Orthopedics Hyperguide Review | Dr Hutaif General Ortho -...
Updated: Feb 2026
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Key Medical Takeaway
In this comprehensive guide, we discuss everything you need to know about ORTHOPEDICS HYPERGUIDE MCQ 851-900. In an X-linked dominant scenario l l, an affected man transmits the condition to 100% of his daughters but none of his sons. Conversely, an affected woman transmits the condition to 50% of her sons and 50% of her daughters. This inheritance pattern ensures that heterozygotes will express the condition.
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ORTHOPEDICS HYPERGUIDE MCQ 851-900
QUESTION 1
A woman has an X-linked dominant condition (single allele being dominant). Which of the following is true:
1
25% of the offspring will be affected
2
100% of the daughters will be affected
3
25% of the sons will be affected
4
100% of the sons will be affected
5
50% of the offspring will be affected
With X-linked dominant, heterozygotes will have the condition. If a woman has this condition, then she will transmit it to 50% of her sons and daughters.
In contrast, affected men transmit the condition to all of his daughters (because the daughter gets his X chromosome), but to none of the sons because the son gets the Y chromosome.
With X-linked recessive, the patterns are different between women and men.
X-linked recessive woman: An X-linked woman with the recessive allele is a carrier, but she is not affected because the allele is recessive.
C arrier females (X-linked recessive) transmit the condition to 50% of her daughters (who become carriers) and 50% of her sons
(the sons are affected because their only X chromosome has the recessive gene). Correct Answer: 50% of the offspring will be affected
QUESTION 2
Which of the following are actions of parathyroid hormone (PTH):
1
Increases kidney absorption of calcium and increases kidney absorption of phosphate
2
Increases kidney absorption of calcium and decreases kidney absorption of phosphate
3
Directly activates osteoclast precursor cells to differentiate into osteoclasts
4
Decreases 1 alpha hydroxylase activity in the kidney
5
C auses increased production of calcium binding protein
Parathyroid hormone increases calcium reabsorption from the kidney tubular cells and inhibits the reabsorption of phosphate. Remember that PTH signals the osteoblasts to release receptor activator of nuclear factor -kB ligand (RANKL), which causes
osteoclast activation â this is an indirect action. PTH actions:
Facilitates absorption of calcium in the gastrointestinal system
Increases 1,25 dihydroxy vitamin D in the kidney by stimulating 1 alpha hydroxylase
Facilitates reabsorption of calcium from the distal tubular renal tubular cells
C alcium is reabsorbed in the proximal and distal tubules, but only distal tubule is PTH dependent
Inhibits reabsorption of phosphate in the kidney
Stimulates release of calcium and phosphate from bone (indirectly)
C auses release of receptor activator of nuclear factor -kB ligand (RANKL) from the surface of the osteoblasts
QUESTION 3
Which of the following cells has receptors for parathyroid hormone (PTH):
1
Osteoblasts, osteoclasts, and distal kidney nephron
2
Osteoblasts, osteoclasts, and gastrointestinal cells
3
Osteoclasts and osteoclast progenitor cells
4
Osteoblasts and distal kidney nephron
5
Osteoclast progenitor cells
PTH actions:
Facilitates absorption of calcium in the gastrointestinal system
Increases 1,25 dihydroxy vitamin D in the kidney by stimulating 1 alpha hydroxylase
Facilitates reabsorption of calcium from the distal tubular renal tubular cells
C alcium is reabsorbed in the proximal and distal tubules, but only distal tubule is PTH dependent
Inhibits reabsorption of phosphate in the kidney
Stimulates release of calcium and phosphate from bone (indirectly)
C auses release of receptor activator of nuclear factor -kB ligand (RANKL) from the surface of the osteoblasts
Parathyroid hormone exerts its affects through receptors on osteoblasts and kidney nephron cells. Parathyroid hormone effects on the gut are indirect through an increased synthesis of 1,25 dihydroxy vitamin D. Parathyroid hormone acts on osteoblasts to release RANKL, which then acts on the osteoclast progenitor cells to differentiate into osteoclasts.
QUESTION 4
Which of the following is an action of 1,25 dihydroxy vitamin D:
1
Increases synthesis of calcium binding protein
2
C auses kidney tubule cells to absorb calcium
3
Increases bone resorption by directly signaling osteoclasts
4
Increases parathyroid hormone (PTH) production
5
C auses kidney tubule cells to absorb phosphorus
Vitamin D acts on the intestinal to increase calcium absorption. C alcium binding protein synthesis is increased. Vitamin D is an intracellular messenger, acting through the nucleus.
Vitamin D actions:
Increase the efficiency of calcium absorption in the intestine (primarily duodenum) Increases synthesis of calcium binding protein (and others)
Increases passage of calcium through the cell membrane
Moves calcium through the cell cytoplasm and into the circulation
Increases bone resorption by telling the osteoblasts to release receptor activator of nuclear factor -kB ligand
Osteoblasts have vitamin D receptors
Vitamin D receptors exert a negative feedback on 1,25 dihydroxy vitamin D production
Decreases PTH production
QUESTION 5
Which of the following cause the release of receptor activator of nuclear factor -kB ligand (RANKL) from the osteoblast cell surface:
1
Osteoprotegerin
2
Transforming growth factor beta
3
Insulin-like growth factor
4
Parathyroid hormone (PTH) receptor
5
C alcitonin
Osteoclast progenitor cells are activated to transform into osteoclasts when the RANKL activates the RANK receptor. The following factors cause release of RANKL from the osteoblast:
PTH
1,25 dihydroxy vitamin D Interleukin 11
Prostaglandin E2
QUESTION 6
Which of the following cause the release of receptor activator of nuclear factor -kB ligand (RANKL) from the osteoblast cell surface:
1
C alcitonin
2
1,25 dihydroxy vitamin D
3
Transforming growth factor B
4
Insulin-like growth factor
5
Tumor necrosis factor
Osteoclast progenitor cells are activated to transform into osteoclasts when the RANKL activates the RANK receptor. The following factors cause release of RANKL from the osteoblast:
PTH
1,25 dihydroxy vitamin D Interleukin 11
Prostaglandin E2
QUESTION 7
C alcitonin has which of the following functions:
1
Inhibits the release of receptor activator of nuclear factor -kB ligand (RANKL) from the surface of osteoblasts
2
Increases the release of osteoprotegerin from the surface of osteoblasts
3
C auses osteoclasts to withdraw from the bone surface
4
C auses a decrease in conversion of vitamin D into 25 hydroxy vitamin D
5
C auses a decrease in conversion of 25 hydroxy vitamin D into 1,25 dihydroxy vitamin D
C alcitonin has 1 major action:
Inhibits osteoclastic bone resorption â the osteoclast shrinks and withdraws from the bone surface
C alcitonin can be used in the following conditions:
Paget's disease
Osteoporosis
Hypercalcemia of malignancy
C alcitonin is used less frequently today than in the past. Diphosphonate agents are the main therapeutic agents. Correct Answer: C auses osteoclasts to withdraw from the bone surface
QUESTION 8
Which of the following soft tissue tumors may cause tumor-induced osteomalacia:
1
Liposarcoma
2
Malignant fibrous histiocytoma
3
Synovial sarcoma
4
Hemangiopericytoma
5
Atypical lipoma
Tumor-induced osteomalacia can be caused by a small tumor of bone or soft tissue (phosphaturic tumor). Small tumors may not be detected.
I. General Features
A. Presentation
1/. C hronic, vague symptoms - principally, bone pain
2/. Muscle weakness
3/. Fractures may occur
B. Metabolic profile
1/. Hypophosphatemia
2/. Low reabsorption of phosphate from the kidney
3/. 1,25 dihydroxy vitamin D - low or normal
4/. 25 hydroxy vitamin D, 24,25 dihydroxy vitamin D - normal
C . Tumor types
1/. Soft tissue
a. Hemangiopericytoma b. Sclerosing angioma
c. Benign angiofibroma d. Neurofibromatosis
D. Pathophysiology
1/. A molecule that wastes phosphorus - phosphatonin
E. Radiographic features
1/. Osteopenia
2/. Pseudofractures
3/. C oarsened trabeculae
4/. Soft tissue - a small, well-circumscribed soft tissue mass may be noted
F. Treatment
1/. Oral phosphate
2/. 1,25 dihydroxy vitamin D Correct Answer: Hemangiopericytoma
QUESTION 9
Which of the following bone tumors may cause tumor-induced osteomalacia:
1
Osteosarcoma
2
Ewing's sarcoma
3
Osteoblastoma
4
Adamantinoma
5
Malignant fibrous histiocytoma
Tumor-induced osteomalacia can be caused by a small tumor of bone or soft tissue (phosphaturic tumor). Small tumors may not be detected.
I. General Features
A. Presentation
1/. C hronic, vague symptoms - principally, bone pain
2/. Muscle weakness
3/. Fractures may occur
B. Metabolic profile
1/. Hypophosphatemia
2/. Low reabsorption of phosphate from the kidney
3/. 1,25 dihydroxy vitamin D - low or normal
4/. 25 hydroxy vitamin D, 24,25 dihydroxy vitamin D - normal
C . Tumor types
1/. Bone
a. Nonossifying fibroma b. Osteoblastoma
c. Giant cell tumor d. Fibrous dysplasia
D. Pathophysiology
1/. A molecule is produced by the tumor that wastes phosphorus - phosphatonin
E. Radiographic features
1/. Osteopenia
2/. Pseudofractures
3/. C oarsened trabeculae
4/. Soft tissue - a small, well-circumscribed soft tissue mass may be noted
F. Treatment
1/. Oral phosphate
2/. 1,25 dihydroxy vitamin D Correct Answer: Osteoblastoma
QUESTION 10
Which of the following would be the metabolic profile for a patient with tumor-induced osteomalacia:
1
Low serum calcium, low serum phosphate
2
Low serum calcium, high serum phosphate
3
Normal serum calcium, low serum phosphate
4
Normal serum calcium, high serum phosphate
5
High serum calcium, low serum phosphate
I. General Features
A. Presentation
1/. C hronic, vague symptoms - principally, bone pain
2/. Muscle weakness
3/. Fractures may occur
B. Metabolic profile
1/. Hypophosphatemia
2/. Low reabsorption of phosphate from the kidney
3/. 1,25 dihydroxy vitamin D - low or normal
4/. 25 hydroxy vitamin D, 24,25 dihydroxy vitamin D - normal
C . Pathophysiology
1/. A molecule is produced by the tumor that wastes phosphorus - phosphatonin
D. Radiographic features
1/. Osteopenia
2/. Pseudofractures
3/. C oarsened trabeculae
4/. Soft tissue - a small, well-circumscribed soft tissue mass may be noted
E. Treatment
1/. Oral phosphate
2/. 1,25 dihydroxy vitamin D
QUESTION 11
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
In a patient with metabolic bone disease, which of the above metabolic patterns is most likely vitamin D-deficient rickets:
1
Scenario 1
2
Scenario 2
3
Scenario 3
4
Scenario 4
5
Scenario 5
In patients with vitamin D-deficient rickets, a low amount of vitamin D is present in the diet. Because of a low calcium level in patients with vitamin D deficiency, patients develop secondary hyperparathyroidism.
The increased parathyroid hormone (PTH) causes increased absorption of calcium from the small intestine and decreased absorption of phosphorus from the kidney. Therefore, serum calcium is low or normal, serum phosphate is decreased, and PTH is high. Increased bone resorption occurs, and 25 hydroxy and 1,25 dihydroxy vitamin D are low.
Patients are treated with supplemental vitamin D in their diet. Correct Answer: Scenario 1
QUESTION 12
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
In a patient with metabolic bone disease, which of the above scenarios would be consistent with dietary phosphate deficiency:
1
Scenario 1
2
Scenario 2
3
Scenario 3
4
Scenario 4
5
Scenario 5
Dietary phosphate deficiency is rare. Patients have a normal serum calcium and parathyroid hormone level, and the vitamin D
levels are also normal. Because of an insufficient amount of phosphate, normal bone mineralization does not occur. Patients are treated with supplemental neutral phosphate.
QUESTION 13
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
A patient has gastrointestinal surgery and develops osteomalacia (rickets). Which of the above scenarios would be the most likely metabolic panel:
1
Scenario 1
2
Scenario 2
3
Scenario 3
4
Scenario 4
5
Scenario 5
Patients who have gastrointestinal surgery or have gastrointestinal disease (eg, C rohn's disease) may develop osteomalacia. The metabolic parameters are similar to that seen with dietary vitamin D deficiency â a low calcium level and resulting hyperparathyroidism.
C alcium is poorly absorbed or a steatorrhea is present, which binds the calcium so that it cannot be well absorbed. Because of a low calcium level, patients develop secondary hyperparathyroidism.
The increased parathyroid hormone (PTH) causes increased absorption of calcium from the small intestine and decreased absorption of phosphorus from the kidney. Therefore, serum calcium is low or normal, serum phosphate is decreased, and PTH is high. Increased bone resorption occurs, and 25 hydroxy and 1,25 dihydroxy vitamin D are low.
QUESTION 14
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
A patient has phosphate diabetes (vitamin D-resistant rickets). Which of the above metabolic profiles would most likely result:
1
Scenario 1
2
Scenario 3
3
Scenario 4
4
Scenario 6
5
Scenario 7
Phosphate diabetes is a type of vitamin D-resistant rickets. Patients are unable to reabsorb phosphate in the kidney tubules. The serum phosphate level is low, and patients are unable to mineralize osteiod because of the low phosphate. Serum calcium, parathyroid hormone, and vitamin D levels are normal. Patients are treated with large amounts of neutral phosphate in the diet.
Patients are resistant to vitamin D because of their inability to reabsorb phosphate in the kidney tubules. Correct Answer: Scenario 3
QUESTION 15
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
Which of the above metabolic profiles occurs in a patient who had vitamin D-resistant rickets with the inability to produce adequate amounts of the 1,25 dihydroxy vitamin D:
1
Scenario 3
2
Scenario 4
3
Scenario 5
4
Scenario 6
5
Scenario 7
Vitamin D-resistant rickets may occur when there is an inability to convert 25 hydroxy vitamin D into 1,25 dihydroxy vitamin D. Patients develop secondary hyperparathyroidism. A low serum calcium level causes an increased parathyroid hormone (PTH)
level. Parathyroid hormone causes the kidneys not to reabsorb phosphorus, and the serum phosphate is low. The serum 1,25 dihydroxy vitamin D level is low.
The metabolic profile is: Serum calcium Low
Serum phosphate Low
Serum PTH High
25 vitamin D Normal
1,25 vitamin D Very low
Treatment is by dietary 1,25 dihydroxy vitamin D. Correct Answer: Scenario 4
QUESTION 16
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L L H H L L L
Which of the above metabolic profiles occurs in a patient with vitamin D-resistant rickets with end-organ insensitivity to 1,25 dihydroxy vitamin D:
1
Scenario 3
2
Scenario 4
3
Scenario 5
4
Scenario 6
5
Scenario 7
One form of vitamin D-resistant rickets is end-organ insensitivity to 1,25 dihydroxy vitamin D. The small intestine gastrointestinal cells are not able to respond to 1,25 dihydroxy vitamin D. The serum calcium is low, and patients develop secondary hyperparathyroidism - high serum parathyroid hormone (PTH). The high serum PTH causes the kidneys not to reabsorb phosphate so that the serum phosphate level is low.
The metabolic profile is: Serum calcium Low
Serum phosphate Low
Serum PTH High
25 vitamin D Normal or high
1,25 vitamin D Normal or high
Treatment is difficult; some patients with mild involvement are treated with vitamin D, and patients with severe disease may require calcium infusions.
QUESTION 17
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
Which of the above metabolic profiles occurs in a patient with renal tubular acidosis:
1
Scenario 3
2
Scenario 4
3
Scenario 5
4
Scenario 6
5
Scenario 7
In patients with renal tubular acidosis, the kidney has to secrete a positive ion (Na, C a) to balance the pH. The secretion of calcium ions results in ostomalacia or rickets as there is insufficient calcium to mineralize newly formed osteiod.
With low serum calcium levels, the serum parathyroid hormone (PTH) level increases, causing decreased reabsorption of phosphate. Vitamin levels are normal. Renal tubular acidosis is the only condition in which there is increased urinary excretion of calcium.
The metabolic profile is: Serum calcium Low
Serum phosphate Low
Serum PTH High
25 vitamin D Normal
1,25 vitamin D Normal
Urinary C a High
The treatment of renal tubular acidosis is to alkalinize the urine. Correct Answer: Scenario 6
QUESTION 18
Serum Urine
C a P AP PTH 25 D 1,25 D C a Scenario 1 L L H H L L L Scenario 2 N L H N N N N Scenario 3 N L N N N N N Scenario 4 L L H H N L L Scenario 5 L L H H N/H N/H L Scenario 6 L L H H N N H Scenario 7 L H H H L L L
Which of the above metabolic profiles occurs in a patient with renal osteodystrophy:
1
Scenario 1
2
Scenario 3
3
Scenario 5
4
Scenario 6
5
Scenario 7
In patients with renal osteodystrophy, the renal tubular cells are damaged, resulting in the retention of phosphate. The kidney cells are unable to produce 1,25 dihydroxy vitamin D. Because the serum calcium level is low, patients develop secondary hyperparathyroidism.
The metabolic profile is: Serum calcium Low
Serum phosphate High
Serum PTH High
1,25 vitamin D Low
The treatment is correction of the hyperparathyroidism. Correct Answer: Scenario 7
QUESTION 19
Which of the following serum metabolic profiles describes a patient with hypophosphatasia:
1
Normal calcium, normal dihydroxy vitamin D, and low alkaline phosphatase
2
Low calcium, normal dihydroxy vitamin D, and low alkaline phosphatase
3
Low calcium, low dihydroxy vitamin D, and low alkaline phosphatase
4
High calcium, high dihydroxy vitamin D, and low alkaline phosphatase
5
High calcium, high dihydroxy vitamin D, and high alkaline phosphatase
Hypophosphatasia is the inability to synthesize alkaline phosphatase by the bone, leukocytes, kidney, and intestine
1/. Autosomal recessive
2/. High levels of phosphoethanolamine in the urine
3/. When severe (high mortality)
a. Growth retardation, failure to thrive b. Irritability, fever, vomiting
4/. When mild
a. Fractures
b. Short stature
c. Poor fracture healing d. Osteomalacia
5/. Radiographic features a. Osteopenia
b. C up-shaped deformities of the proximal long bones
6/. Histological features - unmineralized osteiod seams
7/. Laboratory features
a. Low serum alkaline phosphatase
b. Normal Ca, 1,25 dihydroxy vitamin D
8/. C ause - inability to mineralize osteiod because the absence of alkaline phosphatase
9/. Treatment - high doses of vitamin D
QUESTION 20
Which of the following inheritance patterns occurs in patients with hypophosphatasia:
1
Autosomal recessive
2
Autosomal dominant
3
X-linked dominant
4
X-linked recessive
5
Sporadic
Hypophosphatasia is the inability to synthesize alkaline phosphatase by the bone, leukocytes, kidney, and intestine
1/. Autosomal recessive
2/. High levels of phosphoethanolamine in the urine
3/. When severe (high mortality)
a. Growth retardation, failure to thrive b. Irritability, fever, vomiting
4/. When mild
a. Fractures
b. Short stature
c. Poor fracture healing d. Osteomalacia
5/. Radiographic features a. Osteopenia
b. C up-shaped deformities of the proximal long bones
6/. Histological features - unmineralized osteiod seams
7/. Laboratory features
a. Low serum alkaline phosphatase
b. Normal C a, 1,25 dihydroxy vitamin D
8/. C ause - inability to mineralize osteiod because the absence of alkaline phosphatase
9/. Treatment - high doses of vitamin D Correct Answer: Autosomal recessive
QUESTION 21
Which of the following is the basic defect in patients with pseudohypoparathyroidism (Albright Hereditary Osteodystrophy
[AHO]):
1
End-organ resistance to 1,25 dihydroxy vitamin D
2
End-organ resistance to parathyroid hormone (PTH)
3
Inability to reabsorb phosphate in the kidney
4
Inability to produce 1,25 dihydroxy vitamin D
5
Inability to synthesize alkaline phosphatase
Pseudohypoparathyroidism (AHO) - end-organ insensitivity; in AHO, germline mutation that leads to loss of function of Galpha S (GNAS1); causes end-organ resistance to PTH
1/. PHP - short stature, short metacarpals (4th and 5th), rounded facies a. Mental retardation, tetany
b. Sex-linked dominant
2/. Laboratory features a. Hypocalcemia
b. Hyperphopshatemia c. Normal PTH
QUESTION 22
Which of the following is the mode of inheritance for pseudohypoparathyroidism (Albright Hereditary Osteodystrophy [AHO]):
1
Autosomal recessive
2
Autosomal dominant
3
Sex-linked dominant
4
Sex-linked recessive
5
Sporadic
Pseudohypoparathyroidism (AHO) - end-organ insensitivity; in AHO, germline mutation that leads to loss of function of Galpha S (GNAS1); causes end-organ resistance to PTH
1/. PHP - short stature, short metacarpals (4th and 5th), rounded facies a. Mental retardation, tetany
b. Sex-linked dominant
2/. Laboratory features a. Hypocalcemia
b. Hyperphopshatemia c. Normal PTH
QUESTION 23
Which of the following is the defect in pseudohypoparathyroidism (Albright Hereditary Osteodystrophy [AHO]):
1
C artilage oligometric matrix protein
2
Fibroblast growth factor receptor 3
3
Sulfate transport protein
4
Type II collagen
5
Galpha S (GNAS1)
Pseudohypoparathyroidism (AHO) - end-organ insensitivity; in AHO, germline mutation that leads to loss of function of Galpha S (GNAS1); causes end-organ resistance to PTH
1/. PHP - short stature, short metacarpals (4th and 5th), rounded facies a. Mental retardation, tetany
b. Sex-linked dominant
2/. Laboratory features a. Hypocalcemia
b. Hyperphopshatemia c. Normal PTH
The other responses are also important to know:
C artilage oligometric matrix protein - pseudoachondroplasia
Fibroblast growth factor receptor 3 - achondroplasia Sulfate transport protein - diastrophic dysplasia Type II collagen - spondyloepiphyseal dysplasia
QUESTION 24
Which of the following methods reduce radiation exposure to a surgeon during fluoroscopic procedures:
1
Avoiding the inverted C -arm position
2
Avoiding collimation of the radiation beam
3
Limiting the use of the foot pedal for controlling the fluoroscopy unit
4
Always standing on the opposite side of the C -arm
5
Increasing the amperage of each exposure
One of the best ways to limit radiation exposure is to increase distance from the C -arm. Surgeons should always stand on the opposite side of the C -arm and remember the following methods for reducing radiation exposure:
Increase distance (doubling distance reduces exposure by a factor of 4) Inverted position of the C -arm (increases distance)
Shielding: 90% attenuated by 0.25-mm apron
C ollimation (reduces the size of the beam)
Foot pedal to control the fluoroscopy unit (decreases the amount of exposure)
QUESTION 25
At which of the following distances can surgeons expect to have no radiation exposure from scatter from a fluoroscopy unit:
1
6 in
2
1 ft
3
2 ft
4
3 ft
5
6 ft
Radiation exposure decreases by a factor of 4 when a surgeon doubles the distance from the radiation beam. No radiation exists 6 ft from a fluoroscopy unit.Correct Answer: 6 ft
QUESTION 26
Which of the following amounts of radiation is received from a chest radiograph:
1
1 mrem
2
10 mrem
3
25 mrem
4
500 mrem
5
1,000 mrem
Surgeons should know the radiation doses from common diagnostic tests. C ommon radiation exposures:
C hest radiograph
Hip radiograph
Hip computed tomography
C -arm (in beam)
Mini C -arm (in beam)
25 mrem
500 mrem
1,000 mrem
1,200 mrem/min to 4,000 mrem/min
120 mrem/min to 400 mrem/min
QUESTION 27
Which of the following amounts of radiation is received from a hip radiograph:
1
10 mrem
2
25 mrem
3
100 mrem
4
500 mrem
5
1,000 mrem
Surgeons should know the radiation doses from common diagnostic tests. C ommon radiation exposures:
C hest radiograph
Hip radiograph
Hip computed tomography
C -arm (in beam)
Mini C -arm (in beam)
25 mrem
500 mrem
1,000 mrem
1,200 mrem/min to 4,000 mrem/min
120 mrem/min to 400 mrem/min
QUESTION 28
Which of the following amounts of radiation are received from a computed tomography (C T) scan of the hip:
1
25 mrem
2
100 mrem
3
500 mrem
4
1,000 mrem
5
5,000 mrem
Surgeons should know the radiation doses from common diagnostic tests. C ommon radiation exposures:
C hest radiograph 25 mrem Hip radiograph 500 mrem Hip computed tomography 1,000 mrem
C -arm (in beam 1,200 mrem/min to 4,000 mrem/min
Mini C -arm (in beam 120 mrem/min to 400 mrem/min
QUESTION 29
Which of the following amounts of radiation are the maximum annual exposures to the whole body, thyroid gland, and hands:
1
1 rem, 15 rem, 25 rem
2
2 rem, 30 rem, 50 rem
3
5 rem, 60 rem, 100 rem
4
10 rem, 75 rem, 150 rem
5
20 rem, 100 rem, 200 rem
Surgeons should know the maximum annual exposures of radiation.
Total body dose
Eye Thyroid Skin, hands Fetus
