Basic Science & Non-Tumor pathology Flashcards
1
Q
Which bone graft substitue disappears the most quickly in vivo?
A
Calcium sulfate
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
3
Q
What kind of collagen is fibrocartilage?
A
Type 1
same as bone
So scar = type 1 collagen
4
Q
What cell type accounts for 90% of the adult skeleton?
A
osteoCYTE
5
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
6
Q
What is the bending rigidity of a plate proportional to?
A
Thickness ^3
7
Q
What is false about osteocalcin?
- It is the most abundant noncollagenous protein of bone
- It is secreted by osteoclasts
- It is involved in mediating calcium homeostasis
- It has been used as a biochemical marker of bone formation
- It is part of the organic matrix of bone
A
2
It is secreted by osteoBLASTS
8
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
9
Q
How much devascularization does reaming cause?
A
It devascularizes 50-80% of the cortex
10
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
11
Q
What happens with removal of the AER?
A
Limb truncation
AER controls longitudinal growth
12
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%
13
Q
Distraction osteogenesis - bone forms by what type of ossifciation?
A
intramembranous (primary) ossifciation
14
Q
Name 4 results of joint immobilization on articular cartilage
A
cartilage thinning
tissue softening
reduced proteoglycan content
cartilage erosion
15
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
16
Q
What is the mechanism of botox?
A
Inhibition of ACh release from presynaptic vesicles
17
Q
How do local anesthetics works?
A
Interfere with conduction (depolarization)
18
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%
19
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!
20
Q
3 radiographic findings in osteopetrosis
A
Rugger jersey spine
Erlenmeyer flask distal femur
Thickened cortex/lack of a IM canal
21
Q
Phases of ligament healing
A
inflammatory
- neutrophils & macrophage mediated with growth factors involved
Proliferative
remodeling
maturation
22
Q
What happens to water content of cartilage with normal aging? in OA?
A
Decreases with normal aging
Increases with OA
23
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
24
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
25
When does enchondral ossification occur in fracture healing (what stage)?
repair
26
Why don't you want your anesthesiologist to use nitrous oxide as an inducin agent for spine or pelvic surgery?
Causes abdominal distension and makes fluoroscopy difficult to interpret
27
Descirbe direct insertion of ligament or tendon onto bone:
= fibrocartilagenous insertion
via 4 transition zones:
Zone 1: tendon or ligament
Zone 2: fibrocartilage
Zone 3: mieralized fibrocartilage
Zone 4: bone
28
Effect of tapping prior to screw insertion on pullout strength
decreases it
29
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?
Increased cortical thickness
Decreased medullary canal volume
As you age, you get thinner cortices and therefore larger canal volumes
30
Function of PTH
Increases blood Ca
Decreases phosphate
31
What is the effect of physiological stress on cartilage?
*physiologic* stress stimulates chondrocyte synthesis and protects against chondrolysis
vs
*excessive* stress promotes chondrolysis (in-vitro only)
32
Why do you place a concave bend when putting on a compression plate for a transverse fracture?
To achieve compression on both the near and and far cortices
33
After 5 year, what percentage of donor and recipieint chondrocytes will be present on an osteoarticular allograft?
None
5 years after implantation, allograft articular cartilage is completely acellular
No donor or recipient chondrocytes will be present
34
What is the primary pathologic process in Paget's disease?
Increased osteoclastic mediated bone resorption
excessive bleeding during THA, malalignment during TKA
High Cardiac output heart failuire
Normal Ca serum, elevate bone turnover markers
Paget's sarcoma
* less than 1% will develop malignant Paget's sarcoma (secondary sarcoma)
* osteosarcoma \> fibrosarcoma and chondrosarcoma
* most common in pelvis, femur, and humerus
* poor prognosis
* 5-year survival for metastatic Paget's sarcoma \< 10%
* treatment includes chemotherapy and wide surgical resection
35
Where do SH I fracture occur through?
zone of provisional calficiation (part of hypertrophic)
36
Name the only irreversible COX inhibitor
ASA
37
What side of the fracture should compression plating be done?
Tension side
But may be sacrificed to have a plate lie flat on the bone
(JAAOS 2014)
38
Diagnosis and cause of x-ray findings (see pic)
Osteogenesis imperfecta
Multiple bands caused by bisphoshonate usage (specifically Pamidronate)
39
Function of Retinoic acid in embryology. What happens when it's knockedout
Regulates zone of polarizing activity
if blocked, get limb bud abortion
40
WNT7 function
dorsoventral patterning of limb
41
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
see pic
42
what is the effect of bisphosphonates take post lumbar fusion?
Decreases fusion rates
(it increases the fusion mass itself but decreases the actual rate of fusion)
43
When do you achieve peak bone mass?
Between at 16-25
44
Carrying a load in the ipsilateral hand does what to joint reactive forces at the hip?
decrease it
Increases A
45
Stages of tendon healing
Hemostasis
Inflammation
Organogenesis (type III Collagen)
Remodeling(type 1 collagen)
46
Main risk of interscalene block?
sensory neuropathy
47
Investigations for Gaucher's
CBC - thrombocytopenia, anemia
cardiac exam: murmurs
GI exam: hepatosplenomegaly
***_AR_*** deficiency of B-glucocerebrosidase, lysosomal disease, Askenazi Jew, Osteonecrosis (bone crisis), deformity of D. or P.femur.
Bone marrow histo shows binucleate cell filled with glucocerebroside,
48
What is the torsional rigidity of solid and cannulated IM nail proportional to?
Solid: r^4
Cannulated: r^3
49
Describe the screw home mechanism
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)
50
What is the only zone where articular cartilage progenitor cells have been found?
Superficial (tangential) zone
51
Inheritance of osteopetrosis?
_AR_: infantile form (fatal), intermediate form - carbonic anhydrase II dysfunction)
* Frequent fracture, blindness, deafness (enlarging skul), anemia (marrowc rowding), ***frequent infections (osteo of the Jaw)***
_AD_: Adult form (MC, benign)
Avoid nails for femurs, Plate. Navigation for arthroplastyl, infection risk
52
Where do muscle strains and tears normally occur?
Myotendinous junction
53
Patient with degenerative arthritis and this urine sample.
Diagnosis?
What is the pathophys?
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
54
How do bisphosphonates work?
inhibits osteoclasts by inhibiting ruffled border (where the bone resorption occurs)
NITROGEN BISPHOSPHONATES -1000-fold more potent than non-N
* Block farnesyl pyrophosphate synthase - Results in a loss of GTPase formaton
* key to ruffled border formaton and cell survival - cell apoptosis
Non-NITROGEN BISPHOSPHONATES
* Metabolized into a nonfunctonal adenosine triphosphate (ATP) analogue
* induces apoptosis
55
4 factors that can alter neuromonitoring signals:
Halogenated anesthetics
Nitrous oxide
Hypothermia
Hypotension
56
What does the zone of polarizing activity do?
What 4 molecules control/are associated with it?
Controls AP development of the limb bud
THINK: Z**_PA_** controls PA (posterior to anterior) growth
Duplication mutation results in mirror-image duplication
57
Which phase of bone healing is abnormal in OI?
remodeling
So they heal normally, but don't remodel so are more fragile
58
7 orthopaedic manifestations of osteogenesis imperfecta
Bone fragility and recurrent fractures
ligamentous laxity
short stature
scoliosis
codfish vertebrae
basilar invagination
olecranon apophyseal avulsion fracture
59
What happens to chondrocytes in articular cartilage with normal aging
Decreases in amount (hypoplastic)
increases in size (hypertrophic)
60
Why is the increased water content of cartilage in OA pathologic. Describe in 3 lines
Increased water content leads to:
increaed permeability of cartilage
decreased strength of cartilage
Decreased Young's modulus of elasticity
61
Where does Vit D get hydroxylated?
Where does it exert it's effect?
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
62
Factor deficiencies for hemophilia A & B
A: FVIII
B: FIX
63
What common type of rickets has low phosphate, normal calcium and normal PTH?
X-linked hypophosphatemic
64
Genetics: what is imprinting?
Genetic phenomenon where certain genes are expressed in a parent-or-origin specific manner
ie:
Angelman
Prade-willi
65
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
D
It is not a glycoprotein that binds calcium, however it is involved in calcium homeostasis
osteocalcin
* most abundant non-collagenous protein in the matrix (10%-20% of total)
* produced by mature osteoblasts
* function
* promotes mineralization and formation of bone
* directly involved in regulation of bone density
* attracts osteoclasts
* signaling
* stimulated by 1,25 dihydroxyvitamin D3
* inhibited by PTH
* clinical application
* marker of bone turnover
* can be measured in urine or serum
66
8 risk factors for fungal infection
JAAOS 2014
67
Function of HOX
segementation of limbs
radio-ulnar & tib/fib patterning of limbs
68
In hemophila, 2 options for synovectomy
Which is better?
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
69
rhBMP-7 is approved for what use?
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
70
5 radiographic findings in osteogenesis imperfecta
evidence of multiple fractures
thin cortices
generalized osteopenia
saber shins
wormina bones on skull x-rays
71
3 times that endochondral ossification occurs
Longitudinal physeal growth
Embryonic long bone formation
Non-rigid fracture healing (secondary healing)
72
Type of collagen involved in osteogenesis imperfecta?
Type 1 (bONE)
COL1A1 & COL1A2 genes
73
List 5 mechanisms of wear
Adhesion
Abrasion
Transfer
Fatigue
Third body
74
Name 5 non-modifibale variables affecting bone healing
Blood supply: most important
Head injury
Mechanical factors
Radiation
Extenral stimulators (LIPUS, bone stimulators)
75
Progressive right shoulder pain. No signs of malignancy.
2 most common dDx
What must you order?
Charcot joint
Osteomyelitis
Must order: c-spine MRI to r/o syrinx (most common cause of shoulder Charcot joint)
and infection workup
76
Rescue drug for malignant hyperthermia?
Dantrolene
77
How do you diagnose Ehler's Danlos?
Collagen typing of skin biopsy
78
What is this graph of?
What happens in area X?
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
79
ACL deficient knees show the greatest different in what motion compared to normal knees?
Axial rotation in 50 degrees of flexion
| (not anterior tibial translation)
80
6 molecules that stimulate bone resorption
* _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)_
81
What muslces are more prone to atrophy with disuse?
Ones that cross a single joint
82
8 things that impair ligament healing
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
83
Define weeping lubrication
Fluid shifts out of articular cartilage in response to load
surfaces are separated by hydrostatic pressure
84
Thickest articular cartilage zone?
Intermediate zone
Contains round chondrocytes & abundant proteoglycan
85
Function of calcitonin
Decreases blood Ca
86
Screw lead
distance advanced with one revoluation
87
Screw working length
length of bone traversed with one revoluation
DIFFERENT THAN PLATE WORKING DISTANCE
88
What cell produces synovial fluid?
Type B synovial cell
| (fibroblast-like cell)
89
Function of collagen in cartilage?
Provides framework and tensile strength
90
List 8 eays to increase stability in a traditional ex-fix
_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
91
Function of Groove of Ranvier (NOT *node* of Ranvier)
Is a ring that bridges the epiphysis to diaphysis of the physeal area
increaes strength
**responsible for appositional growth**
92
When do osteoblasts and fibroblasts proliferate in fracture healing (what stage?)
reactive
93
Compared to bicortical non-locked plates, what characteristics does a unicortical locking plate have?
(2)
Less torsional strength
Improved axial strength
94
Genetics: what is anticipation?
AD (usually) disorder that comes on earlier and worse with subsequent generations
95
6 Orthopaedic manifestations of Rickets
Brittle bones
Bowing of long bones
ligamentous laxity
flattening of the skull
enlargement of costal cartilage (rachitic rosary)
Kyphosis (cat back)
96
What kind of hypersensitivity reaction is that of allergy of metallic ortho implants?
What are the other types of immune response
Ortho allergy: type IV (delayed/cell-mediated)
Other types
I: anaphylactic (IgE mediated)
II: antibody dependent
III: antibody-antigen complex
IV: delayed/cell mediated
97
Describe viscoelasticity of cartilage
When it's loaded quickly, it's very stiff
When it's loaded slowly, it's not stiff
98
Cause of this in a middle-aged/older patient
Also has silvery, plaque-like rash
HLA-B27+ in 50%
Psoriatic arthritis
Arthritis mutilans - destruction of joints causes telescoping of fingers
99
Strain required for absolute stability/healing?
\<2%
100
What zone of articular cartilage has the lowest concentration of water?
It has the highest concentration of what?
Deep zone
lowest concentration of water
highest concentration of proteoglycans
101
Paget's disease:
Name 3 abnormal findings:
ALP: **increased**
urine hydroxyproline: **increased**
Urine N-telopeptide, alpha-C-telopeptide, deoxypyridinoline: **increased**
102
15 findings in Ehler's Danlos
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
103
IN hemophilia, what level should the patient's factors be at on presentation and pre-op?
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
104
Lab findings in most common type of rickets in western world
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)
105
Screw pitch
distance between the threads
106
Hemophilia: What factor levels are needed in:
Acute hematoma
Acute hemarthrosis & soft tissue surgery
Skeletal surgery
Acute hematoma: 30%
Acute hemarthrosis & soft tissue surgery: 50%
Skeletal surgery: 100%
107
Name 3 characteristics of synovial fluid
_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.
108
What's the function of proteoglycan in cartilage?
What is the most responsible for this behaviour?
What is proteoglycan it made up of
Function: attract water and provide compressive strength
Most hydrophilic: aggrecan
Proteoglycan made up of GAG subunits, including chondroitin sulfate and keratin sulfate
109
What are 3 stages of secondary fracture healing?
_inflammatory_
everything cellular happens in this stage
_Repair_
enchondral ossification
_Remodeling_
110
# Define: (genetics)
Transcription
Reverse transcription
Translation
_Transcription_
DNA --\> mRNA
_Reverse transcription_
RNA --\> DNA
_Translation_
mRNA --\> protein
111
Orthopaedic manifestations of gaucher's (4)
Osteomyelitis
fractures
joint contactures
AVN
112
What medication is *contraindicated* in Paget's disease? Why is it contraindicated?
Teriparatide
It is an osteoblast activator
Contraindicated due to increased risk of sarcomatous transformation
113
What does the femur do when the knee flexes
It ERs
| (the tibia relatively IRs)
114
4 things that increase in articular cartilage with normal aging
Chondrocyte size (although absolute amount decreases)
Protein content
STiffness
Increased ratio of keratin sulfate to chondroitin sulfate (proteoglycans)
115
Most common type of Rickets in north america?
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
116
X-ray Findings in hemophila
4 specific to the knee
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
117
What kind of cartilage has a tidemark?
Mature
Immature cartilage has no tidemark
Mitotic figures in immature cartilage cease when the tidemark forms
118
What must you do pre-op for osteogenesis imperfecta in all patients?
Pre-op anesthesia consult for increased risk of malignant hyperthermia
119
Define hydrodynamic lubrication
fluid seaprates surfaces when one surface is sliding on the other
120
Define Boundary lubricatoin
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
121
What is the major source of blood to the growth plate?
Perichondrial artery
122
What do the nucleus pulposus and the annulus fibrosis form from? (embryologically)
Nucleus pulposus: notochord
Annulus fibrosus: sclerotome (one of the somite layers)
123
Side effects of bisphosphonates in kids?
Transient hypocalcemia
Transient hypophosphatemia
Transient increased in parathyroid hormone
NO effect on growth if taken at recommeded doses
124
Why is it bad to have fibrocartilage healing of articular cartialge?
It sucks compared to articular cartilage
* Decreased resiliency
* Decreaed stiffness
* Poorer wear characteristics
* Increased prediliction for arthritis
125
Define elastohydrodynamic lubrication
Thin films of lubricant separate the surfaces
Is the main mechanism during dynamic joint function
Involves elastic deformation of articular surfaces
126
Rescue drug for local anesthetic systemic toxicity (LAST) due to intravascular bupivicaine injection?
20% lipid emulsion
127
True or false
Both ligaments and tendons have toe regions on their stress-stain curve?
True
Ligaments have an elongated toe region
vs
tendons have a smaller toe region as they recruit fibers quickly
128
What type of bone formation occurs without a cartilage model?
intramembranous
129
Molecules that inhibit bone resorption (5)
_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
130
Describe indirect insertion of ligament/tendon onto bone
Fibrous insertion
Most common form
superficial fibers insert into periosteum
Deep fibers insert directly onto bone via perforating collagen fibers called Shapey's fibers
131
Name the 5 types of cartilage. Give an example of each
Hyaline: articular
fibroelastic: meniscus
fibrocartilage: enthesis
elastic cartilage: trachea
Physeal cartilage: growth plate
132
Inreased PTH levels suggest what type of rickets?
Nutritional
133
What molecule slows growth in the hypertrophic zone?
PTHrP
134
A cane held in the contralateral arm does what to joint reactive force?
decreases it
135
What is the most specific marker for the osteoblast phenotype?
Osteocalcin
136
2 signals from osteoblasts that downregulate osteoclastic activity
calcitonin
IL-10
137
What happens to cartilage with OA?
138
Sustained compression & distration have what effect on the growth plate growth?
What law is this?
Compression: decreased *longitudinal* growtih
Distraction: increased longitudinal growth
Hueter-Volkman principle
139
How does healing of an IM nail occur?
Endochondral ossification
AND
intramembranous ossification
\*I think if there is 1 answer it will be endochondral (secondary)
140
What is the bending rigidity of an IMN proportional to?
r^4
141
Outer & inner diameters
Outer: diameter out to th eedge of the threads
Inner: diameter of the core
142
5 things that decrease in articular cartilage with normal aging
Absolute number of cells
Water content (increases with OA)
Solubility
Proteoglycan size
Elasticity
143
Strain of what percentages lead to:
Primary intramembranous healing
Secondary endochondral bone healing
Nonunion
Primary intramembranous healing:
Secondary endochondral bone healing: 2-10%
Nonunion: \>10%
144
2 signals from osteoblasts that upregulate osteoclast activity
RANKL
IL-1
145
Define plyometric contraction
rapid lengthening followed by contraction of a muscle group
ie jumping repeatedly onto boxes
146
5 non-ortho manifestations of osteogenesis imperfecta
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
147
Name 5 patient associated variables (modifiable) that affect bone healing:
_Nutritional deficieincy:_
* Vit D
* Calcium
* Gastric bypass
_DM_
_Nicotine (smoking)_
_HIV_
_Meds:_
* NSAIDs
* Systemic steroids
* bisphosphonates
* Quinolone
148
What makes up the most and least proportion of cartilage by percent weight?
Water is most
Cells (chondrocytes) are least
Water \> collagen \> proteoglycan \> noncollagenous proteins \> cells
149
Functio of sonic hedgehog gene?
provides size and shape of long bones
150
Compare tendons to ligaments: 3 points
tendons are stiffer (higher Young's modulus)
Tendons are stronger
Tendons have *less* hysteresis (more efficient)
Overall, tendons are better
151
Define boosted lubrication
AKA fluid entrapment
concentration of lubricating fluid in pools
trapped by regions of bearing surfaces that are making contact
152
Neuromonitoring with continuous EMG. What do the following mean?
Burst activity
Sustained Train
_Burst:_
NOT a cause of concern
surgical instrument contact with nerve root
_Sustained train:_
a cause of concern
indicates traction injury to nerve
153
Why do people take creatine when they workout?
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)
154
Changes that occur with strength training
Recruitment of Satellite cells
Improved coordination of muscle firing
hypertrophy
(orthobullets)
155
Strenght of tendon following repair
When is it the weaknes, strongest?
what is the max strenght it will get to?
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
156
Risk factors for osteoporosis in men:
* 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
157
What tendons/muscles are more prone to injry?
ones that cross 2 joints
158
Muscle force generation is most dependent on what?
Cross-sectional area
159
Dietary requirements of calcium for:
kids
adults
adolescents
pregant women, postmenopausal women, bone healing
Lactating women
kids: 600mg/d
adults: 750mg/d
adolescents: 1300mg/d
pregant women, postmenopausal women, bone healing: 1500mg/d
Lactating women: 2000mg/d
160
Name these zones of the physis
A: epiphysis
B: resting/reserve
C: proliferative
D: Hypetrophic
E: metaphysis
161
What side is the best to place a load bearing plate on?
Tension side
162
Give 5 examples of where intramembraous bone formation occurs
_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_
163
Disuss early mobilization of tendon repair
Allows earlier ROM but decreased tendon repair strength
beneficial for flexor tendon healing to prevent adhesion formation
164
What stage of fracture healing are fibroblasts and mesenchymal cells present
Inflammatory (stage 1)
165
During single leg stance in walking, how much body weight is placed on the leg?
~3x
So abductors have to generate 3x body weight of force to keep it upright
166
6 x-ray findings in Rickets
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)
167
4 ways to increase stability with locking screws
Bicortical locking screws
Number of screws
Screw divergence from screw hole
Longer plate
168
4 ways to maximize pullout strength of a screw
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
169
What type of cell is this?
Osteoclast
Multinucleated giant cell in bone
Derived from hematopoeitic cells from a macrophage lineage
170
Name the zones of articular cartialge and characteristics of each
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
171
3 nonoperative treatment options in osteopetrosis
High dose calcitriol (1,25 dihydroxy Vit D) (AR form)
Bone marrow transplant (AR form)
Interferon gamma 1 beta (AD form)
172
Vitamin D–Resistant (Hypophosphatemic)
Vitamin D–Resistant Hypophosphatemic
– X-linked dominant
– Most common type of rickets in United States
– Impaired renal tubular resorption of PO4
– Normal GFR, impaired vitamin D3 response
– 10th percentile height (stunted)
– Low phosphorus levels (marked)
– Lower limb deformities
– Treat with PO4 and high-dose 1,25(OH) vitamin D
(need both to prevent iatrogenic low-Ca++ and resultant hyper-PTH syndrome)
– Use of the 1,25(OH) vitamin D is recommended due
to 4-hr turnover of the agent and less likelihood of
vitamin D toxemia/overload
– Treatment course is for rest of patient’s life—not
just until full recovery from episode
– Growth hormone before ambulating to prevent bowing
