Bone

Question 1

Give the structure of Compact - Cortical bone

Answer 1

• Dense but less flexible
• Osteon- concentric rings ( lamellae) of calcified matrix surrounding vertically oriented blood vessels
• Separating the lamellae = lacunae -extra cellular fluid and bone cells
• Osteocytes - projections canaliculae receive information from other osteocytes in other lacunae - what’s happening with the whole body , bone making and breaking.

Question 2

Give the Structure of compact bone

Answer 2

• Solid hard layer
• External layer of all bones
• Compact takes vertical stress not lateral impact

Question 3

Give the Structure of Spongy bone -

Answer 3

• Lattice like
• Light
• Well organised along lines of stress , giving strength and resisting stress and forces without breaking
• Osteocytes in lacunae on the surface of the trabeculae
• Nutrients directly from the blood in medullary cavities
• Projections of bone transfer stress through

Question 4

What is Osteogenic bone? -

Answer 4

undifferentiated cells - develops into osteoblast

Question 5

What are Osteoblasts?-

Answer 5

build matrix and collagen fibres but can’t divide - forms bone tissue.

Question 6

What is an Osteocyte?-

Answer 6

maintains bone tissue - mature cells

Question 7

What are Osteoclasts?-

Answer 7

clear bone cells - ruffled border - functions in resorption , destruction of bone matrix.

Question 8

What is the constant process of remodelling called?-

Answer 8

Coupling

Question 9

How does bone form ?

Answer 9

New cartilage on the epiphyseal side of the epiphyseal plate , old layer of cartilage calcified.
Appositional growth- blood vessels stimulate osteoblasts to make more bone. Length and the width need to grow at the same time.

Question 10

Blood supply of bone -

Answer 10

• Periosteal artery , periosteum and outer osteons of compact bone
• Nutrient artery , nutrient foramen , medullary cavity and osteons of inner bones
• Metaphyseal arteries , Spongy bones and marrow in this area.
• Epiphyseal arteries , spongy bone and marrow in this area

Question 11

Briefly explain Osteoporosis-

Answer 11

Primary - expected loss of bone mass with age

Secondary - metabolic bone disease, cancer , malignancy , melanomas , malnutrition , certain drugs , lots of weight bearing

Question 12

Severity of Bone fractures -

Answer 12

• open/compound - soft tissue involement
• impacted - shaft of femur into head of femur
• comminuted - lots of different pieces
• closed/simple - less soft tissue involvemtn
• displaced
• compressed

Question 13

Give the 4 stages of fracture healing-

Answer 13

1 - Hematoma formation
2- Fibrocartilaginous callus formation
3- Bony callus formation
4- Bone remodelling

Question 14

Give the formation of the Hematoma-

Answer 14

• Nutrient artery
• Clot produced in 6-8 hours , bone cells die
• Inflammation= Phagocytic cells + osteaoclasts
• New capillaries grow in damaged area - angiogenesis

Question 15

Formation of Bony Callus

Answer 15

• Fibroblasts invade the procallus and lay down collagen
• Chondroblasts produce fibrocartilage.
• Osteoblasts secrete spongy bone that joins the broken ends of bones
• Last 3-4 months

Question 16

Formation of Bone remodelling -

Answer 16

• Compact bone replaces spongy in bone callus
• remodelled to normal shape
• sometimes a palpable lump remains

Question 17

Closed Immobilisation

Answer 17

Sling , cast , Splint

Question 18

Open Immobilisation

Answer 18

Internal fixation, External fixation, Open reduction

Question 19

Complications of Bone injury

Answer 19

• delayed / mal/non union
• avascular necrosis
• Sudecks Atrophy - distrubance in the nervous system
• Compartment syndrome - bleeding/pressure- drainage
• Volkmanns ischemia - forearm , increased pressure
• Myositis Ossificans - bone layed bone in muscle