Biomechanics of Bone Flashcards
What percent of total body weight is bones, cartilage, ligaments, & joints?
20%
Do long or short bones produce more torque?
Long
Bones increase in size from ______ to ______.
Superior ; Inferior
proximal to distal
Where does hematopoiesis occur?
Inside the cavities of bone
Cortical vs. Cancellous Bone
Cortical: compact, very dense, outer layer
Cancellous: spongy, very porous, inner layer
Example of sesamoid bone
Patella
What percent of bone is water?
20-30%
What percent of bone is minerals and collagen?
60-70%
What does Wolff’s law state?
In response to decreased stress osteoclasts dominate to resorb tissue.
In response to increased stress osteoblasts dominate to deposit tissue.
What 3 things is osteoporosis related to?
- Hormonal factors (i.e. menopause)
- Nutritional imbalances (i.e. calcium intake)
- Lack of exercise
Bone is anisotropic & viscoelastic. What does this mean?
Anisotropic means bone response depends on direction of load application
Viscoelastic means bone response depends on rate & duration of loading
During the elastic response what happens when the load is removed?
The tissue returns to its original shape/length
During the plastic response what happens when the load is removed?
The tissue is permanently deformed
What does the area under the stress-strain curve represent?
The strength of the bone
5 types of loading
1) Compression
- Presses ends of bones together
2) Tension
- Pulls or stretches bone apart
3) Shear
- Parallel to the surface of object
4) Bending
- Applied to area having no direct support
5) Torsional
- Twisting force
What do you gather in the history portion of an exam? (LO DR FICARA)
Location
Onset (MOI)
Duration
Radiation
Frequency Intensity Character Associated Signs and Symptoms Relieving Aggravating
What percent of injuries to athletes are stress fractures?
10%
What is cartilage?
Firm, flexible tissue that has no blood supply or nerves
What nourishes cartilage?
Fluid within joint
2 Functions of Cartilage
1) Increases joint stability
2) Distributes load in joint, which reduces contact stress
2 Types of Cartilage
1) Articular
2) Fibrocartilage
What is articular cartilage aka?
hyaline
Where can you find articular cartilage?
joint ends at articulations
Articular cartilage is __ - __ percent water
60-80
What is articular cartilage made of?
collagen and proteoglycan
2 functions fibrocartilage
- Improve fit between bones
- Intermediary between hyaline cartilage and other connective tissues
Where can you find fibrocartilage?
- Intervertebral discs
- Jaw
- Knee
What do ligaments consist of?
collagen, elastin, and reticulin
What happens to ligaments with increased loading?
They become stronger and stiffer
What is the maximum strength of ligaments related to?
cross-sectional area
3 things that cause joint stability
- Ligaments
- Gravity
- Vacuum
Examples of Simple, Compound, and Complex Joints
Simple joint consists of two articulating surfaces
-The Hip for example
Compound joint consists of three or more articulating surfaces
- The Wrist for example
Complex joint consists of two surfaces with articular disc or fibrocartilage
- The Knee for example
7 Types of Diarthrodial Joints
- Hinge
- Pivot
- Condylar
- Ellipsoid
- Saddle
- Ball and Socket
- Plane/Gliding
Example of a ellipsoid joint
Metacarpophalangeal
What are synarthrodial or fibrous joints
Bones are held together by fibrous articulations, which allows for little or no movement
Example: sutures in skull
What are amphiarthrodial or cartilaginous joints
Hyaline cartilage or fibrocartilage holds joints together which allows for little movement
Example: Intervertebral discs
