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6. Spine MCQs

Practice Set 360 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 7181

Topic: 6. Spine

A 6-year-old boy with a known mutation in the COL2A1 gene presents for routine follow-up. He exhibits a short-trunk dwarfism phenotype, coxa vara, and myopia. Which of the following spinal pathologies is he at highest risk of developing, necessitating careful preoperative screening before any procedure requiring general anesthesia?

. Thoracolumbar kyphosis secondary to wedged vertebrae
. Atlantoaxial instability due to odontoid hypoplasia
. Lumbar spinal stenosis due to short pedicles
. Cervical kyphosis due to absent posterior elements
. Basilar invagination due to bone fragility

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

Correct Answer: Atlantoaxial instability due to odontoid hypoplasiaThe patient's presentation and COL2A1 mutation are diagnostic of Spondyloepiphyseal Dysplasia Congenita (SEDC). A hallmark of SEDC (and other type II collagenopathies) is delayed or defective ossification of the odontoid process, leading to odontoid hypoplasia and subsequent atlantoaxial instability. This poses a severe risk of spinal cord injury during neck extension, such as during endotracheal intubation. Therefore, cervical spine flexion-extension radiographs are mandatory prior to general anesthesia.

Question 7182

Topic: 6. Spine

A 7-year-old child with short-trunk dwarfism, normal intelligence, and corneal clouding is diagnosed with Morquio syndrome (MPS IV). Radiographs show universal platyspondyly with central anterior beaking. Which accumulated metabolite is most likely responsible for this condition, and what is the primary life-threatening spinal concern?

. Heparan sulfate; lumbar stenosis
. Keratan sulfate; atlantoaxial instability
. Dermatan sulfate; thoracolumbar kyphosis
. Chondroitin sulfate; basilar invagination
. Hyaluronic acid; severe scoliosis

Correct Answer & Explanation

. Keratan sulfate; atlantoaxial instability

Explanation

Correct Answer: Keratan sulfate; atlantoaxial instabilityMorquio syndrome (Mucopolysaccharidosis Type IV) is caused by a deficiency in N-acetylgalactosamine-6-sulfatase (Type A) or beta-galactosidase (Type B), leading to the accumulation of keratan sulfate. Unlike many other MPS types, intelligence is typically normal. The most critical orthopedic manifestation is severe atlantoaxial instability due to odontoid hypoplasia and ligamentous laxity, which can lead to life-threatening cervical myelopathy if not identified and fused prophylactically.

Question 7183

Topic: 6. Spine

A 45-year-old male with achondroplasia presents with severe neurogenic claudication and bilateral lower extremity weakness. He is scheduled for a lumbar decompression. Which of the following best describes the primary pathoanatomic cause of his spinal stenosis?

. Progressive degenerative spondylolisthesis
. Decreased interpedicular distance caudally and short pedicles
. Severe lumbar hyperlordosis causing facet overriding
. Accumulation of mucopolysaccharides in the ligamentum flavum
. Dural ectasia leading to nerve root compression

Correct Answer & Explanation

. Decreased interpedicular distance caudally and short pedicles

Explanation

Correct Answer: Decreased interpedicular distance caudally and short pediclesSpinal stenosis in achondroplasia is primarily caused by a congenital narrowing of the spinal canal. This is due to premature fusion of the neurocentral synchondroses, resulting in abnormally short, thickened pedicles and a characteristic decrease in the interpedicular distance from the upper lumbar spine to the lower lumbar spine (the opposite of the normal anatomical widening). Superimposed degenerative changes (disc herniation, facet hypertrophy) later in life precipitate the clinical symptoms of stenosis.

Question 7184

Topic: 6. Spine
A 15-year-old female with Osteogenesis Imperfecta Type III presents with new-onset lower extremity hyperreflexia, sleep apnea, and dysphagia. Which of the following radiographic findings is most likely responsible for her acute neurological deterioration?
. Odontoid hypoplasia with C1-C2 instability
. Upward migration of the odontoid process into the foramen magnum
. Severe progressive thoracic scoliosis
. Spontaneous epidural hematoma
. Cervical kyphosis with anterior cord compression

Correct Answer & Explanation

. Upward migration of the odontoid process into the foramen magnum

Explanation

The patient is presenting with symptoms of brainstem and lower cranial nerve compression. In severe forms of Osteogenesis Imperfecta (such as Type III), the skull base is abnormally soft due to defective type I collagen. This can lead to basilar invagination (or basilar impression), where the cervical spine (specifically the odontoid process) migrates upward into the foramen magnum, compressing the cervicomedullary junction. This is a life-threatening complication requiring urgent neurosurgical evaluation.

Question 7185

Topic: 6. Spine

A 10-year-old girl is diagnosed with pseudoachondroplasia based on a confirmed COMP gene mutation. She has short-limb dwarfism but a normal facial appearance. Which of the following statements regarding the natural history of her spinal involvement is most accurate?

. She is at high risk for progressive, life-threatening atlantoaxial instability.
. Lumbar spinal stenosis will inevitably develop by the third decade of life.
. Radiographic vertebral abnormalities such as platyspondyly typically improve or resolve by adulthood.
. Severe, rigid scoliosis requiring surgical fusion occurs in over 80% of patients.
. Cervical kyphosis is the most common indication for spinal surgery in this condition.

Correct Answer & Explanation

. Radiographic vertebral abnormalities such as platyspondyly typically improve or resolve by adulthood.

Explanation

Correct Answer: Radiographic vertebral abnormalities such as platyspondyly typically improve or resolve by adulthood.Pseudoachondroplasia is caused by mutations in the Cartilage Oligomeric Matrix Protein (COMP) gene. While children often exhibit significant spinal radiographic abnormalities, including platyspondyly and anterior vertebral beaking (resembling Morquio syndrome), a unique feature of pseudoachondroplasia is that these spinal changes typically improve or completely resolve by adulthood. Therefore, major spinal surgery is rarely required, and the primary orthopedic issues in adults are severe early-onset osteoarthritis of the appendicular joints.

Question 7186

Topic: Thoracolumbar Spine & Deformity

A 5-year-old child with diastrophic dysplasia presents with a progressive scoliosis measuring 45 degrees. Which of the following statements regarding the management of scoliosis in this specific skeletal dysplasia is most accurate?

. Bracing is highly effective and is the gold standard for curves under 50 degrees.
. The scoliosis is typically flexible and easily managed with serial casting.
. Curves are often rigid, progress rapidly, and respond poorly to orthotic management.
. Scoliosis in this condition is usually secondary to a leg length discrepancy and resolves with a shoe lift.
. Surgical intervention should be delayed until skeletal maturity regardless of curve magnitude.

Correct Answer & Explanation

. Curves are often rigid, progress rapidly, and respond poorly to orthotic management.

Explanation

Correct Answer: Curves are often rigid, progress rapidly, and respond poorly to orthotic management.Scoliosis in diastrophic dysplasia is notoriously difficult to manage. The curves tend to appear early, progress rapidly, and become extremely rigid. Unlike idiopathic scoliosis, bracing is generally ineffective and poorly tolerated in diastrophic dysplasia. Early surgical intervention (often requiring anterior release and posterior fusion, or growth-friendly constructs in very young children) is frequently necessary to prevent severe, life-threatening deformity.

Question 7187

Topic: 6. Spine

A 5-year-old child with a known COMP gene mutation presents with a waddling gait, short limbs, and normal facial features. Which of the following spinal pathologies must be urgently evaluated with flexion-extension radiographs?

. Severe progressive scoliosis
. Thoracolumbar kyphosis
. Atlantoaxial instability
. Lumbosacral spondylolisthesis
. Basilar invagination

Correct Answer & Explanation

. Atlantoaxial instability

Explanation

This patient has pseudoachondroplasia, caused by a COMP gene mutation. Odontoid hypoplasia and ligamentous laxity are hallmarks of this condition, making them highly susceptible to atlantoaxial instability and subsequent cervical myelopathy.

Question 7188

Topic: 6. Spine

A 3-year-old boy presents with multiple large joint dislocations, spatulate thumbs, and a prominent forehead. Plain radiographs of the cervical spine are most likely to reveal which of the following life-threatening deformities?

. Atlanto-occipital dissociation
. Cervical kyphosis with subluxation
. Congenital cervical block vertebrae
. Basilar invagination
. Atlantoaxial rotatory fixation

Correct Answer & Explanation

. Cervical kyphosis with subluxation

Explanation

The clinical presentation is classic for Larsen syndrome (FLNB mutation). Cervical kyphosis with associated subluxation is a hallmark and potentially lethal complication that requires early detection and frequently posterior cervical fusion.

Question 7189

Topic: 6. Spine

When evaluating the lateral spine radiographs of patients with mucopolysaccharidoses, specific patterns of vertebral body beaking help differentiate the syndromes. Which of the following accurately describes the classical radiographic distinction?

. Hurler syndrome features anterior-central beaking, while Morquio syndrome features anterior-inferior beaking
. Hurler syndrome features anterior-superior beaking, while Morquio syndrome features anterior-central beaking
. Hurler syndrome features anterior-inferior beaking, while Morquio syndrome features anterior-central beaking
. Hurler syndrome features anterior-inferior beaking, while Hunter syndrome features anterior-central beaking
. Both Hurler and Morquio syndromes feature anterior-superior beaking

Correct Answer & Explanation

. Hurler syndrome features anterior-inferior beaking, while Morquio syndrome features anterior-central beaking

Explanation

In Hurler syndrome (MPS I), the hypoplastic vertebrae typically exhibit anterior-inferior beaking. In contrast, Morquio syndrome (MPS IV) is characterized by anterior-central beaking of the vertebral bodies.

Question 7190

Topic: 6. Spine

A 40-year-old male with achondroplasia requires surgical decompression for severe, progressive neurogenic claudication. Preoperative imaging confirms multilevel lumbar spinal stenosis. Which of the following anatomical considerations is most critical when performing the laminectomy?

. The stenosis is isolated to the ligamentum flavum, requiring only isolated flavectomies
. The primary stenosis is at the central canal due to lengthened pedicles
. The stenosis is diffuse, typically requiring wide, multilevel laminectomies extending into the lateral recesses while preserving the facet joints
. Decompression must include extensive facetectomies at every level due to facet hypertrophy, necessitating routine instrumented fusion
. A routine single-level laminotomy is sufficient due to the focal nature of the dysplasia

Correct Answer & Explanation

. The stenosis is diffuse, typically requiring wide, multilevel laminectomies extending into the lateral recesses while preserving the facet joints

Explanation

Spinal stenosis in achondroplasia is multi-level and caused by short pedicles, thickened laminas, and decreased interpedicular distance. Decompression requires wide, multilevel laminectomies with lateral recess clearance, taking care to preserve the facets to avoid iatrogenic instability.

Question 7191

Topic: 6. Spine

A 2-week-old neonate presents with a 'cauliflower' ear, short limbs, and 'hitchhiker' thumbs. You are asked to consult regarding a spinal deformity. Which of the following cervical spine anomalies is most characteristic and carries a risk of spontaneous resolution versus fatal progression?

. Cervical kyphosis
. Cervical lordosis
. Os odontoideum
. Congenital absence of the C1 arch
. Klippel-Feil anomaly

Correct Answer & Explanation

. Cervical kyphosis

Explanation

The diagnosis is diastrophic dysplasia (SLC26A2 mutation). Cervical kyphosis is a frequent finding; it can spontaneously resolve in some infants but can be severe, progressive, and fatal in others, requiring close monitoring.

Question 7192

Topic: 6. Spine

A 12-year-old male presents with short-trunk dwarfism, a barrel chest, and a waddling gait. Radiographs show flattening of the vertebral bodies (platyspondyly) with severe odontoid hypoplasia. Laboratory testing reveals normal intelligence and excessive keratan sulfate in the urine. Deficiency of which enzyme is responsible?

. Alpha-L-iduronidase
. Iduronate-2-sulfatase
. Galactosamine-6-sulfatase (GALNS)
. Arylsulfatase B
. Beta-glucuronidase

Correct Answer & Explanation

. Galactosamine-6-sulfatase (GALNS)

Explanation

The clinical picture is classic for Morquio syndrome type A (MPS IVA), characterized by normal intelligence, severe spine/skeletal dysplasia, and excessive urinary keratan sulfate. It is caused by a deficiency in Galactosamine-6-sulfatase (GALNS).

Question 7193

Topic: 6. Spine
A 6-year-old boy with Osteogenesis Imperfecta Type III presents with new-onset hyperreflexia, upper extremity weakness, and lower cranial nerve deficits. Plain radiographs of the skull base and cervical spine are most likely to demonstrate which of the following?
. Cervical kyphosis
. Atlantoaxial rotatory subluxation
. Basilar invagination
. Spina bifida occulta of C1
. Klippel-Feil syndrome

Correct Answer & Explanation

. Basilar invagination

Explanation

Basilar invagination, where the odontoid process migrates upwards into the foramen magnum, is a known and potentially lethal complication of severe Osteogenesis Imperfecta (Type III/IV). It presents with brainstem compression and lower cranial nerve deficits.

Question 7194

Topic: 6. Spine
During the evaluation of an infant with a suspected skeletal dysplasia, radiographs demonstrate asymmetric limb shortening and stippled epiphyses. Which of the following spinal deformities is most strongly associated with this X-linked dominant condition?
. Cervical hyperlordosis
. Severe progressive congenital-type scoliosis
. Thoracolumbar kyphosis that resolves with walking
. Basilar invagination
. Lumbosacral agenesis

Correct Answer & Explanation

. Severe progressive congenital-type scoliosis

Explanation

The condition described is Chondrodysplasia Punctata (Conradi-Hรผnermann syndrome), an X-linked dominant disorder. It is characterized by asymmetric limb involvement, stippled epiphyses, and a severe, progressive scoliosis driven by asymmetric vertebral development.

Question 7195

Topic: 6. Spine

A 6-year-old child with achondroplasia presents for follow-up of a rigid, persistent thoracolumbar kyphosis of 60 degrees. The deformity has failed orthotic management and features significant anterior apical vertebral wedging. What is the most definitive and appropriate treatment?

. Continued bracing until skeletal maturity
. Posterior spinal fusion alone
. Anterior and posterior spinal fusion
. Vertebral column resection
. Growing rod constructs

Correct Answer & Explanation

. Anterior and posterior spinal fusion

Explanation

In older children with achondroplasia, persistent rigid thoracolumbar kyphosis with fixed anterior apical wedging no longer responds to conservative measures. Combined anterior and posterior spinal fusion is recommended to prevent progression and neurological compromise.

Question 7196

Topic: 6. Spine

Which of the following describes the fundamental pathophysiological mechanism causing cervical myelopathy in patients with Spondyloepiphyseal Dysplasia Congenita (SEDc)?

. Dural ectasia leading to anterior meningocele
. Thickened ligamentum flavum and short pedicles
. Odontoid hypoplasia resulting in atlantoaxial instability
. Progressive basilar invagination due to bone softening
. Premature fusion of the cervical facet joints

Correct Answer & Explanation

. Odontoid hypoplasia resulting in atlantoaxial instability

Explanation

SEDc (COL2A1 mutation) is characterized by delayed or defective ossification of multiple epiphyses, prominently affecting the odontoid process. This odontoid hypoplasia leads to atlantoaxial instability and subsequent cervical myelopathy.

Question 7197

Topic: 6. Spine

A neonate is diagnosed with Campomelic Dysplasia. In addition to severe bowing of the long bones and potential sex reversal, which of the following spinal and neurological findings is most frequently associated with this condition?

. Cervical kyphosis with hypoplastic pedicles
. Atlanto-occipital assimilation
. Spina bifida cystica
. Lumbosacral spondyloptosis
. Diastematomyelia

Correct Answer & Explanation

. Cervical kyphosis with hypoplastic pedicles

Explanation

Campomelic dysplasia (SOX9 mutation) features congenital bowing of long bones, respiratory distress (tracheomalacia), and XY phenotypic females. In the spine, it classically presents with cervical kyphosis and hypoplastic pedicles.

Question 7198

Topic: 6. Spine

A 10-year-old girl with Cleidocranial Dysplasia is undergoing a routine spinal evaluation. Which of the following is the most commonly encountered spinal abnormality in this population?

. Severe cervical kyphosis requiring fusion
. Odontoid agenesis
. Spina bifida occulta with delayed ossification of the neural arch
. Hemivertebrae at multiple levels
. Progressive dural ectasia

Correct Answer & Explanation

. Spina bifida occulta with delayed ossification of the neural arch

Explanation

Cleidocranial dysplasia (RUNX2 mutation) involves defective intramembranous ossification. The spine often exhibits delayed ossification of the neural arches, frequently presenting as multi-level spina bifida occulta.

Question 7199

Topic: 6. Spine

When planning cervical spine fusion for atlantoaxial instability in a patient with Morquio syndrome, the surgeon must be acutely aware of the patient's airway and systemic risks. Which of the following statements regarding the cervical spine in Morquio syndrome is true?

. Instability is solely due to ligamentous laxity, as the odontoid is usually normal
. Surgical intervention is rarely needed as the instability spontaneously stabilizes by adulthood
. It combines odontoid hypoplasia with severe ligamentous laxity, making C1-C2 instability the leading cause of mortality
. Instability is typically treated with an anterior cervical discectomy and fusion
. Subaxial cervical spine instability is more common than upper cervical instability

Correct Answer & Explanation

. It combines odontoid hypoplasia with severe ligamentous laxity, making C1-C2 instability the leading cause of mortality

Explanation

In Morquio syndrome (MPS IV), severe odontoid hypoplasia combined with intrinsic ligamentous laxity leads to gross C1-C2 instability. If untreated, this results in progressive myelopathy, which is the leading cause of death in these patients.

Question 7200

Topic: 6. Spine

A 50-year-old female with achondroplasia requires surgical decompression for severe neurogenic claudication. Which of the following characteristic pathoanatomic features of the achondroplastic spine most directly contributes to her lumbar spinal stenosis?

. Increasing interpedicular distance caudally
. Widened foramen magnum
. Decreasing interpedicular distance from L1 to L5
. Congenital spondylolysis
. Hypertrophy of the uncinate processes

Correct Answer & Explanation

. Decreasing interpedicular distance from L1 to L5

Explanation

In the normal spine, the interpedicular distance increases from L1 to L5. In achondroplasia, there is a pathognomonic progressive decrease in the interpedicular distance from L1 to L5, resulting in severe congenital spinal stenosis.

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