basic science csv Flashcards
(274 cards)
1
Q
LATERAL PIVOT SHIFT FOR THE ELBOW– SEX with VAL gets better when flexed!!!
A
supination and extension then apply a valgus force when flexing and the RH reduces at 40 degrees of flexion
2
Q
PIVOT SHIFT MNEMONIC: VALIRE FLEuR De li
A
VALGUS force on IR and EXTended knee- FLEx REDUCES the knee at 30 degrees
3
Q
SNAPPING HIP: if you can see it it’s _____ snapping hip. if you can hear it it’s _____ snapping hip.
A
if you can see it it’s EXTERNAL snapping hip. if you can hear it it’s INTERNAL snapping hip.
4
Q
PI = PT + SS
A
to become a PI- you have to do a lot of PT and be hard as Stainless Steel!! Pelvic incidence = pelvic tilt + sacral slope
5
Q
aging is dry
A
water content of cartIlage decreases with normal aging
6
Q
OA is wet
A
water content of cartIlage increases with osteoarthritis
7
Q
PSSR - PISSER WITH AGE- PISSER USE INCREASES!! (INCREASED COMPONENTS OF CARTILAGE WITH AGE)
A
Protein -Stiffness (passive glycation leads to increased Stiffness of collagen) -chondrocytes Size -Ratio of PG keratin sulfate to chondroitin sulfate
8
Q
NEWSS - WITH AGE you have less NEWSS! (DECREASED COMPONENTS OF CARTILAGE WITH AGE)
A
Number of cells- Elasticity- Water (differentiates from OA where water content actually increases)- proteoglycan Size- Solubility
9
Q
TorTicolliS (TTS)
A
TILTS TOWARDS SCM! head TITLTS TOWARDS the SCM side- and chin rotates away
10
Q
what do the accessory and proper collateral ligaments restrict in thumb UCL injury?
A
VOWELS GO TOGETHER ETC…. FP EA… -PCL is primary restraint to radial deviation with FLEXED MCP -ACL restrains radial deviation with EXT MCP
11
Q
what BMP for OPEN TIBIA fxs?
A
bmp twO = Open tibias
12
Q
rhBMP-2 in GRADE 3 OPEN tibial shaft fxs?
A
accelerate early fracture healing decrease need for BONE GRAFTING decrease need for 2ND SURGERYS decrease INFECTION
13
Q
malformations with entire bone (absence- duplication of entire bone) - MOLECULAR BIO?
A
nuclear proteins and transcriptions factors
14
Q
Anterolateral bowing
A
NF1
15
Q
anterior / anteromedial bowing
A
fibular hemimelia
16
Q
posteromedial bowing
A
calcaneovalgus foot
17
Q
what inserts at the sublime tubercle?
A
MCL insertion subliMe tuberCLe
18
Q
what inserts at the supinator crest of ulna?
A
LUCL insertion
19
Q
screw home mechanism?
A
-tibia EXternally rotates on femur as the knee EXtends. -cuz LTP under LFC translates posterior as MFC and MTP don’t translate.
20
Q
LFC and contact area moves posterior on the tibia during what knee ROM?
A
knee flexion from 0 to 120 degrees.
21
Q
MFC and contact area remain relatively stationary during what knee ROM?
A
flexion from 0 to 120 degrees.
22
Q
In what ROM do both condyles exhibit femoral rollback?
A
Beyond 120 degrees of flexion
23
Q
what is the “comma sign””? “
A
arc formed by a portion of the SGHL/CHL complex -useful marker of the superolateral corner of torn subscapularis tendon.
24
Q
Pott’s DISEASE
A
DESTRUCTION OF VERTEBRAE –> HORRIBLE KYPHOSIS SPARES DISC* Ziehl-Neelsen stain= mycobacterium “red snappers”” against blue background. AFB ON Lowenstein-Jensen medium is dxtc BUT 10 WKS TO GROW. DECOMPRESSION then Isoniazid- rifampin- pyrazinamide- and streptomycin”
25
Mazabraud syndrome
poly FD + iM Myxomas
26
HISTO DDX:
ABC- GCT- TELANGIECTATIC OSTEOSARC
27
Benign tumors USUALLY CURETTAGE & BG
COC FAG CHONDROBLASTOMA- OSTEOBLASTOMA- CHONDROMYXOID FIBROMA- ABC- GCT
28
Benign tumors OCCASSIONALLY CURETTAGE & BG
i knew that! (i NEU that)! NOF- UBC- ENCHONDROMA
29
which has higher risks for astxc DVT and SXTC PE: TKA vs THA?
TKA HIGHER risk of ASXTC DVT THA HIGHER risk of SXTC PE
30
1st physical sign of PE?
dyspnea or tachypnea
31
MC EKG signs associated with PE?
sinus tachycardia right axis deviation right BBB
32
with MOM- smaller implant diameter is associated with higher or lower serum metal ions?
elevated serum metal ion levels.
33
with MOM- cup abduction angle >55 degrees is associated with higher or lower serum metal ions?
elevated serum metal ion levels. Cup abduction angles >55 degrees is more vertical and edge loading.
34
Compression stocking
Mechanical increases fibrinolytic system decreases venous stasis
35
ASA
Inhibits PG and thromboxane production
36
IV heparin
Enhances Antithrombin 3 ability to inhibit factors IIa (thrombin)- III- Xa
37
Unfractionated heparin (subcutaneous)
Enhances Antithrombin 3 ability to inhibit factors IIa (thrombin)- III- Xa
38
LMWH (Lovenox)
Enhances Antithrombin 3 ability to inhibit factors IIa (thrombin) and Xa
39
Fondaparinux
Xa
40
Coumadin
Affects LIVER Vit K metabolism LIMITS production of clotting factors 2- 7- 9- 10 (1972)
41
Dextran
Dilutional-- fluid overload
42
Dorr noted that wound complications and hematomas seen only in warfarin or LMWH- and NOT in...
ASA clopidogrel compression devices
43
Sclerostin (from OSTEOCYTES) inhibits what pathway?
Wnt pathway INHIBITION DECREASES BONE MASS
44
Wnt pathway regalates what process?
important regulators of bone mass stimulates production of OSTEOBLASTS
45
increased Wnt signaling is seen with what 2 diseases?
high bone mass seen in sclerosteosis and Van Buchem disease
46
Up-regulation of Wnt signaling does what to osteoblasts & chondrocytes?
good for fracture healing: suppression of chondrocyte formation and enhanced ossification. Wnt and hedgehog pathways control differentiation of progenitor cells into osteoblasts or chondrocytes.
47
LOWER postop fcnl scores- WHAT diameter and WHAT cup inclination are associated with HIGH cobalt and chromium levels after MOM resurfacing?
SMALLER implant diameter LARGER cup inclination
48
osteoclasts cause resorption lacunae BY RELEASING WHAT?
release cathepsin K and acid
49
XRT is better to be done PREOP or POSTOP Iin spine MET decompression?
XRT POSTOP better! XRT preop = 3x wound complications
50
what drug increases risk of osteoporosis and fracture?
anticonvulsant use (phenobarbital- carbamazepine- phenytoin- and valproate)
51
3 risk factors for nonunion of TYPE 2 ODONTOID FX
Increased fracture displacement posterior displacement increased angulation
52
ACSM recs on appropriate loads during training? NOVICE TRAINING
loads corresponding to 8-12 repetition max (RM)
53
ACSM recs on appropriate loads during training? INTERMEDIATE/ADV TRAINING
wider loading range- 1-12 RM periodized fashion
54
ACSM recs on appropriate loads during training? LOCAL MUSCULAR ENDURANCE TRAINING
light to mod loads (40-60% of 1 RM) high repetitions (> 15) short rest periods (< 90 s)
55
EMG denervation seen with what nerve problem? (fasciculations and positive short waves)
radiculopathy
56
Amyotrophic lateral sclerosis is a motor neuron disease that affects what?
both UMN & LMN rapid progression of weakness- muscle atrophy- fasciculations- spasticity- dysarthria- dysphagia- and respiratory compromise.
57
Sclerostin and dickkopf-1 (Dkk-1) are direct inhibitors of what pathway related to bone and/or cartilage regulation?
Wnt/Beta-catenin (_Å-catenin) pathway Knocking out or inhibiting sclerostin or Dkk-1 --> increased bone mass cuz constitutive activation of Wnt/_Å-catenin pathway.
58
BMPs work through WHAT to cause osteoblastic differentiation?
SMADs
59
PTH at physiologic levels binds to osteoblasts- causing a series of events that lead to
osteoblast-mediated osteoclast activation thus increased bone resorption
60
MC mechanism of wear: well-functioning THA
Adhesive wear
61
MC mechanism of wear: TKA revision with several small cement particles in the articulation
Abrasive wear
62
MC mechanism of wear: TKA with poly sterilized with gamma radiation in air
Delamination
63
Adhesive wear
2 surfaces forced together under a load WITH motion. When adhesive forces exceed material strength- material is removed from the weaker material.
64
2 MODES of Abrasive wear?
2-body and 3-body abrasive wear.
65
2-body abrasive wear?
asperites or projections from one surface remove material from the opposing articulating surface. roughened surface (scratched ball)
66
3-body abrasive wear
third body particle interposed between bearing surfaces results in removal of material from 1 or both articular surfaces.
67
Fatigue wear
surface / subsurface cyclic shear stresses or strains in softer material of an articulation exceed fatigue limit for that material.
68
Delamination
surface damage seen with oxidized poly knees with crossing wear patterns and high-contact stresses.
69
Most "metal allergy"" is classified as hypersensitivity type ____? "
4 or delayed-type hypersensitivity response (cell-mediated response)
70
Type I hypersensitivity
anaphylaxis
71
Type II hypersensitivity
antibody mediated- such as seen in Grave's disease or hemolytic anemia.
72
Type III hypersensitivity
immune complex diseases such as serum sickness or systemic lupus erythematosus.
73
study design: series of cases presented with outcomes (WO a control population or comparison group)
case series
74
what study design? patients receive a particular treatment and outcomes are then examined
case series
75
what study design? groups followed over time on the basis of receiving or NOT receiving an exposure (not randomized)
cohort
76
what study design? both groups receive both interventions over defined time period. ex. Groups A and B both receive the drug as well as placebo.
crossover design clinical trial allows within-participant comparisons
77
what study design? participants randomized to 2 or more groups- each of which receives a different tx or intervention. ex. Group A receives drug and Group B receives placebo.
parallel design trial allows comparison btwn groups
78
Serum creatine phosphokinase is elevated in what disease?
DMD
79
Increased granulation tissue production occurs with prolonged immobilization following contusion injury. This condition may lead to what?
myositis ossificans
80
CT of abdomen and pelvis are necessary OR unnecessary for WU of bone sarcomas?
UNNECESSARY BONE sarcomas (chondrosarcs) rarely metastasize to visceral organs. primary site of metastasis: LUNGS NEED CT chest and MRI of extremity
81
Implants composed of polylactic acid are excreted by what body system after absorbed?
RESPIRATORY Polylactic acid suture and suture anchors are bioabsorbable hydrolysis of ester background in vivo. Resulting lactic acid enters Krebs cycle and excreted as CO2 by the lungs.
82
2-stage process of bacterial biofilm development?
1. adhesion of individual bacteria to a substrate regulated by adhesions. After several bacteria have attached- 2. quorum sensing (cell-to-cell communication) allows BIOFILM MATURATION and GENE EXPRESSION that activate virulence factor and antibacterial resistance of the bacteria.
83
During endochondral ossification of growth plate- WHAT contributes most to longitudinal growth of long bones?
chondrocyte hypertrophy intracellular volume and increased chondrocyte height cause growth of long bones.
84
What is the strongest predictor of persistent infection in early postop deep wound infections if implants retained until fracture union?
use of an IMN in open fracture
85
Rhizomelia
disproportion of proximal limb length ex. shortened limbs of achondroplasia (hip or shoulder)
86
MOA of Premature arrest following growth plate injury?
Vascular invasion across the physis -SH III and IV fxs create disruption thru all physeal zones. -A conduit blood vessels not normally present between metaphysis and epiphysis creates influx of osteoblasts and formation of bony bar which prevents further longitudinal growth.
87
perichondral ring of LaCroix (fibrocartilagenous periosteal ring surrounding the physis) PROTECTS against what?
50% of resistance to shear stress
88
MOA: Tetracyclines
Inhibit protein synthesis thus bacterial growth
89
3 specific mechanisms of tetracycline resistance
increased tetracycline efflux ribosome protection tetracycline modification
90
MOA: resistance to rifampin
Alteration of RNA polymerase
91
MOA resistance to? -lactam antibiotics
Altered membrane-binding protein
92
What has the most positive effect on wear-resistance of UHMWPE?
Radiation
93
What directly increases cross-linking?
Radiation
94
What changes POLY from partial crystalline to amorphous state?
Remelting
95
UHMWPE is manufactured via what process?
ram bar extrusion and compression molding.
96
Radiation is used to do what to POLY?
sterilize and cross-link
97
what directly increases cross-linking? what does cross linking to do wear?
level of radiation cross linking increases wear resistance
98
what quenches Free radicals generated during radiation?
either remelting or annealing
99
what does remelting do to wear characteristics?
reduces wear characteristics
100
describe the process of annealing
UHMWPE heated BELOW melting point avoids the reduction in crystallinity MORE free radicals REMAIN
101
describe the process of remelting
UHMWPE heating ABOVE melting point changing it from partial crystalline to amorphous state removing ALL free radicals
102
Friedrich ataxia
spinocerebellar disorder: ataxic gait- areflexia- weakness- loss of propioception- scoliosis foot deformity (cavus- varus- clawtoes)
103
DOes Charcot-Marie-Tooth
Hip dysplasia
104
Malignant hyperthermia
myelomeningocele
105
What protein promotes tumor cell attachment to bone during metastasis?
Integrin
106
Osteocalcin secreted by what? what role does it play?
secreted by osteoblasts role in mineralization and calcium homeostasis
107
inhibition of cell-wall synthesis via inhibition of peptidoglycan synthesis
Cephalosporins and penicillin are bactericidal
108
irreversibly bind 30S ribosomal proteins- inhibiting translation
aMINoglycosides
109
inhibit cell-wall synthesis by disrupting addition of cell-wall subunits
Glycopeptides (vancomycin)
110
inhibit DNA-dependent RNA polymerase excellent biofilm penetration
Rifamycins Bacteria develop rapid resistance to Rifampin when used as monotherapy
111
bind 50S ribosomal subunits
MACROlides (erythromycin)
112
Heuter-Volkmann principle
bone placed in longitudinal tension will stimulate longitudinal growth compressive longitudinal forces inhibit longitudinal growth
113
Healing after a tendon repair or rupture undergoes what stages?
1 inflammatory 2 cellular proliferation 3 remodeling
114
During the inflammatory phase
neutrophils and macrophages migrate into the injury site and release chemotactic factors that recruit fibroblasts. A tendon is thought to be weakest 5 to 21 days after repair- which coincides with the inflammatory phase
115
During the proliferative phase-
inflammatory cells secrete cytokines and growth factors (PDGF- IGF- (BMP) -12 and BMP 13- and TGF-beta) that promote differentiation of fibroblasts
116
remodeling stage.
Fibrosis and decreased cellularity
117
Conditions related to PTH
hypoparathyrodism- pseudohypoparathyroidism- renal osteodystrophy
118
Conditions related to Vitamin D
Rickets
119
Hypophosphatasia
AR-- inborn error in production of alkaline phosphatase (tissue-nonspecific isoenzyme of alkaline phosphatase: TNSALP)- leading to low alkaline phosphatase-- Increased urinary phosphoethanolamine
120
main problem with renal osteodystrophy?
uremia related phosphate retention
121
MCComp of ROD?
pathological fracture
122
with ROD- amyloid stains pink on
Congo red stain
123
labs characteristic of renal osteodystrophy (high turnover)
Decreased calcium- increased serum phosphate- increased alkaline phosphate- and increased parathyroid hormone
124
labs of nutritional rickets due to vitamin D deficiency.
Decreased calcium- decreased serum phosphate- increased alkaline phosphate- increased parathyroid hormone
125
labs of low-turnover renal osteodystrophy
Increased calcium- normal serum phosphate- increased alkaline phosphate- normal parathyroid hormone
126
low-turnover renal osteodystrophy is classically caused by
excess deposition of aluminum into bone impairs PTH release from parathyroid gland disrupts mineralization
127
labs of hypoparathroidism
LOW calcium- HIGH serum phosphate- NL alkaline phosphate- LOW PTH
128
labs of primary hyperPTH
HIGH calcium- NL serum phosphate- NL or HIGH alkaline phosphate- HIGH PTH
129
defect in mineralization of osteoid matrix caused by inadequate calcium and phosphate prior to closure of physis?
rickets
130
defect in mineralization of osteoid matrix caused by inadequate calcium and phosphate after physeal closure?
osteomalacia
131
what physeal zone with rickets?
zone of provisional calcification
132
pseudofracture on compression side of bone
Looser's zones
133
MC form of rickets
XLD Vitamin D-Resistant Rickets (Familial Hypophosphatemic Rickets) inability of renal tubules to absorb phosphate
134
Hypophosphatemic rickets
mutated PHEX gene caused by inability of kidney proximal tubules to reabsorb phosphate
135
labs of Hypophosphatemic rickets
normal serum calcium and PTH low serum phosphorous elevated alkaline phosphatase
136
key lab factor that differentiates nutritional from hypophosphatemic rickets
elevated PTH
137
hereditary vitamin D dependant rickets type I
Loss of function mutations in 25 (OH) vitamin D hydroxylase gene decrease in 1-25(OH) 2 vitamin D
138
Hereditary vitamin D dependant rickets type II
defect in intracellular receptor for 1-25-(OH) 2-vitamin D3 increase in 1-25(OH) 2 vitamin D
139
Hyperphosphatemia
mutation in GALNT3 gene elevated serum phosphate decreased PTH/calcium
140
Lyme arthritis tx?
oral amoxicillin- doxycycline- or cefuroxime for 4 weeks. IV ceftriaxone with neurologic involvement such as facial nerve palsy or meningitis
141
What mechanism is responsible for the initiation of mechanical failure seen at the midstem modular junction of modular revision hip stems?
Fretting fatigue contacting components experience cyclic loads while small oscillatory motion occurs between them. increases tensile and shear stress- leading to small flaws that result in crack propagation.
142
stress-strain curve demonstrates what of a material?
mechanical properties nonlinear curve seen with toe- linear- and failure regions-- modulus of elasticity (slope of stress/strain)- tensile strength- ultimate strain- and strain energy density
143
load-elongation curve demonstrates what of a material?
structural properties nonlinear curve shows a toe region- linear region (slope is stiffness)- and a failure region.
144
stress-strain curve
mechanical properties
145
load-elongation curve
structural properties
146
external fixation heals fracture thru
endochondral mechanism. Bland-appearing cartilage callus fits with nonunion
147
Tendons should have what ratio of matrix protein?
95% collagen type I <5% collagen type III
148
In articular cartilage- Interleukin 1 (IL-1) increases
matrix metalloproteinase that directly degrade cartilage
149
chondroprotective functions -increases both collagen and proteoglycan synthesis while inhibiting matrix degradation and cell proliferation
TGF beta
150
accelerates arthritis
IGF1
151
-anabolic effects on proteoglycan synthesis -prevents tissue catabolism by preventing an IL-1 beta-induced decrease in proteoglycan synthesis
Glucosamine
152
tx for Parosteal osteosarcoma
Wide resection
153
pathogenesis of posttraumatic osteoarthritis
Fracture-related chondrocyte death (apoptosis) concentrated along matrix cracks in superficial layer of cartilage Apoptosis is accentuated by a series of aspartate-specific cysteine proteases
154
Ethylene oxide sterilization affects wear properties or not?
no effect on wear properties of poly and should not affect its potential to contribute to osteolysis
155
Elastic modulus
mathematical description of the tendency of a material to be deformed elastically in response to an applied force.
156
Viscoelastic materials such as bone
exhibit time-rate-dependent stress-strain behavior as a function of internal friction. modulus of viscoelastic materials increase as strain rate increases.
157
Material properties
characterize mechanical functional limits of a material independent of the size or shape of that material.
158
HA binds to lubricin- a glycoprotein- creating a cross-linked network. Boundary lubrication occurs when
fluid film has been depleted and contacting bearing surfaces are separated only by a boundary lubricant of molecular thickness- which prevents excessive bearing friction and wear. In articular cartilage- this monolayer of glycoprotein is adsorbed on each of the opposing articular surfaces.
159
Aggrecan
interacts with HA and link proteins to create a proteoglycan aggregate this attracts water to cartilage and gives tissue its viscoelastic properties
160
Reverse TSA improves kinematics in RC deficient joint by what directional change to the COR?
Medial
161
What method of spinal fixation requires the largest force to disrupt the bone-implant interface?
Pedicle screws
162
Amphotericin and nystatin exerts antifungal activity MOA
binding to sterols disrupting the cell membrane.
163
Sulfonamides and trimethopim mimic the metabolite substrate
block synthesis of metabolites such as folic acid.
164
Rifampin MOA
inhibits bacterial RNA polymerase- blocking synthesis of RNA
165
Tetracycline chloramphenicol clindamycin bind to
ribosomes block bacterial growth by inhibiting protein synthesis.
166
percentage of astxc pseudotumors in MOM?
5.00%
167
What factor induces myofibrillar muscle protein synthesis (MPS)?
Resistance exercise above 60% 1-repetition maximum (RM) Resistance exercise induces myofibrillar MPS that drives muscle hypertrophy
168
Aerobic-zone exercise does not result in hypertrophy of skeletal muscle- but it does
increase oxidative capacity.
169
Etanercept modifies natural history of inflammatory arthropathies thru what MOA?
Inhibitory binding to TNF alpha-- decreases activation of mesenchymal cells- reducing pannus formation- cartilage destruction- and osteoclastic bone resorption
170
IL-1 production in response to inflammatory stimulus contributes to the
rapid loss of proteoglycans- leading to cartilage destruction and osteoclastic bone resorption.
171
anakinra
competitive inh of IL-1 type I receptor.
172
Abatacept
selective costimulation modulator inhibits T lymphocyte activation implicated in juvenile idiopathic arthritis.
173
pseudotumors occur in MOM hip resurfacing arthroplasty (MOMHRA) cuz increased wear attributable to what?
edge loading associated loss of fluid-film lubrication
174
Edge loading is from what?
abnormal contact stresses in setting of a malpositioned cup orientation
175
Alveolar rhabdomyosarcoma (ARMS)
PAX3-FKHR fusion gene
176
Alveolar rhabdomyosarcoma (ARMS)
t(1-- 13) t(2-- 13)
177
MOA of monoclonal Ab used to tx osteoporosis (denosumab)
inh of RANK ligand (RANKL)
178
Level 1 evidence includes randomized controlled trial with
statistically significant difference or no statistically significant difference but narrow confidence interval
179
level 2 therapeutic study would include a....
lesser-quality randomized controlled trial (eg- <80% follow-up- no blinding- or improper randomization)
180
non-randomized prospective cohort study that compares results of tx or systematic reviews of level II studies or level I studies with heterogenous results
level 2
181
normal joint fluid values volume WBC PMN total protein glucose
volume < 3.5 mL WBC < 200 cells/™Êl PMN < 25% total protein 1 g to 2 g/d glucose nearly equal to blood
182
how a RCT gets a level 2 rating?
-poor randomization technique- such as randomization by days of the week or hospital record number (from which investigators can easily determine the randomization assignment) -less than 80% follow-up -evaluators unblinded to treatment assignment.
183
Osteoclastic bone resorption is stimulated by what molecular interaction?
(RANK) -(RANKL)
184
OPG
receptor competitively binds RANK blocking interaction with RANKL and inhibiting osteoclastogenesis
185
PTH increases serum calcium indirectly by what 3 processes?
1 binding to osteoblasts 2 increasing expression of RANKL 3 decreasing expression of OPG
186
pannus of RA and monosodium urate crystals of gouty tophi trigger the release of what?
inflammatory cytokines such as IL-6- IL-8 and TNF alpha.
187
Loss of function of OPG gene results in what disease?
osteoporosis
188
metalloproteinase MMPs are matrix-degrading enzymes that increase permeability of the basement membrane. what can this allow in regards to cancer?
cancer cell invasion metastasis to occur
189
Platelet-derived growth factor has been shown to have what effect on tumors?
promote tumor migration and prevent cell death.
190
How are free radicals removed from highly cross-linked polyethylene?
Thermal processing: heat treatment of cross-linked polyethylene to remove free radicals
191
which thermal processing method is better?
annealing prefered because better mechanical properties of poly.
192
Trabecular bone is remodeled through osteoclast activation that creates a resorption pit
known as a Howship lacuna. After pit is formed- osteoclasts are replaced by osteoblasts that form new bone matrix. cement line separates new bone formation from resorption.
193
Cutting cones are created in
cortical bone remodeling.
194
Haversian canals vs Volkmann canals?
Haversian canals carry nerves and blood vessels longitudinally in bone. Volkmann canals connect different Haversian canals.
195
Trabecular bone is remodeled through the formation of what?
Howship lacunae.
196
most common soft-tissue sarcoma of the foot
Synovial sarcoma
197
Ring chromosomes
parosteal osteosarcoma
198
Creep
increased displacement over time attributable to same force- such as during initial period of poly compression of THA and methylmethacrylate in taper-designed cemented femoral stems
199
What molecules have been shown to promote fibrosis during muscle injury?
TGF-_Å1
200
severity of biologic response to particulate poly wear debris is directly proportional to what
particle number- response is dose-dependent. particles sized between 0.2 ™Êm and 7-8 ™Êm are most stimulatory- but a direct proportional correlation does not exist with sizes outside of this range.
201
What dominant intracellular proteins become directly phosphorylated as a result of BMP binding to its receptors?
SMADs
202
>65 yos at increased risk for adverse GI effects when placed on NSAIDs- and should be placed on what at the same time?
PPI prophylaxis
203
What technique results in largest reduction of free radicals?
Thermal stabilization thru remelting
204
myasthenia gravis
progressive weakness loss of acetylcholine receptors 2/2 to AI antibodies at NMJ Rest periods allow uptake of Ach and initial strength- but easy fatigability. tx aimed at immunomodulation acetyl cholinesterase inhibitors coupled with thymectomy can control symptoms
205
what test is used when data are nonparametric- meaning either not normally distributed or variances are not equal among groups?
Mann-Whitney U test
206
what test is used with parametric- normally distributed data?
Student t test ANOVA
207
what is used to assess the relationship between a dependent variable and multiple independent variables?
regression analysis
208
Argatroban
Direct thrombin inhibition -prevents conversion of fibrinogen to fibrin
209
Aspirin
-Binding of COX-1 and COX-2 -suppressing thromboxane A2 -effectively preventing platelet aggregation
210
Fondaparinux
Inhibition of factor Xa thru antithromin binding -conformational change in antithrombin enhances ability to inhibit Factor Xa.
211
Enoxaparin
Inhibition of factor Xa thru antithromin binding -conformational change in antithrombin enhances ability to inhibit Factor Xa.
212
Warfarin
-Inh of vit K-dep carboxylation -interfering with cyclic interconversion of vitamin K and its 2- 3 epoxide -hepatic synthesis of factors II- VII- IX- and X with reduced activity
213
biggest RF for nonunion in post spine fusion?
smoking
214
Compared to autograft- ALLOGRAFT demonstrates... ______ inflammatory response _____ rate of biological incorporation and remodeling _____ proportion of large-diameter collagen fibrils
PROLONGER inflammatory response -SLOWER rate of biological incorporation and remodeling -HIGHER proportion of large-diameter collagen fibrils.
215
Hemophilia A
XLR deficiency of factor 8 recurrent spontaneous hemarthroses- synovitis and joint destructioN
216
von Willebrand disease
lack of von Willebrand factor decreased platelet aggregation mucosal bleeding NOT hemarthroses
217
Protein C and S deficiencies
AD lead to thrombosis- NOT bleeding- as protein C and S shut off thrombin formation.
218
Redosing of abx should occur
3 to 4 hours after initial dose for procedures that extend beyond 3 to 4 hours.
219
current recs for abx prophylaxis for major ortho procedures is to administer IV abx ......
within 1 hour of surgical incision.
220
3 basic mechanisms of antibiotic resistance
1 avoidance 2 decreased susceptibility 3 inactivation
221
Biofilm formation is a classic example of what mechanism of abx resistance?
avoidance biofilm creates a physical barrier to the antibiotic
222
high-shear environments ______ biofilm production
stimulate
223
MOA of calcitonin?
Interferes with osteoclast maturation inhibits phosphate reabsorption decreases calcium reabsorption in kidneys.
224
1st stage of osteoarthritis is marked by
increase in water 2/2 to disruption of matrix
225
One hallmark of osteoarthritic cartilage is a reduced repair mechanism attributable to what cell response?
decreased chondrocyte response to growth factor stimulation (TGF-alpha and ILGF-1).
226
Microscopic evidence and process of cartilage degeneration with decreased water content in terminal phases of osteoarthritis
1 fibrillation of superficial and transition zones 2 disruption of tidemark by subchondral blood vessels 3 subchondral bone remodeling
227
Wnt-induced signal protein 1 increases what cell and what process?
chondrocyte protease expression. Failure to restore tissue balance ultimately leads to continued destruction and osteoarthritis.
228
diffusely positive S-100 and pleomorphic large elongated spindle-shaped blue cells
malignant peripheral nerve sheath tumor (MPNST) NF1 inherited AD
229
toughness
amount of energy per volume a material can absorb before failure (fracture)
230
HOW TO CALCULATE TOUGHNESS?
area under stress/strain curve (joules per meter cubed- J/m3)
231
creep
increased load deformation with time under constant load
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load relaxation
decrease in applied stress under conditions of constant strain
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hysteresis (energy dissipation)
characteristic of viseoelastic materials loading curve does NOT follow unloading curve difference between curves is energy that is dissipated
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Elastic zone
zone where a material will return to original shape for a given amount of stress
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toe region
straightening of crimped ligament fibrils applies to a ligaments stress/strain curve
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Yield point
transition point between elastic and plastic deformation
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Yield strength
amount of stress necessary to produce a specific amount of permanent deformation
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Plastic zone
zone where a material will NOT return to its orginal shape for a given amount of stress
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Breaking point
object fails and breaks
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Ultimate (Tensile) strength
load to failure
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Hooke's law
when a material is loaded in the elastic zone- stress is proportional to the strain
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Young's modulus of elasticity
measure of stiffness (ability to resist deformation) of a material in elastic zone slope of the stress/strain curve in elastic zone
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HIGER modulus of elasticity indicates what type of material?
stiffer material
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SIR- COST COULD PUSH POLLY TO CANCEL HER TELEPHONE CARRIER
CERAMIC- COCR- SS- TITANIUM- CORTICAL BONE- PMMA- PE- CANCELLOUS- TENDON- LIGAMENT- CARTILAGE
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Brittle material
material that exhibits linear stress stain relationship until point of failure ONLY ELASTIC DEFORMATION PMMA ceramics
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Ductile Material
large amount of plastic deformation before failure METAL
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Viscoelastic material
material that exhibits a stress-strain relationship dependent on load and rate by which load is applied exhibit a time-dependent mechanical behavior function of internal friction of a material LIGAMENTS AND BONE
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Fatigue failure
failure at a point below the ultimate tensile strength secondary to repetitive loading depends on magnitude of stress and number of cycles
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Endurance limit
maximal stress under which an object is immune to fatigue failure regardless of the number of cycles
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Creep
progressive deformation of metal in response to constant force over an extended period of time
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Corrosion
chemical dissolving of metal
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galvanic corrosion
dissimilar metals leads to electrochemical destruction
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mixing metals 316L stainless steel and Co-Cr has highest risk of what type of corrosion?
galvanic corrosion can be reduced by using similar metal
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crevice corrosion? what metal is most prone?
in fatigue cracks due to differences in oxygen tension 316L stainless steel most prone
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fretting corrosion
at contact sites between two materials with micromotion against each other leading to mechanical wear and material transfer at the surface. -head-neck junction in THA
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ability of a material to absorb energy and plastically deform without fracturing
toughness
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rupture of a material under repeated cyclic stresses- at a point below the normal static breaking strength
fatigue failure
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Free radical oxidation- or oxidative corrosion- is a
chemical reaction involving a change in the oxidation state of polyethylene or metal.
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what metal forms adherent oxide coating through self passivation and is corrosion resistant?
TITANIUM
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STAINLESS STEEL components
primarily iron-carbon alloy with lesser elements of chromium molybdenum MANGANESE
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Cobalt alloy components
COBALT CHROMIUM MOLYBDENUM
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ranking of ultimate strength- from highest to lowest is:
1) cobalt chrome 2) titanium 3) stainless steel 4) cortical bone
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Endurance limit VS FATIGUE STRENGTH?
BOTH ARE THE SAME-- maximum cyclic load (10 million cycles) that a standard sized metal can absorb before fracture
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Ductility
how much strain a material can take before rupturing
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PMMA
reaches ultimate strength at 24 hours-- strongest in compression-- Young's modulus between cortical and cancellous bone
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CERAMIC
typically brittle- low fracture toughness- LOW TENSILE STRENGTH- high compressive strength
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TORSION/ SIPRAL FX
longer the bone- greater the stresses on the outer cortex under torsion
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ultimate strength
Load at which a material fractures
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Tantalum is often used in implants where bony ingrowth is desired.
very resistant to corrosion
270
mnemonic for primary hypercoagulopathies (inherited)
FAC DR SD! (fac doctor SD) Factor V leiden mutation (Factor) Antithrombin III deficiency (At3) protein C Deficiency (C Def) activated protein C Resistance (C Res) protein S Deficiency (S Def)
271
What is the function of the homeobox gene products (HOX genes)?
Regulate somatization of the axial skeleton direct the formation of limbs and organs along the A-P axis (imaginary line that runs from head to tail in animals)
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WHAT ARE inheritable genetic alterations that do not involve DNA mutation?
Epigenetic changes (DNA methylation- histone modification- nucleosome location- or noncoding RNA)
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WHAT ARE genes that are artificially introduced into a single-celled embryo and are present in all cells of that organism?
TRANSGENES
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HOW MUCH CALCIUM TO TAKE PER DAY IF POSITIVE HX of osteoporosis- confirmed by a T-score <-2.5?
1000-1500mg of calcium per day at baseline
