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6. Spine MCQs

Practice Set 60 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 1181

Topic: 6. Spine

Which of the following conditions does not have a risk of cervical deformity greater than the general population:

. Neurofibromatosis
. Larsen syndrome
. Diastrophic dysplasia
. Achondroplasia
. Down syndrome

Correct Answer & Explanation

. Achondroplasia

Explanation

Achondroplasia is associated with frequent stenosis of the foramen magnum in infancy, as well as lower cervical stenosis. However, it is not associated with an actual deformity of the cervical spine. By contrast, neurofibromatosis, Larsen syndrome, and diastrophic dysplasia are associated with infantile cervical kyphosis. Down syndrome is associated with the risk of upper cervical instability.

Question 1182

Topic: 6. Spine

In patients with single thoracic idiopathic scoliosis treated with posterior pedicle screw constructs, the distal extent of the fusion may be stopped at which of the following levels with respect to the neutral vertebra and still routinely maintain balance:

. Three levels above
. Two levels above
. One level above
. One level below
. Two levels below

Correct Answer & Explanation

. One level above

Explanation

In single thoracic idiopathic scoliosis, the distal extent of the fusion may be stopped at one level above the neutrally rotated vertebra and still maintain trunk balance.

Question 1183

Topic: 6. Spine

Which of the following radiographic criteria is required for the classic diagnosis of Scheuermann's disease?

. Anterior wedging of at least 5 degrees in three consecutive vertebrae
. Anterior wedging of at least 10 degrees in two consecutive vertebrae
. Schmorl nodes in at least five consecutive vertebrae
. Thoracic kyphosis greater than 40 degrees with neutral wedging
. Hyperlordosis of the lumbar spine with sacral dysplasia

Correct Answer & Explanation

. Anterior wedging of at least 5 degrees in three consecutive vertebrae

Explanation

Sorensen's criteria for classic Scheuermann's kyphosis require anterior wedging of at least 5 degrees in three or more consecutive vertebrae. Endplate irregularities and Schmorl nodes are supportive but not strictly required for the formal definition.

Question 1184

Topic: 6. Spine

In infantile idiopathic scoliosis, a rib-vertebra angle difference (RVAD) of Mehta greater than what value is highly predictive of curve progression?

. 10 degrees
. 20 degrees
. 30 degrees
. 40 degrees
. 50 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

Mehta's rib-vertebra angle difference (RVAD) is used to predict progression in infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly predicts curve progression, whereas an RVAD less than 20 degrees typically resolves spontaneously.

Question 1185

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with back pain and L5 radiculopathy. Radiographs show a Grade III isthmic spondylolisthesis at L5-S1 with a high pelvic incidence. Which of the following is the most appropriate surgical strategy if conservative management fails?
. Pars interarticularis repair (Buck's procedure)
. L5-S1 posterior uninstrumented in situ fusion
. L5-S1 posterior instrumented fusion with reduction
. L4-S1 posterior instrumented fusion
. Anterior lumbar interbody fusion without posterior instrumentation

Correct Answer & Explanation

. L4-S1 posterior instrumented fusion

Explanation

For high-grade (Grade III or IV) isthmic spondylolisthesis in adolescents, L4 to S1 posterior instrumented fusion is often recommended due to the severe slip angle and high pelvic incidence. A single-level L5-S1 fusion in high-grade slips carries a high rate of hardware failure and pseudarthrosis.

Question 1186

Topic: 6. Spine

A 12-year-old male with Duchenne muscular dystrophy presents with a 45-degree sweeping thoracolumbar scoliosis and progressive loss of sitting balance. What is the primary indication to extend the spinal fusion down to the pelvis in this neuromuscular patient?

. To preserve lumbar lordosis
. To correct associated hip flexion contractures
. To correct pelvic obliquity and restore sitting balance
. To prevent the crankshaft phenomenon
. To optimize pulmonary function tests

Correct Answer & Explanation

. To correct pelvic obliquity and restore sitting balance

Explanation

In nonambulatory patients with neuromuscular scoliosis, extending the fusion to the pelvis is primarily indicated to correct pelvic obliquity. This provides a level pelvis, which is essential for maintaining sitting balance and preventing skin breakdown.

Question 1187

Topic: Thoracolumbar Spine & Deformity

In a patient with idiopathic adolescent scoliosis, at what thoracic curve magnitude does right-sided heart failure (cor pulmonale) typically begin to occur?

. 60 degrees
. 80 degrees
. 100 degrees
. Greater than 110 degrees
. 140 degrees

Correct Answer & Explanation

. Greater than 110 degrees

Explanation

In idiopathic scoliosis, restrictive lung disease becomes clinically significant at curves >80 degrees. However, right-sided heart failure (cor pulmonale) typically occurs when the thoracic curve exceeds 110 degrees.

Question 1188

Topic: 6. Spine

Among the following patterns of congenital spinal deformity, which carries the highest risk of rapid curve progression?

. Block vertebra
. Wedge vertebra
. Fully segmented hemivertebra
. Unilateral unsegmented bar with a contralateral hemivertebra
. Incarcerated hemivertebra

Correct Answer & Explanation

. Unilateral unsegmented bar with a contralateral hemivertebra

Explanation

Unilateral unsegmented bar with a contralateral hemivertebra has the highest risk of progression in congenital scoliosis. This is due to tethered growth on the concave side coupled with active growth on the convex side.

Question 1189

Topic: Thoracolumbar Spine & Deformity

When evaluating an AP radiograph of an infant with idiopathic scoliosis, a Rib Vertebral Angle Difference (RVAD) of Mehta greater than what value is considered highly predictive of curve progression?

. 5 degrees
. 10 degrees
. 20 degrees
. 30 degrees
. 45 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

The Rib Vertebral Angle Difference (RVAD) of Mehta evaluates the risk of progression in infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly predicts an aggressive, progressing curve rather than a resolving one.

Question 1190

Topic: 6. Spine

A 16-year-old non-ambulatory patient with spastic quadriplegic cerebral palsy presents with a 75-degree neuromuscular scoliosis and marked pelvic obliquity. To maximize sitting balance, the distal extent of the spinal fusion should be:

. L4
. L5
. S1
. The Pelvis
. Sacral ala only

Correct Answer & Explanation

. The Pelvis

Explanation

In non-ambulatory neuromuscular patients with scoliosis and pelvic obliquity, spinal fusion must be extended to the pelvis. This securely corrects the obliquity, prevents ischial decubitus ulcers, and establishes a level platform for sitting.

Question 1191

Topic: 6. Spine

According to the Sorensen criteria, a definitive radiographic diagnosis of Scheuermann's kyphosis requires which of the following findings?

. Schmorl's nodes in at least 2 adjacent vertebrae
. Greater than 5 degrees of posterior wedging in 2 adjacent vertebrae
. Greater than 5 degrees of anterior wedging in at least 3 adjacent vertebrae
. Greater than 10 degrees of anterior wedging in a single vertebra
. Vertebral endplate irregularities without wedging

Correct Answer & Explanation

. Greater than 5 degrees of anterior wedging in at least 3 adjacent vertebrae

Explanation

Sorensen criteria for Scheuermann's kyphosis require anterior wedging of greater than 5 degrees in at least three consecutive vertebrae. This structural deformity is distinct from flexible postural roundback, which lacks these bony wedging changes.

Question 1192

Topic: Thoracolumbar Spine & Deformity

Which of the following spinopelvic parameters is an anatomical constant for a given individual and, when elevated, strongly correlates with a higher risk of spondylolisthesis progression?

. Thoracic kyphosis
. Pelvic incidence
. Lumbar lordosis
. Sacral slope
. Pelvic tilt

Correct Answer & Explanation

. Pelvic incidence

Explanation

Pelvic incidence (PI) is a fixed anatomical parameter that defines the shape of the pelvis. A high PI creates a steeper lumbosacral angle, resulting in increased shear forces across the L5-S1 junction and a higher risk of spondylolisthesis progression.

Question 1193

Topic: 6. Spine

In the evaluation of adult spinal deformity, which of the following radiographic parameters has been shown to most closely correlate with decreased health-related quality of life (HRQOL) scores?

. Sagittal vertical axis (SVA)
. Cobb angle of the major curve
. Lumbar lordosis
. Pelvic tilt
. Coronal balance

Correct Answer & Explanation

. Sagittal vertical axis (SVA)

Explanation

Sagittal vertical axis (SVA) measures global sagittal alignment and is the single most important radiographic parameter correlating with poor HRQOL. Positive sagittal imbalance results in significantly increased energy expenditure to maintain an upright posture.

Question 1194

Topic: 6. Spine

When grading a patient with cervical spondylotic myelopathy, the Nurick classification system primarily evaluates which functional aspect?

. Upper extremity manual dexterity
. Lower extremity gait and ambulatory status
. Bowel and bladder function
. Subjective pain scores
. Deep tendon reflex hyperactivity

Correct Answer & Explanation

. Lower extremity gait and ambulatory status

Explanation

The Nurick classification grades the severity of cervical spondylotic myelopathy based solely on gait disturbance and ambulatory status. Grade 0 denotes root symptoms only, while Grade 5 indicates a wheelchair-bound or bedridden patient.

Question 1195

Topic: 6. Spine

Which of the following radiographic findings is a required criterion for the classic diagnosis of Scheuermann's kyphosis (Sorensen criteria)?

. Anterior wedging of at least 5 degrees in three consecutive vertebrae
. Schmorl's nodes in at least two consecutive vertebrae
. Thoracic kyphosis greater than 40 degrees with isolated apical wedging
. Endplate irregularities in the lumbar spine only
. Pedicle widening at the apical vertebra

Correct Answer & Explanation

. Anterior wedging of at least 5 degrees in three consecutive vertebrae

Explanation

The Sorensen criteria for Scheuermann's kyphosis require anterior wedging of at least 5 degrees in three or more consecutive vertebrae. Associated findings often include Schmorl's nodes and endplate irregularities, but the sequential wedging is diagnostic.

Question 1196

Topic: 6. Spine

A 1-year-old child presents with a left thoracic infantile idiopathic scoliosis measuring 25 degrees. The rib-vertebra angle difference (RVAD) of Mehta is calculated at 25 degrees. What is the most likely clinical course?

. Spontaneous resolution of the curve
. Rapid progression requiring immediate surgical fusion
. Progression of the curve requiring serial casting or bracing
. Development of severe restrictive lung disease by age 3
. Conversion to a right-sided curve over time

Correct Answer & Explanation

. Progression of the curve requiring serial casting or bracing

Explanation

A Mehta's rib-vertebra angle difference (RVAD) greater than 20 degrees is highly predictive of curve progression in infantile idiopathic scoliosis. These progressive curves typically require intervention such as serial elongation-derotation-flexion (EDF) casting.

Question 1197

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast has a Grade II isthmic spondylolisthesis at L5-S1. She complains of radicular pain and hamstring tightness. Which of the following best explains the mechanism of her hamstring tightness?

. Direct compression of the S1 nerve root
. Reflexive spasm to stabilize the pelvis and prevent further sagittal slip
. L5 nerve root irritation in the neural foramen
. Piriformis syndrome secondary to altered gait
. Tethered cord syndrome

Correct Answer & Explanation

. Reflexive spasm to stabilize the pelvis and prevent further sagittal slip

Explanation

Hamstring tightness in pediatric isthmic spondylolisthesis (the "Phalen-Dickson sign") is a reflexive spasm meant to vertically orient the pelvis (retroversion) to decrease lumbar lordosis and prevent further anterior translation.

Question 1198

Topic: 6. Spine

A 14-year-old non-ambulatory male with Duchenne muscular dystrophy presents with a progressing 50-degree thoracolumbar scoliosis and pelvic obliquity. What is the most appropriate surgical strategy?

. Anterior spinal fusion without instrumentation
. Posterior spinal fusion stopping at L5
. Posterior spinal fusion extending to the pelvis
. Growing rod construct
. Observation until the curve reaches 70 degrees

Correct Answer & Explanation

. Posterior spinal fusion extending to the pelvis

Explanation

In non-ambulatory patients with Duchenne muscular dystrophy and significant pelvic obliquity, posterior spinal fusion must typically extend to the pelvis to provide a stable, level sitting base and prevent further deformity.

Question 1199

Topic: 6. Spine

Which of the following conditions is the primary indication for the use of a Vertical Expandable Prosthetic Titanium Rib (VEPTR) device?

. Adolescent idiopathic scoliosis greater than 50 degrees
. Scheuermann's kyphosis with rigid deformity
. Thoracic insufficiency syndrome in a growing child
. Neuromuscular scoliosis in a post-pubertal patient
. High-grade spondylolisthesis with sagittal imbalance

Correct Answer & Explanation

. Thoracic insufficiency syndrome in a growing child

Explanation

VEPTR is specifically designed to manage thoracic insufficiency syndrome by expanding the constrained thorax. This allows for lung growth and treats early-onset complex spinal deformities without permanently fusing the spine.

Question 1200

Topic: 6. Spine

In adult spinal deformity surgery, achieving optimal sagittal balance requires matching the postoperative lumbar lordosis (LL) to the patient's pelvic incidence (PI). The postoperative LL should ideally fall within how many degrees of the PI?

. +/- 2 degrees
. +/- 5 degrees
. +/- 10 degrees
. +/- 15 degrees
. +/- 20 degrees

Correct Answer & Explanation

. +/- 10 degrees

Explanation

Sagittal plane correction in adult spinal deformity aims for a lumbar lordosis (LL) within 10 degrees of the pelvic incidence (PI). A PI-LL mismatch greater than 10 degrees correlates with residual pain and adjacent segment disease.

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