ISCD Exam UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS
State the definition of osteoporosis - CORRECT ANSWER NEWEST DEFINITION:
"osteoporosis is a skeletal disorder characterized by compromised bone strength predisposing to an
increase risk of fracture. Bone strength reflects the integration of two main features: bone density and
bone quality"
Osteoporosis can also be defined based on the presence or history of a low-trauma or fragility fracture
-2.5 T score or below
What is a fragility/low trauma fracture - CORRECT ANSWER a fracture resulting from the
force of a fall from a standing height or less; or a bone that breaks under the conditions that would not
cause a normal bone to break
Summarize the pathophysiology of osteoporosis - CORRECT ANSWER bone loss occurs when
resorption exceeds formation - this can happen due to a number of things; age related bone loss,
disease related to bone loss (ex: malabsorption diseases like certain cancers), menopause, lifestyle,
etc. As bone loss occurs, there is loss of quality as well as quantity. WHO classifies osteoporosis as -
2.5 or below T-score.
What is the definition of prevalence - CORRECT ANSWER frequency of disease at a specific
point in time ("30% of women over age 50 have osteoporosis")
What is the definition of incidence - CORRECT ANSWER new cases of disease over a specific
period of time ("the incidence of hip fractures in an elderly population is 12 per 1000 person-years")
Explain the prevalence and incidence of osteoporosis and fractures - CORRECT
ANSWER prevalence of osteoporosis: estimated 200 million people have osteoporosis
worldwide
Incidence of osteoporosis: hip fracture projected to increase 240% in women and 320% in men by
2050
,In women, the incidence of clinical vertebral fractures begins to increase around age 55-60 and rises
linearly (5-10 yrs later for men)
In women, the incidence of hip fractures begins to raise about age 65 and increases exponentially (5-
10 yrs later for men)
Distal forearm fractures - mortality and morbidity - CORRECT ANSWER third most common
osteoporotic fracture
Risk increases early in women (age 45-50) and levels off 60-65
Most likely caused by fall on outstretched hand
Vertebral fracture - mortality and morbidity - CORRECT ANSWER VERTEBRAL
FRACTURE IS THE MOST COMMON OSTEOPOROTIC FRACTURE
Types: wedge, biconcave, or crush
Many occur with everyday activities (lifting, pushing, pulling)
After vertebral fracture, there is a gradual increase in mortality
Five-year excess mortality is increased by about 20%
Hip fractures - mortality and morbidity - CORRECT ANSWER 2nd most common osteoporotic
fracture
Most caused by fall from standing height
24-30% excess mortality within 1 year
Five-year excess mortality is increased by about 20%
List the economic costs of osteoporosis and compare with other diseases - CORRECT
ANSWER distribution of health care dollars for osteoporosis amount to about 52% for
hospitalization, 30% for nursing home care and 13% for outpatient care
Osteopenia (low bone density) and osteoporosis: 44 mil
Hypercholesterolemia: 98.6 mil
Hypertension: 73.5 mil
Diabetes: 23.6 mil
,Explain the value of bone densitometry for diagnosis, fracture risk estimation and monitoring -
CORRECT ANSWER for diagnosis of osteoporosis, bone densitometry allows diagnosis of
osteoporosis in asymptomatic individuals prior to fracture using the WHO classification (-2.5 t score
or below)
CAVEATS- some patients with -2.5 or below do not have osteoporosis, while some patients with
above -2.5 may be diagnosed with osteoporosis ...Low BMD does not equal bone loss
Using BMD to predict fracture risk is important because BMD is correlated with bone strength and
BMD is predictive of future fractures in epidemiologic studies
What cells are responsible for bone modeling and remodeling? - CORRECT
ANSWER osteoclasts
Osteoblasts
Osteocytes
Define osteoclasts - CORRECT ANSWER cells that remove ('c' CHOMP) old bone
Define osteoblasts - CORRECT ANSWER cells that build ('b' BUILD) new bone
Define osteocytes - CORRECT ANSWER cells derived from osteoblasts that are mature bone
cells thought to be regulators of remodeling
What is the bone remodeling cycle - CORRECT ANSWER coordinated sequence of activation,
resorption, and formation
When does bone loss occur? - CORRECT ANSWER when resorption exceeds formation
When is peak bone mass reached? - CORRECT ANSWER it is reached when the growth in the
size of bones and accumulation of bone mineral has stabilized
Different skeletal sites reach maturity at different times: trochanter, mid-teens; femoral neck, late
teens; spine, early 20s.
Dramatic increase in BMD during adolescence
Peak reached in teens or early twenties
, Overall, age 30
What is the composition of bone? - CORRECT ANSWER bone matrix is 90% collagen and
10% other proteins
Cortical bone makes up the shafts of long bones and the outer envelope of all bones (appendicular
skeleton) - makes up 80% of the skeleton, 20% of surface area
Cancellous or trabecular bone makes up the inner parts of the bones (axial skeleton) - accounts for
20% of skeleton, but 80% of surface area
Describe basic DXA anatomy - CORRECT ANSWER central skeleton: vertebral column and
proximal femur (axial skeleton plus hips and shoulders)...spine, ribs, pelvis, shoulders, and hips
Peripheral skeleton: upper extremities and lower extremities (arms and legs)
Describe basic DXA anatomy for the spine - CORRECT ANSWER lumbar spine regions of
interest (ROI) - analysis includes L1-L4. The surrounding structures, ribs (T12) and iliac crests, may
help with positioning
Describe basic DXA anatomy for the hip - CORRECT ANSWER ROI: femoral neck box, total
proximal hip, greater and lesser trochanters, ward's area
Explain the basic principles of operation for DXA (central skeletal) - CORRECT
ANSWER central DXA is the current gold standard to which everything else is compared
Has excellent reproducibility
Low radiation dose (1-3 usv)
What is attenuation? - CORRECT ANSWER a reduction in the number of photons in an xray
beam (intensity) - determined largely by the tissue density and thickness
As such, the denser the tissue, the more electrons it contains and the greater the attenuation of photons
Why use dual energy xray? - CORRECT ANSWER using 2 diff xray energies allows a DXA
device to record attenuation profiles at two different photon energies
How does dual x-ray work? - CORRECT ANSWER at low energy (30-50 kev) bone attenuation
is greater than soft tissue attenuation, whereas at high-energy (greater than 70 kev) bone attenuation is
QUESTIONS AND CORRECT ANSWERS
State the definition of osteoporosis - CORRECT ANSWER NEWEST DEFINITION:
"osteoporosis is a skeletal disorder characterized by compromised bone strength predisposing to an
increase risk of fracture. Bone strength reflects the integration of two main features: bone density and
bone quality"
Osteoporosis can also be defined based on the presence or history of a low-trauma or fragility fracture
-2.5 T score or below
What is a fragility/low trauma fracture - CORRECT ANSWER a fracture resulting from the
force of a fall from a standing height or less; or a bone that breaks under the conditions that would not
cause a normal bone to break
Summarize the pathophysiology of osteoporosis - CORRECT ANSWER bone loss occurs when
resorption exceeds formation - this can happen due to a number of things; age related bone loss,
disease related to bone loss (ex: malabsorption diseases like certain cancers), menopause, lifestyle,
etc. As bone loss occurs, there is loss of quality as well as quantity. WHO classifies osteoporosis as -
2.5 or below T-score.
What is the definition of prevalence - CORRECT ANSWER frequency of disease at a specific
point in time ("30% of women over age 50 have osteoporosis")
What is the definition of incidence - CORRECT ANSWER new cases of disease over a specific
period of time ("the incidence of hip fractures in an elderly population is 12 per 1000 person-years")
Explain the prevalence and incidence of osteoporosis and fractures - CORRECT
ANSWER prevalence of osteoporosis: estimated 200 million people have osteoporosis
worldwide
Incidence of osteoporosis: hip fracture projected to increase 240% in women and 320% in men by
2050
,In women, the incidence of clinical vertebral fractures begins to increase around age 55-60 and rises
linearly (5-10 yrs later for men)
In women, the incidence of hip fractures begins to raise about age 65 and increases exponentially (5-
10 yrs later for men)
Distal forearm fractures - mortality and morbidity - CORRECT ANSWER third most common
osteoporotic fracture
Risk increases early in women (age 45-50) and levels off 60-65
Most likely caused by fall on outstretched hand
Vertebral fracture - mortality and morbidity - CORRECT ANSWER VERTEBRAL
FRACTURE IS THE MOST COMMON OSTEOPOROTIC FRACTURE
Types: wedge, biconcave, or crush
Many occur with everyday activities (lifting, pushing, pulling)
After vertebral fracture, there is a gradual increase in mortality
Five-year excess mortality is increased by about 20%
Hip fractures - mortality and morbidity - CORRECT ANSWER 2nd most common osteoporotic
fracture
Most caused by fall from standing height
24-30% excess mortality within 1 year
Five-year excess mortality is increased by about 20%
List the economic costs of osteoporosis and compare with other diseases - CORRECT
ANSWER distribution of health care dollars for osteoporosis amount to about 52% for
hospitalization, 30% for nursing home care and 13% for outpatient care
Osteopenia (low bone density) and osteoporosis: 44 mil
Hypercholesterolemia: 98.6 mil
Hypertension: 73.5 mil
Diabetes: 23.6 mil
,Explain the value of bone densitometry for diagnosis, fracture risk estimation and monitoring -
CORRECT ANSWER for diagnosis of osteoporosis, bone densitometry allows diagnosis of
osteoporosis in asymptomatic individuals prior to fracture using the WHO classification (-2.5 t score
or below)
CAVEATS- some patients with -2.5 or below do not have osteoporosis, while some patients with
above -2.5 may be diagnosed with osteoporosis ...Low BMD does not equal bone loss
Using BMD to predict fracture risk is important because BMD is correlated with bone strength and
BMD is predictive of future fractures in epidemiologic studies
What cells are responsible for bone modeling and remodeling? - CORRECT
ANSWER osteoclasts
Osteoblasts
Osteocytes
Define osteoclasts - CORRECT ANSWER cells that remove ('c' CHOMP) old bone
Define osteoblasts - CORRECT ANSWER cells that build ('b' BUILD) new bone
Define osteocytes - CORRECT ANSWER cells derived from osteoblasts that are mature bone
cells thought to be regulators of remodeling
What is the bone remodeling cycle - CORRECT ANSWER coordinated sequence of activation,
resorption, and formation
When does bone loss occur? - CORRECT ANSWER when resorption exceeds formation
When is peak bone mass reached? - CORRECT ANSWER it is reached when the growth in the
size of bones and accumulation of bone mineral has stabilized
Different skeletal sites reach maturity at different times: trochanter, mid-teens; femoral neck, late
teens; spine, early 20s.
Dramatic increase in BMD during adolescence
Peak reached in teens or early twenties
, Overall, age 30
What is the composition of bone? - CORRECT ANSWER bone matrix is 90% collagen and
10% other proteins
Cortical bone makes up the shafts of long bones and the outer envelope of all bones (appendicular
skeleton) - makes up 80% of the skeleton, 20% of surface area
Cancellous or trabecular bone makes up the inner parts of the bones (axial skeleton) - accounts for
20% of skeleton, but 80% of surface area
Describe basic DXA anatomy - CORRECT ANSWER central skeleton: vertebral column and
proximal femur (axial skeleton plus hips and shoulders)...spine, ribs, pelvis, shoulders, and hips
Peripheral skeleton: upper extremities and lower extremities (arms and legs)
Describe basic DXA anatomy for the spine - CORRECT ANSWER lumbar spine regions of
interest (ROI) - analysis includes L1-L4. The surrounding structures, ribs (T12) and iliac crests, may
help with positioning
Describe basic DXA anatomy for the hip - CORRECT ANSWER ROI: femoral neck box, total
proximal hip, greater and lesser trochanters, ward's area
Explain the basic principles of operation for DXA (central skeletal) - CORRECT
ANSWER central DXA is the current gold standard to which everything else is compared
Has excellent reproducibility
Low radiation dose (1-3 usv)
What is attenuation? - CORRECT ANSWER a reduction in the number of photons in an xray
beam (intensity) - determined largely by the tissue density and thickness
As such, the denser the tissue, the more electrons it contains and the greater the attenuation of photons
Why use dual energy xray? - CORRECT ANSWER using 2 diff xray energies allows a DXA
device to record attenuation profiles at two different photon energies
How does dual x-ray work? - CORRECT ANSWER at low energy (30-50 kev) bone attenuation
is greater than soft tissue attenuation, whereas at high-energy (greater than 70 kev) bone attenuation is
