BLOOD SUPPLY OF BONES

Dr Thouseef A MajeedMS Ortho PG VMKVMCH

Salem

Types of bones

Anatomy of a long bone

Copyright 2009 John Wiley & Sons, Inc.

Bone tissue cell types

• Osteogenic cells – unspecialized stem cells

• Osteoblasts – bone builders

• Osteocytes – mature bone cells derived from osteoblasts

• Osteoclasts – bone ‘breakers’ are multinucleate

• Bone receives 5-10% of cardiac output

• Bones that receive tenous blood supply – scaphoid– talus– femoral head– odontoid

Blood supply to long bone comes from three

sources

– Nutrient artery system

– Metaphyseal and epiphyseal system

– Periosteal system

Copyright 2009 John Wiley & Sons, Inc.

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

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

• 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.

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.

Layers of Epiphysis

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.

• 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.

• 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.

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.

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.

• 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.

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.

• 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

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

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

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

.

Centripetal flow

• The medullary nutrient system is

interpted ,the periosteal system

provides a reverse supply and blood

flow becomes centripetal (Towards the

center)

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.

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

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.

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 .

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.

Blood supply of head and neck of femur

Blood supply of scaphoid

Blood supply of talus

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)

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

• 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

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

Osteomyelitis

Hair pin arrangements of arterioles

Sluggish flow

Tortous blood vessels and skimming of bacteria

References

• Turek• Apleys • Inderbir Singh text book of histology

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