HW
How does the mechanical property of human bone compare to properties of cattle, horse, and pig? (Compare Modulus of Elasticity, Ultimate tensile strength, Ultimate compressive strength for Tibia and femoral bone)
The modulus of elasticity of the human femur bone is 17.6 GPa, which is higher than that of the pig-14.9 but lower than that of the cattle-25.0, and horses-25.5 (Pal 30). Similarly, the modulus elasticity of the human tibia bone is 18.4 GPa, which is higher than that of the pig-17.2, but lower than that of the horses-23.8 and cattle-24.5.
Explain how many structural layers exist in the bone, how do they differ in microstructure and shape? What is the intended purpose of each layer?
The bone is a composite of a hierarchical structure. The lowest level contains mineralized collagen fibrils. In the next level, the fibrils are arranged in two distinct forms that include stacks of thin sheets known as lamellae. In the second form, the fibrils are woven and are arranged in a unidirectional manner (Keaveny et al. 2). The lamellar bone is mostly found in the adult humans while the woven bone is usually seen in situations that require rapid growth such as in children and the initial healing process of a fracture. Mainly, the lamellae bone in humans is structured to withstand the mechanical requirements while the woven layer is found in children and facilitate growth.
The cortical bone is approximately four times the total weight of the cancellous bone. In the case of size, the porosity of each bone is considered where that of the cortical bone is between 5 to 30% while that of the cancellous bone ranges between 30 to 90% (Pal 27).
How does structure of the cancellous bone in the femoral bone vary with the height at the transverse plane?
The bone structure is composed of two sets of trabeculae that are arranged in a nonlinear form. One originates from the inner side of the shaft with an upward curve that resembles a fan (Pal 27). The other one arises from the outer part of the shaft with an upward and medial run to the upper surface of the head and neck.
Works Cited
Keaveny, Tony M., Elise F. Morgan, and Oscar C. Yeh. "Bone Mechanics." Standard Handbook of Biomedical Engineering and Design, 2004, pp. 1-24.
Pal, Subrata. The design of Artificial Human Joints & Organs. New York: Springer, 2013.
