces during bone remodeling. Finally, the cells form differentiate to form fibroblasts and fibrocytes. These fibroblasts and fibrocytes secrete and form the matrix for fibrous connective tissue which is an essential component of the
So far, various techniques have been used for reconstruction and regeneration of maxillary and mandibular bone defects. Autogenous bone grafting, guided bone regeneration (GBR), distraction osteogenesis and nerve transpositioning are among these regenerative techniques (1-8). Decision making for the treatment could be influenced by the type, size and location of the bone defects (2, 3, 9, 10). GBR had high success rate in treating small alveolar defects such as dehiscence or fenestration. Regenerative bony walls around the defect with ingrowing blood vessels can begin osteogenesis (11) larger bone defects with insufficient regenerative walls and an low quality avascular bed need varied amount of autogeneous bone graft from extra oral or intra oral donor sites, however, the patient may suffer from complications in donor site as well as bone graft resorption.(10, 12-15)
The skeletal system consists of 206 bones and has other body attachments that assist in connecting them which are tendons, ligaments, and cartilage. The skeletal system provides vital functions for the human body. The functions this system provides are support, movement, protection, blood cell production, storage for calcium and endocrine regulation. Bone serves as the basic unit of the human skeletal system. Ossification is characterized as a process that produces new bone. This process is also known as bone formation. Bone formation consists of two types of development. They are intramembranous and endochondral formation. Intramembranous ossification takes place when cells within the membrane change and become osteochondral progenitor cells.
Osteonecrosis has become a subject of interest amongst orthopaedic surgeons predominantly during the last four to five decades.
Osteoporosis is a condition, which advances with age, resulting in fragile, weak bones due to a decrease in bone mass. Externally osteoporotic bone is shaped like normal bone, however it’s internal appearance differs. Internally the bone becomes porous due to a loss in essential minerals, including phosphate and calcium. The minerals are loss more quickly than they can be replaced and in turn cause the bones to become less dense and weak. The bones become prone to fracture, due to their weakness. Therefore the awareness of the disease tends to occur after a fracture has been sustained. The bones most commonly affected are the ribs, wrist, pelvis and the vertebrae.
The collarbone is a big doubly curved long bone that joins the arm to the trunk of the body.Based directly above the first rib it keeps the scapula in place so that the arm can hang freely.
The skeletal system helps with endocrine regulation, protection, support, movement, calcium storage, and blood cell production. The skeletal system consists of 206 bones, in the adult human body, all of which are divided into two major divisions. One division, the axial skeleton made up from 80 bones, runs along the body’s midline and the other division, the appendicular skeleton which has 126 bones.
Osteoporosis is a serious disease that leads to a faster than normal loss of the bone density, which puts the bone at a higher risk for fractures. In order to understand the causes of Osteoporosis, it is important to understand how bones are formed. Bone is a living tissue that is made mainly of collagen, calcium phosphate, and calcium carbonate. The mixture of collagen and calcium gives the bone strength and flexibility. The body deposits new bones and removes old ones; moreover, there are two types of bone cells that control the reproduction of bones. Cells called osteoclasts breakdown bone tissues thus, damaging the bone. Once the damaged bone is removed, cells called osteoblasts, use minerals including calcium and phosphate from the blood stream to make new healthy bone tissues. In order for osteoblasts and osteoclasts to work properly, hormones such us thyroid, estrogen, testosterone, and growth hormones are
The skeletal provides functions such as support, protection, and movement. The skeletal system provides a framework that supports the body with muscles attached to them acting as levers allowing for movement. As bones are very rigid they provide support for vital organs such as the heart, lungs and brain. A physiological function of the skeletal system is the production of stem cells through red bone marrow found in the proximal epiphysis (the ends) which can become lymphocytes (white blood cells), erythrocytes (red blood cells) and thrombocytes (platelets).
The skeletal system is made of all the bones, connective tissues and joints in the body. Bones, cartilage are some of the bones that make up the Skeletal system. The Skeletal system helps perform important everyday functions, for example; support, movement and protection, etc. The skeletal system helps form blood cells. The skeletal system helps store calcium and phosphorus, which is important and beneficial to the other functions in the body.
Solid Freeform Fabrication(SFF) has been possibly the most large scale fabrication technique among the different types of design and fabrication methods (Bose, et al., 2012). The main feature of SFF has three dimensional parts which are printed layer-by-layer depending on computer aided design (ask plagiarism). The fabrication of SFF on polymer, ceramic, metal and composite scaffolds has been widely accepted in bone tissue engineering applications (Bose, et al.,
Describe the microscopic features of osseous tissue that help long bones withstand compressive forces without breaking.
The skeletal system is composed of two hundred and six bones in the human body. Functions such as the tendons, cartilage, and ligaments connect the bones and tissues together. Bone tissues make up about 18% of the weight of the human body. There are two types of tissue inside the bones. They consist of; compact bone and spongy bone. First, compact bone depicts the main shaft of long bones in the human body such as the arms and legs. Its tissue is dense and hard and it also makes up the outer layer of most bones in our body. Meanwhile, spongy bone tissue is made up of smaller plates occupied with red bone marrow. Mostly, it is found at the ends of long bones such as the head of the femur.
The Skeletal System, also known as the Skeleton make up a framework that support the body and protect the organs. The Skeleton consists of the bones and joints of the body. In the human body there is 300 bones at birth, these then fuse together to make 206 bones in a fully grown adult. The Skeleton is made up of two divisions: The axial and appendicular Skeleton.