How your blood supply circulates through bones 

A dense vascular network delivers oxygen and nutrients to all 206 bones in the human body.

Bone receives 5-10% of cardiac output

Bones that receive tenuous blood supply

scaphoid

talus

femoral head

odontoid

Blood supply to long bone comes from three sources  

nutrient artery system

metaphyseal-epiphyseal system

periosteal system

Nutrient Artery System

High pressure system that branches from major systemic arteries

Enter the cortex through the nutrient foramen and enter the medullary canal

then branch into ascending and descending branches

then branch into arterioles and supply the inner 2/3 of mature bone via the haversion system 

Metaphyseal epiphyseal system

Arteries arise from periarticular vascular plexus

e.g. geniculate arteries

Periosteal System

Low pressure system that supplies the outer 1/3 of bone

connected by

Volkman’s artery (perpendicular to long axis)

Haversion system (parallel to long axis)

Intracortical Vascularization

Intracortical vessels travel within canals

Primary Haversian canals

Secondary Volkmann canals

Direction of Arterial Flow

Normal intraosseous blood flow rate is 5-20ml/min/100g of bone 

Mature bone

flow is centrifugal (inside to outside)

because of high pressure nutrient artery system and low pressure periosteal system

Immature bone

flow is centripetal (outside to inside)

because low pressure periosteal system predominates

Factors increasing blood flow

hypoxia

hypercapnia

sympathectomy

Direction of Venous Flow

 Mature bone  

flow is centripetal (outside to inside)

cortical capillaries drain to venous sinusoids, which drain to the emissary venous system

Growth Plate

Perichondrial artery is the major source of nutrition of the growth plate 

Pathoanatomy

Fractures

patterns of blood flow following fracture

immediate phase

initial decrease in blood flow after fracture

flow is centripetal (outside to inside)

because high pressure nutrient artery system is disrupted

low pressure periosteal system predominates

hours to days

increase in blood flow (regional acceleratory phenomenon)

peaks at 2 weeks and returns to normal in 3-5 months

Intramedullary nails

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

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Blog at WordPress.com.

Up ↑

%d bloggers like this: