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ORTHOPEDICS HYPERGUIDE MCQ 551-600
QUESTION 1
Articular cartilage is composed of 4 zones. The chondrocytes of which of the following zones produce a high concentration of collagen and a low concentration of proteoglycan:
1
Superficial tangential zone
2
Middle zone
3
Deep zone
4
Calcified zone
5
Tidemark zone
The 4 articular cartilage layers have different functions and properties: superficial tangential zone, middle zone, deep zone, and calcified zone. The chondrocytes in the superficial tangential zone produce high concentrations of collagen and low concentrations of proteoglycan.
The functions of each of the zones is as follows:
Zone Function
Superficial tangential zone
Parallel arrangement of the collagen fibrils provides the greatest tensile stiffness; chondrocytes produce high concentrations of collagen and low amounts of proteoglycan
Middle zone Has properties intermediate between the superficial tangential zone and deep zone
Deep (radial) zone
Has the largest collagen fibrils and the highest concentration of proteoglycans, and lowest amount of water
Calcified zone Cells have a small volume and are surrounded by calcified cartilage
The functions of each of the zones is as follows:
Zone Function
Superficial tangential zone
Parallel arrangement of the collagen fibrils provides the greatest tensile stiffness; chondrocytes produce high concentrations of collagen and low amounts of proteoglycan
Middle zone Has properties intermediate between the superficial tangential zone and deep zone
Deep (radial) zone
Has the largest collagen fibrils and the highest concentration of proteoglycans, and lowest amount of water
Calcified zone Cells have a small volume and are surrounded by calcified cartilage
QUESTION 2
Which of the following types of collagen is the most common type in articular cartilage:
1
Type I
2
Type II
3
Type IV
4
Type IX
5
Type X
Type II collagen is the predominant type in articular cartilage (95%). There are a number of other collagens in smaller amounts
(Types IV, VI, IX, X, and XI).
Type VI: Assists with matrix attachment
Types IX, XI: May help form and stabilize the collagen fibrils formed from Type II collagen
(Types IV, VI, IX, X, and XI).
Type VI: Assists with matrix attachment
Types IX, XI: May help form and stabilize the collagen fibrils formed from Type II collagen
QUESTION 3
A 12-year-old boy has multiple exostoses (osteochondromas). What is the most likely pattern of inheritance in this condition:
1
Autosomal recessive
2
Autosomal dominant
3
X-linked recessive
4
X-linked dominant
5
Almost always a spontaneous mutation
Multiple exostoses is transmitted in an autosomal dominant pattern. This condition is transmitted by both sexes with incomplete penetrance in females. This condition is more common in males.
QUESTION 4
Which of the following describes the microscopiCfeatures of a bone island:
1
Interlacing network of bone trabeculae in a loose, vascular, stromal connective tissue
2
Compact cortical bone
3
Scattered giant cells in a mononuclear cell background with chicken-wire calcification
4
PleomorphiCspindle cells with osteoid production
5
Prominent mature bone formation and low-grade malignant spindle cell tumor
Bone islands are microscopically composed of lamellar compact bone identical to the cortical bone. The other possible answers describe specifiClesions:
Chondroblastoma: Scattered giant cells in a mononuclear cell background with chicken-wire calcification
Osteosarcoma: PleomorphiCspindle cells with osteoid production
Parosteal osteosarcoma: Prominent mature bone formation and low-grade malignant spindle cell tumor
Osteoblastoma: Interlacing network of bone trabeculae in a loose, vascular, stromal connective tissue
Chondroblastoma: Scattered giant cells in a mononuclear cell background with chicken-wire calcification
Osteosarcoma: PleomorphiCspindle cells with osteoid production
Parosteal osteosarcoma: Prominent mature bone formation and low-grade malignant spindle cell tumor
Osteoblastoma: Interlacing network of bone trabeculae in a loose, vascular, stromal connective tissue
QUESTION 5
Which of the following lesions would display a low to moderate signal on T1 weighted images and high signal on T2 weighted images:
1
Lipomas
2
Subcutaneous fat
3
Cortical bone
4
Malignant fibrous histiocytoma
5
Tendons
All soft tissue sarcomas have the same signal sequence - low on T1 weighted images and high on T2 weighted images. It is important to remember the appearances of common tissues on both T1 and T2 weighted images:
 T1 weighted T2 weighted
Fat High Moderate Tendons Low Low Ligaments Low Low Fascial layers Low Low Cortical bone Low Low Muscle Moderate Moderate Normal marrow High Moderate Soft tissue sarcomas Low High
Fluid (ganglions, effusions) Low High
Pigmented villonodular synovitis* Very low Very low
Signal drop out (very low signal on gradient echo sequences) Correct Answer: Malignant fibrous histiocytoma
 T1 weighted T2 weighted
Fat High Moderate Tendons Low Low Ligaments Low Low Fascial layers Low Low Cortical bone Low Low Muscle Moderate Moderate Normal marrow High Moderate Soft tissue sarcomas Low High
Fluid (ganglions, effusions) Low High
Pigmented villonodular synovitis* Very low Very low
Signal drop out (very low signal on gradient echo sequences) Correct Answer: Malignant fibrous histiocytoma
QUESTION 6
Which of the following tissues is low signal on both T1 and T2 weighted images:
1
Subcutaneous fat
2
Joint fluid
3
Muscle
4
Soft tissue sarcomas
5
Tendons
Tissues that are principally composed of collagen and fibroblasts are low signal on both T1 and T2 weighted sequences include tendons, ligaments, and fascial layers.
It is important to remember the appearances of common tissues on both T1 and T2 weighted images:
 T1 weighted T2 weighted
Fat High Moderate Tendons Low Low Ligaments Low Low Fascial layers Low Low Cortical bone Low Low Muscle Moderate Moderate Normal marrow High Moderate Soft tissue sarcomas Low High
Fluid (ganglions, effusions) Low High
Pigmented villonodular synovitis* Very low Very low
Signal drop out (very low signal on gradient echo sequences) Correct Answer: Tendons
It is important to remember the appearances of common tissues on both T1 and T2 weighted images:
 T1 weighted T2 weighted
Fat High Moderate Tendons Low Low Ligaments Low Low Fascial layers Low Low Cortical bone Low Low Muscle Moderate Moderate Normal marrow High Moderate Soft tissue sarcomas Low High
Fluid (ganglions, effusions) Low High
Pigmented villonodular synovitis* Very low Very low
Signal drop out (very low signal on gradient echo sequences) Correct Answer: Tendons
QUESTION 7
Which of the following describes the radiographiCfeatures of a bone island:
1
Ovoid, compact, heavily mineralized intramedullary lesion with thorny spicules
2
Large, nodular, heavily mineralized lesion on the surface of the bone
3
Surface lesion with spiculated bone formation
4
Well-demarcated nidus surrounded by a distinct zone of sclerosis
5
Cortically based lytiCmetaphyseal lesion with a sclerotiCborder
Bone islands are also referred to as enostosis. They are usually solitary and composed of dense, compact bone within the medullary cavity. Patients are often asymptomatiCand the bone island is discovered as an incidental finding.
There are three features that may lead to confusion: The lesion may be as large as 3 cm to 5 cm.
The bone scan may show mild activity within the lesion.
Bone islands may grow slowly (approximately 1 mm per year).
The other possible answers describe the radiographiCfeatures of other lesions:
Osteoid osteoma: Well-demarcated nidus surrounded by a distinct zone of sclerosis
Parosteal osteosarcoma: Large, nodular, heavily mineralized lesion on the surface of the bone
Periosteal osteosarcoma:Surface lesion with spiculated bone formation
Non-ossifying fibroma: Cortically based lytiCmetaphyseal lesion with a sclerotiCborder
There are three features that may lead to confusion: The lesion may be as large as 3 cm to 5 cm.
The bone scan may show mild activity within the lesion.
Bone islands may grow slowly (approximately 1 mm per year).
The other possible answers describe the radiographiCfeatures of other lesions:
Osteoid osteoma: Well-demarcated nidus surrounded by a distinct zone of sclerosis
Parosteal osteosarcoma: Large, nodular, heavily mineralized lesion on the surface of the bone
Periosteal osteosarcoma:Surface lesion with spiculated bone formation
Non-ossifying fibroma: Cortically based lytiCmetaphyseal lesion with a sclerotiCborder
QUESTION 8
Which of the following statements is not true of the meniscus:
1
Only the peripheral 25% to 30% of the meniscus has a vascular supply.
2
The medial meniscus functions as a secondary restraint to anterior tibial translation.
3
Fifty percent of the compressive load of the knee is transmitted through the meniscus when the knee is extended.
4
Meniscal fibrochondrocytes have the ability to proliferate and synthesize matrix. One should remember these features of the meniscus:
5
The lateral meniscus is semicircular in shape.
1/. Only the peripheral 25% to 30% of the meniscus has a vascular supply.
2/. The medial meniscus functions as a secondary restraint to anterior tibial translation (when the anterior cruciate ligament is cut).
3/. Fifty percent of the compressive load of the knee is transmitted through the meniscus when the knee is extended.
4/. Eighty-five percent of the compressive load of the knee is borne by the menisci when the knee is in 90° of flexion.
5/. Meniscal fibrochondrocytes have the ability to proliferate and synthesize matrix.
6/. The medial meniscus is semicircular in shape; the lateral meniscus is circular in shape. Correct Answer: The lateral meniscus is semicircular in shape.
2/. The medial meniscus functions as a secondary restraint to anterior tibial translation (when the anterior cruciate ligament is cut).
3/. Fifty percent of the compressive load of the knee is transmitted through the meniscus when the knee is extended.
4/. Eighty-five percent of the compressive load of the knee is borne by the menisci when the knee is in 90° of flexion.
5/. Meniscal fibrochondrocytes have the ability to proliferate and synthesize matrix.
6/. The medial meniscus is semicircular in shape; the lateral meniscus is circular in shape. Correct Answer: The lateral meniscus is semicircular in shape.
QUESTION 9
Which of the following collagen macromolecules found in articular cartilage confers the major amount of tensile strength and resistance to shear stress:
1
Type X collagen
2
Type II collagen
3
Type IX collagen
4
Type XI collagen
5
Type VI collagen
Type II collagen is the major collagen moiety found in articular cartilage. As such it confers the major amount of tensile strength and resistance to shear stress. Articular cartilage is a highly ordered structure with a flattened layer of chondrocytes at the surface and a tangential arrangement of surface collagen. Progressing into the transitional zone the collagen fibrils assume a random orientation. In the radial zone the fibrils become oriented perpendicular to the joint surface and interface with the subchondral bone
QUESTION 10
Which of the following statements is true:
1
Cortical bone has a larger surface area than cancellous bone.
2
Cortical bone has a higher density than cancellous bone.
3
Cortical bone has higher metaboliCactivity than cancellous bone.
4
Cortical bone remodels more rapidly than cancellous bone.
5
Cortical bone has a higher porosity than trabecular bone.
Cortical bone is denser, less porous, and stiffer and stronger than cancellous bone. Cortical bone has less surface area, a slower metaboliCrate, and remodels slower than cancellous bone
QUESTION 11
Which of the following statements is not true regarding vitamin D metabolism:
1
Vitamim D is transformed into 25 hydroxy vitamin D in the liver.
2
Vitamin D is synthesized initially from 7 dehydrocholesterol in the skin.
3
1,25 dihydroxy vitamin D is produced in the liver as a result of parathyroid hormone stimulation.
4
25 hydroxy vitamin D has a longer half life than 1,25 dihydroxy vitamin D.
5
1,25 dihydroxy vitamin D increases calcium absorption across the gut wall.
1,25 dihydroxy vitamin D is produced in the kidney, not the liver. Vitamin D is transformed into 25 hydroxy vitamin D in the liver. This metabolite has an approximate half-life of 3 days. Via parathyroid hormone stimulation, this metabolite is hydroxylated again in the kidney to form the active metabolite of vitamin D, namely 1,25 dihydroxy vitamin D. This form has a short half-life of approximately 8 hours
QUESTION 12
Which of the following clinical findings is not associated with hyperparathyroidism:
1
Bone pain
2
Brown tumors
3
PathologiCfractures
4
Renal stones
5
Increased erythrocyte sedimentation rate and anemia
Features of hyperparathyroidism include bone pain, Brown tumors, pathologiCfractures, and kidney stones. Hypercalcemia and a low or normal phosphate level are also present. The parathyroid levels are high in patients with hyperparathyroidism.
An increased sedimentation rate and anemia are associated with multiple myeloma. Correct Answer: Increased erythrocyte sedimentation rate and anemia
An increased sedimentation rate and anemia are associated with multiple myeloma. Correct Answer: Increased erythrocyte sedimentation rate and anemia
QUESTION 13
During fracture repair systemiCas well as local factors come into play. Which of the following is considered a systemiCfactor in fracture healing:
1
Degree of vascular injury
2
Degree of bone loss
3
Age
4
Type of bone affected
5
Degree of immobilization
The degree of vascular injury is considered a local factor in fracture healing. Other such factors include degree of local trauma, type of bone affected, degree of bone loss, degree of immoblization, infection and local pathologiCconditions. SystemiCfactors include age of the patient, hormone function, functional activity, nerve function and nutritional state
QUESTION 14
Linear elastiCtheory is used as model for real material behavior. All of the following are fundamental assumptions of this theory except:
1
Stress and strain are not proportional to each other.
2
Srain is reversible when the stress is removed.
3
The material is insensitive to the rate of load application.
4
The proportionality constant is called elastiCmodulus.
5
Strain is dimensionless.
One of the fundamental assumptions of linear elastiCtheory is that stress and strain are proportional to each other. The proportionality constant expressed by these two entities is the material's elastiCmodulus. Stress is the internal reaction of a material to an externally applied force distributed over the cross-section of the material. Strain is the internal deformations of a material in response to an applied stress
QUESTION 15
Enchondral ossification is responsible for mineralization in all of the following conditions except:
1
Callus formation during fracture healing
2
HeterotopiCbone formation
3
Cartilage degeneration in osteoarthritis
4
EmbryoniClong bone development
5
Perichondrial bone formation
Enchondral bone formation or ossification is bone formation on a cartilage module. Enchondral bone formation occurs in each of
the following scenarios: embryoniClong bone development, epiphyseal secondary center of ossification formation, callus formation during fracture healing, degenerating cartilage of osteoarthritis, calcifying cartilage tumors, and bone formed with use of demineralized bone matrix.
Intramembranous bone formation includes: flat bone development (pelvis, clavicle, and skull bones), bone formation during distraction osteogenesis, and perichondrial bone formation.
the following scenarios: embryoniClong bone development, epiphyseal secondary center of ossification formation, callus formation during fracture healing, degenerating cartilage of osteoarthritis, calcifying cartilage tumors, and bone formed with use of demineralized bone matrix.
Intramembranous bone formation includes: flat bone development (pelvis, clavicle, and skull bones), bone formation during distraction osteogenesis, and perichondrial bone formation.
QUESTION 16
During chondrocyte maturation at the growth plate, an orderly sequence of morphologiCand biochemical changes occur. Which of the following statements regarding these changes is false:
1
Cells from the proliferating and upper hypertrophied zones are metabolically aerobically active and accumulate intracellular lipid and glycogen.
2
Proliferating chondrocytes in the upper growth plate contribute to most of the increase in long bone length.
3
During hypertrophy of chondrocytes, the major proteoglycan produced is in the form of macromolecular complexes composed of aggrecan monomers bound noncovalently by a link glycoprotein to a hyaluroniCacid backbone filament.
4
Type X collagen is produced in abundant amounts during endochondral ossification in the zone of provisional calcification.
5
Indian hedgehog and PTHrP form a negative feedback loop.
Proliferation of chondrocytes in the upper growth plate does contribute somewhat to longitudinal growth. However, it is the process of cell hypertrophy that contributes most to increases in long bone length
QUESTION 17
Which of the following skeletal dysplasias is a result of a mutation in FGF receptor-3:
1
Multiple exostoses
2
Multiple epiphyseal dysplasia
3
Achondroplasia
4
Pseudoachondroplasia
5
Schmid metaphysial dysplasia
A mutation in the fibroblast growth factor (FGF) receptor-3, leads to achondroplastiCdwarfism. The other answers have corresponding genetiCdefects:
Multiple epiphyseal dysplasia â Cartilage oligomeriCmatrix protein (COMP) of type IX collagen (COL9A2) Pseudoachondroplasia â COMP
Schmid metaphyseal dysplasia â Type X collagen Multiple hereditary exostoses â EXT1 and EXT2 genes Correct Answer: Achondroplasia
Multiple epiphyseal dysplasia â Cartilage oligomeriCmatrix protein (COMP) of type IX collagen (COL9A2) Pseudoachondroplasia â COMP
Schmid metaphyseal dysplasia â Type X collagen Multiple hereditary exostoses â EXT1 and EXT2 genes Correct Answer: Achondroplasia
QUESTION 18
Which of the following wear mechanisms is the worst possible situation:
1
Adhesive wear
2
Fatigue
3
Third body
4
Corrosive wear
5
Fretting
A third body or particle becomes trapped between the two surfaces or materials in contact. The particle often scratches the bearing surface and results in rapid generation of wear products and further degradation of the bearing surface
QUESTION 19
Which of the following statements inaccurately describes human bone as a biomaterial:
1
Bone is isotropic.
2
Bone is viscoelastic.
3
Bone's strength and elastiCmodulus are approximately proportional to the square of its density.
4
Bone is a composite.
5
Bone remodels its structure to maintain overall resistance to loading while the material itself weakens.
Bone is anisotropiCas the properties of the material vary with the direction of loading. This is true of most biologiCmaterials and thus makes them difficult, if not impossible, to fully categorize
QUESTION 20
All of the following are true regarding abrasion chondroplasty except:
1
The subchondral bone plate is penetrated, allowing the subjacent bone marrow communication with the synovial fluid compartment.
2
The organized collagen fibril orientation of normal articular cartilage is usually achieved in over 70% of cases.
3
Incomplete integration of the fibrocartilaginous matrix with the adjacent normal cartilage matrix may occur impairing the tissue's resistance to shear stress.
4
The procedure depends on the ability of mesenchymal stem cells located in the subchondral bone marrow to differentiate into fibrocartilaginous tissue.
5
Patients must be nonweight bearing for 8-12 weeks after chondroplasty.
This statement is false. The organized collagen fibril orientation of normal articular cartilage, with tangentially oriented fibrils at the surface layer and radially oriented fibrils in the deep layer, never develops after the abrasion chondroplasty
QUESTION 21
Which of the following techniques used to repair articular surface defects does not involve the use of mesenchymal stem cells:
1
Abrasion chondroplasty
2
Perichondral transplants
3
Autologous chondrocyte transplantation
4
Mesenchymal stem cell transplantation
5
Realignment osteotomy and periochondral transplant
In this technique, a small amount of cartilage is harvested arthroscopically from a non-weight bearing articular surface and the chondrocytes isolated by collagenase digestion. The isolated cells are then expanded in tissue culture and suspended in a collagen gel carrier. The resultant chondrocyte population is then reimplanted in a second procedure under a periosteal flap used to cover the articular cartilage defect
QUESTION 22
Which of the following statements regarding the healing potential of the anterior cruciate ligament (ACL) and medical collateral ligament (MCL) is false:
1
MCL fibril diameters are larger and more densely packed than ACL fibrils.
2
MCL cells are more spindle shaped with cytoplasmiCprocesses which are in contact with collagen, while ACL cells are more oval shaped and have ground substance between the cell and collagen fibrils.
3
MCL fibroblasts proliferate less rapidly than ACL fibroblasts.
4
MCL fibroblasts have increased expression of integrins on the cell surface as compared minimal integrin expression on healing
5
Healing MCL has higher mRNA for pro-collagen expression than healing ACL.
ACL cells.
This statement is false. MCL fibroblasts proliferate more rapidly than ACL fibroblasts and respond differently to growth factors
This statement is false. MCL fibroblasts proliferate more rapidly than ACL fibroblasts and respond differently to growth factors
QUESTION 23
Of the four phases of fracture repair when fixation of any variety is used, which phase occurs rapidly and crosses gaps:
1
Primary response
2
Extramedullary callus formation
3
Intramedullary callus formation
4
Primary osteonal response
5
Intramedullary callus and primary osteonal response
The extramedullary callus formed in a fixed fracture develops rapidly, requires motion, crosses gaps and depends on soft tissue viability. Immobilization inhibits this process
QUESTION 24
Which of the following cell type-cell function pairings is false:
1
Pre-osteoblasts â stem cell for osteoblasts
2
Osteoblasts â synthesize organiCmatrix
3
Ostecytes â maintain mineral homeostatsis
4
Osteoclasts â synthesize organiCmatrix
5
Osteoblasts â receptors for PTH
Osteoclasts resorb bone by attaching to the bone surface, releasing enzymes, and dissolve the organiCmineral phases of bone. Osteoclasts do not have hormone receptors
QUESTION 25
The following statements are all true regarding parathyroid hormone (PTH) function except:
1
Increases activity of hepatiChydroxylase for conversion to 25 (OH) Vitamin D
2
Increases calcium retention in the kidney via increased excretion of phosphate
3
Stimulates production of 1, 25 dihydroxy Vitamin D in the kidney
4
Directly stimulates increased gut absorption of calcium
5
Indirectly increases bone resorption via 1,25 dihydroxy Vitamin D
This statement is false. PTH indirectly stimulates increased gut absorption of calcium via its direct effect of increasing renal production of active Vitamin D
QUESTION 26
Which of the following individuals has the highest dietary calcium requirement:
1
A healthy growing child
2
A healthy pregnant 23-year-old woman
3
A healthy 60-year-old post-menopausal woman
4
A healthy adolescent
5
A healthy 29-year-old post-partum lactating mother
A healthy child requires approximately 400-700 mg of dietary calcium per day. An adolescent requires approximately 1300 mg per day. An adult requires 500 mg dietary of calcium per day. A pregnant woman requires 1500 mg of dietary calcium per day to support her own needs and those of the growing fetus. A post-partum lactating mother requires the highest intake of dietary calcium at 2000 mg per day. A post-menopausal woman requires roughly 1500 mg per day
QUESTION 27
Which of the following is not a facilitator of calcium absorption:
1
Parathyroid hormone
2
1,25 dihydroxy Vitamin D
3
GastriCpH
4
Ca:P ratio of 1:1 or 1:2
5
Achlorhydria
1,25 dihydroxy Vitamin D increases the absorption of calcium and phosphorus from the small intestine. A reduction of stomach acid decreases the absorption of calcium in the gut. Parathyroid hormone indirectly stimulates gut absorption by increasing the amount of 1,25 dihydroxy Vitamin D
QUESTION 28
Laboratory findings found in rickets and/or osteomalacia, include the following except:
1
Decreased urinary calcium
2
Normal or decreased serum calcium
3
Decreased serum phosphorous
4
Increased parathyroid hormone
5
Decreased alkaline phosphatase
Vitamin D deficiency results in osteomalacia. The lack of Vitamin D may be secondary to dietary deficiency, gastrointestinal complications, or renal insufficiency. With a Vitamin D deficiency, one sees the following:
Normal or decreased calcium Decreased serum phosphorus Increased serum alkaline phosphatase Increased serum parathyroid hormone
Decreased serum 1,25 dihydroxy Vitamin D Decreased urinary calcium
Normal or decreased calcium Decreased serum phosphorus Increased serum alkaline phosphatase Increased serum parathyroid hormone
Decreased serum 1,25 dihydroxy Vitamin D Decreased urinary calcium
QUESTION 29
Which of the following disease state-therapy pairs is correct:
1
Vitamin D deficiency â increased dietary phosphate and low intake of Vitamin D
2
Renal osteodystrophy â low calcium, high phospate diet.
3
Renal osteodystrophy â selective parathyroidectomy
4
Vitamin D resistant rickets â high intake of Vitamin D and increased dietary calcium
5
Paget's disease â chroniCetidronate use
Renal osteodystrophy is treated with increased dietary calcium, low dietary phosphate, selective use of calcium phosphate binders, and selective parathyroidectomy (neck exploration). Paget's disease cannot be treated with longterm etidronate because this first-generation diphosphonate inhibits bone resorption and formation
QUESTION 30
Which of the following is not a form of primary hyperparathyroidism:
1
Single parathyroid adenoma
2
Renal osteodystrophy
3
Parathyroid hyperplasia
4
Malignant parathyroid tumor
5
Multiple parathyroid adenoma
Primary hyperparathyroidism can be caused by single or multiple parathyroid adenomas, parathyroid hyperplasia, or a malignant parathyroid tumor. Secondary forms include renal osteodystrophy, Vitamin D deficiency, and age-related osteoporosis
QUESTION 31
Which of the following terms is used to describe a localized conduction block in a peripheral nerve in which the nerve is intact and full recovery is expected:
1
First-degree injury (neuropraxia)
2
Second-degree (axonotmesis)
3
Third-degree
4
Fourth-degree
5
Fifth-degree
A first-degree injury is a neuropraxia. There is a local conduction block in which the nerve is intact and full recovery is expected.
First-degree: Neuropraxia, the nerve structure is intact, full recovery is expected
Second-degree: Axonotmesis, severance of the axon leading to Wallerian degeneration, continuity of endoneurial sheath is retained, repair is orderly, complete motor and sensory loss with denervation and fibrillation potentials
Third-degree: Injury to axons and the endoneurial tube, arrangement of individual fascicles is maintained (perineurium intact), recovery is variable
Fourth-degree: Injury to axons, endoneurial tube, fascicles with the nerve trunk intact, Wallerian degeneration and a higher incidence of proximal nerve cell body degeneration, repair is unlikely and surgical repair of the nerve is necessary
(excision and grafting)
Fifth-degree: Loss of nerve trunk continuity, neuroma formation in the proximal stump, Wallerian degeneration distally
First-degree: Neuropraxia, the nerve structure is intact, full recovery is expected
Second-degree: Axonotmesis, severance of the axon leading to Wallerian degeneration, continuity of endoneurial sheath is retained, repair is orderly, complete motor and sensory loss with denervation and fibrillation potentials
Third-degree: Injury to axons and the endoneurial tube, arrangement of individual fascicles is maintained (perineurium intact), recovery is variable
Fourth-degree: Injury to axons, endoneurial tube, fascicles with the nerve trunk intact, Wallerian degeneration and a higher incidence of proximal nerve cell body degeneration, repair is unlikely and surgical repair of the nerve is necessary
(excision and grafting)
Fifth-degree: Loss of nerve trunk continuity, neuroma formation in the proximal stump, Wallerian degeneration distally
QUESTION 32
Which of the following terms is used to describe complete severance of a peripheral nerve with loss of the nerve trunk continuity:
1
First-degree injury (neuropraxia)
2
Second-degree (axonotmesis)
3
Third-degree
4
Fourth-degree
5
Fifth-degree
A fifth-degree injury refers to complete disruption of the nerve trunk.
First-degree: Neuropraxia, the nerve structure is intact, full recovery is expected
Second-degree: Axonotmesis, severance of the axon leading to Wallerian degeneration, continuity of endoneurial sheath is maintained, repair is orderly, complete motor and sensory loss with denervation and fibrillation potentials
Third-degree: Injury to axons and the endoneurial tube, arrangement of individual fascicles is maintained (perineurium intact), recovery is variable
Fourth-degree: Injury to axons, endoneurial tube, fascicles with the nerve trunk being intact, Wallerian degeneration and a higher incidence of proximal nerve cell body degeneration, repair is unlikely and surgical repair of the nerve is necessary (excision and grafting)
Fifth-degree: Loss of nerve trunk continuity, neuroma formation in the proximal stump, Wallerian degeneration distally
First-degree: Neuropraxia, the nerve structure is intact, full recovery is expected
Second-degree: Axonotmesis, severance of the axon leading to Wallerian degeneration, continuity of endoneurial sheath is maintained, repair is orderly, complete motor and sensory loss with denervation and fibrillation potentials
Third-degree: Injury to axons and the endoneurial tube, arrangement of individual fascicles is maintained (perineurium intact), recovery is variable
Fourth-degree: Injury to axons, endoneurial tube, fascicles with the nerve trunk being intact, Wallerian degeneration and a higher incidence of proximal nerve cell body degeneration, repair is unlikely and surgical repair of the nerve is necessary (excision and grafting)
Fifth-degree: Loss of nerve trunk continuity, neuroma formation in the proximal stump, Wallerian degeneration distally
QUESTION 33
Which of the following describes the sequence in which motor and sensory nerves fail in response to an injury:
1
Motor, proprioceptor, touch, temperature, and pain
2
Pain, proprioceptor, touch, temperature, and motor
3
Touch, proprioceptor, temperature, pain, and motor
4
Temperature, touch, temperature, motor, and pain
5
Proprioceptor, touch, temperature, pain, and motor
Motor and sensory nerves fail in the following sequence: Motor
Proprioceptor Touch Temperature Pain
Recovery is usually in the reverse order.
Proprioceptor Touch Temperature Pain
Recovery is usually in the reverse order.
QUESTION 34
Following a traumatiCnerve injury, in which time period would a physician find denervation activity with fibrillation and positive sharp waves in the affected muscles:
1
Immediately following the injury
2
7 to 10 days following injury
3
2 to 5 weeks following injury
4
6 to 8 weeks following injury
5
12 weeks following injury
Nerve conduction studies can help distinguish between the three principle types of nerve injury: neuropraxia, axonotmesis, and neurotmesis.
The following is the sequence of events following traumatiCnerve injury:
Timing ElectrophysiologiCabnormality
Onset of injury Conduction block across nerve injury site
7 to 10 days Reduced amplitudes on distal stimulation
2 to 5 weeks Denervation changes on electromyographiC(EMG) (fibrillation, positive sharp waves)
6 to 8 weeks Re-innervation on EMG Correct Answer: 2 to 5 weeks following injury
The following is the sequence of events following traumatiCnerve injury:
Timing ElectrophysiologiCabnormality
Onset of injury Conduction block across nerve injury site
7 to 10 days Reduced amplitudes on distal stimulation
2 to 5 weeks Denervation changes on electromyographiC(EMG) (fibrillation, positive sharp waves)
6 to 8 weeks Re-innervation on EMG Correct Answer: 2 to 5 weeks following injury
QUESTION 35
Following a traumatiCnerve injury, in which time period would a physician find re-innervation of the affected muscles:
1
Immediately following the injury
2
7 to 10 days following injury
3
2 to 5 weeks following injury
4
6 to 8 weeks following injury
5
12 weeks following injury
Nerve conduction studies can help distinguish between the three principle types of nerve injury: neuropraxia, axonotmesis, and neurotmesis.
The following is the sequence of events following traumatiCnerve injury:
Timing ElectrophysiologiCabnormality
Onset of injury Conduction block across nerve injury site
7 to 10 days Reduced amplitudes on distal stimulation
2 to 5 weeks Denervation changes on electromyographiC(EMG) (fibrillation, positive sharp waves)
6 to 8 weeks Re-innervation on EMG Correct Answer: 6 to 8 weeks following injury
The following is the sequence of events following traumatiCnerve injury:
Timing ElectrophysiologiCabnormality
Onset of injury Conduction block across nerve injury site
7 to 10 days Reduced amplitudes on distal stimulation
2 to 5 weeks Denervation changes on electromyographiC(EMG) (fibrillation, positive sharp waves)
6 to 8 weeks Re-innervation on EMG Correct Answer: 6 to 8 weeks following injury
QUESTION 36
Which of the following collagen types accounts for 10% to 20% of the wet weight of articular cartilage:
1
Type I
2
Type II
3
Type V
4
Type IX
5
Type XI
Collagen type II is the most common type of collagen in articular cartilage. Other collagen types include: Type V
Type VI Type IX Type X Type XI
The major components of cartilage are: Water: 65% to 80%
Type II collagen:10% to 20%
Aggrecan: 4% to 7%
The minor components (
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Type VI Type IX Type X Type XI
The major components of cartilage are: Water: 65% to 80%
Type II collagen:10% to 20%
Aggrecan: 4% to 7%
The minor components (
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