Injury and Healing- Bones Flashcards
1
Q
What makes up the musculoskeletal system?
A
Musculoskeletal system–> bone, muscle, connective tissue
connective tissue–> tendon, ligaments, cartilage
2
Q
What is a joint?
A
a junction between 2 or more separate bones
3
Q
How many bones in the skeleton?
A
206 bones (+sesamoids)
270 in children
4
Q
What are the 2 skeletons in the body?
A
axial and appendicular
5
Q
What is the axial skeleton?
A
vertebral column, cranium, rib cage
6
Q
What is the appendicular skeleton?
A
pectoral girdle, upper and lower limbs, pelvic girdle
7
Q
What are the functions of the skeleton?
A
- support- helps you stand up
- protection- protects your vital organs
- movement- works with muscles so you can get around
- mineral storage- stores calcium and phosphate
- produces blood cells
8
Q
How do flat bones develop in utero?
A
Intramembranous mesenchymal cells»_space; bone
9
Q
How do long bones develop in utero?
A
Endochondral mesenchymal»_space; cartilage»_space; bone
10
Q
What is intramembranous ossification?
A
When mesenchymal cells turn to bone
- forms flat bones of skull, clavicle and mandible
- bone development from fibrous membranes
11
Q
What is the template for mesenchymal cells?
A
12
Q
What is osteoid?
A
Unmineralized organic tissue that eventually undergoes calcification and is deposited as lamellae or layers in the bone matrix.
13
Q
What is the process of intramembranous ossification?
A
Condensation of mesenchymal cells which differentiate into osteoblasts – Ossification centre forms
Secreted osteoid traps osteoblasts which become osteocytes
Trabecular matrix and periosteum form
Compact bone develops superficial to cancellous bone. Crowded blood vessels condense into red bone marrow
14
Q
What is endochondral ossification?
A
mesenchymal to cartilage bone
Development of long bone from a hyaline cartilage model
15
Q
What is the process of endochondral ossification?
A
- Bone collar formation
- Cavitation
- Periosteal bud invasion
- Diaphysis elongation
- Epiphyseal ossification
16
Q
What is diaphysis?
A
the shaft or central part of a long bone.
17
Q
What is the primary ossification centre in endochondral ossification?
A
diaphysis
18
Q
What is the secondary ossification centre in endochondral ossification?
A
epiphysis
19
Q
What is the epiphysis?
A
The ends of long bones
20
Q
What are bones made of?
A
cells and matrix
21
Q
What are the bone cells?
A
Osteogenic cells
Osteocyte
Osteoblast
Osteoclasts
22
Q
What are osteogenic cells?
A
Bone stem cells
23
Q
What are osteocytes?
A
‘Mature’ bone cell
Formed when an osteoblast becomes imbedded in its
secretions
Sense mechanical strain to direct osteoclast and
osteoblast activity
24
Q
What are osteoblasts?
A
‘Bone forming’ think BLAST BUILDING
Secretes ‘osteoid’
Catalyse mineralisation of osteoid
25
What are osteoclasts?
Bone breaking'
Dissolve and resorb bone by phagocytosis
Derived from bone marrow
26
Where are osteogenic cells found?
Deep layers of periosteum
27
Where are osteoblasts found?
Growing portions of bone, including periosteum and endosteum
28
Where are osteocytes found?
Entrapped in matrix
29
Where are osteoclasts found?
Bone surfaces and at sites of old, injured or unneeded bone
30
What is the bone matrix composed of?
Organic component (40%)= type I collagen and ground substance
ground substance= proteoglycans, glycoproteins, cytokine and growth factors
Inorganic component (60%)= calcium hydroxyapatite and Osteocalcium phosphate
31
What are the different types of bone?
Immature bone
Mature bone
32
What is immature bone?
Woven. immature/ disorganised
First bone that is produced
Laid down in a ‘woven’ manner – relatively weak
Mineralized and replaced by mature bone
33
What is mature bone?
Mineralized woven bone
Lamellar (layer) structure – relatively strong
Can be split into cortical and cancellous bone
34
What is cortical bone?
Cortical/ compact/ lamellar
‘Compact’ – dense
Suitable for weight baring
35
What is cancellous bone?
cancellous/ spongy
‘Spongy’ – honeycomb structure
Not suitable for weight baring
36
What is the parietal bone of the skull made of?
Cortical and cancellous bones
cortical outside, cancellous inside
37
How is compact/ cortical bone organised?
Into osteons
Compact bone: has osteons
Few spaces
Provides protection, support and resists stresses produced by weight of movement
38
What are osteons?
Repeated structural units ‘Osteons’ – concentric ‘Lamellae’ around a central ‘Haversian Canal’
‘Haversian Canal’ – contain blood vessels, nerves and lymphatics.
Lacunae – small spaces containing osteocytes Tiny Canaliculi radiate from lacunae filled with extracellular fluid.
Volkmans canal – transverse perforating canals
39
What is the structure of long bones?
Periosteum – Connective tissue covering
Outer Cortex – compact bone
Cancellous bone
Medullary cavity - contains yellow bone marrow (and sometimes red bone marrow)
Nutrient Artery
Articular cartilage: on surface of bone at a joint only
40
How do bones grow?
Interstitial and appositional
41
What is interstitial growth?
increase in length
in long bones
42
What is appositional growth?
increase thickness and diameter
43
Where does interstitial growth occur?
physis (physeal plate)
44
What is the physis?
physis (physeal plate)
Zone of elongation in long bone
Contains hyaline cartilage
Epiphyseal side – hyaline cartilage active and dividing to form hyaline cartilage matrix
Diaphyseal side – Cartilage calcifies and dies and then replaced by bone
45
What are the steps of appositional growth?
Appositional growth – deposition of bone beneath the periosteum to increase thickness
1. Ridges in periosteum create groove for periosteal blood vessel
2. Periosteal ridges fuse, forming an endosteum-lined tunnel
3. Osteoblasts in endosteum build new concentric lamellae inward toward center of tunnel, forming a new
osteon
4. Bone grows outwards as osteoblasts in periosteum build new circumferential lamellae. Osteon formation repeats as new periosteal ridges fold over blood vessel.
46
What is the role of bone in calcium homeostasis?
Bone – Stores 99% of total body calcium
Calcium hydroxyapatite – structural support
Calcium is deposited and withdrawn during bone remodelling
Regulated by PTH and Calcitriol (Kidneys)
Calcitonin (Thyroid) – stimulates calcium uptake into bone
Vitamin D – helps the body absorb and use calcium
47
What are the mechanisms of bone fracture?
Trauma= low or high E
Stress
Pathological
48
What is an example of low and high E trauma mechanisms of fracture?
low E= stairs
high E= car accident
49
Do stress fractures always show on x-rays?
No
50
How does a stress fracture when it is a abnormal stress on normal bone?
overuse-->
Stress exerted on bone> bones capacity to remodel-->
Bone weakening-->
Stress fracture-->
Risk of complete fracture
51
What are our weight bearing bones?
femur, tibia, metatarsals, navicular
52
What activities are related to stress fractures?
athletes, occupational, military, female athlete triad
53
What is the mechanism of fracture when it is a normal stress on abnormal bone?
Pathological
54
What are the pathological reasons for abnormal bone?
Osteoporosis
Malignancy (eat at bone)
Vitamin D deficiency
Osteomyelitis
Osteogenesis imperfecta
Paget's
Infection of bone, so puss in bone= weaker
55
What changes in osteoporosis?
Bone size doesn't change, there is just a thinner cortex
56
What is osteopenia?
The stage before osteoporosis is called osteopenia. This is when a bone density scan shows you have lower bone density than the average for your age, but not low enough to be classed as osteoporosis. Osteopenia does not always lead to osteoporosis.
57
What happens during osteopenia and osteoporosis?
Osteoclast activity > Osteoblast activity -> Disrupted microarchitecture
Female > Male 4:1
Postmenopausal Osteoporosis – Women 50-70
Senile Osteoporosis - > 70
Secondary osteoporosis: Any age, 60% Male
Hypogonadism
Glucocorticoid excess
Alcoholism
Associated with ‘fragility fractures’ – hip, spine, wrist
Low energy trauma-> fracture
58
What happens during vitamin D deficiency?
Vitamin D facilitates calcium, magnesium and phosphate absorption
Dietary or synthesized from the sun
Inadequate Calcium or Phosphate-> Defect in osteoid matrix mineralization
Paeds – Rickets, Adults - Osteomalacia
59
What happens during congenital osteogenesis imperfecta?
‘Brittle Bone Disease’
Hereditary – autosomal dominant or recessive
Decreased Type I Collagen due to:
Decreased secretion
Production of abnormal collagen
->Insufficient osteoid production
Effects:
Bones
Hearing
Heart
Sight
60
What happens in paget's disease?
Genetic & Acquired factors
Excessive bone break down and disorganized remodeling-> deformity, pain, fracture or arthritis
May transform into a malignant disease
4 stages:
1. Osteoclastic Activity
2. Mixed osteoclastic-
osteoblastic activity
3. Osteoblastic activity
4. Malignant degeneration
Can become cancer (not sure why)
61
What are the primary bone cancers?
62
What are the types of malignancies that cause fractures?
Blastic (bone forming)
Lytic (bone eating)
63
What are the general principles of tissue healing?
Bleeding-> inflammation -> new tissue formation -> remodelling
blood -> neutrophils, macrophages-> -BLASTS (fibro-, osteo-, chondro)-> macrophages, osteoclasts, osteoblasts
64
What are the 3 steps that fracture healing?
Inflammation
repair
Remodelling
65
What happens during inflammation of fracture healing?
Haematoma formation
Release of Cytokines
Granulation tissue and blood vessel formation
66
What happens during repair of fracture healing?
Soft Callus formation (Type II Collagen - Cartilage)
Converted to hard callus (Type I Collagen - Bone)
67
What happens during remodelling of fracture healing?
Callus responds to activity, external forces, functional demands and growth
Excess bone is removed
68
What is Wolff's law?
Bone Grows and Remodels in response to the forces that are placed on it
69
What are the two different types of bone healing?
Primary and secondary bone healing
70
What is primary bone healing?
Intramembranous healing
Absolute stability
Direct to woven bone
71
What is secondary bone healing?
Endochondral healing
Involves responses in the periosteum and external soft tissues
Relative stability
Endochondral ossification: more callus
72
How long does it take for a fracture to heal?
3-12 weeks depending on site
Phalanges: 3 weeks
Metacarpals: 4-6 weeks
Distal radius: 4-6 weeks
Forearm: 8-10 weeks
Tibia: 10 weeks
Femur: 12 weeks
73
When do you start seeing healing on XR from a fracture?
Signs of healing are visible on XR from 7-10 days
74
What are the principles of management of a fracture?
75
What are the ways of healing a fracture?
reduction
hold
fixation
rehabilitate
76
How does reduction work?
Children remodel faster
77
How does hold work?
78
How does fixation work?
79
How does rehabilitation work?
80
When can a patient have fusion?
If the broken bones are very close together
81
How would you get more information about an accident of damage/ fracture to leg?
Get a history from the patient and a bystander if possible
Do an examination of the patient’s leg looking for skin integrity, deformity, function, tenderness and neurovascular status (they do not need to learn the full form examination)
Request an x-ray with 2 views (AP and lateral)
82
What might you expect when examining a patient from an accident with a fracture?
Inability to weight bear
Severe pain
Swelling and point tenderness
Deformity
Scrapes / abrasions
Wound if open fracture
Loss of movement
Loss of sensation if nerve injury
83
What is the difference between open and closed fractures?
open the skin has been penetrated and vice versa
