Presentation blood supply on bone. .pptx

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1. BLOOD SUPPLY OF LONG BONES Presented by- DR.RISHABH RAI JR1 Department of orthopaedics

2. Anatomy of long bone

3. Types of cells in bone tissue Osteogenic cells- Unspecialised stem cells. Osteoblasts- Bone builders Osteocytes- Mature bone cells derived from osteoblasts. Osteoclasts-Bone ‘breakers’,these are multinucleate cells.

4. HAVERSIAN SYSTEM

5. Bone receives 5-10% of cardiac output. Bones with a tenuous blood supply include- -Scaphoid -Talus -Femoral head -Odontoid

6. Blood supply to long bones comes from three sources- Nutrient artery system Metaphyseal-epiphyseal system Periosteal system

7. NUTRIENT ARTERY SYSTEM

8. NUTRIENT FORAMEN Oblique canal situated in the diaphysis of long bones. Nutrient canals slope away from 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 shaft. “Go to elbow and flee the knee”

9. All long bones have one or more nutrient arteries that enter through a nutrient foramen. It is a high pressure system that branches from major systemic arteries. Enter the diaphyseal cortex through 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 where they anastomose with metaphyseal and epiphyseal vessels.

10. Within the cortex they give rise to branches,some extending longitudinally along the axis of long bone while others proceed radially and ultimately forms capillaries within the haversian system. Some arteriolas transfers the entire cortex to reach and anastomose with periosteal arteriolar network. Within the marrow,some arterioles are short and profusely branched to supply the capillaries for the marrow. This system enables blood supply to atleast the inner 2/3rd of the mature diaphyseal cortex via the haversian system . 60% of cortical bone vascularised by nutrient arteries.

11. METAPHYSEAL SYSTEM Derived from the neighbouring systemic vessels. These arteries directly go into the metaphysis and reinforce the metaphyseal branches of the primary nutrient artery.

12. 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 and receives nutrition from two sources. Epiphyseal vessels that supply resting,germinal,proliferating and upper hypertrophic cell layers by diffusion. Metaphyseal vessels that supply zone of provisional calcification.

13. 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,and terminal branches of nutrient artery. Obliteration of epiphyseal blood supply results in necrosis of epiphysis and deprives deeper cartilage cells of growth plate for their nutrition.

14. Longitudinal growth ceases and 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.

15. ANATOMY OF PERIOSTEUM Periosteum consists of two layers- 1) outer fibrous layer - contains fibroblasts. 2) inner cambium layer - contains progenitor cells that develop into osteoblasts.

16. PERIOSTEAL SYSTEM Low pressure system that supplies outer 1/3rd of bone. Forms an extensive network of vessels,covers entire length of bone shaft. Periosteal vessels send small branches through minute channels in cortex to supply about outer 1/3rd of mature diaphyseal cortex.

17. 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 1/3rd portion of the cortex.

18. PAEDIATRIC BLOOD SUPPLY Circulation in paediatric bone differs from adult circulation due to requirements of growth and 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.

19. In final few mm before terminal arteriolar 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.

20. 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 emissary 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.

21. PHYSIOLOGY OF BLOOD FLOW 5-20 ml/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.

22. BLOOD FLOW THROUGH 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

23. Centrifugal flow Arterial flow in mature bone is centrifugal(inside to outside),which is the net effect of the high pressure nutrient artery system and the low pressure periosteal system. Centripetal flow When fracture disrupts the nutrient artery system,the periosteal system pressure predominates and blood flow is centripetal(outside to inside). Flow in immature developing bone is centripetal because the highly vascularised periosteal system is the predominant component. Venous flow in mature bone is centripetal. Cortical capillaries drain into venous sinusoids,which drain to the emissary venous system. Factors increasing blood supply - -Hypoxia -Hypercapnea -Sympathectomy

24. 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 1/3 rd 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.

25. Metaphyseal and Epiphyseal 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.

26. 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 greater number of blood vessels become actively functional and demonstrate by micro angiographic methods

27. 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 ischemic and necrotic,outer 1/3rd remains viable.

28. 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 interference 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.

29. Fracture healing Bone blood flow is the major determinant of how well a fracture heals. 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.

30. Blood supply of head and neck of femur

31. Blood supply to femoral head : At birth : Vessels from lateral side: lateral epiphyseal artery No ligamentum teres. 4 months to 4 years : Epiphyseal ossification begins. Ascending cervical branches.(metaphyseal and lateral epiphyseal vessels) After 4 months metaphyseal branches decrease.

32. 4-7 years: Epiphyseal plate is firm barrrier between epiphysis and metaphysis. Only source is lateral epiphyseal arteries. Adolescent period: Growth plate extends beneath both epiphysis. Extracapsular arterial ring. Ascending cervical branches (retinacular arteries) Artery of ligamentum teres. Epiphyseal blood supply. Metaphyseal blood supply.

33. Blood supply of scaphoid Volar branch enters scaphoid tubercle and supplies distal 20-30%. Dorsal scaphoid branch of radial artery enters through numerous small foramina along the spiral groove and dorsal ridge and has nearly 80% of blood supply.

34. Blood supply of talus

35. 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 ischaemic and necrotic ( often followed the development of periosteal newborn formation).

36. 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.

37. If the nutrient artery is supressed (intramedullary nailing) compensatory periosteal vascular proliferation occurs and the viability of cortex to a great extent. When the medullary nutrient blood supply is interrupted + stripping of periosteum = entire thickness of cortex becomes necrotic.

38. Non-union Scaphoid fracture Neck of femur fracture Talus fracture Distal tibial fracture Should be fixed due to- -the nutrient artery divides into three ascending branches and a single descending branch. -Bulk of muscle is more over proximal tibia than distal tibia.

39. Osteomyelitis Hair pin arrangements of arterioles. Sluggish flow. Tortuous blood vessels and skimming of bacteria.

40. References- Millers. Turek. Google images.

41. Thank you!!!