Case Study: A young boy appears to have broken several bones in multiple locations. He eats junk food & he is lactose intolerant. Its questioned as to how his diet relates to his injury.
Upstream Causes
Downstream Effects
Direct
Indirect
Direct
Indirect
Problem # 2
Problem #1
Feedback
Background
Bones
Broken bone injury
Occurred in a boy, the age of 12
He ran & fell forward
Landing on right arm
Broken bones & their locations
Part of the humerus is protruding through the skin
Factors that contributed to easy breaks in such a young boy
Bones are classified by their shape & location
Bone functions
Hormone production
Blood cell formation
Mineral & growth factor storage
Triglyceride storage
Anchorage
Support
Protection
Only in certain areas
Such as
Vertebrae surround the spinal cord
Rib cage protects vital organs
Fused bones of skull protect brain
The femur for example does not protect anything
Skeletal muscles use bones as levers to move body
Anatomy of bones classified by shape
Divided into 2 groups
Axial skeleton
Appendicular
Ex: bone stores Ca & P, along w/growth hormone
Which is then released into the bloodstream as the body needs it
Hematopoiesis ( blood cell formation) occurs in red marrow of certain bones
Fat can be stored in bone as yellow marrow
For an energy source
Bone produce osteocalcin (hormone)
Which regulate
Glucose homeostasis
Energy expenditure
Insulin secretion
The skeleton provides a framework for the body to be used by muscles
Includes
Vertebral column
Rib cage
Skull
Includes
Bones of upper & lower limbs
Girdles (shoulder & hip bones)
Short bones
Flat bones
Irregular bones
Special type of short bone
Sesamoid bones
Shape
Long bones
Shape
Consists of a shaft & 2 ends
Ex: All limbs except patella, wrist, & ankle bones
Known for elongated shape, not overall size
Other ex: the 3 bones in the fingers (phalanges)
Cubed
Ex: Bones of wrist & ankle
Form in a tendon
Vary in size & # in individuals
Ex: Patella
Shape
Flat
A bit curved
Thin
Example
scapulae
Ribs
Sternum
Most cranial bones
Shape
They have complicated shapes
Examples
Vertebrae
Hip bones
Longer than they are wide
Characteristics of bone
They are organs
Structure
Contain
Epithelial in blood vessels in the bone
Dense connective tissue covering their external surface
Cartilage in their articular cartilages
Nervous tissue in their nerves
Smooth muscle around blood vessels
Sometimes muscle fibers
3 bone structural levels
Gross anatomy
Spongy bone
Compact bone
Internal layer - AKA -> trabecular bone
The honeycomb of small flat pieces -> trabeculae
Thin plates of spongy bone -> Diploe
The network of spongy material
Importance: Adult's way of making blood in bones
Anatomy
All contain 3 general structures
Bone ends
Membranes
Shaft
AKA -> Epiphyses
AKA -> Diaphysis
Forming the long axis
Constructed of
A collar of compact bone surrounding a medullary cavity
Contains NO bone tissue yet contains yellow marrow
Between the marrow & compact bone -> spongy bone
Spongy bone resides here
Between the epiphyses & diaphysis
Epiphyseal line
A remnant of the epiphyseal plate -> "Growth plate"
A disc of hyaline cartilage
Function: Grows during childhood to lengthen bones
Both are called metaphysis
Periosteum
Double layer membrane
Endosteum
Covers external part of bone EXCEPT joint surfaces
Containing nerve fibers, perforating fibers, & blood vessels
Outer layer composition: Dense IRREGULAR connective tissue
Inner osteogenic layer contains osteoprogenitor cells
Stem cells that give rise to most bone cells
Containing
Osteoblasts
Osteoclasts
Bone-forming cells
Bone-destroying cells
Within the bone
Covers trabeculae & lines canals that pass through compact bone
Containing
Same cells as the inner layer of periosteum
Osteoprogenitor cells
Other structural components
Well vascularized
Main vessels in diaphysis
Nutrient artery
Nutrient vein
Nutrient foramen
Nerves accompany blood vessels here also
Hematopoietic tissue
Blood forming tissue
AKA red marrow
In infants
In adults
Location
Medullary cavity of diaphysis
All areas of spongy bone
Red marrow is replaced w / yellow marrow
Red marrow is only found in spongy bone cavities between trabeculae of spongy bone -> diploe
Such as
Heads of
Sternum
Ribs
Flat bones of skull
Clavicles
Scapulae
Hip bones
Vertebrae
Femur
Humerus
Microscopic anatomy
5 major cell types in bone tissue
Osteoblast
Osteocytes
Osteoprogenitor cells
Bone lining cells
Osteoclasts
Mitotically active stem cells
Location
Periosteum
Endosteum
Function: When stimulated, some of these become
Osteoblast
Which can become
Osteocytes
Function: Bone forming cells
Shape
In growing bones
Also actively mitotic
That secrete bone matrix
Shape
When actively depositing matrix
Cube shaped
When inactive
Resemble flattened osteoprogenitor cells
Shape
Spidery looking & conform to shape of lacunae
Mature bone cells
Function
Flattened or squamous cells
Shape
Monitor & maintain the bone matrix
Act as sensors
Respond to stimuli
Communicate this info -> osteoclasts & osteoblasts
In bone remodeling
Trigger bone remodeling to maintain calcium homeostasis
Flat cells
Location: Bone surfaces where bone remodeling occurs
Function: Thought to help maintain matrix
Shape
Giant multinucleated cells
They have a ruffled border -> Increase surface area
Location: At sites for bone resorption (breaking down bone)
Function: Break down bone
External dense outer layer of bone
Chemical composition of bone (Made of 2 different things in matrix)
Soft organic components
Includes
Osteoid
Allowing it to resist stretch
Hard inorganic components
Includes
Mineral salts AKA hydroxyapatites
Allowing it to resist compression
Cells
Osteoprogenitor cells
Osteoblasts
Osteocytes
Bone lining cells
Osteoclasts
The protein part (collagen)
Makes up 1/3 of matrix
Secreted by osteoblasts
Bone formation
Endochondral ossification
Process
Intramembranous ossification
Bones formed
1) Hyaline cartilage is surrounded by perichondrium initially
Mesenchymal cells become osteoblasts
Perichondrium becomes periosteum
A collar bone forms when the osteoblasts secrete osteoid against the hyaline cartilage diaphysis
2) Cartilage calcifies in center of diaphysis & develops into cavities -> Area of deteriorating cartilage matrix
3) Periosteal bud invades cavities -> Spongy bone replaces cartilage
4) Diaphysis elongates & medullary cavity forms
Characteristics
Begins in 2nd month of development
In the collar bone, condrocytes in shaft enlarge -> Primary ossification center
Secondary ossification centers appear in epiphyses
Month 3 of development
Week 9 until birth
5) The epiphyses ossify
Then ossification is complete, hyaline cartilage remains only in epiphyseal plates & articular cartilages
Bones formed
Mainly long bones w/some others
Flat bones
Such as
Cranial bones
Clavicles
Characteristics
Begins at week 8 of development
Process
1) Ossification begins w / a membrane of fibrous connective tissue
2) Osteoid, secreted by osteoblasts, begins to calcify in days time
Mesenchymal cells cluster & differentiate into osteoblasts
3) Immature spongy bone & periosteum form
Trapped osteoblasts become osteocytes
Osteoblasts on outside make compact bone on surfaces
4) Red marrow develops
Whats left over from the connective tissue is what forms the periosteum
Postnatal bone growth
2 Ways bones grow
Appositional growth
Interstitial growth AKA longitudinal growth
All bones that grow in thickness
Long bones lengthen by
Growth of the epiphyseal plate cartilage & its replacement by bone
Occurs within the tissue
Occurs on the outside of bone by means of addition of it
Process
4) Ossification zone
3) Calcification zone
Goal
2) Hypertrophic zone
1) Proliferation zone
Cartilage cells (condroblasts) undergo mitosis
Pushing the epiphysis away from diaphysis
Which lengthens the long bone
The older condrocytes closer to diaphysis enlarge
Their lucunae erode & enlarge
Leaving interconnecting spaces
Adding Ca in order that the matrix becomes calcified
Chondrocytes die
Matrix deteriorates
Blood vessels invade
Osteoclasts partly erode the cartilage spicules created from the calcification process
Then osteoblasts cover them with new bone
Spongy bone replaces them
Osteoclasts digest spicules & the medullary cavity lengthens
Push the epiphysis up & add bone to diaphysis
Which pushes the the epiphyses further apart
Process
1) Osteoblasts in periosteum add more matrix layers on the external surface of bone
2) At the same time that step one is occurring, in the endosteal surface of the diaphysis, osteoclast remove bone
Goal: The outside gains more layers & the inside loses layers to widen bone w/out making it too heavy
Bone remodeling
Hormones responsible in bone remodeling
Calcitonin
PTH
Stimulate osteoclast to break down bone matrix
Produced by thyroid to help slow down osteoclast activity
Hormones responsible in bone growth
Thyroid hormones
Estrogens & testosterone
Growth hormone
Masculinization or feminization of parts of skeleton depend on theses levels
Modulate the activity of growth hormone
Released by anterior pituitary gland
Process
Characteristics
Remodeling replaces 5-10% of our skeleton every yr
Our entire skeleton is replaced about every 10 yrs
Spongy - Every 3-4 yrs
Compact - Every 10 yrs
2 main steps involved
Bone resorption
Bone deposition
Includes removal of old matrix w/replacement of new
Occurs: From embryo -> death
Osteoblasts deposit Ca & proteins throughout osteoid
Creating calcified bone matrix
Increase blood-Ca levels
In adults, both of these work at the same rate
Goal of both of these
To regulate BLOOD-Ca LEVELS
Maintain Ca homeostasis
Keeping bone strong
PTH is released
Osteoclasts remove the minerals & proteins
Fracture classification
Position of bone ends
Completeness of break
Whether the bone ends penetrate the skin
Displaced
Nondisplaced fractures
Bone ends are lined in position
Bone ends are not lined in position
The bone is broken all the way through
The bone is an open (compound) fracture
Common types of fractures
Epiphyseal break
Spiral
Compression
Greenstick
Comminuted
Depressed
Bones shatter in many pieces
Ex: In elderly
Bone is crushed
Ex: Calcaneous shatters if you land on your heels too hard
Twisted break
Ex: Machinery accidents or abused child
Epiphysis separates from diaphysis along the plate
Is a serious injury b/c it could effect growth
Growth hormone & steroids are possibles -> mitosis
Broken bone is pressed inward
Ex: skull fracture
Bone breaks incompletely (only one side breaks)
Common in kids w/ more organic matrix
Fracture Treatment & Repair
Treatment
Begins w/ reduction
Realignment of broken bones
Stages of bone healing in a simple fracture
Closed external reduction
Open internal reduction
Physician's hand put bone ends into position
Bone ends are secured together surgically w/screws & plates
After reduced
Immobilized by
Traction
Cast
Time it takes adults to heal (small - medium )
6-8 wks
2) Fibrocartilaginous callus forms
3) Spongy bone forms -> Bony callus forms
1) Lots of blood pulling -> Hematoma forms
4) Bone remodeling occurs
When a bone breaks, blood vessels in bone are torn
The hemorroraged blood clots forming hematoma
Tissue becomes swollen
Blood vessels grow into new clot
Fibroblast & condroblasts invade the fracture site
Bony callus is removed
Compact bone is laid down
Fibrocartilaginous callus spans the break & connects the broken bone ends
Osteoblasts form spongy bone
Young kids bones don't break that easily
Factors that led to this
Diet
Lactose intolerance
Bones are still going through growth stages
Junk food mainly consumed
Needs more nutrients
Fragment of bone in the wound
Breaking elbow (olecranon)
No consumption of dairy
Part of humerus is protruding through the skin
Fragment of bone in the wound
Classification of fracture
Right elbow (olecranon) broken
Open compound fracture
Classification of fracture
Closed simple fracture
Other possible types of breaks
epiphyseal break
Greenstick break
Other possible types of breaks
Greenstick fracture
Displaced fracture
Incomplete fracture
Incomplete fracture
Factors to consider during treatment process
Location of break
Boys diet
Age of boy
Needs Ca for bone remodeling
So the bones can store Ca for the body's processes
Possibly not getting enough amino acids for osteoid production
Making 1/3 of matrix
The epiphyseal plate is still active in males until about 21 yrs
Diet would benefit from change
Mico & macro nutrients are important for the healing process
By adding more minerals so they are properly stored
So the body can use it for bone remodeling
Humerus break
If an epiphyseal break
A method for growth continuation should be addressed
Olecranon break
In order to maintain bone symmetry on all side of body
If a greenstick fracture
The bones need to be re-brocken
He would possibly require steroids or growth hormone
To stimulate mitosis for growth
So its important to look at factors possible for affecting growth
Possible treatments
Other consequences of not taking care of the breakage
Bones can grow at an angle
& Placed in the proper position
Once the proper methods are exercised to place bone in place
A cast or traction could be placed around bone
So proper repair can take place