Blood Supply of Long Bone by Aakash Pandit

Blood supply of long bone
avascular necrosis of femoral head
free fibula flap reconstructive surgery
Osteomyelitis

1. Blood supply of long bone

2. Long bones – those that are longer than they are wide Humerus Radius Ulna Metacarpals Phalanges  Clavicle Femur Tibia Fibula

3. Bone and Blood Bone strictly relies on blood supply for its correct homeostasis.  Apart from its classical role in the transport of oxygen, nutrients and systemic factors, the blood also conveys bone cell precursors pivotal for bone formation. At the same time, bone cells influence blood homeostasis by regulating haematopoiesis. Evidence accumulating over the years clearly demonstrates a strong coupling of angiogenesis and osteogenesis under physiologic conditions. Ref : Bone and Blood |Nadia Rucci & Anna Teti |Department of Biotechnological and Applied Clinical Sciences, University of L’Aquila, L’Aquila, Italy|

4. Sources of blood supply Nutrient Artery System Metaphyseal System Epiphyseal System Periosteal System

5. Nutrient artery Enter through an oblique canal situated on the diaphysis of long bones aka nutrient foramen . It supplies inner 2/3rd of cortex, medullary cavity and metaphysis.

6. Nutrient artery are high pressure system that branches from the systemic arteries.  They enter bone through cortex and eventually enter medullary cavity where they branch into ascending & descending branches. These branches travel to the end of bone anastomosing with epiphyseal and metaphyseal arteries.  In the cortex they divide longitudinally and radially/transversely  according to the Haversian and Volkmann's canal respectively. Thus, forming the Capillary network of Haversian system. Some arterioles enter the cortical bone and anastomose with periosteal arterial system whereas some perfuse bone marrow.

7. Periosteal arterial system  Periosteal vessels send small branches through Volkmann's canal in cortex to supply about outer 1/3rd of cortex. Extensive network of vessels covers entire length of the bone shaft.   Anastomoses with adjacent skeletal muscles so in cases in which the nutrient artery of muscle has been damaged, then periosteal vessels may temporarily serve as the primary blood supply; Children, while periosteum is actively engaged in circumferential bone growth, blood supply in this area is much more abundant than it is in adult.

8. Epiphyseal arterial system The epiphysis has openings that permit passage of large number of vessels into and out of the ossification centers. In femoral and radial heads, which are almost entirely covered by cartilage vessels enter in region between articular cartilage & growth-plate cartilage. Epiphyseal vessels are responsible for permitting longitudinal growth to occur.

9. Metaphyseal arterial system These arteries directly go into the metaphyses and reinforce/anastomose with the metaphyseal branches of the primary nutrient artery. Metaphyseal vessels nourish osteoprogenitor cells , which lay down bone on cartilage matrix. Following the growth arrest of the cartilage plate, there is an extensive anastomoses between epiphyseal vessels, metaphyseal vessels, & terminal branches of Nutrient Artery.

10. Growth plate itself is avascular & receives nutrition from 2 sources. Epiphyseal arteries Epiphyseal vessels that supply resting, germinal, proliferating, and upper hypertrophic cell layers by diffusion Metaphyseal Arteries Metaphyseal vessels that supply zone of provisional calcification.

11. Ref : UpToDate 

12. Pediatric blood flow In young child, epiphyseal vessels are separated from metaphyseal vessels. 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.

13. Venous drainage  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. ONLY 5-10% OF VENOUS DRINAGE IS THROUGH NUTRIENT VEIN; REMAINING IS THROUGH PERIOSTEAL VENOUS DRINAGE

14. Ref : Orthobullets

15. Osteomyelitis  Hair pin arrangement of metaphyseal arterioles Circulating organisms tend to start the infection in the metaphyseal ends of the long bones because of the sluggish circulation in the metaphyseal capillary loops.  More common in infants and children.

16. Avascular necrosis of bone Infarction of bone and marrow, usually very painful. Most common site is femoral head (watershed zone) due to insufficiency of medial circumflex femoral artery. C auses include  1. Overdose of Corticosteroids e.g. Prednisone (reason is unknown) 2. Trauma  3. Alcoholism – increase level of fat in blood due to hepatic steatosis  4. SLE, Caisson's Disease (DCS "Bends"), Gaucher's disease and Cancer 

17. Ref: 30th Edition First Aid for the USMLE Step 1

18. OrthoInfo, American Academy of Orthopedic Surgeons

19. ORTHOINFO, AMERICAN ACADEMY OF ORTHOPEDIC SURGEONS ​

20. Free fibular flap  The initial use of free fibular flap was limited to the reconstruction of long bone defects of the extremities until 1989, where this flap was used for restoration of segmental mandibulectomy defects. The fibula is a long non-weight bearing bone of the lower extremity with adequate cortical thickness rendering it one of the strongest bones available for mandibular reconstruction. How to harvest free fibula flap for mandibular reconstruction? Practical tips and tricks |Chirom A Singh | Rajeev Kumar | Pirabu Sakthivel |Department of Otorhinolaryngology & Head and Neck surgery, All India Institute of Medical Sciences, New Delhi, India  |

21. Approximately 22 to 25 cm of bone can be harvested while preserving 6 to 7 cm of bone both distally and proximally to maintain the integrity of the ankle and knee joints as well as the common peroneal nerve, making this donor site unique in terms of the ability to restore total or subtotal defects of the mandible. The strength of the cortical bone effectively withstands the powerful forces of mastication when used for mandibular reconstruction.  How to harvest free fibula flap for mandibular reconstruction? Practical tips and tricks |Chirom A Singh | Rajeev Kumar | Pirabu Sakthivel |Department of Otorhinolaryngology & Head and Neck surgery, All India Institute of Medical Sciences, New Delhi, India |

22. https://www.microsurgeon.org/fibulaflap

23. Thank you :)