Biomechanics Flashcards
Name 4 applications of tissue mechanics
- Predict threshold and mechanisms of injury and effects of disease
- Develop realistic surgical simulations
- Develop FE models
- Investigate mechanisms of structural disorders
What is elastin?
A highly elastic protein in connective tissue that allows tissues in the body to resume their shape after stretching or contracting.
What is a structural property of elastin?
It is made of long flexible molecules crosslinked together to form a 3D network
What is a mechanical property of elastin?
Young’s Modulus = 0.4MPa
What is collagen?
The main structural protein found in the extracellular space in various connective tissues (like tendons, ligaments etc)
What is a structural property of collagen?
Three stranded helix structure
What is a mechanical property of collagen?
Depending on the degree of mineralisation, collagen tissues may be rigid (bone), compliant (tendon) or both (cartilage)
What are the two types of bone?
Cortical and cancellous
What is a structural property of bone?
Made of two materials: HA and collagen fibres
HA gives rigidity and strength
Collagen gives its toughness and prevents brittle cracking
What is a mechanical property of bone?
Young’s modulus for cortical bone (weight bearing) = 20GPa
What is cartilage?
Tissue that lines surfaces of most joints
What is a structural property of cartilage?
Hydrated tissue made of cells and collagen fibres in a fluid matrix.
What is a cool mechanical property of cartilage?
It acts as a shock absorbing system: i.e. under high rates of loading it is stiff and protects the bone, but under low rates of loading it is not stiff and passes the load onto the bone
What do ligaments do?
Bind together joints, providing strength and stability.
What is a structural property of ligaments/tendons?
Bands of dense connective tissue bundles made of collagen fibres.
What is a mechanical property of ligaments?
Carry only tensile loads
What is a mechanical property of tendons?
Carry tensile loads from muscle to bone
Carry compressive loads when wrapped around bone like a pulley
What is a structural property of skin?
Constructed of layers of collagen fibre networks
What is a mechanical property of skin?
It’s structure changes during wound healing: scar tissue is much stiffer due to dense collagen fibres crosslinking and aligning in a single direction (opposed to their random formation in normal skin)
Why is spinal cord tissue stiffer than brain tissue?
It has a set of highly organised longitudinally running fibres, rather than random alignment in the brain
What is laboratory motion analysis used for?
To measure the kinematics and dynamics of human or animal motion (e.g. gait analysis)
What are two limitations of laboratory motion analysis?
Trying to place markers on bony landmarks
Determining the forces in individual muscles
What are three methods of data acquisition for laboratory motion analysis?
Video acquisition
3D optical acquisition
Analog acquisition
