basic science Flashcards
receiver operator curve
true positive (1-Sp) on y-axis; false negative (1-Sp) on x-axis
confirmation bias
when surgeons recall studies that prove their treatment and forget contradictory evidence
pelvic incidence and lordosis
PI - LL should be LESS THAN 11
Lesch Nyhan syndrome
severe MR; SELF MUTILATING/AGGRESSIVE; severe progressive scoli; wheel chair bound; hib sublux/dislocation is very common
gene for Lesh Nyhan
- x-link rec; males; hypoxanthing guanine phosphoribosyl transferase (HPRT) - needed for purine metabolism
deficiency in morquio syndrome
n-acetylgalactosamine 6- sulfate sulfatase
deficiency in hurler
alpha L iduronidase;
deficiency in gaucher
beta gluccocerebrosidase
degnen disc disease has what effect on chondrocytes
apoptosis
order of inflammatory cytokines
IL 1 B; TNF alpha; then Nitric oxide and MMP’s
what is min brace hrs/day for 90%success in AIS
12 hours - success defined as avoiding surgical threshold of 50 deg
what is inducible resistance in MRSA
a plasmid changes resistance via 50S ribosome ; seen in eryhtromycin resistant strains - causes resistance to Clinda - use a D-Zone test to rule this out
type 1 error is a
false positive - reject the null when you should accept the null
osteocalcin made by
osteoblasts; attracts osteoclastss and is abundant in matrix; regulates mineralization and bone denisity
fibrillin gene defect does what in marfans
alters binding of TGF b and leads to high levels in tissue - causes the aortic root dilitation
gymnasts wrist occurs at which part of physis
zone of prov calcification - generally repetitive loading stress occurs here as it interferes with metaphyseal perfusion - may see physeal widening from active hypertrophic zone
how do thiazolidinedione meds work
activate PPARy to differentiate mesenchymal cells towards fat cells - down regulate osteoblastic transcription factors leading to increased fracture risk
what is the pathophys of MHE
defect in heparin sulfate which leads to poor chondrocyte organization and dev of exostoses
drug elution time for vanc/tobra in cement
4 months
what is condition with ACVR1 gene defect
fibrodysplasia ossificans (stone man)
tx of infantile hipdysplasia without dislocation
pavlik if US shows low alpha angle
what does BMP 2 do
in inflammatory phase of bone healing it recruits mesenchymal stem cells
best approach for talar neck fractures
2 incision med/lateral with med mal osteotomy if needed
time dependent vs concentration dependent abx
vanc is time dependent -needs good trough dosing b/w doses; gent is concentration dependent
what is lubricin in joints
NOT part of cartilage matrix but MADE by c-cytes - glycoprotein to reduce friction
Anakinra blocks which cytokine
IL-1
what is fretting corosion
micromotion between two metals that are NOT loose
crevice corrosion is
affects oxygen tension due to micromotion disrupting the passivation layer
fisher test is for
categorical variable for SMALL numbers of data
Chi-Sq test is for
categorical variable for LARGE numbers of data
which two tests are for comparing categorical data
Fisher for small; chi-sq for large
Unpaired t test is for
continuous data
extrinsic vs intrinsic tendon healing
extrinsic is FASTER but MORE adhesions
how does primary bone healing occur at midpoint
osteoclasts and blasts invovled in remodeling of lamellar bone - OC use cutting cones; OB lay down new bone behind
what med helps spinal fusion in osteoporotic
teraperatide
best mdium for kingella growth
blood agar
kingella is gram
negative
time of sx before presentation kingella
9 days
what is granada agar used for
to isolate group B strep
what happens to disc during degeneration
increase Colllagen 1, and NON-enzyme x-links (this process increased adv glycation end products); Collagen 2 DECREASES;
increased cross linking in UHMWPE does what
decreases wear and decreased TOUGHness
how is primary bone healing accomplished
haversion remodeling
what enzyme is responsible for tumor invasion
MMPs - breakdown basement layer and interstitial stroma
what modality is BEST for detecting physeal bar
T1 MRI - bc wil show unossified bars too
Injury to what zone of physis causes growth arrest
resting zone - closes to epiphysis
what is order of zones of physis
epiphysis - resting > proliferation > hypertrophic (maturation, degen, provisional calicifcation) > metaphysis
where do most physeal fractures occur
in hypertrophic zone bw Provisional Ca and metaphysis
how to manage peds growh arrest from distal radius
simple bar - excise and fat; if small arrest in teenager epiphysiodesis of ulna is enough if asymptomatic) ; if large - corrective osteotomy
what is fatigue wear
progressive mechanical use and result of repetiive cyclic loads
post trauma ankle OA has similar impact on QoL as
ESRD and CHF_
pagets gene mutation
5q35-qter - ubiquitin binding protein sequestosome 1
what effect does motion have on tenon healing
collagen ORGANIZTION more than production
what condition shows tgf-beta excess
marfans
what is oncogenic osteomalacia
seen with osteoblastoma, fibrous dysplasia; and fibromas - FGF23 excess leads to poor phosphate resorption in kidneys and inhibits 1-alpha hydroxylase (low Phos and low 1,25 vit D)
what is pathogenisis of atlantoaxial sublux in rhA
Transverse lig becomes incompetent and Anterior ADI is wide
polylactic vs polyglycolic acids
used to make resorbable implants - PG has higher stiffness and resorbs FASTER 6-12 months vs 24 months for PL
what embroynic structure forms the disk
sclerotome
best stain for cartilage
safranin O and alcian blue
what is mode of failure for interference screw
graft tear, pull out or slippage
what is equation for number needed to treat
1/Absolute risk reduction
best mri for acute trauma
STIR - better than T2 bc STIR will supress fat and marrow edema
what is result of excess muscle-ski motion at ex-fix pin
increased inflammation and thus more pin site infections
how to double ex-fix pin stiffness without changing pin
bury the shank in proximal cortex
what is effect of HA coated ex-fix pin
improves pin/bone interface but INCREASED extraction torque
osteoclasts staining via
cathepksin K stain or TRAP
increased pin spread does what to a ex-fix
increased stability
in compression plating which screws get max stress
those FURTHEST from fracture - this is opposite of bridge plating
how to improve torsional strain in plate
4 screws on either side; no more improvement after 4
best rigidity construct for bridge plate
lowest working distance, and one more screw close to fracture, then one far away - like ex-fix
what is definition of frailty
decreased physio reserve and inability to respond to stressors
if you see peroneal tendon with third tendon
excise- p. quartus
growth factor timeline in masquelet
peak at 4 weeks; baseline at 6 months
where does artery of adamkiewc originate
T8-L1
what perecent of patients have lasting sx from plexus injury after lateral spine surgery
< 5% at 1 y; but start with up to 34% with LE weakness
what is ant retractor up against during post approach
psoas
what is distal limit of ant hip approach
femoral NERVE
risk of MRSA colonization
higher in blacks; lower in adv age and females
main risk of haringe approach to hip
Sup gluteal NERVE (not artery)
how do osteoblasts affect immute system and Hematopoitic cells
jagged1 - notch pathway
HYPERcoagulopathies
MTHFFR gene has highest risk; Factor V leiden; Proten C and S deficiency, Protein C resistance, elevated factor VIII (opposite of hemophilia)
conditions that increas risk of DVT
pregancny, cancer, OCP, hormone tx
what counterintuitive hypercoag state occurs after starting warfarin
rapid rise in INR after unopposed warfarin in post-arthroplasty - has to do with rapid consumption of protein C
other names for thromboplastin
TF, Platelet TF, CD 142
which shoulder arthroplasty patients get LMWH
if higher risk and not mobilized; ASA and antiplatelet alone is NOT enough
what E source after 4 min of aerobic
glycogen and FA
when is ATP used
first 10 seconds of anaerobic
avulsion 5th MT jones frx tx
SURGERY
osteophyte formatio pathway
IHH stimulates chondrocyte differentiation - leading to endochondral ossification
abatacept MoA
blcoks T-cell activiation via MHC
how does L5 root get injured in L5-S1 fusion
lateral exit of Sacral screw heading towards ALA
case series is what L of evidence
4; also includes poor quality cohort studies or case control
sarcomere units
A band is myosin section; I band is actin filament; H band is area with NO acitin myosin overlap; z band bisects I band
what is osteonectin
glycoprotein that is secereted by osteoBLASTS and binds to calcium - therby regulating mineralization
annulus fibrosis is derived from
mesoderm
osteoblast pathway for immune regulation
via PTH to jagged (osteoblast) notch (h-poeitic cells)
what is role of BMP 2
chondrocyte differentiation pathway for mesenchymal cells
which BMP is osteoinductive
5,6,7,
what is BMP 1
MMP for propreptidase 1,2, 3 collagen
refractory osgood schlater treated with
resection of TT OSSICLE ONLY - does not involve patellar tendon
deficiency in heparin sulfatase
san fillipo syndrome
beta galactosidase deficiency leads to
morquio
morquio defect
beta galactosidase deficiency
systematic review of RCT and level 2 studies is overall
level 2
tibial tubercle ossification and fusion
11 and 14 ossify (F, M); and 14 and 18 fusion
cathepskin K inhibtor works to decrease which cells activitiy
osteoclasts
what is start of common pathway for coag
X to Xa conversion which leads to conversion of prothrombin to thrombin
what does aspirin block
Thromboxane A2
the Xa inhibitors
Fondaparinaux(indirect); Apixaban and Rivaroxiban (direct)
which zone of cartilage has least proteoglycan
superfiical
what fixation method is at risk for pull out
staple
what fixation method is at risk for breakage
transfixtion pin
what fixation method is at risk for cortical bone pull through
cortical button
golgi organs purpose
relay muscle tension and length, proprioception
pacinian corpuscles relay
deep pressure and vibration
ruffini ends conve
sustained presure sensation
merkel cells convey
sustained touch and pressure sensation
decorin protein role
regulates collagen fiber size (decorates with diff collagen sizes)
osteocalcin requires
vitamin K and is a gamma carboxylation of glutamic acid
gene assay tests
PCR -DNA; northernblot and RT PCR - RNA level; and Western blot is for protein
freeze dried vs frozen allografts
freeze dried have same compression and tensile strength; but less torsional and bending
does frozen graft have osteoinductive potential
yes limited; and has osteoconductive; lasts 1-5 years
quad weakness leads to what during swing phase
knee hyperextension; hip flexors rapidly contract to flex femur and then gluts rapidly contract to slow femur - as a result tibia swings forward and hyperextends
what is needed to maintain articular cartilage phenotype
PTH-RP
role of aggreca
exerts swelling pressure against restraint of collagen
what does type 6(VI) collagen do
mechanical signaling to chondrocytes
how does clonazepam increase osteoporosis
does NOT interfere with vitamin D BUT can increase sclerositin levels and therby decrease osteoblast
max length for nerve conduit
3cm
order of nerve function return
sympathetic, pain, temp, touch, proprioception, motor
where do obturatator arter and sup gluteal arise
INTERNAL iliac
general muscle fiber type
slow oxidative (type I), fast oxidative-glycolytic (type IIA), and fast glycolytic (type IIB)
Type I fibers
type 1 smaller and contract more slowly and less forcefully but are fatigue resistant. Type IIA is intermediate, type IIB is fastest most powerful but most fatigue-prone myofibril type.
definition of specificity
probability that negative person will test negative - TN / FP + TN
lab values in type 1 Vit D Rickets
low ca, low phos, low 1,25, high ALP, PTH
lab values in type 2 Vit D Rickets
low Ca, low phos, HIGH 1,25, HIGH ALP and PTH
x linked hypophosphatasia
low PO4; NORMAL CA; ALP high, NORMAL PTH, LOW VIT D 1,25 - bc kidneys can resorb phosphate
where does scfe happen
maturation zone of hypertrophic zone
where does scurvy and corner fractures occur
zone of provisional calification
what conditions affect the reserve zone of physis
Gauchers and Diastrophic Dysplasia
rifampin affects
RNA polymerase
CaSo4 vs CaP04
phosphate is stronger; BOTH are wear to shear and torsion
non nitrogen containing bisphos have
ATP analog that causes apoptosis of osteoclasts etidronate, and clonodrate
power equation
1- type 2 error (beta)
what makes a RCT level 2
follow up less than 70%
what is Rh factor
IgM against the IgG
ranking of tensile strength in implants
cobalt, titanium, stainless steel and cortical bone
effect of bisphos in Osteogenesis imperfecta
improves bone density, reduces fracture and reduces bone pain
COMP mutation leads to
pseudoachondroplasia and MED
COL2A1 mutation
SED - same as MED but with spine involvement
what is nitrogen containing bisphos
alendronate - works via farnesyl trasnfersase
Xlinked hypophosphatemic rickets vs hypophosphatasia
X-linked hypophos is a LOW phos and normal Ca due to bad kidney receptor - vit D resistent rickets; hypophosphatasia is s due to bad ALP; ca and phos are HIGH
what molecules are for compressive strength vs tensile
compressive - Ca-HA and proteoglycans and tensile is type 1 collagen
what gene contols axial skeleton development
HOX
level of evidence prospective cohort
level 2
what does lovenox do
enhances binding of AT3 to thrombin
what stimulates osteoblasts to differenitate
PTH and TGF b - for mesenchymal cells
definition of sensitivity
probability that positive Is a true positive IN THOSE WITH disease
which BMP invovled in FOP
BMP 4
what bmp is NOT osteoinductive
BMP 3
what nerves are obturator
L234
deep peroneal nn supplies which foot muscles
EHL, EDB
structure of osteons aka Haversions systems
osteons are defined by cement lines; inside are vascular canals that care artery, vein, neve; volkman are transverse connections; haversian CANALS are along the long axis
bone maturity woven vs lamellar
woven is immature; lammelar is more stiff and more organized
what makes mature osteoblasts
BMP; beta cantenin, PDGF, IDGF, TGF B;
how to bisphos prevent osteosclasts
inhibits ability to make microtubules at ruffled border leading to apoptosis
what cancer can you use bisphos to prevent skeletal events
multiple myeloma
collagen 1 composiition
1 alpha-2 chain; 2 alpha-1 chains - triple helxi
most abundant non collagen protein in bone
osteocalcin
ostenectin secreted by
platelets and osteoBlasts
bone vascularity high vs low pressure
nutrient artery is 2/3 of bone supply and is HIGH pressure; low pressure is periosteal supplies outer 1/3 via Volkman
how does estrogen help bone growth
inhibits adenylyl cyclase and decreases RANKL
which IL stimulate bone RESORPTION
IL 1 and 10 stimulate osteoclasts; IL 6 in myeloma
vitamin D requirements 1500
if pregnant, fracture healing; or post-menopause
vit D requirement 2000
lactating
vitamin D requirement 750
adults;
vitamin D requirement 1000-1350
yound adults and teens
vitamin D for kids
600-800
protrusio vs coxa prufunda
profunda is acetabulum is medial to iliosichial line; protrusio is femoral head is medial to ilioishcial line
gene transmission of duchenne
X-linked recessive
scleraxis does what
transcription factor for tendon/ligament
dexa scoring is Z or T
T score
indepdence lost at 1 year after hip fracture
50% at 1 year
what factor stimulates cartilage regeneration
TGF B
what happens to FGFR in achondroplasia
abnormally turned ON
what is pathologic cell in pagets and osteopetrosis
osteoclasts - but in pagets its INCREASED resorption; and in osteopetrosis its decreases osteoclasts
role of fibronectin
cell adhesion; growth, migration and development
fibrillin is associated with
elasin DEPOSITION
which metal has highest bacteria adherence
Ti-Alloy > Steel> pure titanium; tantalum Is relatively resistent
denosumab blocks and binds to
RANKL (LIGAND)
cells of nucleus pulposes as disc degenerates
decrease in size and cell
huntingtons repeat
CGG
inheritance of hemophilia
xlinked RECESSIVE
what factors BLOCK the osteolytic cascade
IL1 receptor antagonis; OPG, IFN gamma, IL 4 and IL 10
what factors mediate osteolysis
TNFa; IL6; IL 1; PG2; RANKL
what gait mechanic are a/w with KNEE oa progression
ADDUctor moment at tibia
what leads to cartilage brittleness with age
increaseing advanced end glyoclation products over time
heparin works by binding
Antithrombin 3
tensile strength of nerves comes from
collagen 1
what does transient osteoporosis of hip look like on MRI
BRIGHT on T2 bc more bone marrow edema; T1 is hypointense
tx of transient osteoP of hip
protected WB ; can last 6-8months -no surgery needed self limiting
ZPA zone of polarizing activity affect
hand polarization
order of nerve structure
ENDO; Perineural, fascile; EPI
sural nn runs with which vein
LESSER saphenous vein
what is purpose of funnel plot
to show publication bias in meta analysis - would want even funnel shape
what is best test to compare frequency or proportions
Chi-Squared test
sheathed tendons get their blood supply from
VINCULA - NOT paratenon
what restrains the swelling pressure from aggrecan
Collagen (2)
what is pathology of factor V leiden
leads to hypercoag due to increase thrombin activation
muscle fibers 1 vs 2
1 is slow; lower strength and speed; uses aerobic and oxidative energy; atrophies first; 2 is fast; fatigues quickly and is glycolytic
ach and muscle contraction
ACH binding leads to ca release - ca then binds tropoin - changes tropomyosin and leads to exposure of actin for myosin binding
what is tx for familial vit D resistent rickets
phosphate replacement and Vit D (calcitriol)
what are the vitamin D versions
D3; then 25D3 then 1,25 D3(Calcitriol)
tib ant activation during heel strike
eccentric followed by conccentric
microfracture stimulates what cells
mesenchymal cells from the marrow tomake fibrocartilage
what happens in factor v leidein
prevents inibition by activated factor C’
duchenne inheritance
xlinked RECESSIVE
how much force in medial knee if neutral
65% in neutral leg
what is epigenetics
gene alterations that do NOT involve DNA mutations
what is most common sx with PE
dyspnea - NOT tachycardia
renal osteodystrophy labs
hypoCa bc phosphate retained binds to Ca and damaged kidney cant make 1,25 Calcitriol; hyper PTH results
what other conditions are seen with renal osteodys
osteomalaciA, AVN, tendinitis and rupture; CTS due to amyloid; and brown tumors from hyperPTH
what is LOW turnover renal osteodystrophy
normal PTH; deposits of Alumininum in bone; impaired PTH release; disrupts mineralization
labs in vit D dependent type 1
low vit D 1,25 and low Ca,lowphos, high PTH and ALP
labs in vit D dependent type 2
HIGH vit D 1,25 and low Ca,lowphos, high PTH and ALP
labs in x linked vit D resistnet
LOW phos, normal Ca; low vit D 1,25 HIGH PTH and ALP
labs in hypophosphatasia
LOW ALP; high Ca, and hi phos; normal Vit D
Labs in renal osteodys
low Ca; high phos; high PTH; high ALP; low vit D
what happesn to proteoglycans in disk with aging
decreased - they get broken down
follow up time frame for lateral condyle growth arrest
3 years
LMWH is associated with increased
thrombocytopenia
muscle tension determinted by
cross section volume
what is effect of SCD
increased cardiac output; stroke volume; EF and MAP; pre load; reduce afterload
what cells fix muscle injuries
satellite cells
poland syndrome features
syndactyly with unaffected thumb; ipsilateral chest wall issues - absent pec; or assymetric nipples
max dose of abx in PMMA
up to 10gm of vanc and up to 12.5gm tobra for 40 gram PMMA
diff types of drug recall
class 1 is for serious harm or death; class 2 is temporary or reversible adverse events, class 3 is no adverse issues
which part of tendon covering provides neuro signal
ENDOtenon - closed layer to tendon; paratenon is most superficial
Strategies to minimize confounding
randomization, restricted enrollment, matching, and post hoc analyses.
force and excursion of muscle related to
muscle architecture - number and orientation of fibers
terres major innerveated by
lower subscap
how much can you lenghten leg before injuring sciatic
10% of femur or 4cm
transfemoral amputaiton increases how much E
60% increase
what Growth factor is for Chondrogenesis
TGF
forteo uses in osteoporosis fracture
can help if bisphos resistent
