Diagnostic Imaging Flashcards
Purpose of Bone:
Storage of Ca+ + (In form of CaPO4).
Protection of vital organs.
Support for body and mechanical basis for movement.
what are the two forms of bone growth
intramembranous ossification or endochondral ossification (chondrification)
Intramembranous ossification
Direct ossification of the mesynchyme
Occurs during the embryonic period within the mesynchymal tissue, without prior cartilage formation
Formation of the periosteum
endochondral ossification
Mesenchyme is chondrified into a cartilaginous bone model
Bone forms later by replacing the membranous model with calcified cartilage
Occurs only in the presence of blood supply
Advances the ends of the cartilaginous model
when do Secondary centers of ossification form
Birth
where do long bone grow from
growth at the epiphysis
where do short bones grow from
growth plate for entire bone
The length of bone increases only by
Interstitial growth within the cartilage
Endochondral ossification
epiphysis and metaphysis movement
Interstitial growth of cartilage moves epiphysis further from metaphysis
Calcification
death and replacement of cartilage (endochondral ossification)
What is Appositional Growth:
growth in width
Activity of the osetoblasts
Located in the deep layer of the periosteum
Intramembranous ossification
what is Interstitial growth
increase in the length of bones
Endochondral ossification
Growth at the metaphysis and diaphysis of a long bone
Four Zones of the epiphyseal plate
Zone of resting cartilage
Zone of young proliferation
Zone of maturing cartilage
Zone of calcifying cartilage
Zone of resting cartilage
Anchors the epiphyseal plate to the epiphysis
Contains immature chondrocytes and delicate vessels
Zone of young proliferation
Site of the most active interstitial growth
Zone of maturing cartilage
Enlargement and maturation of the cartilage cells near the metaphysis
Zone of calcifying cartilage
Structurally the weakest zone
Active boney deposition on the metaphysis
Were the cells are ossifying – weakness
what are Chondrocytes
cells that produce the cellular matrix and eventually differentiate into osteoblasts (secrete osteoid which hardens to new bone)
why does Bone Growth and Remodeling occur
Occurs because of the growth of long bones
Occurs due to factors that demand removal of calcium from the bone
Occurs because the Haversian systems are continually being eroded
how is Bone Balance maintained
Bone balance is the result of osteoblastic vs. osteoclastic activity
Juvenile has a + or - bone balance
postive
Lay down more bone
Geriatric has a + or - bone balance
negative
Absorbing more bone
Wolff’s Law
(Law of Physical Stress)
Bone is deposited in sites subjected to increased stress
Bone is resorbed from sites of decreased stress
Alignment of trabecular systems is along the lines of stress
on a curved bone which side is more bone laid down on vex or cave
Marked cortical thickening is observed on the concave (compressive) side of a curved bone
Electrical properties of bone (-) on the concave side (deposition) (+) on the convex side (resorption)
Long
Tubular (e.g. Humerus and Femur) have a body and 2 ends
Short
Cuboidal (e.g. Carpals and Tarsals) found only in the foot or wrist
Flat
Protective function (e.g. bones of cranial vault) help to form the walls of cavities
Irregular
Bones of the face
Sesamoid
Protect tendons from wearing (e.g. patella) (resembled sesame seeds)
where are RBC formed
bone marrow
Compact Bone
(Cortical)
Very dense, little space
Highly organized lamellar network of fibers, packaged in osteons.
Fibers in each layer or osteon oriented in different directions
Trabecular Bone
Cancellous
Less dense, more space than compact
More metabolically active
Contain blood vessels, nerve fibers and fat
Hemopoietic tissue
Flat bones, metaphyseal regions of long bones
More flexible
Mechanical Properties of Bone
Must deal with various types of loading
types of loading that bones deal with
Compression, Tension, Torsion, Shear
where is compression felt
Compression is felt on every bone because of gravity (weight bearing)
what can take some of the tension force felt by bone away
muscles
Bending Mechanisms: Tension Failure
Transverse Fractures
Greenstick Fractures
Oblique Fractures
transverse, greenstick, oblique - which one heal the best
oblique - This heals because the is more SA and more area for blast and clast to lay down
Greenstick - Will heal better because the periosteal sheath is still intact
transverse: Hard to heal
Twisting Failure due to what kind of movement
torsion
Traction Failure leads to what kind of fracture
Avulsion fracture
Compression Failure leads to what kind of fracture
compressive fracture
what is Torus fractures
buckle fracture
What is the most common frx in lower forearm in young children
Torus (buckle) frxs of distal metaphysis of radius & ulna
FOOSH
Salter-Harris fracture
fracture that can occur to a growth plate
Salter-Harris Classification type 1
Plane of separation along the epiphyseal plate through the zone of cartilage transformation
type 1 blood supply and future growth
Blood supply intact and future growth is normal
Type 1 is cause by
Usually produced by a shearing type force
type 1 periosteum
Periosteal attachments will sometimes remain intact
Salter-Harris Classification type 2
Most common (75%)
Fracture extends across the corner of metaphysis
Type 2 healing and blood
Future growth is considered normal because blood supply remains intact
type 2 peri
Periosteal hinge remains intact
Salter-Harris Classification type 3
Rare
This isan intra-articular fracture extending from the physis into theepiphysis
Usually occurs at distal tibia
type 3 future growth
Future growth usually normal but displaced fractures produce an irregular articular surface
Salter-Harris Classification type 4
Intra-articular fracture that extends throught the epiphyseal plate and into the metaphysis
type 4 future growth
ORIF with “perfect” fixation needed to have any chance at union
May lead to nonunion/malunion with progressive disturbance of growth
Salter-Harris Classification type 5
Crushing injuries, jumping from heights
Diagnosis is difficult secondary to lack of displacement
type 5 blood supply and future growth
May lead to permanent damage with a complete or partial cessation of growth leading to limb length discrepancy and deformity
intraarticular fracture
a fracture that crosses a joint surface
agulated fracture
The two ends of the broken bone are at an angle to each other
Fracture translation
the movement of fractured bones away from each other
distracted fracture
A fracture resulting in increased overall bone length, is due to distraction (widening) of the bone components.
Overriding–
A displaced fracture where the bone fragments overlap
Callus
A soft callus (a type of soft bone) replaces the blood clot that formed in the inflammatory stage
The callus holds the bone together, but isn’t strong enough for the body part to be used
Application of weight bearing in remodeling stage of fracture healing is good or bad
good for healing
will grow stringer in the direction of compressive loads
factors that effect fracture healing time
Age of the Patient
Site and Configuration of the Fracture
Initial Displacement of the Fracture
Blood Supply to Fracture Fragments
age and fracture healing
Younger Patients Heal Faster
Intact CV system
More metabolic activity
Bones surrounded by muscle vs. bones that lie subcutaneously or within joints- which heal faster
Bones surrounded by muscle heal faster than bones that lie subcutaneously or within joints
because of blood supply
Cancellous bone healing vs. compact bone
Cancellous bone heals faster than compact bone
less structure
Epiphyseal separations vs. epiphyseal fractures healing
Epiphyseal separations heal faster than epiphyseal fractures
Non-displaced vs. displaced fractures healing rate
Non-displaced fractures with intact periosteal sleeve heal twice as fast as displaced fractures.
The greater the displacement, the longer the healing time
Reduced vascularization and non-union.
Reduced vascularization increases risk of non-union.
what are Nonunion fracture
Fractures that still allow free movement of the bone ends at 3-4 months after injury demonstrate delayed union
are classified as hypervascular (hypertrophic) or avascular (atrophic) based upon their capability of biologic reaction (vitality of the bone ends).
Reduced vascularization realtionship with avascular necrosis
Reduced vascularization increases risk of avascular necrosis
Avascular necrosis is most common where
more common with intra-articular fractures, especially of the femoral head/neck, femoral condyles, proximal and talar neck.
when do you use Protection Alone
Sling
Undisplaced stable fractures of ribs, phalanges, metacarpals, clavicle (in children)
Mild compression fractures of spine
Impaction fracture of proximal humerus
when do you use Immobilization by External Splinting without Reduction
Undisplaced but unstable fracture
what is External Splinting without Reduction
Relative immobilization: can still move other aspects of the extremity.
Casts, splints
Closed Reduction followed by immobilization
Displaced fracture where surgeon predicts reduction can be done accurately and maintained without need for surgery.
Closed Reduction with External Fixation
Severely comminuted unstable fractures
Open fractures with extensive soft tissue damage including arteries and nerves
Closed Reduction with Internal Fixation
Can reduce fracture without surgery but cannot maintain it with immobilization
Unstable fracture of femoral neck
Place pins and screws after reduction is achieved.
Open Reduction Internal Fixation (ORIF)
Used when closed reduction is impossible
Displace avulsion fractures, intra-articular fractures
Soft tissue entrapment in fracture
Displaced fracture crossing epiphyseal plate in children.
fever may be a sign of
infection
Persistent signs of inflammation around the joint of the fracture may be a sign of
infection
Radiodensity
Refers to the amount of radiation an object absorbs.
Radiopaque
Easily absorbs radiation therefore they are more radiant dense
Radiolucent
Easily penetrated by radiation, less dense and permit the x-ray beam to pass through them
Air in Xray
black
Fat in x ray
– Gray black
water in x ray
Gray
bone in x ray
White
contrast media in x ray
White outline
in x ray does the density of an object matter
yes, think of block of cheese
Arthrogram
inject the body with heavy metals
Detailed view of what’s happening inside your joints
Improves visualization
Myelogram
Spine – Subarachnoid space where it mixes with CSF
Look for problems in the spinal canal
Discogram
Nucleus: contrast liquid is injected into the center of one or more spinal discs
Back pain
Arteriogram
X ray of Specific Vessels
CT Scans
radiography that gives slices of the body
Provides greater visualization of soft tissue but can’t pick up histological changes.
MRI T1
Shorter time between pulses
T1 images distinguish fat from CSF or those with high water content
Soft tissue appears gray
MRI T2
Longer time between pulses
Fat and CSF are both hyper-intense, but fat can be suppressed
Muscle injury will appear bright with it’s increase in water content
what is T1 good at showing
the difference in fluid from fat
what is T2 good at showing
“fat surpressed” and shows clearer visualization of discs and the fluid
muscle injury with show bright because of the swelling
