His right elbow appears broken, and part of the bone in the upper arm appears to be protruding from the skin. There appear to be fragments of bone in the wound.
Upstream
Background
Downstream
Direct Cause
Indirect Cause
12 year old boy fell forward while running
potential vitamin/mineral deficiency due to dietary restrictions resulted in weak bones
Anatomy of long bones
Cell
Tissue
Organ
Bone Growth
Bone Formation
Bone Remodeling: consists of bone deposit and bone resorption
Stages of Bone Healing
Raw materials required for bone growth and repair
Classification of Bone Fractures
Epiphysis
Compound comminuted fracture of right distal humerus
How the location of the break affects treatment
Suspected vitamin and mineral deficiency causing rickets
compound: the bone has perforated the soft tissue
comminuted: bone has fractured into shards
Treatment
Surgery
Antibiotics
Immobilization of joint/bone
Physical therapy
Because of lactose intolerance, vitamin and mineral supplements needed
Deficient in vitamin D and calcium
Elbow requires specific type of brace - hanging U splint
requires traction
Rickets will resolve within months with proper treatment
closed reduction
Prepubescent: may have involvement of epiphyseal plate
Limb development may be affected
risk of cellulitis and osteomyelitis
Spongy
Compact (Lamellar)
made up of a honeycomb of small, needle-like or flat pieces of bone called trabeculae
open spaces are filled with red or yellow bone marrow
dense outer layer on bone that appears smooth and solid
suspected rickets
Diaphysis
Location of epiphyseal plate
Metaphysis
tubular shaft that forms long axis of bone
ends of long bones that consist of compact bone externally and spongy bone internally
where the epiphysis and diaphysis meet
compact bone surrounds medullary cavity that contains yellow marrow in adults
where bone growth occurs
articular cartilage covers joint surfaces
Membranes
Periosteum
Endosteum
white, double layered membrane that covers external surfaces except joints
Osteogenic Layer
Fibrous Layer
contains many nerve fibers and blood vessels that continue on to the shaft through nutrient foramen openings
anchoring points for tendons and ligaments
outer layer consisting of dense irregular connective tissue consisting of Sharpey's fibers that secure bone to matrix
inner layer abutting bone and containing primitive osteogenic stem cells that give rise to most bone cells
delicate connective tissue membrane covering internal bone surface
covers trabeculae of spongy bone tissue
lines canals that pass through compact bone
contains osteogenic cells that can differentiate into other bone cells
red marrow produces red blood cells, platelets, and many white blood cells
yellow marrow produces fat, cartilage, and bone
Osteogenic cells
Osteoblasts
Osteocytes
Bone lining cells
Osteoclasts
also called osteoprogenitor cells
mitotically active stem cells in endosteum and periosteum
when stimulated, differentiate into different types of bone cells
some remain as osteogenic cells
bone forming cells that secrete unmineralized bone matrix called osteoid
actively mitotic
amitotic mature bone cells in lacunae
maintain bone strength and act as stress or strain sensors
respond to mechanical stimuli on bone - both positive and negative
communicate information to osteoblasts and osteoclasts so bone remodeling can occur
flat cells on bone surfaces believed to also help maintain matrix
called periosteal cells on outer surface, endosteal cells on internal surface
derived from the same hematopoietic stem cells that become macrophages
giant, multinucleate cells that function in bone resorption
when active, located in depressions called resorption bays
cells have ruffled borders that increase surface area for enzyme degradation of bone
also helps seal off area from surrounding matrix
consists of osteon (Haversian system), canals and caniculi, and interstitial and circumferential lamellae
organized around lines of stress
Organic
Inorganic
includes bone cells and osteoid
resilience of bone is due to sacrificial bonds in/between collagen molecules that stretch/break to dissipate energy and prevent fractures
if no additional trauma, bonds reform
Hydroxyapatites (mineral salts)
make up 65% of bone composition
consists mainly of calcium phosphate crystals between collagen fibers
responsible for hardness and resistance to compression
Also called osteogenesis
begins in month 2 of fetal development
Postnatal growth occurs until early adulthood
Endochondral Ossification
Intramembranous Ossification
Both occur up to about week 8 of fetal development
bone forms by replacing hyaline cartilage
bones are called cartilage (endochondral) bones
form most of skeleton
bone develops from fibrous membrane
called membrane bones
essentially all bones inferior to the skull except the clavicle
Five major steps:
- Bone collar forms around diaphysis of cartilage model.
- Central cartilage in diaphysis calcifies then develops cavities.
- Periosteal bud invades cavities, leading to formation of spongy bone
- Diaphysis elongates and medullary cavity forms
- Epiphysis ossify.
Hyaline cartilage remains only in epiphyseal plate and articular cartilage
forms frontal, parietal, occipital, temporal, and clavicle bones
Four steps involved:
- Ossification centers are formed when mesenchymal cells cluster and become osteoblasts.
- Osteoid is secreted then calcified.
- Woven bone is formed when osteoid is laid down around blood vessels, resulting in trabeculae
- Lamellar bone replaces woven bone and red bone marrow forms.
outer layer of woven bone forms periosteum
long bones grow lengthwise at epiphyseal plate
Plate has 5 zones:
- Resting zone
- Proliferation zone
- Hypertrophic zone
- Calcification zone
- Ossification zone
area of cartilage on epiphyseal side of plate that is relatively inactive
area of cartilage on diaphyseal side is rapidly dividing
area with older chondrocytes closer to diaphysis; cartilage lacunae enlarge and erode, forming interconnected spaces
surrounding cartilage matrix calcifies; chondrocytes die and deteriorate
chondrocyte deterioration leaves spiculesof calcified cartilage at plate junction
spicules are eroded by osteoclasts and covered with new bone by osteoblasts, forming spongy bone
medullary cavity enlarges as spindles are eroded
Epiphyseal plate closes at the end of adolescence
(18 for women, 21 for men)
no more longitudinal growth of bone
Resorption
function of osteoclasts
secrete enzymes and protons that break down matrix
acidity converts calcium salts to soluble forms
also phagocytize dead osteocytes and demineralized matrix
Deposit
new bone matrix laid down by osteoblasts
osteoid seam: band of unmineralized bone matrix that marks area of new matrix
calcification front: abrupt transition zone between osteoid seam and mineralized bone
Three types are either/or
Displaced or non displaced
Complete or incomplete
Compound (open) or simple (closed)
Compound: skin is penetrated
Simple: skin is not penetrated
Displaced: ends are out of normal alignment
Nondisplaced: ends retain normal position
Complete: broken all the way through
Incomplete: not broken all the way through
can also be described by location, appearance, and nature of break
Other types of fractures:
Comminuted: bone broken into three or more fragments
Compression: bone is crushed
Spiral: ragged break occurs due to twisting forces
Epiphyseal: epihysis separates from the diaphysis at the epiphyseal plate
Depressed: broken bone is pressed inward
Greenstick: bone breaks incompletely, like a green twig; only one side breaks, the other bends
- Hematoma formation
- Fibrocartilagenous callus formation
- Bony callus formation
- Bone remodeling
capillaries grow into hematoma, phagocytic cells clear debris
torn blood vessels hemorrhage, causing a blood clot called a hematoma to form
site is swollen, painful, and inflamed
fibroblasts secrete collagen fibers to span break and connect broken ends
fibroblasts, cartilage, and osteogenic cells begin reconstruction of bone
new trabeculae appear in fibrocartilagenous callus
callus is converted to spongy bone
excess material on diaphysis exterior and within medullary cavity is removed
compound bone laid down to reconstruct shaft walls
final structure resembles original structure