Download - Blood supply of long bones
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BLOOD SUPPLY OF BONES
Dr Thouseef A MajeedMS Ortho PG VMKVMCH
Salem
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Types of bones
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Anatomy of a long bone
Copyright 2009 John Wiley & Sons, Inc.
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Bone tissue cell types
• Osteogenic cells – unspecialized stem cells
• Osteoblasts – bone builders
• Osteocytes – mature bone cells derived from osteoblasts
• Osteoclasts – bone ‘breakers’ are multinucleate
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• Bone receives 5-10% of cardiac output
• Bones that receive tenous blood supply – scaphoid– talus– femoral head– odontoid
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Blood supply to long bone comes from three
sources
– Nutrient artery system
– Metaphyseal and epiphyseal system
– Periosteal system
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Copyright 2009 John Wiley & Sons, Inc.
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Nutrient foramen• Oblique canal situated in the
diaphysis of long bones.
• Nutrient canals slope away from the knee for femur tibia and fibula.
• Canal facing towards elbow in radius, ulna, and humerus
• 90% of long bones have single nutrient foramen in middle third of the shaft
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Nutrient artery system• All long bones have one or more nutrient
arterites that enter through a nutrient foramen
• High pressure system that branches from major systemic arteries
• Enter the cortex through the nutrient foramen and enter the medullary canal
– Then branches into ascending and descending branches
– Each branch sends lateral oriented arteriolar branches
– Ascending and descending branches travels to the end of the bone they anastomosis with metaphyseal and epiphyseal vessels
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• With in the cortex they give rise to branches ,
Some extending longitudinally along the axis of
long bone while others proceed radially and
ultimately forms capillaries with in the haversion
system .
• Some arterioles transfers the entire cortex to
reach and anastomose with periosteal arteriolar
network.
• With in the marrow , Some arterioles are short
and profusely branched to supply the capillaries
for the marrow .
• This system supplies the inner 2/3 of mature bone
via the haversion system.
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Metaphyseal system• Derived from the neighboring
systemic vessels.
• These arteries directly go into
the metaphyses and reinforce
the metaphyseal branches of
the primary nutrient artery.
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Layers of Epiphysis
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Epiphyseal arteries• The epiphysis has openings that permit
passage of large number of vessels into and
out of the ossification centers.
• Growth plate itself is avascular & receives
nutrition from 2 sources.
• Epiphyseal vessels that supply resting,
germinal, proliferating, and
upper hypertrophic cell layers by diffusion
• Metaphyseal vessels that supply zone of
provisional calcification.
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• In young child, epiphyseal vessels are separated
from metaphyseal vessels.
• Following growth arrest of the cartilage plate,
there is an anastomoses between epiphyseal
vessels, metaphyseal vessels, & terminal
branches of nutrient artery.
• Obliteration of epiphyseal blood supply results
in necrosis of epiphysis & deprives deeper
cartilage cells of growth plate for their nutrition.
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• Longitudinal growth ceases &collateral
circulation is not quickly restored, permanent
closure of epiphyseal plate occurs.
• Epiphyseal vessels are responsible for
permitting longitudinal growth to occur.
• Metaphyseal vessels nourish osteoprogenitor
cells , which lay down bone on cartilage matrix.
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Anatomy of periosteum• Periosteum consists of two
layers outer fibrous and
inner cambium layer.
• The fibrous layer contains
fibroblasts
• The cambium layer contains
progenitor cells that develop
into osteoblasts.
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Periosteal System• Low pressure system that supplies
the outer 1/3 of bone
• Forms an extensive network of
vessels covers entire length of the
bone shaft.
• Periosteal vessels send small
branches through minute channels in
cortex to supply about outer 1/3 of
cortex.
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• Periosteal arteries are the arteries
of periosteum being especially
numerous beneath the muscular
and ligamentous attachment.
• Beneath the periosteum they divide
into branches and thereby entering
the Volkmann’s canals to supply the
outer one third (1/3) portion of the
cortex.
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Paediatric Blood supply
• Circulation in pediatric bone differs from adult circulation due to requirements of growth & presence of epiphyseal plate.
• Terminal branches of nutrient artery, along with metaphyseal vessels, approach growth plate in a parallel relationship.
• Branches are so numerous as they reach growth plate that there is almost one vessel for each column of cartilage cells.
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• In final few mm before terminal
arteriole reaches cartilage, it is
encased in a tube of enchondral
bone
• Children, while periosteum is
actively engaged in circumferential
bone growth, blood supply in this
area is much more abundant than it
is in adult
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Venous drainage of bone• Long bones posses a large venous sinus
• Long bones drains into central venous
sinus ,from Central venous sinus through
nutrient vein, periosteal veins and emissery
veins it drains out
• Metaphyseal/epiphyseal veins – drain blood
from the proximal and distal regions of the
medullary cavity
• Periosteal veins – drain blood from the ends of
long bones and the red bone marrow
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Physiology of blood flow
• 5-20ml/min in 100gm of wet bone tissue
• 4-10% of resting cardiac output
• Metaphysis has highest blood flow stimulating factors
– sympathetic nerves
– acid metabolites
– increased or decreased CO2 tension
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Blood Flow throug the bone• The direction and extent of blood flow
with in the diaphyseal cortex remains
controversial
• There are two theories behind this
Centrifugal flow and centripetal flow
Centrifugal flow
• With the blood entering the endosteal
aspect from the medullary nutrient system
and flowing through the periosteal surface
.
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Centripetal flow
• The medullary nutrient system is
interpted ,the periosteal system
provides a reverse supply and blood
flow becomes centripetal (Towards the
center)
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Periosteal flow • The role of periosteal vessels has not
been clearly defined.
• Periosteal system originates mainly from
the surrounding muscles and provide the
blood supply to the outer one third to
one half of cortex .
• At the outer aspect of the cortex many
thin walled vessels with in the haversian
canal are observed to be in continuity
with arterioles with in the periosteum.
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Metaphysal and Epiphysal flow
• The end of the long bones are supplied by vessels that enter the
metaphysis and epiphysis through small foramina at the periphery.
• After entering the bone these arterioles branch into arterial
arcades, forming a dense interlocking network
• The vessels becoming progressively smaller in caliber as they
approach subchondral zone
• In subchondral zone they terminate as small capillary loops
• The epiphyseal,Metaphyseal arterioles anastomose with terminal
twigs of medullary nutrient artery and contribute 20-40% of the
total supply of the entire bone
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Variations In Cortical Blood Flow
• In a normal extremities, not all blood vessels are functional at
the same time. Blood transport occurs through a limited number
of vessels, the other being considered in a resting state
• Under certain conditions(fracture of opposite extremities) a
grater number of blood vessels become actively functional and
demonstrate by micro angiographic methods.
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Impairment of diaphyseal blood supply• If the circulation in bone marrow and periosteum is interrupted , an
increase in metaphyseal blood flow occurs
• If circulation through nutrient arteries and metaphyseal vessels are
interrupted, proliferation of periosteal vessels and increased periosteal
blood flow takes place(often accompanied by periosteal newborn
formation)
• When the blood flow through the nutrient artery is interrupted,
approximately 2/3rd of the cortex becomes ischeamic and necrotic, outer
third remains viable .
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Reversal of venous blood flow
• Under certain circumstances blood flow through large peripheral
veins can be reversed into alternative routes with in the
medullary cavity
• When there is interferance with venous return through main
veins of extremities , the medullary pressures with in the regional
long bones are increased .so collateral venous return takes place
through medullary venous channels.
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Blood supply of head and neck of femur
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Blood supply of scaphoid
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Blood supply of talus
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Applied aspects
Periosteal stripping
• If the periosteum is stripped and left detached from the cortex and
nutrient artery is preserved, only outer third of the cortex become
ischeamic and necrotic ( often followed the development of
periosteal newborn formation)
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Intra medullary nail
• Unreamed intramedullary nails preserve endosteal
blood supply
• Reaming devascularizes inner 50-80% of the cortex and
delays revascularization of endosteal blood supply.
• Loose fitting nails spare cortical perfusion and allow
more rapid reperfusion
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• Tight fitting nails compromise cortical perfusion and reperfusion is
slow
• If the nutrient artery is supressed (intra medullary nailing)
compensatory periosteal vascular proliferation occurs and the
viability of cortex to a great extent .
• When the medullary nutrient blood supply is interepted + stripping
of periosteum = entire thickness of cortex becomes necrotic
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Nonunion1. scaphoid fracture2. neck of femur fracture 3. Talus fracture
Distal tibial fractures
Should be fixed due to
the nutrient artery divides into three ascending branches & a single
descending branch.
Bulk of muscle is more over proximal tibia than distal tibia
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Osteomyelitis
Hair pin arrangements of arterioles
Sluggish flow
Tortous blood vessels and skimming of bacteria
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References
• Turek• Apleys • Inderbir Singh text book of histology
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