Biomechanics & Surgery: Tissue Mechanics II Bone

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Questions and Answers

Which of the following statements best describes the mechanical behavior of cortical bone under tensile load in the transverse direction?

Cortical bone has higher strength and toughness in the transverse direction.

Cortical bone is most brittle and exhibits minimal plastic deformation. (correct)

Cortical bone has equal mechanical properties in tension and compression.

Cortical bone is most ductile and exhibits significant plastic deformation.

How does the mechanical behavior of trabecular bone differ from cortical bone?

Trabecular bone is more susceptible to fatigue failure compared to the more brittle cortical bone.

Trabecular bone has equal mechanical properties in all directions, unlike the anisotropic behavior of cortical bone.

Trabecular bone has higher stiffness and strength but lower toughness compared to cortical bone.

Trabecular bone has lower stiffness and strength but higher toughness compared to cortical bone. (correct)

How does the distribution of stress differ between compressive and tensile loads on a bone under bending?

The stress distribution is higher in tension compared to compression. (correct)

The stress distribution is uniform throughout the bone cross-section.

The stress distribution is linearly proportional to the distance from the neutral axis.

The stress distribution is higher in compression compared to tension.

How does the rate of loading affect the mechanical properties of bone tissue?

Increased loading rate increases the stiffness and strength of bone, and also influences the fracture pattern and soft tissue damage. Signup and view all the answers

What is the clinical relevance of understanding the mechanical properties of bone tissue?

It helps in the design of orthopedic implants and devices. Signup and view all the answers

What is the primary function of the organic matrix in bone?

To provide tensile strength and structural integrity to the bone Signup and view all the answers

What is the primary role of the non-collagenous matrix proteins in bone?

To promote mineralization and bone formation Signup and view all the answers

Which of the following is the most accurate description of the hierarchical structure of bone?

Bone has seven hierarchical levels, ranging from isolated crystals and collagen fibrils to the whole bone structure Signup and view all the answers

Which of the following is a key mechanical property of the healthy bone tissue?

High compressive strength and high tensile strength Signup and view all the answers

Which of the following is a common mode of mechanical failure in bone tissue?

Shear failure Signup and view all the answers

What is the primary organic component of bone tissue?

Type I collagen Signup and view all the answers

Which of the following is NOT a characteristic of trabecular bone?

Composed of parallel cylindrical units Signup and view all the answers

Which of the following mechanical properties is NOT exhibited by bone tissue?

Ductility Signup and view all the answers

What is the primary mode of mechanical failure in bone tissue?

Tensile failure Signup and view all the answers

Which of the following conditions is associated with altered bone mechanical properties?

All of the above Signup and view all the answers

Study Notes

Bone Mechanical Characteristics

Bone exhibits nonlinear elastic behavior with a moderate plastic region
Mechanical characteristics vary according to:
Geometry
Load mode applied
Direction of load
Rate of loading
Frequency of loading

Cortical Bone

Cortical bone is most brittle under tensile forces in the transverse direction
It is tougher and stronger in compression

Trabecular Bone

Can absorb considerable energy while maintaining a minimum mass

Anisotropic Behavior

Bone exhibits different mechanical properties when loaded along different axes
Stiffer and more plastic in one direction, less stiff and no plasticity in another direction

Bending Load

Compression and tension stress not equally distributed, increased magnitude farther from neutral axis

Torsional Load

Twist about an axis, shear stress developed, magnitude of stress proportional to distance from axis

Rate Dependency: Viscoelasticity

Increased loading rate, increased stiffness, increased load
Loading rate influences the fracture pattern and soft tissue damage

Reduced Load Effect on Bone

Immobilized for 60 days, bed rest reduces bone mass by 1%/wk

Material Composition

Organic Matrix (~40% dw)

Type I collagen (90%)
Proteoglycans
Non-collagenous matrix proteins
Amorphous ground substance

Inorganic Matrix (~60% dw)

Calcium hydroxyapatite, provides compressive strength to bone

Microstructure

Seven hierarchical levels:
1. Isolated crystals & collagen fibrils
2. Mineralized collagen fibril
3. Mineralized fibril array
4. Fibril array patterns
5. Single osteon
6. Spongy and compact bone
7. Whole bone

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Description

Explore the function, physiology, composition, and biomechanics of bone tissue, including cortical, lamellar, trabecular, and cancellous bone. Learn about the mechanical properties and viscoelasticity of bone tissue. Recommended readings are provided for further understanding.