Structural Adaptation of Bones

1990 ◽  
Vol 43 (5S) ◽  
pp. S126-S133 ◽  
Author(s):  
S. C. Cowin

Living bone tissue, like many other connective tissues, is a structural material that adapts its form and microstructure to changing environmental loading conditions. Bone tissue adapts not only its shape, but also its density and the details of its microstructure including its anisotropy. The anisotropy of bone is adapted in both its degree or strength and in the orientation of its principal axes of symmetry. These adaptive features of bone tissue are often referred to as aspects of Wolff’s law, although, strictly speaking, the term “Wolff’s law” applies only to the structural adaptation of spongy or trabecular bone. In this paper the composition, microstructure, mechanical properties and structurally adaptive features of bone are briefly reviewed. An algebraic formulation of Wolff’s law at remodeling equilibrium is described, and the nature of an evolutionary Wolff’s law is sketched.

1986 ◽  
Vol 108 (1) ◽  
pp. 83-88 ◽  
Author(s):  
S. C. Cowin

An elastic constitutive relation for cancellous bone tissue is developed. This relationship involves the stress tensor T, the strain tensor E and the fabric tensor H for cancellous bone. The fabric tensor is a symmetric second rank tensor that is a quantitative stereological measure of the microstructural arrangement of trabeculae and pores in the cancellous bone tissue. The constitutive relation obtained is part of an algebraic formulation of Wolff’s law of trabecular architecture in remodeling equilibrium. In particular, with the general constitutive relationship between T, H and E, the statement of Wolff’s law at remodeling equilibrium is simply the requirement of the commutativity of the matrix multiplication of the stress tensor and the fabric tensor at remodeling equilibrium, T* H* = H* T*. The asterisk on the stress and fabric tensor indicates their values in remodeling equilibrium. It is shown that the constitutive relation also requires that E* H* = H* E*. Thus, the principal axes of the stress, strain and fabric tensors all coincide at remodeling equilibrium.


RSC Advances ◽  
2016 ◽  
Vol 6 (46) ◽  
pp. 39982-39992 ◽  
Author(s):  
Tejinder Kaur ◽  
Arunachalam Thirugnanam

The development of living bone tissue constructs with structural, mechanical and functional similarities to natural bone are the major challenges in bone tissue engineering.


Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1319
Author(s):  
Muhammad Umar Aslam Khan ◽  
Wafa Shamsan Al-Arjan ◽  
Mona Saad Binkadem ◽  
Hassan Mehboob ◽  
Adnan Haider ◽  
...  

Bone tissue engineering is an advanced field for treatment of fractured bones to restore/regulate biological functions. Biopolymeric/bioceramic-based hybrid nanocomposite scaffolds are potential biomaterials for bone tissue because of biodegradable and biocompatible characteristics. We report synthesis of nanocomposite based on acrylic acid (AAc)/guar gum (GG), nano-hydroxyapatite (HAp NPs), titanium nanoparticles (TiO2 NPs), and optimum graphene oxide (GO) amount via free radical polymerization method. Porous scaffolds were fabricated through freeze-drying technique and coated with silver sulphadiazine. Different techniques were used to investigate functional group, crystal structural properties, morphology/elemental properties, porosity, and mechanical properties of fabricated scaffolds. Results show that increasing amount of TiO2 in combination with optimized GO has improved physicochemical and microstructural properties, mechanical properties (compressive strength (2.96 to 13.31 MPa) and Young’s modulus (39.56 to 300.81 MPa)), and porous properties (pore size (256.11 to 107.42 μm) and porosity (79.97 to 44.32%)). After 150 min, silver sulfadiazine release was found to be ~94.1%. In vitro assay of scaffolds also exhibited promising results against mouse pre-osteoblast (MC3T3-E1) cell lines. Hence, these fabricated scaffolds would be potential biomaterials for bone tissue engineering in biomedical engineering.


2005 ◽  
Vol 898 ◽  
Author(s):  
Devendra Verma ◽  
Rahul Bhowmik ◽  
Bedabibhas Mohanty ◽  
Dinesh R Katti ◽  
Kalpana S Katti

AbstractInterfaces play an important role in controlling the mechanical properties of composites. Optimum mechanical strength of scaffolds is of prime importance for bone tissue engineering. In the present work, molecular dynamics simulations and experimental studies have been conducted to study effect of interfacial interactions on mechanical properties of composites for bone replacement. In order to mimic biological processes, hydroxyapatite (HAP) is mineralized in presence of polyacrylic acid (PAAc) (in situ HAP). Further, solid and porous composites of in situ HAP with polycaprolactone (PCL) are made. Mechanical tests of composites of in situ HAP with PAAc have shown improved strain recovery, higher modulus/density ratio and also improved mechanical response in simulated body fluid (SBF). Simulation studies indicate potential for calcium bridging between –COO− of PAAc and surface calcium of HAP. This fact is also supported by infrared spectroscopic studies. PAAc modified surfaces of in situ HAP offer means to control the microstructure and mechanical response of porous composites. Nanoindentation experiments indicate that apatite grown on in situ HAP/PCL composites from SBF has improved elastic modulus and hardness. This work gives insight into the interfacial mechanisms responsible for mechanical response as well as bioactivity in biomaterials.


Author(s):  
Vipul P. Gohil ◽  
Paul K. Canavan ◽  
Hamid Nayeb-Hashemi

This research is aimed to study the variations in the biomechanical behavior of bone and bone tissues with osteoporosis and bone tumors. Osteoporosis and bone tumors reduce the mechanical strength of bone, which creates a greater risk of fracture. In the United States alone, ten million individuals, eight million of whom are women, are estimated to already have osteoporosis, and almost 34 million more are estimated to have low bone mass (osteopenia) placing them at increased risk for osteoporosis. World Health Organization defines osteopenia, as a bone density between one and two and a half standard deviations (SD) below the bone density of a normal young adult. (Osteoporosis is defined as 2.5 SD or more below that reference point.). Together, osteoporosis and osteopenia are expected to affect an estimated 52 million women and men age 50 and older by 2010, and 61 million by 2020. The current medical cost of osteoporosis total is nearly about $18 billion in the U.S. each year. There is a dearth of literature that addresses the effects of osteoporosis on bone tissue properties. Furthermore, there are few studies published related to the effect of bone tumors such as Adamantinoma of long bones, Aneurysmal bone cyst, Hemangioma and others on overall behavior of bone. To understand the variations in bio-mechanical properties of internal tissues of bone with osteoporosis and bone tumor, a 2D finite element (FE) model of bone is developed using ANSYS 9.0 ® (ANSYS Inc., Canonsburg, PA). Trabecular bone is modeled using hexagonal and voronoi cellular structure. This finite element model is subjected to change in BVF (bone volume fraction) and bone architecture caused by osteoporosis. The bone tumor is modeled as finer multi-cellular structure and the effects of its size, location, and property variation of tumor on overall bone behavior are studied. Results from this analysis and comparative data are used to determine behavior of bone and its tissue over different stage of osteoporosis and bone tumor. Results indicate that both bone tumor and osteoporosis significantly change the mechanical properties of the bone. The results show that osteoporosis increases the bone tissue stiffness significantly as BVF reduces. Bone tissue stiffness is found to increase by 80 percent with nearly 55 percent reduction of BVF. The results and methods developed in this research can be implemented to monitor variation in bio-mechanical properties of bone up to tissue level during medication or to determine type and time for need of external support such as bracing.


2015 ◽  
Vol 3 (23) ◽  
pp. 4679-4689 ◽  
Author(s):  
Ya-Ping Guo ◽  
Jun-Jie Guan ◽  
Jun Yang ◽  
Yang Wang ◽  
Chang-Qing Zhang ◽  
...  

A bioinspired strategy has been developed to fabricate a hybrid nanostructured hydroxyapatite–chitosan composite scaffold for bone tissue engineering.


2015 ◽  
Vol 50 (1) ◽  
pp. 15-20 ◽  
Author(s):  
MJ Hossan ◽  
MA Gafur ◽  
MM Karim ◽  
AA Rana

In this study, hydroxyapatite (HAp) and gelatin (GEL) scaffolds were prepared to mimic the mineral and organic component of natural bone. The raw material was first compounded and resulting composite were molded into the petridishes. Using Solvent casting process, it is possible to produce scaffolds with mechanical and structural properties close to natural trabecular bone.The mechanical properties of composites were investigated by Thermo-mechanical analyzer (TMA), Vickers microhardness tester, Universal testing machine. It was observed that the composite has maximum tensile strength of 37.13MPa ( oven drying) and % elongation of 7.68 (Oven drying) and 2.04 (Natural drying) at 15% of Hap respectively. These results demonstrate that the prepared composite scaffold is a potential candidate for bone tissue engineering.Bangladesh J. Sci. Ind. Res. 50(1), 15-20, 2015


Author(s):  
Angelique Balguid ◽  
Anita Mol ◽  
Niels Driessen ◽  
Carlijn Bouten ◽  
Frank Baaijens

The mechanical properties of collagenous tissues are known to depend on a wide variety of factors, such as the type of tissue and the composition of its extracellular matrix. Relating mechanical roles to individual matrix components in such a complex system is difficult, if not impossible. However, as collagen is the main load bearing component in connective tissues, the relation between collagen and tissue biomechanics has been studied extensively in various types of tissues. The type of collagen, the amount and type of inter- and intramolecular covalent cross-links and collagen fibril morphology are involved in the tissues mechanical behavior (Beekman et al., 1997; Parry et al., 1978; Avery and Bailey, 2005). From literature it is known that the the collagen fibril diameter distribution can be directly related to the mechanical properties of the tissue. In particular, the diameter distribution of collagen fibrils is largely determined by the tissues requirement for tensile strength and elasticity (Parry et al., 1978).


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