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Orthopedic Surgery Ultimate > Basic Science & Non-Tumor pathology > Flashcards

Basic Science & Non-Tumor pathology Flashcards

1
Q

Which bone graft substitue disappears the most quickly in vivo?

A

Calcium sulfate

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2
Q

What is the rate of decay in bone mass after skeletal maturity?

After menopause in women?

A

0.3-0.5% per year after skeletal maturity

a further 2-3% for untreated women during the decade after menopause

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3
Q

Standard vs. MIPO plating has what effect on blood flow?

A

Decreased periosteal AND medullary blood flow

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4
Q

What kind of collagen is fibrocartilage?

A

Type 1

same as bone

So scar = type 1 collagen

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5
Q

What cell type accounts for 90% of the adult skeleton?

A

osteoCYTE

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6
Q

rhBMP-2 is approved for what uses?

A

Single level ALIF from L2-S1 in DDD with a fusion device

open tibial shaft fratures stabilized with an IM N and treated with 14 days of initial injury

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7
Q

What is the bending rigidity of a plate proportional to?

A

Thickness ^3

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8
Q

What is false about osteocalcin?

  1. It is the most abundant noncollagenous protein of bone
  2. It is secreted by osteoclasts
  3. It is involved in mediating calcium homeostasis
  4. It has been used as a biochemical marker of bone formation
  5. It is part of the organic matrix of bone
A

2

It is secreted by osteoBLASTS

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9
Q

What is the increase in mortality risk after a fragility fracture of:

vertebra

hip

A

Vertebral fragility fracture: 15% increase

Hip fragility fracture: 20% increase

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10
Q

How much devascularization does reaming cause?

A

It devascularizes 50-80% of the cortex

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11
Q

Muscle duration and speed of contraction are most dependent on what?

A

Fiber type

Type II (fast twitch) contract faster, stronger and fatigue quicker

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12
Q

What happens with removal of the AER?

A

Limb truncation

AER controls longitudinal growth

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13
Q

Name the rare, but deadly, complication of Paget’s

What is the prognosis?

A

Paget’s Sarcoma

secondary transformation into osteosarcoma > chondrosarcoma > spindle cell sarcoma

<1%

5 year survival <5%

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14
Q

Distraction osteogenesis - bone forms by what type of ossifciation?

A

intramembranous (primary) ossifciation

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15
Q

Name 4 results of joint immobilization on articular cartilage

A

cartilage thinning

tissue softening

reduced proteoglycan content

cartilage erosion

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16
Q

What’s the role of collagen in artiular cartilage?

A

Prevent swelling of articular cartilage that would otherwise occur due to the effect of aggrecan in drawing in water

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17
Q

What is the mechanism of botox?

A

Inhibition of ACh release from presynaptic vesicles

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18
Q

How do local anesthetics works?

A

Interfere with conduction (depolarization)

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19
Q

Rate of decrease of vertebral fragility fractures after bisphosphonate treatment at 1 & 3 years?

A

1 year: 60% decrease

3 years: 40% decrease

Also decreased non-vertebral fraglity fractures 40%

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20
Q

Area of growth plate pathology in rickets

A

zone of provisional calcification

This is why there is a widening of physis on xray, bc the physis doesn’t ossify!

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21
Q

3 radiographic findings in osteopetrosis

A

Rugger jersey spine

Erlenmeyer flask distal femur

Thickened cortex/lack of a IM canal

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22
Q

Phases of ligament healing

A

inflammatory

  • neutrophils & macrophage mediated with growth factors involved

Proliferative

remodeling

maturation

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23
Q

What happens to water content of cartilage with normal aging? in OA?

A

Decreases with normal aging

Increases with OA

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24
Q

What supplies the inner and outer parts of bone? (blood vessels)

A

Nutrient artery system supplies inner 2/3

is a high pressure system

Periosteal system supplies outer 1/3

is a low pressure system

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25
Q

50 year old DM patient comes in with sudden onset of unilateral leg weakness, absent reflexes on that side and weight loss of about 15 - 20 lbs. No history of radiculopathy or back issues. Diagnosis? 1 differential

A

Diabetic lumbosacral plexopathy (basically diabetic neuropathy)

Acute, stepwise onset of unilateral weakness

Associated with poor diabetic control, absent reflexes and weight loss (up to 40 lbs)

dDx: tumour

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26
Q

When does enchondral ossification occur in fracture healing (what stage)?

A

repair

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27
Q

Why don’t you want your anesthesiologist to use nitrous oxide as an inducin agent for spine or pelvic surgery?

A

Causes abdominal distension and makes fluoroscopy difficult to interpret

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28
Q

Descirbe direct insertion of ligament or tendon onto bone:

A

= fibrocartilagenous insertion

via 4 transition zones:

Zone 1: tendon or ligament

Zone 2: fibrocartilage

Zone 3: mieralized fibrocartilage

Zone 4: bone

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29
Q

Effect of tapping prior to screw insertion on pullout strength

A

decreases it

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30
Q

The femur radiograph of a healthy 25-year-old female is compared to the femur radiograph of a healthy 85-year-old female:

What best describes the 25-year-old’s femur in terms of cortical thickness and medullary canal volume?

A

Increased cortical thickness

Decreased medullary canal volume

As you age, you get thinner cortices and therefore larger canal volumes

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31
Q

Function of PTH

A

Increases blood Ca

Decreases phosphate

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32
Q

What is the effect of physiological stress on cartilage?

A

physiologic stress stimulates chondrocyte synthesis and protects against chondrolysis

vs

excessive stress promotes chondrolysis (in-vitro only)

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33
Q

Why do you place a concave bend when putting on a compression plate for a transverse fracture?

A

To achieve compression on both the near and and far cortices

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34
Q

After 5 year, what percentage of donor and recipieint chondrocytes will be present on an osteoarticular allograft?

A

None

5 years after implantation, allograft articular cartilage is completely acellular

No donor or recipient chondrocytes will be present

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35
Q

What is the primary pathologic process in Paget’s disease?

A

Increased osteoclastic mediated bone resorption

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36
Q

Where do SH I fracture occur through?

A

zone of provisional calficiation (part of hypertrophic)

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37
Q

Name the only irreversible COX inhibitor

A

ASA

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38
Q

What side of the fracture should compression plating be done?

A

Tension side

But may be sacrificed to have a plate lie flat on the bone

(JAAOS 2014)

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39
Q

Diagnosis and cause of x-ray findings (see pic)

A

Osteogenesis imperfecta

Multiple bands caused by bisphoshonate usage (specifically Pamidronate)

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40
Q

Function of Retinoic acid in embryology. What happens when it’s knockedout

A

Regulates zone of polarizing activity

if blocked, get limb bud abortion

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41
Q

WNT7 function

A

dorsoventral patterning of limb

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42
Q

A 27-year-old male undergoes intramedullary nailing of a midshaft tibia fracture with static locking proximally and distally. There is minimal healing noted 3 months postoperatively and the decision is made to dynamize the nail. For intramedullary nail dynamization, an interlocking screw should be placed in which of the holes shown in Figure A?

A

A

see pic

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43
Q

what is the effect of bisphosphonates take post lumbar fusion?

A

Decreases fusion rates

(it increases the fusion mass itself but decreases the actual rate of fusion)

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44
Q

When do you achieve peak bone mass?

A

Between at 16-25

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45
Q

Carrying a load in the ipsilateral hand does what to joint reactive forces at the hip?

A

decrease it

Increases A

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46
Q

Stages of tendon healing

A

Hemostasis

Inflammation

Organogenesis

Remodeling

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47
Q

Main risk of interscalene block?

A

sensory neuropathy

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48
Q

Investigations for Gaucher’s

A

CBC - thrombocytopenia, anemia

cardiac exam: murmurs

GI exam: hepatosplenomegaly

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49
Q

What is the torsional rigidity of solid and cannulated IM nail proportional to?

A

Solid: r^4

Cannulated: r^3

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50
Q

A bicortical locking screw has what biomechanical advantage over a non-locked bicortical screw?

A

Significantly more resistance to all applied forces

Just better

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51
Q

Describe the screw home mechanism

A

The tibia (not femur) ERs 5 degrees during the last 15 degrees of knee extension

This locks the knee, decreasing work performed by the quad during standing

(so the femur IRs)

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52
Q

A long oblique diaphyseal fracture is internally fixed with 2 lag screws. There is 2 mm of residual fracture fragment gap following screw fixation. This construct has which of the following compared to a comminuted diaphyseal fracture internally fixed with a long bridge plating technique?

Greater interfragmental strain

Greater ductility

Greater primary Haversian remodeling

Greater union rate

Greater callus volume formation

A

Greater interfragmental strain

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53
Q

What kind of bone healing involves cutting cones?

A

Primary bone healing (intramembranous)

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54
Q

What is the only zone where articular cartilage progenitor cells have been found?

A

Superficial (tangential) zone

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55
Q

8 ways to increase stability in a circular ex-fix (Ilizarov)

A

Wire factors:

  • Larger diameter wires
  • Olive wires
  • Extra wires
  • Wires crossing perpendicular to each other
  • Increased wire tension

Ring factors:

  • Decreased ring diameter
  • Placement of two central rings close to the fracture
  • Increased number of rings
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56
Q

Inheritance of osteopetrosis?

A

AR: infantile form

AD: Adult form

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57
Q

Where do muscle strains and tears normally occur?

A

Myotendinous junction

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58
Q

Patient with degenerative arthritis and this urine sample.

Diagnosis?

What is the pathophys?

A

Ochronosis (Alkaptonuria)

Degenerative arthritis + black urine

Due to defect in homogenistic acid oxidase enzyme

Leads to excess deposition of homogenistic acid in joints

No treatment available

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59
Q

How do bisphosphonates work?

A

inhibits osteoclasts by inhibiting ruffled border (where the bone resorption occurs)

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60
Q

Name the 5 things that make up articular cartilage

A

Extracellular matrix, made up of:

  • water (highest percentage by weight)
  • collagen
  • proteoglycans
  • noncartilagenous proteins

Cells, made up of:

  • Mature & immature Chondrocytes
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61
Q

4 factors that can alter neuromonitoring signals:

A

Halogenated anesthetics

Nitrous oxide

Hypothermia

Hypotension

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62
Q

Define working length

A

distance between the two screws that are closest to the fracture

it is the distance between the SCREWS, not the screw to the fracture

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63
Q

Name 4 manifestations of osteopetrosis

A

anemia

hearing loss

cranial nerve palsies

fractures

Blindness, hearing loss, dental abscesses, OM in severe (AR) form

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64
Q

Osteopetrosis: what is the defect?

A

Inactive osteoclast carbonic anhydrase

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65
Q

What does the zone of polarizing activity do?

What 4 molecules control/are associated with it?

A

Controls AP development of the limb bud

THINK: ZPA controls PA (posterior to anterior) growth

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66
Q

Which phase of bone healing is abnormal in OI?

A

remodeling

So they heal normally, but don’t remodel so are more fragile

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67
Q

7 orthopaedic manifestations of osteogenesis imperfecta

A

Bone fragility and recurrent fractures

ligamentous laxity

short stature

scoliosis

codfish vertebrae

basilar invagination

olecranon apophyseal avulsion fracture

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68
Q

What happens to chondrocytes in articular cartilage with normal aging

A

Decreases in amount (hypoplastic)

increases in size (hypertrophic)

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69
Q

Why is the increased water content of cartilage in OA pathologic. Describe in 3 lines

A

Increased water content leads to:

increaed permeability of cartilage

decreased strength of cartilage

Decreased Young’s modulus of elasticity

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70
Q

What is Substance P? What does capsaicin do to it?

A

Substance P plays a role in pain neurotransmitting

Capsaicin decreses substance P

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71
Q

3 technical considerations when operating on a patient wtih osteopetrosis

A

Cannot use intramedullary guides

Will need several drills

Risk of fracture with implantation (brittle bone)

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72
Q

Where does Vit D get hydroxylated?

Where does it exert it’s effect?

A

Hydroxylated in Liver (25-OH) & Kidney (1,25-OH)

Increases calcium absorption from intestines and bone, along with PTH

No effect for calcium in kidneys

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73
Q

Factor deficiencies for hemophilia A & B

A

A: FVIII

B: FIX

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74
Q

Diagnosis?

A

Pseudogout

X-ray shows chondrocalcinosis (calcification in fibrocartilage strucutres (menisci))

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75
Q

What common type of rickets has low phosphate, normal calcium and normal PTH?

A

X-linked hypophosphatemic

76
Q

Genetics: what is imprinting?

A

Genetic phenomenon where certain genes are expressed in a parent-or-origin specific manner

ie:

Angelman

Prade-willi

77
Q

What is false about osteocalcin?

A. It is the most prevalent non-collagenous protein in bone

B. It is expressed by mature osteoblasts

C. It is considered a marker for osteoblast differentiation

D. It is a glycoprotein that binds calcium

E. Higher levels are correlated with increases in bone mineral density during osteoporosis treatment

A

D

It is not a glycoprotein that binds calcium, however it is involved in calcium homeostasis

78
Q

On a cellular level, what determines a deep vs. superficial cartilage laceration?

How do each of these heal?

A

Through tidemark is deep

Deep laceration: fibrocartilage healing (type I)

Superficial: chondrocyte proliferation but no actual healing b/c there’s no blood supply there (so dumb)

79
Q

8 risk factors for fungal infection

A

JAAOS 2014

80
Q

What bone graft susbtitute is associated with increased serous wound drainage?

What do we use it for?

A

Calcium sufate

used for tibial plateau fractures

81
Q

Function of HOX

A

segementation of limbs

radio-ulnar & tib/fib patterning of limbs

82
Q

In hemophila, 2 options for synovectomy

Which is better?

A

Surgical synovectomy

Radioactive synoviorthesis: Destruction of synovial tissue with intra-articular injection of radioactive agent)

Radioactive synoviorthesis is better

Has been shown to reduce recurrent bleeding more than surgical synovetomy

83
Q

rhBMP-7 is approved for what use?

A

Alternative to autograft in recalcitrant long bone nonunions where use of autograft is unfeasible

alternative to autograft in compromised patients (DM, smoers etc) in revision lmbar fusion

84
Q

5 radiographic findings in osteogenesis imperfecta

A

evidence of multiple fractures

thin cortices

generalized osteopenia

saber shins

wormina bones on skull x-rays

85
Q

Radius of curvature of a femoral nail is often greater/less than that of the actual femur?

A

Greater

(ie has a smaller curve b/c diameter is bigger)

That’s why you get anterior perforation of the femur if you’re not careful

86
Q

3 times that endochondral ossification occurs

A

Longitudinal physeal growth

Embryonic long bone formation

Non-rigid fracture healing (secondary healing)

87
Q

Type of collagen involved in osteogenesis imperfecta?

A

Type 1 (bONE)

COL1A1 & COL1A2 genes

88
Q

List 5 mechanisms of wear

A

Adhesion

Abrasion

Transfer

Fatigue

Third body

89
Q

Name 5 non-modifibale variables affecting bone healing

A

Blood supply: most important

Head injury

Mechanical factors

Radiation

Extenral stimulators (LIPUS, bone stimulators)

90
Q

Progressive right shoulder pain. No signs of malignancy.

2 most common dDx

What must you order?

A

Charcot joint

Osteomyelitis

Must order: c-spine MRI to r/o syrinx (most common cause of shoulder Charcot joint)

and infection workup

91
Q

Rescue drug for malignant hyperthermia?

A

Dantrolene

92
Q

How do you diagnose Ehler’s Danlos?

A

Collagen typing of skin biopsy

93
Q

What is this graph of?

What happens in area X?

A

Load-elongation curve (aka stress-strain curve) for a tendon

Area X = toe region

non-linear region in which the tendons are crimped and have to initially elongate

94
Q

ACL deficient knees show the greatest different in what motion compared to normal knees?

A

Axial rotation in 50 degrees of flexion

(not anterior tibial translation)

95
Q

6 molecules that stimulate bone resorption

A
  • RANKL

RANKL is secreted by osteoblasts and binds to RANK receptor on osteoclast precursors and mature osteoclast cells

  • PTH

Secreted by many cancer cells

Activation of it sreceptor stimulates adenylyl cclase

Binds to cell-surface receptors on osteoblasts to stimulate production of RANKL and M-CSF

  • IL-1

Stimulates osteoclast differentiation

  • 1,25 dihydroxy Vitamin D

Stimulates RANKL expression

  • Prostaglandin E2

Actiates adenylyl cyclase and stiulates reapsorption

  • IL-6 (myeloma)
  • MIP-1A (myeloma)
96
Q

What muslces are more prone to atrophy with disuse?

A

Ones that cross a single joint

97
Q

8 things that impair ligament healing

A

intra-articular

  • extra-articular ligaments (e.g. knee MCL) have a greater capacity to heal compared with intra-articular ligaments (e.g. knee ACL)

increasing age

immobilization

  • reduces strength of both intact and repaired ligament

smoking

NSAIDS

diabetes

alcohol intake

decreased growth factors (bFGF, NGF, and IGF-1)

decreased expression of genes involved with tendon and ligament healing

  • procollagen I
  • cartilage oligomeric matrix protein (COMP)
  • tenascin-C
  • tenomodulin
  • scleraxis
98
Q

Define weeping lubrication

A

Fluid shifts out of articular cartilage in response to load

surfaces are separated by hydrostatic pressure

99
Q

Thickest articular cartilage zone?

A

Intermediate zone

Contains round chondrocytes & abundant proteoglycan

100
Q

Function of calcitonin

A

Decreases blood Ca

101
Q

Screw lead

A

distance advanced with one revoluation

102
Q

Screw working length

A

length of bone traversed with one revoluation

DIFFERENT THAN PLATE WORKING DISTANCE

103
Q

What cell produces synovial fluid?

A

Type B synovial cell

(fibroblast-like cell)

104
Q

Function of collagen in cartilage?

A

Provides framework and tensile strength

105
Q

List 8 eays to increase stability in a traditional ex-fix

A

Pin Factors

  • Larger diameter pins (most important - Proportional to r^4, so a HUGE difference)
  • More pins
  • Pins in different planes
  • Increased spacing between pins

Fracture factors:

  • Contact of ends of fracture

Rod factors:

  • Rods closer to bone
  • Increasing size or stacking of rods
  • Rods in different planes
106
Q

Function of Groove of Ranvier (NOT node of Ranvier)

A

Is a ring that bridges the epiphysis to diaphysis of the physeal area

increaes strength

responsible for appositional growth

107
Q

When do osteoblasts and fibroblasts proliferate in fracture healing (what stage?)

108
Q

Compared to bicortical non-locked plates, what characteristics does a unicortical locking plate have?

(2)

A

Less torsional strength

Improved axial strength

109
Q

Genetics: what is anticipation?

A

AD (usually) disorder that comes on earlier and worse with subsequent generations

110
Q

6 Orthopaedic manifestations of Rickets

A

Brittle bones

Bowing of long bones

ligamentous laxity

flattening of the skull

enlargement of costal cartilage (rachitic rosary)

Kyphosis (cat back)

111
Q

What kind of hypersensitivity reaction is that of allergy of metallic ortho implants?

What are the other types of immune response

A

Ortho allergy: type IV (delayed/cell-mediated)

Other types

I: anaphylactic (IgE mediated)

II: antibody dependent

III: antibody-antigen complex

IV: delayed/cell mediated

112
Q

Describe viscoelasticity of cartilage

A

When it’s loaded quickly, it’s very stiff

When it’s loaded slowly, it’s not stiff

113
Q

Cause of this in a middle-aged/older patient

Also has silvery, plaque-like rash

HLA-B27+ in 50%

A

Psoriatic arthritis

Arthritis mutilans - destruction of joints causes telescoping of fingers

114
Q

Strain required for absolute stability/healing?

115
Q

What zone of articular cartilage has the lowest concentration of water?

It has the highest concentration of what?

A

Deep zone

lowest concentration of water

highest concentration of proteoglycans

116
Q

Paget’s disease:

Name 3 abnormal findings:

A

ALP: increased

urine hydroxyproline: increased

Urine N-telopeptide, alpha-C-telopeptide, deoxypyridinoline: increased

117
Q

15 findings in Ehler’s Danlos

A

Hyperelastic, fragile skin

Joint hypermobility and dislocation

Generalized ligamentous laxity

Poor wound healing

Early onset arthritis

Soft tissue and bone fragility

Soft tissue calcification

Mitral valve prolapse

Aortic root dilatation

Developmental dysplasia of the hip

Clubfoot pes planus

Scoliosis

High palate

Gastroparesis

118
Q

IN hemophilia, what level should the patient’s factors be at on presentation and pre-op?

A

Increase factor levels by risk of potential blood loss and bleeding - depends on surgery

Acute hematoma

Increase blood factor levels to 30%

Acute hemarthrosis and soft tissue surgery

Increase blood factor levels to 40-50%

Skeletal surgery

Increase blood factor levels to 100% for first week following surgery

Then maintain at >50% for a second week

119
Q

Lab findings in most common type of rickets in western world

A

Familial hypoposphatemic rickets

Low serum phosphate (inability of kidney to resorb P drives this disease)

increased ALP

serum Ca is N or low N

PTH IS NORMAL (vs. nutritional, where it’s high)

120
Q

Screw pitch

A

distance between the threads

121
Q

Hemophilia: What factor levels are needed in:

Acute hematoma

Acute hemarthrosis & soft tissue surgery

Skeletal surgery

A

Acute hematoma: 30%

Acute hemarthrosis & soft tissue surgery: 50%

Skeletal surgery: 100%

122
Q

Name 3 characteristics of synovial fluid

A

Non-newtonian motion:

shear stress is not proportional to shear rate

Pseudo-plastic:

undergoes shear thinning

Thixotropic

undergoes shear thinning with time when sheared at a constant rate

In other words:

Synovial fluid exhibits non-Newtonian flow characteristics (the viscosity coefficient μ is not a constant; the fluid is not linearly viscous); its viscosity increases as the shear rate decreases and vis versa.

123
Q

What’s the function of proteoglycan in cartilage?

What is the most responsible for this behaviour?

What is proteoglycan it made up of

A

Function: attract water and provide compressive strength

Most hydrophilic: aggrecan

Proteoglycan made up of GAG subunits, including chondroitin sulfate and keratin sulfate

124
Q

What are 3 stages of secondary fracture healing?

A

inflammatory

everything cellular happens in this stage

Repair

enchondral ossification

Remodeling

125
Q

Define: (genetics)

Transcription

Reverse transcription

Translation

A

Transcription

DNA –> mRNA

Reverse transcription

RNA –> DNA

Translation

mRNA –> protein

126
Q

Orthopaedic manifestations of gaucher’s (4)

A

Osteomyelitis

fractures

joint contactures

AVN

127
Q

What medication is contraindicated in Paget’s disease? Why is it contraindicated?

A

Teriparatide

It is an osteoblast activator

Contraindicated due to increased risk of sarcomatous transformation

128
Q

What does the femur do when the knee flexes

A

It ERs

(the tibia relatively IRs)

129
Q

4 things that increase in articular cartilage with normal aging

A

Chondrocyte size (although absolute amount decreases)

Protein content

STiffness

Increased ratio of keratin sulfate to chondroitin sulfate (proteoglycans)

130
Q

Most common type of Rickets in north america?

A

Familial hypophosphatemic (Vit D resistant)

PTH IS NORMAL! (vs. nutritional - PTH is high)

Remember that Vit D deficient rickets is rare in western world b/c of vit D supplementatio in everything

131
Q

X-ray Findings in hemophila

4 specific to the knee

A

Epiphyseal overgrowth

Generalized osteopenia

Fractures

Irregularity of joint space

Joint effusion

Specific findings to Knee

Squaring of patella and femoral condyles (Jordan’s sign)

Ballooning of distal femur

Widening of intercondylar notch

Patella appear long and thin on lateral

132
Q

What kind of cartilage has a tidemark?

A

Mature

Immature cartilage has no tidemark

Mitotic figures in immature cartilage cease when the tidemark forms

133
Q

What must you do pre-op for osteogenesis imperfecta in all patients?

A

Pre-op anesthesia consult for increased risk of malignant hyperthermia

134
Q

Define hydrodynamic lubrication

A

fluid seaprates surfaces when one surface is sliding on the other

135
Q

Define Boundary lubricatoin

A

Lubricant only partially separates surfaces

superficial zone proteins have a role in this lubrication (in native articular cartilage)

Occurs on Bearing surfaces that are non-deformable

136
Q

What is the major source of blood to the growth plate?

A

Perichondrial artery

137
Q

What do the nucleus pulposus and the annulus fibrosis form from? (embryologically)

A

Nucleus pulposus: notochord

Annulus fibrosus: sclerotome (one of the somite layers)

138
Q

Side effects of bisphosphonates in kids?

A

Transient hypocalcemia

Transient hypophosphatemia

Transient increased in parathyroid hormone

NO effect on growth if taken at recommeded doses

139
Q

Why is it bad to have fibrocartilage healing of articular cartialge?

A

It sucks compared to articular cartilage

  • Decreased resiliency
  • Decreaed stiffness
  • Poorer wear characteristics
  • Increased prediliction for arthritis
140
Q

Define elastohydrodynamic lubrication

A

Thin films of lubricant separate the surfaces

Is the main mechanism during dynamic joint function

Involves elastic deformation of articular surfaces

141
Q

Rescue drug for local anesthetic systemic toxicity (LAST) due to intravascular bupivicaine injection?

A

20% lipid emulsion

142
Q

True or false

Both ligaments and tendons have toe regions on their stress-stain curve?

A

True

Ligaments have an elongated toe region

vs

tendons have a smaller toe region as they recruit fibers quickly

143
Q

What type of bone formation occurs without a cartilage model?

A

intramembranous

144
Q

Molecules that inhibit bone resorption (5)

A

Osteoprotegrin (OPG)

  • Decoy receptor produced by osteoblasts and stroma cells that binds and sequesters RANKL
  • Inhibits osteoclast differentiation, fusion and actiation

Calcitonin

  • Interacts directlywith the osteoclast via cell-surface receptors

Estrogen

  • Causes decrease in RANKL
  • Stimulates bone production (anabolic) and prevents resorption
  • Inhibits activation of adenylyl cycclase

Transforming growth factor beta

  • Increases OPG

IL-10

  • Suppresses osteoclasts
145
Q

Describe indirect insertion of ligament/tendon onto bone

A

Fibrous insertion

Most common form

superficial fibers insert into periosteum

Deep fibers insert directly onto bone via perforating collagen fibers called Shapey’s fibers

146
Q

Name the 5 types of cartilage. Give an example of each

A

Hyaline: articular

fibroelastic: meniscus
fibrocartilage: enthesis

elastic cartilage: trachea

Physeal cartilage: growth plate

147
Q

Inreased PTH levels suggest what type of rickets?

A

Nutritional

148
Q

What molecule slows growth in the hypertrophic zone?

149
Q

A cane held in the contralateral arm does what to joint reactive force?

A

decreases it

150
Q

What is the most specific marker for the osteoblast phenotype?

A

Osteocalcin

151
Q

2 signals from osteoblasts that downregulate osteoclastic activity

A

calcitonin

IL-10

152
Q

What happens to cartilage with OA?

153
Q

Sustained compression & distration have what effect on the growth plate growth?

What law is this?

A

Compression: decreased longitudinal growtih

Distraction: increased longitudinal growth

Hueter-Volkman principle

154
Q

How does healing of an IM nail occur?

A

Endochondral ossification

AND

intramembranous ossification

*I think if there is 1 answer it will be endochondral (secondary)

155
Q

What is the bending rigidity of an IMN proportional to?

156
Q

Outer & inner diameters

A

Outer: diameter out to th eedge of the threads

Inner: diameter of the core

157
Q

5 things that decrease in articular cartilage with normal aging

A

Absolute number of cells

Water content (increases with OA)

Solubility

Proteoglycan size

Elasticity

158
Q

Strain of what percentages lead to:

Primary intramembranous healing

Secondary endochondral bone healing

Nonunion

A

Primary intramembranous healing:

Secondary endochondral bone healing: 2-10%

Nonunion: >10%

159
Q

2 signals from osteoblasts that upregulate osteoclast activity

A

RANKL

IL-1

160
Q

Define plyometric contraction

A

rapid lengthening followed by contraction of a muscle group

ie jumping repeatedly onto boxes

161
Q

5 non-ortho manifestations of osteogenesis imperfecta

A

Blue sclera

hearing loss

brownish opalescent teeth (dentinogenesis imperfecta)

wormian skull bones (puzzle piece instrasutural skull bones)

increased risk of malignant hyperthermia

  • get anesthesia workup
162
Q

Name 5 patient associated variables (modifiable) that affect bone healing:

A

Nutritional deficieincy:

  • Vit D
  • Calcium
  • Gastric bypass

DM

Nicotine (smoking)

HIV

Meds:

  • NSAIDs
  • Systemic steroids
  • bisphosphonates
  • Quinolone
163
Q

What makes up the most and least proportion of cartilage by percent weight?

A

Water is most

Cells (chondrocytes) are least

Water > collagen > proteoglycan > noncollagenous proteins > cells

164
Q

Functio of sonic hedgehog gene?

A

provides size and shape of long bones

165
Q

Compare tendons to ligaments: 3 points

A

tendons are stiffer (higher Young’s modulus)

Tendons are stronger

Tendons have less hysteresis (more efficient)

Overall, tendons are better

166
Q

Define boosted lubrication

A

AKA fluid entrapment

concentration of lubricating fluid in pools

trapped by regions of bearing surfaces that are making contact

167
Q

Neuromonitoring with continuous EMG. What do the following mean?

Burst activity

Sustained Train

A

Burst:

NOT a cause of concern

surgical instrument contact with nerve root

Sustained train:

a cause of concern

indicates traction injury to nerve

168
Q

Why do people take creatine when they workout?

A

Prevents depeltion of ATP during intense exercise, allowing:

increased and longer work

augmenting muscle hypertrophy and offsetting loss of type II muscle fibers

(JAAOS 2014)

169
Q

Changes that occur with strength training

A

Recruitment of Satellite cells

Improved coordination of muscle firing

hypertrophy

(orthobullets)

170
Q

Strenght of tendon following repair

When is it the weaknes, strongest?

what is the max strenght it will get to?

A

tendon repairs are weakest at 7-10 days

most of strength by 21-28 days

maximum strength at 6 months

final strength only reaches 2/3 of normal even years after repair

171
Q

Risk factors for osteoporosis in men:

A
  • age (>70 years)
  • low body weight (body mass index <20 to 25 kg/m2 or lower),
  • weight loss (>10% [compared with the usual young or adult weight or weight loss in recent years])
  • physical inactivity (participates in no physical activity on a regular basis [walking, climbing stairs, carrying weights, housework, or gardening])
  • use of oral corticosteroids
  • previous fragility fracture
172
Q

What tendons/muscles are more prone to injry?

A

ones that cross 2 joints

173
Q

Muscle force generation is most dependent on what?

A

Cross-sectional area

174
Q

Dietary requirements of calcium for:

kids

adults

adolescents

pregant women, postmenopausal women, bone healing

Lactating women

A

kids: 600mg/d
adults: 750mg/d
adolescents: 1300mg/d

pregant women, postmenopausal women, bone healing: 1500mg/d

Lactating women: 2000mg/d

175
Q

Name these zones of the physis

A

A: epiphysis

B: resting/reserve

C: proliferative

D: Hypetrophic

E: metaphysis

176
Q

What side is the best to place a load bearing plate on?

A

Tension side

177
Q

Give 5 examples of where intramembraous bone formation occurs

A

Flat bone embryology

  • Skull
  • mandible
  • maxilla
  • clavicle - cleidocranial dysplasia
  • pelvis

distraction osteogenesis

Blastem bone formation (kids with amputation)

Fracture healing with rigid fixation

One component of IM nailing

178
Q

Disuss early mobilization of tendon repair

A

Allows earlier ROM but decreased tendon repair strength

beneficial for flexor tendon healing to prevent adhesion formation

179
Q

What stage of fracture healing are fibroblasts and mesenchymal cells present

A

Inflammatory (stage 1)

180
Q

During single leg stance in walking, how much body weight is placed on the leg?

A

~3x

So abductors have to generate 3x body weight of force to keep it upright

181
Q

6 x-ray findings in Rickets

A

physeal widening

metaphyseal cupping

bowing (but not always)

Looser’s zones (pseudofracture on compression side of bone)

decreased bone density

prominence of rib heads at osteochondral junction (Rachitic rosary)

182
Q

4 ways to increase stability with locking screws

A

Bicortical locking screws

Number of screws

Screw divergence from screw hole

Longer plate

183
Q

4 ways to maximize pullout strength of a screw

A

Large inner/outer diameter difference (Ie a cancellous screw)

Fine pitch (more stuff to grab on to)

Placing screws in line with trabecular pattern

Augmentation with PMMA

184
Q

What type of cell is this?

A

Osteoclast

Multinucleated giant cell in bone

Derived from hematopoeitic cells from a macrophage lineage

185
Q

Name the zones of articular cartialge and characteristics of each

A

3 zones + tidemark

Superficial

  • collagen parallel to joint
  • flattened chondrocytes
  • condensed collagen fibers
  • no proteoglycans

Intermediate/Transitional zone

  • thickest layer
  • cartilage oblique to joints line
  • round chondrocytes
  • abundant proteoglycan

Deep/Basal layer

  • Collagen perpendicular to joint & crosses tidemark
  • Highest concentration of proteoglycan
  • Round chondrocytes arranged in columns

Tidemark

  • Deep to basal layer
  • Separates true articular cartilage from cartilage that is the remnant of the cartilage anlage
186
Q

3 nonoperative treatment options in osteopetrosis

A

High dose calcitriol (1,25 dihydroxy Vit D) (AR form)

Bone marrow transplant (AR form)

Interferon gamma 1 beta (AD form)

Orthopedic Surgery Ultimate (88 decks)

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