Basic Sciences Flashcards
(219 cards)
1
Q
Osteoblasts are derived from?
A
undifferentiated mesenchymal stem cells,
2
Q
What is RUNX2?
A
multifunctional transcription factor that directs the formation of osteoblasts from UMC
3
Q
Osteoblasts produce ?
A
Osteoblasts produce type I collagen (i.e., bone), alkaline phosphatase, osteocalcin, bone sialoprotein, and RANKL.
4
Q
Osteocytes are ………………………… surrounded by newly formed matrix. They constitute …………….. of the cells in the mature skeleton, are
important for control of ………………………….
A
Osteocytes are former osteoblasts surrounded by newly formed matrix. They constitute 90% of the cells in the mature skeleton, are
important for control of extracellular calcium and phosphorous
5
Q
Osteoclasts are derived from ……………………………. RANKL is produced by ……………………., binds to immature …………………………, and stimulates differentiation into active, mature
osteoclasts that result in an increase in ………………………….
A
Osteoclasts are derived from hematopoietic cells in the macrophage lineage. RANKL is produced by osteoblasts, binds to immature osteoclasts, and stimulates differentiation into active, mature
osteoclasts that result in an increase in bone resorption.
6
Q
What is Osteoprotegerin?
A
Osteoprotegerin inhibits bone resorption by binding and inactivating RANKL.
7
Q
How to Osteoclasts bind to bone?
A
Osteoclasts bind to bone surfaces by means of integrins (vitronectin receptor), effectively sealing the space below, and then create a
ruffled border
8
Q
How do Osteoclasts resorp bone?
A
create a ruffled border and remove bone matrix by proteolytic digestion
through the lysosomal enzyme cathepsin K, Tartrate resistant acid phosphates and carbonic anhydrase involved too.
9
Q
2 types of bisphosphonates?
A
Bisphosphonates directly inhibit osteoclastic bone resorption. Nitrogen-containing bisphosphonates are up to 1000-fold more
potent than non–nitrogen-containing bisphosphonates.
10
Q
How do the 2 different types of bisphosphonates work?
A
N containing Bisphosphonates function by inhibiting farnesyl pyrophosphate synthase in the mevalonate pathway.
Non N Bisphosphonates produce a non functioning ATP analogue which leads to apoptosis of the cells.
11
Q
Name 2 Complications of Bisphosphonate use?
A
Atypical Proximal femoral fractures, osteonecrosis of the jaw and reduced rate of spinal fusion.
12
Q
% of inorganic (mineral) bone matrix?
A
60%
13
Q
% of organic bone components?
A
40%
14
Q
Main component of Inorganic matrix?
A
Calcium hydroxyapatite
constitutes the majority of the inorganic matrix.
15
Q
chemical formula of calcium hydroxyapatite?
A
Ca10 (PO4 )6(OH)2
16
Q
Main component of organic component of bone?
A
Type I collagen is 90% of the organic component,
17
Q
the most abundant noncollagenous protein in bone?
A
osteocalcin
18
Q
Wolff’s law:
A
Remodeling occurs in response to mechanical stress.
19
Q
Hueter-Volkmann law:
A
Compressive forces inhibit growth, whereas tension stimulates it.
20
Q
three major types of bone formation?
A
enchondral formation, bone replaces a cartilage model.
Intramembranous formation occurs without a cartilage model;
aggregates of undifferentiated mesenchymal differentiate into osteoblasts, which
form bone -Appositional bone formation
In appositional formation, osteoblasts lay down new bone on existing bone; the groove of Ranvier supplies the chondrocytes.
21
Q
three stages of fracture repair:
A
inflammation, repair, and remodeling.
22
Q
Fracture healing type varies with treatment method. Closed treatment is through …………………….. and ……………………………ossification. Compression plate
treatment is through ………………………………….
A
Fracture healing type varies with treatment method. Closed treatment is through periosteal bridging callus and interfragmentary enchondral ossification. Compression plate
treatment is through primary cortical healing.
23
Q
BMP-2
A
used for acute open tibia fractures
24
Q
BMP-7
A
is used for tibial nonunions
25
BMP-3
has no osteogenic activity
26
Increased BMP-4?
associated with the pathologic condition of fibrodysplasia ossificans progressiva.
27
Bone grafts have three properties?
Osteoconduction acts as a scaffold for bone growth; osteoinduction involves growth factors that stimulate bone formation; osteogenic grafts contain primitive mesenchymal cells, osteoblasts, and osteocytes.
28
Calcium phosphate–based grafts are ?
capable of osseoconduction and osseointegration. They have the highest compressive strength of
any graft material
29
Calcium sulfate is:
osteoconductive but rapidly resorbed
30
The primary homeostatic regulators of serum calcium are:
PTH and 1,25(OH)2
-vitamin D3. PTH results in increased serum Ca2+
decreased inorganic phosphate level.
31
Bone mass peaks between
16 and 25 years of age
32
Physiologic bone loss affects ...................bone more than ..........................bone.
Physiologic bone loss affects trabecular bone more than cortical bone.
33
Urinary markers of increased bone resorption?
Both urinary hydroxyproline and pyridinoline cross-links are elevated when there is bone resorption.
34
serum marker of increased bone formation?
Serum alkaline phosphatase increases when bone formation increases.
35
The most common cause of hypercalcemia ?
Malignancy
36
Treatment of Hypercalcaemia?
Initial treatment is with hydration, which causes a saline diuresis, along
with loop diuretics
37
phosphorous retention and secondary hyperparathyroidism leads commonly to what?
Renal osteodystrophy
38
Failure of bone mineralisation leads to what?
Rickets (in children) and osteomalacia (in adults)
39
Which zone of the physis is affected in Rickets?
the width of the zone of provisional calcification is increased, which causes physeal widening
and cupping
40
WHO definition of Osteoporosis?
Osteoporosis is a quantitative defect in bone. It is defined as a lumbar bone density of 2.5 or more standard deviations less than the
peak bone mass of a healthy 25-year-old (T-score).
41
Treatment of osteoporosis includes
calcium supplements of 1000 to 1500 mg/day, as well as bisphosphonates.
42
What is Scurvy?
Scurvy results from ascorbic acid deficiency, which causes a decrease in chondroitin sulfate synthesis and ultimately defective collagen growth and repair. Widening in the zone of provisional
calcification is observed.
43
Components of hyaline cartilage?
Articular cartilage is composed of water (65%-80% of wet weight), collagen (10%-20% of dry weight but more than 50% of dry weight), proteoglycans (10%-15% of wet weight), and chondrocytes (5% of
wet weight).
44
Type of collagen in cartilage?
Collagen is 95% type II, contains hydroxyproline, and provides tensile strength
45
Components of proteoglycans?
Proteoglycans are composed of glycosaminoglycans and include chondroitin sulfate and keratin
sulfate; these provide compressive and elastic strength.
46
Chondrocytes are derived from ?
mesenchymal precursors
47
SOX-9?
the SOX-9 transcriptional factor is considered the “master switch for differentiation of mesenchymal precursors to chondrocytes.
48
What is Mechanotransduction?
Mechanotransduction describes how metabolism is regulated by mechanical stimulation.
49
What happens to proteoglycan content with aging and OA?
proteoglycan content, which decreases in both conditions.
50
Changes in cartilage wioth OA?
water content is increased,
proteoglycan content decreased,
keratin sulfate concentration decreased,
and proteoglycan degradation significantly
increased.
Aging is opposite but PG also decreases too in both.
51
Synovial tissue lacks ...............................but allows nutrition via capillary-rich connective tissue.
Synovial tissue lacks a basement membrane but allows nutrition via capillary-rich connective tissue.
52
Type A synovial cells
Type A synovial cells act like macrophages
53
type B cells
type B cells make the synovial non-newtonian ultrafiltrate fluid containing lubricin known as a boundary lubricant
54
What is Charcot arthropathy?
Charcot arthropathy from disturbed sensory innervation is an extreme form of noninflammatory arthritis characterized by radiographic finds worse than clinical complaints and fragments of bone in soft tissue. Diabetes is the most common overall cause and the most common cause of Charcot disease in foot and ankle joints. Syringomyelia is the most common cause in the upper extremity
joints, followed by Hansen disease.
55
What is Onchronosis?
Ochronosis is black cartilage arthritis from alkaptonuria.
56
Hemochromatosis often presents first as arthritis with ......................The cirrhosis and skin “bronzing” develop later.
Hemochromatosis often presents first as arthritis with chondrocalcinosis. The cirrhosis and skin “bronzing” develop later.
57
```
Rheumatoid arthritis (RA) affects ................................... Late synovial changes include h..... cells, increased ......., and abundant ............. Pannus ingrowth denudes articular
cartilage. There are no ............................in pannus.
```
```
Rheumatoid arthritis (RA) affects synovium and soft tissue first. Late synovial changes include hyperplastic cells, increased blood vessels, and abundant lymphocytes. Pannus ingrowth denudes articular
cartilage. There are no lymphocytes in pannus.
```
58
Systemic lupus erythematosus (SLE)
an autoimmune disease (against nucleic acids and nuclear proteins, hence almost always ANA positive) characterized by immune complex deposition with
familiar changes in the skin and kidney.
59
Seronegative spondylarthritides have many overlapping findings but are distinguished by their ............RF titer and usually ..................ANA
Seronegative spondylarthritides have many overlapping findings but are distinguished by their negative RF titer and usually negative ANA
60
tell me about gout?
Gout results in deposition of monosodium urate crystals in joints. The classical radiographic finding is the appearance of punched-out periarticular erosions. Indomethacin is the initial treatment; allopurinol lowers serum acid levels chronically, and colchicine is
used for prophylaxis.
61
CPPD?
CPPD (pseudogout) is characterized by positively birefringent crystals and is a common cause of chondrocalcinosis.
62
What is Hemophilic arthropathy?
most commonly caused by factor VIII deficiency and most commonly involves the knee. Treatment is
through correction of factor levels.
63
What is Myasthenia gravis?
Myasthenia gravis is an autoimmune disease with defects in transmission of nerve impulses to muscles that result from blocking, altering, or destroying acetylcholine receptors at the neuromuscular
junction.
64
what is the mechanism of action of Botulinum?
Botulinum A blocks presynaptic acetylcholine release at the motor end plate.
65
What determines skeletal muscle tension and force?
cross-sectional area.
66
three types of muscle contractions:
isotonic (constant muscle tension), isometric (muscle length remains unchanged), and
isokinetic (constant velocity)
67
Type I skeletal muscle fibers
Type I skeletal muscle fibers are slow twitch and fatigue resistant
68
type II Muscle fibres
fast twitch and fatigable
69
Describe the Phosphagen system?
ATP-creatine phosphate (phosphagen) system is anaerobic, produces no lactate, and is active in muscle activities lasting less than 20
seconds.
70
what system predominates in muscle activity of 20-120seconds?
Lactic acid metabolism is also anaerobic and is active in muscle activities of 20 to 120 seconds.
71
Strength training ......................myofibrils, fiber size, and cross-sectional area, with ........................of type II fibers.
Strength training increases myofibrils, fiber size, and cross-sectional area, with hypertrophy of type II fibers.
72
Muscle tear healing is most reliant upon ...............cells, and ............... stimulates proliferation of myofibroblasts and ..........................fibrosis. In
acute muscle injury, the first cells recruited are ......................
Muscle tear healing is most reliant upon satellite cells, and TGF-β stimulates proliferation of myofibroblasts and increases fibrosis. In
acute muscle injury, the first cells recruited are neutrophils.
73
Preganglionic injuries: ..........................histamine response test with medial scapular winging due to .............................palsy.
Preganglionic injuries: normal histamine response test with medial scapular winging due to serratus anterior palsy.
74
Post-ganglionic injuries: ........................histamine response test (..............), .................innervation to cervical paraspinals.
Post-ganglionic injuries: abnormal histamine response test (with no flare), maintained innervation to cervical paraspinals.
75
.Axon budding proceeds ......................., and ...........................is the first sensation to return.
Axon budding proceeds antegrade, and pain is the first sensation to return.
76
What part of the spinal cord do SSEP monitor and are they sensitive to anaesthesis?
SSEPs only monitor dorsal column sensory pathways and are less sensitive to anesthesia.
77
How do tendons receive nutrition?
Tendons receive blood from the vincular system if they are sheathed and through simple diffusion from the paratenon.
78
Surgical tendon repairs are weakest at days .................. to ......
Surgical tendon repairs are weakest at days 7 to 10.
79
the first collagen produced at sites of tendon injury.?
Type III collagen
80
Achilles tendon is hypovascular .... to......... cm proximal to the calcaneal insertion.
Achilles tendon is hypovascular 4 to 6 cm proximal to the calcaneal insertion.
81
Ligaments are composed of ........................collagen and elastin. They differ from tendons in that they have ...............collagen, .............proteoglycans (and water), highly cross-linked collagen, and are perfused at
insertion sites.
Ligaments are composed of type I collagen and elastin. They differ from tendons in that they have less collagen, more proteoglycans (and water), highly cross-linked collagen, and are perfused at
insertion sites.
82
The nucleus pulposus has a .............collagen/proteoglycan ratio and dries out/desiccates with age, owing to loss of ....................pressure
(from loss of proteoglycans).
The nucleus pulposus has a low collagen/proteoglycan ratio and dries out/desiccates with age, owing to loss of hydrostatic pressure
(from loss of proteoglycans).
83
The annulus fibrosis has a ........collagen/proteoglycan ratio.
The annulus fibrosis has a high collagen/proteoglycan ratio.
84
Innervation of annulus fibrosis
The dorsal root ganglion gives off the sinuvertebral nerve,
85
Interleukin involved in degenerative disc disease?
IL-1β
86
Changes due to the aging process are ......... of intervertebral discs, ...............and fragmentation of proteoglycans, and ................keratin sulfate/chondroitin sulfate ratio, ................ in absolute
quantity of collagen.
Changes due to the aging process are drying out of intervertebral discs, decrease and fragmentation of proteoglycans, and increased keratin sulfate/chondroitin sulfate ratio, but no change in absolute
quantity of collagen.
87
Osteochondral allografts are used for lesions larger than ........cm.
Osteochondral allografts are used for lesions larger than 2 cm.
88
Osteochondral autografts are used for lesions smaller than ......... cm.
Osteochondral autografts are used for lesions smaller than 2 cm.
89
Anti-Scl-70
Anti-Scl-70 is linked to scleroderma.
90
Anti-Jo-1
Anti-Jo-1 is linked to polymyositis and dermatomyositis.
91
Anti-Sm
Anti-Sm is linked to SLE (specific but not sensitive—i.e., only present in one fifth of those with SLE).
92
Anti-RNP
Anti-RNP leads to mixed connective tissue disease
93
Anti-ds-DNA
Anti-ds-DNA is linked to SLE and implicated in SLE nephritis.
94
Antihistone
drug-induced lupus.
95
Anti-Ro and Anti-La
Anti-Ro and Anti-La are linked to Sjögren syndrome.
96
The cell cycle goes from ........ (2N) to ........... (4N) during the S phase.
The cell cycle goes from diploid (2N) to tetraploid (4N) during the S phase.
97
pRb
pRb is implicated in retinoblastoma and osteosarcoma.
98
p53
p53 is implicated in osteosarcoma, rhabdomyosarcoma, and chondrosarcoma.
99
What is a plasmid ?
A plasmid is a small extrachromosomal circular piece of DNA that replicates independently of DNA.
100
Southern Blotting?
Southern—detection of DNA sequences in a sample
"DOWN SOUTH!"
101
Northern Blotting
Northern—detection of RNA in a sample
"Right up north"
102
Western Blotting
Western—detection of specific amino-acid sequences in protein
"Whey protein"
103
ELISA
detects AB and ag
104
RT-PCR
produces DNA from RNA
105
Type I hypersensitivity:
type I: Immediate anaphylactic reaction
associated with allergy
mediated by IgE antibody activation of mast cells and basophils
106
Type II hypersensitivity:
Type II: Antibody dependent (aka cytotoxic) hypersensitivity
mediated by IgG and IgM antibodies
107
Type III hypersensitivity:
Type III: Immune complex (antigen bound to antibody) deposition type of hypersensitivity
mediated by IgG and IgM antibodies which when bound to antigen get deposited in various tissues
108
Type IV hypersensitivity:
Type IV: Delayed-type or cell-mediated hypersensitivity
mediated by T cells, monocytes and macrophages
take several days to develop
examples include
tuberculosis skin test
the immune response to metallic orthopaedic implants is typically a Type IV (delayed-type hypersensitivity reaction)
109
Rheumatoid factor is an ....... against ................
Rheumatoid factor is an IgM against IgG.
110
IgA
IgA is seen in mucosa-associated lymphoid tissue.
111
first cells recruited to the site of injury.
Neutrophils are the first cells recruited to the site of injury.
112
Which cells initiate the inflammatory response in osteolysis/aseptic loosening in response to particles
smaller than what?
Macrophages initiate the inflammatory response in osteolysis/aseptic loosening in response to particles
smaller than 1 µm.
113
Carcinoembryonic antigen (CEA)
colorectal carcinoma
114
Carbohydrate antigen 19-9 (CA-19-9):
pancreatic cancer
115
Carbohydrate antigen 125 (CA-125):
ovarian cancer
116
Cancer antigen 15-3 (CA-15-3):
breast cancer
117
α-Fetoprotein (AFP):
hepatocellular carcinoma
118
AUTOSOMAL DOMINANT CONDITIONS
AUTOSOMAL DOMINANT CONDITIONS
119
Achondroplasia:
FGF receptor 3 (FGFR3)
120
Apert Syndrome:
FGFR2
121
Cleidocranial dysplasia:
CBFA1
122
Charcot-Marie-Tooth (most common variety):
PMP22
123
Pseudoachondroplasia:
COMP
124
SED congenital:
COL2A1 for type II collagen
125
Kniest syndrome:
type II collagen
126
MED type 1:
COMP
127
MED type 2:
type IX collagen
128
Jansen metaphyseal chondrodysplasia:
PTHrP
129
Schmid metaphyseal chondrodysplasia:
type X collagen
130
Ehlers-Danlos (most common variety):
COL
131
Hereditary multiple exostoses:
EXT1/EXT2/EXT3
132
Neurofibromatosis:
NF1, NF2
133
Marfan syndrome:
FBN1
134
Osteogenesis imperfecta (types I and IV):
COL1A1/COL1A2 AD
135
Autosomal recessive:
Autosomal recessive:
136
Diastrophic dysplasia:
DTD-ST (sulfate transport protein)
137
Friedreich ataxia:
frataxin
138
Gaucher disease:
lysosomal glucocerebrosidase
139
Sickle cell disease:
HbSS
140
Osteopetrosis
malignant forM
141
Osteogenesis imperfecta (types II and III):
COL1A1/COL1A2 AR
142
(TAR) syndrome
Thrombocytopenia-aplasia of radius
143
Charcot Marie Tooth (rare form):
connexin gene
144
X-linked recessive:
X-linked recessive:
145
Duchenne and Becker muscular dystrophy
dystrophin
146
Hemophilia:
factors VIII or IX
147
SED tarda:
COL2A1
148
X-linked dominant:
X-linked dominant:
149
Hypophosphatemic rickets:
PHEX
150
Léri-Weill dyschondrosteosis:
SHOX
151
------------------------
-------------------------
152
McCune-Albright syndrome:
Gsα subunit of the receptor/adenylyl cyclase–coupling G proteins
153
t(X : 18)
synovial sarcoma
154
t(11 : 22)
Ewing sarcoma
155
t(2 : 13)
rhabdomyosarcoma
156
t(12 : 16)
myxoid liposarcoma
157
t(12 : 22)
in clear cell sarcoma
158
t(9,22)
in myxoid chondrosarcoma
159
The most common risk factor for Nec Facs?
Diabetes
160
Most common cause of Nec Fas?
Polymicronbial, Gp A b haemolystic streptococcal most common in healthy individulas
161
MOST COMMON CAUSE OF OSTEOMYLITITIS
MOST COMMON CAUSE OF OSTEOMYLITITIS
162
Age 0 to 4 months:
S. aureus, gram-negative bacilli, group B streptococcus
163
Age 4 months to 21 years:
S. aureus, group A streptococci
164
Age older than 21 years:
S. aureus, coagulase-negative staphylococci
165
Patients with sickle cell disease:
S. aureus and Salmonella
166
open fracture
S. aureus, P. aeruginosa, and gram-negative bacill
167
Diabetic patients
polymicrobial (both aerobic and anaerobic)
168
Intravenous drug abusers:
S. aureus, Serratia spp., Pseudomonas spp.
169
Meat handlers:
Brucella spp.
170
Fishermen:
Mycobacterium spp.
171
----------------------------
--------------------------------
172
What is a sequestrum?
(dead bone with surrounding granulation tissue)
173
What is involucrum?
(periosteal new bone)
174
Except for sexually active adults, in whom the most common causative organism is ........................... the most common
cause of septic arthritis is ................
Except for sexually active adults, in whom the most common causative organism is Neisseria gonorrhoeae, the most common
cause of septic arthritis is S. aureus.
175
In non–sexually active adults, ......................... and ............. are the most common causative organisms.
In non–sexually active adults, S. aureus and streptococci are the most common causative organisms.
176
rules on tetanus prophylaxis?
Tetanus immune globulin is administered only when tetanus status is unknown or the patient has received fewer than three immunizations.
Tetanus toxoid is given if the wound is severe or occurred more than 24 hours previously and if the patient has
received no booster vaccination within the previous 5 years.
177
The risk of acquiring disease from a needlestick from contaminated source is as follows: hepatitis B, .........%.in unvaccinated persons;
hepatitis C, ....%; HIV, ............%
he risk of acquiring disease from a needlestick from contaminated source is as follows: hepatitis B, 30% in unvaccinated persons;
hepatitis C, 3%; HIV, 0.3%
178
β-Lactam antibiotics (penicillin and cephalosporins):
inhibit cross-linking of polysaccharides in the cell wall by blocking
transpeptidase enzyme
179
Vancomycin:
interferes with the insertion of glycan subunits into the cell wall
180
Rifampin:
inhibits RNA polymerase F
181
Clindamycin:
binds to 50S ribosomal subunits and inhibits protein synthesis
```
"Buy AT 30 and CELL at 50"
'Buy AT 30'
Aminoglycosides
Tetracyclines
'CELL at 50'
Chloramphenicol
Erythromycin
Linezolid
cLindamycin
```
182
Quinolones (ciprofloxacin):
inhibit DNA gyrase
183
mecA gene ?
Antibiotic resistance is mediated by plasmids and transposons. MRSA has the mecA gene that produces the enzyme penicillin binding protein 2a, which prevents the normal enzymatic acylation of
antibiotics.
184
Virchow triad:
endothelial damage, venous stasis, and hypercoagulability
185
Warfarin
inhibits posttranslational modification of vitamin K–dependent clotting factors (factors II, VII, IX, and X; proteins
C and S)
186
Fat embolism is characterized by the triad of
hypoxemia, CNS depression, and petechiae
187
There are four types of shock:
Hypovolemic: volume loss
• Cardiogenic: ineffective pumping
• Septic: blood pooling from vasodialation
• Neurogenic: blood pooling and bradycardia
188
Malignant hyperthermia
autosomal dominant condition. It is triggered by “-ane” inhalational agents, depolarizing muscle relaxants (succinylcholine), and amide-based local anesthetics. The first signs are increased end-tidal CO2
and tachycardia. Treatment is
with dantrolene sodium, which blocks calcium release by stabilizing
the sarcoplasmic reticulum.
189
How would u reduce radiation exposure in theatre?
decreased radiation exposure with increased distance between surgeon and radiation beam, limiting fluoroscopic time, using the mini c-arm, orienting the beam in a position inverted to the patient, use of protective shielding, and
collimation
190
MRI basic principles are as follows:
T1 weighting:
T2 weighting:
The following appear dark on T1-weighted images and bright on T2-weighted images:
T1 weighting: fat best demonstrates anatomic structure. • T2 weighting: water is best for contrasting normal and abnormal tissues.
• The following appear dark on T1-weighted images and bright on T2-weighted images: water, cerebrospinal fluid, acute
hemorrhage, and soft tissue tumors.
191
Define force?
Force is a mechanical push or pull (load) causing external (acceleration) and internal (strain) effects.
192
Define a moment?
Moment is the rotational effect of a force.
193
What is the mass moment of inertia?
the resistance to rotation
194
Define Stress?
Stress is the intensity of internal force. Stress = force/area. Unit of measure: pascal (N/m2
).
195
Define Strain?
Strain is a measure of deformation resulting from loading. Strain is the change in length/original length. There is no standard unit of
measure.
196
what is Young's modulus of elasticity?
Young’s modulus of elasticity (E) is a measure of material stiffness (ability to resist deformation in tension): E = stress/strain. Materials
with higher E withstand greater forces.
197
List the common orthopaedic materials in order of stiffness
ceramic,
cobalt-chrome, stainless steel, titanium,
cortical bone,
PMMA
, polyethylene,
cancellous bone, tendon/ligament, and cartilage.
198
Material types include the following: • Brittle: .............stress-strain curve with limited capacity for ..................deformation • PMMA
* Ductile: large ...........deformation before failure
* Metal
Material types include the following: • Brittle: linear stress-strain curve with limited capacity for plastic deformation • PMMA
• Ductile: large plastic deformation before failure
• Metal
199
what is meant by viscoelastic materials?
materials that have time- and rate-dependent stress-strain behavior and exhibit hysteresis (loading and unloading curves differ)
• Bone, ligaments, and most biological tissues
200
Define isotropic materials?
mechanical properties are the same for all directions of applied load
• Golf ball
201
Define Anisotropic materials?
mechanical properties vary with direction of applied load
| • Bone is stronger with axial load than with radial load.
202
when dissimilar metals are in direct contact and result in corrosion products (metal oxides and
chlorides).
Galvanic corrosion
203
Risk of galvanic corrosion is highest between?
316 L stainless steel and cobalt-chromium (Co-Cr) alloy.
204
316 L stainless steel contains:
iron-carbon, chromium, nickel, molybdenum, and manganese
205
Cobalt:
cobalt, chromium, molybdenum, and nickel
206
Titanium:
: titanium, aluminum, and vanadium
207
Components of bone cement powder?
PMMA (polymer)
BENZYOL PEROXIDE (INITIATOR)
BARIUM SULPHATE/ZIRCONIUM(RADIO-OPACIFIER)
CHLOROPHYLL
(ANTIBIOTICS)
208
Components of bone cement liquid?
Methymethacralate (monomer)
(accelerator) DMPT
(stabiliser) Hydroquinone.
209
Phases of Cementing?
1. Mixing phase - up to 1 min, wetting and polymerisation
2. waiting phase - variable upto several minutes....chain propagation, neither sticky nor hairy.
3. working phase - 2-4min, heat generation
4. setting phase-
210
1st generation cementing
hand-mixed cement
finger packed cement
no canal preparation or cement restrictor
211
2nd generation cementing
cement restrictor placement
cement gun
femoral canal preparation
brush and dry
212
3rd generation cementing
vacuum-mixing to reduce cement porosity
cement pressurization
femoral canal preparation
pulsatile lavage
213
Main type of lubrication during dynamic function.
Elastohydrodynamic lubrication
214
Hip arthrodesis?
25 to 30 degrees of flexion, 0 degrees of abduction and rotation
215
Knee arthrodesis?
0 to 7 degrees of valgus angulation, 10 to 15 degrees of flexion
216
Ankle arthrodesis?
neutral dorsiflexion, 5 to 10 degrees of external rotation, 5 degrees of hindfoot valgus angulation
217
Shoulder arthrodesis?
30 deg abduction 30 deg flexion 30 deg of int rotation
218
elbow arthrodesis?
Elbow: 90 degrees of flexion if arthrodesis is unilateral. If it is bilateral: one elbow at 110 degrees of flexion for the hand to reach the mouth and the other at 65 degrees of flexion for
perineal hygiene.
219
wrist arthrodesis?
Wrist: 10 to 20 degrees of dorsiflexion for unilateral fusion. If arthrodesis is bilateral, fuse the other side at 0 to 10 degrees of
palmar flexion.
