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6. Spine MCQs

Practice Set 209 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 4161

Topic: 6. Spine

Which of the following congenital spinal anomalies has the highest risk of rapid curve progression and requires the earliest surgical intervention?

. Block vertebra
. Fully segmented hemivertebra
. Unilateral unsegmented bar with a contralateral hemivertebra
. Butterfly vertebra
. Semi-segmented hemivertebra

Correct Answer & Explanation

. Block vertebra

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra at the same level causes a severe tethering effect on one side with unchecked growth on the opposite side. This has a nearly 100% chance of progression and requires early spinal fusion.

Question 4162

Topic: 6. Spine

A 14-year-old non-ambulatory boy with Duchenne muscular dystrophy develops a progressive neuromuscular scoliosis of 45 degrees. Which of the following is an established principle regarding surgical treatment for this patient?

. Surgery should be delayed until the curve exceeds 90 degrees
. Spinal fusion should typically extend to the pelvis to maintain sitting balance
. Bracing is highly effective at stopping curve progression and avoiding surgery
. Only anterior spinal fusion is indicated due to poor bone quality
. Pulmonary function usually improves dramatically after surgical correction

Correct Answer & Explanation

. Surgery should be delayed until the curve exceeds 90 degrees

Explanation

In non-ambulatory patients with Duchenne muscular dystrophy, spinal fusion is usually indicated for curves >20-30 degrees and should extend to the pelvis to correct pelvic obliquity and maintain a stable sitting posture. Pulmonary function decline is slowed, but rarely improves.

Question 4163

Topic: 6. Spine

A 13-year-old boy with infantile idiopathic scoliosis was treated nonoperatively. Radiographs currently show a 55-degree thoracic curve. Which initial radiographic measurement obtained during infancy was most likely predictive of this curve progression?

. Cobb angle greater than 10 degrees
. Rib-vertebra angle difference (RVAD) greater than 20 degrees
. Apical vertebral rotation greater than Grade I
. Risser sign of 0
. Iliosacral angle greater than 15 degrees

Correct Answer & Explanation

. Cobb angle greater than 10 degrees

Explanation

The rib-vertebra angle difference (RVAD), or Mehta angle, is the most reliable predictor of curve progression in infantile idiopathic scoliosis. An RVAD greater than 20 degrees indicates a high likelihood of relentless progression.

Question 4164

Topic: 6. Spine

A 14-year-old female undergoes posterior spinal fusion for adolescent idiopathic scoliosis. Intraoperatively, neuromonitoring demonstrates a sudden, sustained loss of somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) bilaterally during rod derotation. What is the most appropriate immediate first step?

. Administer high-dose methylprednisolone
. Perform a wake-up test
. Release the corrective forces on the spine
. Increase the mean arterial pressure
. Order an emergent intraoperative MRI

Correct Answer & Explanation

. Administer high-dose methylprednisolone

Explanation

In the event of a sudden loss of neuromonitoring signals during deformity correction, the immediate first step is to release the corrective forces (e.g., remove the rods). Subsequent steps include raising mean arterial pressure and optimizing oxygenation.

Question 4165

Topic: 6. Spine

A 6-month-old infant is diagnosed with an atypical, left-sided thoracic congenital scoliosis curve. A screening renal ultrasound is normal. What other diagnostic study is mandatory to rule out commonly associated anomalies?

. Echocardiogram
. MRI of the brain and entire spine
. CT scan of the chest
. Both echocardiogram and MRI of the entire spine
. Chromosomal microarray

Correct Answer & Explanation

. Echocardiogram

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies, as well as intraspinal abnormalities (e.g., tethered cord, diastematomyelia). Therefore, an echocardiogram to rule out cardiac defects and an MRI of the entire spine to rule out neural axis abnormalities are essential.

Question 4166

Topic: 6. Spine

Which of the following vertebral anomalies represents the highest risk of curve progression in congenital scoliosis?

. Block vertebra
. Unilateral unsegmented bar with contralateral hemivertebra
. Fully segmented hemivertebra
. Incarcerated hemivertebra
. Symmetrical wedge vertebra

Correct Answer & Explanation

. Block vertebra

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra creates a severe mechanical imbalance and has the highest risk of progression. It almost always requires early prophylactic surgical fusion.

Question 4167

Topic: 6. Spine

In a 6-month-old infant with infantile idiopathic scoliosis, a Mehta rib-vertebra angle difference (RVAD) of 25 degrees at the apical vertebra is most highly predictive of which of the following?

. Spontaneous resolution of the curve
. High likelihood of progressive curve deformity
. Presence of an underlying syrinx
. Tethered cord syndrome
. Underlying congenital vertebral malformation

Correct Answer & Explanation

. Spontaneous resolution of the curve

Explanation

In infantile idiopathic scoliosis, a Mehta RVAD greater than 20 degrees is highly predictive of curve progression. An RVAD of less than 20 degrees typically characterizes a resolving curve.

Question 4168

Topic: 6. Spine

A 13-year-old non-ambulatory boy with Duchenne muscular dystrophy develops a progressive 45-degree neuromuscular scoliosis with pelvic obliquity. What is the most appropriate management?

. Observation with serial radiographs
. Thoracolumbosacral orthosis (TLSO) bracing for 23 hours a day
. Anterior spinal fusion only
. Posterior spinal fusion to the lower lumbar spine
. Posterior spinal fusion extending to the pelvis

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

Neuromuscular scoliosis in Duchenne muscular dystrophy is rapidly progressive and poorly controlled by bracing. Surgical stabilization typically involves posterior spinal fusion extending to the pelvis to correct pelvic obliquity and optimize seating balance.

Question 4169

Topic: 6. Spine

A 12-year-old premenarchal girl (Risser 0) presents with adolescent idiopathic scoliosis. Radiographs demonstrate a progressive right thoracic curve of 52 degrees. What is the most appropriate definitive management?

. Observation with serial radiographs every 6 months
. Thoracolumbosacral orthosis (TLSO) bracing for 18 hours a day
. Mehta casting
. Posterior spinal fusion with instrumentation
. Vertebral body tethering isolated to the lumbar spine

Correct Answer & Explanation

. Observation with serial radiographs every 6 months

Explanation

Curves greater than 50 degrees in skeletally immature patients have a high risk of progression into adulthood and generally require surgical intervention with a posterior spinal fusion.

Question 4170

Topic: 6. Spine

In the initial radiographic evaluation of infantile idiopathic scoliosis, which of the following measurements is the most reliable predictor of curve progression?

. Cobb angle greater than 10 degrees
. Risser sign
. Rib-vertebra angle difference (RVAD)
. Nash-Moe rotation
. Apical vertebral translation

Correct Answer & Explanation

. Cobb angle greater than 10 degrees

Explanation

Mehta's rib-vertebra angle difference (RVAD) is the most prognostic factor for infantile idiopathic scoliosis. An RVAD greater than 20 degrees strongly predicts progressive disease requiring intervention.

Question 4171

Topic: 6. Spine

A 14-year-old boy with Duchenne muscular dystrophy presents with a progressive thoracolumbar scoliosis measuring 45 degrees. His forced vital capacity (FVC) is 45% of predicted. What is the recommended treatment?

. Observation until the curve reaches 60 degrees
. Custom-molded TLSO
. Anterior spinal fusion only
. Posterior spinal fusion extending to the pelvis
. Growing rod instrumentation

Correct Answer & Explanation

. Observation until the curve reaches 60 degrees

Explanation

In Duchenne muscular dystrophy, spinal fusion to the pelvis is indicated when curves exceed 20-30 degrees and the patient is non-ambulatory, provided FVC >30%. This improves sitting balance and slows pulmonary decline; bracing is ineffective.

Question 4172

Topic: 6. Spine

A 9-month-old boy presents with an infantile idiopathic scoliosis. Radiographs demonstrate a 30-degree left thoracic curve. The rib-vertebral angle difference (RVAD) is calculated to be 25 degrees. What is the most appropriate management?

. Observation with radiographs every 6 months
. Thoracolumbosacral orthosis (TLSO) bracing
. Serial Mehta casting
. Growing rod instrumentation
. Anterior spinal fusion

Correct Answer & Explanation

. Observation with radiographs every 6 months

Explanation

An RVAD (Mehta's angle) greater than 20 degrees in infantile idiopathic scoliosis strongly predicts curve progression. Serial casting (Mehta casting) is indicated to control and potentially correct the deformity in young infants with progressive curves.

Question 4173

Topic: 6. Spine

A 14-year-old boy with Duchenne muscular dystrophy who is wheelchair-bound develops a 45-degree progressive thoracolumbar scoliosis. His forced vital capacity (FVC) is 40% of predicted. What is the most appropriate management of his spinal deformity?

. Custom-molded TLSO bracing
. Anterior release and spinal fusion
. Posterior spinal fusion stopping at L5
. Posterior spinal fusion extending to the pelvis
. Observation until the curve reaches 60 degrees

Correct Answer & Explanation

. Custom-molded TLSO bracing

Explanation

In Duchenne muscular dystrophy, scoliosis progresses rapidly once the patient becomes wheelchair-bound, and bracing is ineffective. Posterior spinal fusion to the pelvis is indicated to maintain sitting balance and comfort before pulmonary function deteriorates too severely.

Question 4174

Topic: 6. Spine

A 2-year-old child presents with a congenital spinal deformity. Radiographs show multiple vertebral anomalies. Which of the following anomaly patterns is associated with the highest risk of rapid curve progression?

. Block vertebra
. Single fully segmented hemivertebra
. Incarcerated hemivertebra
. Wedge vertebra
. Unilateral unsegmented bar with contralateral fully segmented hemivertebra

Correct Answer & Explanation

. Block vertebra

Explanation

A unilateral unsegmented bar combined with a contralateral fully segmented hemivertebra produces maximal asymmetric growth. This specific congenital pattern has a nearly 100% chance of relentless, rapid progression and mandates early surgical fusion.

Question 4175

Topic: 6. Spine

During a posterior spinal fusion for adolescent idiopathic scoliosis in a 15-year-old female, the intraoperative neuromonitoring demonstrates a sudden loss of transcranial motor evoked potentials (MEPs) bilaterally, while somatosensory evoked potentials (SSEPs) remain intact. What is the most likely neurologic event?

. Anterior spinal artery ischemia
. Posterior column mechanical contusion
. Dorsal root ganglion avulsion
. Pedicle screw breach into the lateral recess
. Inadequate depth of anesthesia

Correct Answer & Explanation

. Anterior spinal artery ischemia

Explanation

MEPs monitor the anterior (motor) pathways of the spinal cord, which are supplied by the anterior spinal artery. SSEPs monitor the posterior columns (sensory). Isolated loss of MEPs with intact SSEPs strongly suggests ischemia of the anterior spinal cord, which is highly sensitive to hypotension or over-distraction.

Question 4176

Topic: Thoracolumbar Spine & Deformity

A 13-year-old gymnast presents with chronic lower back pain. Radiographs reveal an isthmic spondylolisthesis at L5-S1 with 60% forward translation (Meyerding Grade III). She has failed 6 months of physical therapy. What is the most appropriate surgical management?

. Pars interarticularis repair (Buck's procedure)
. Anterior lumbar interbody fusion only
. Laminectomy and decompression without fusion
. In situ posterior spinal fusion from L4 to S1
. Complete reduction of the slip and 360-degree fusion

Correct Answer & Explanation

. Pars interarticularis repair (Buck's procedure)

Explanation

For high-grade isthmic spondylolisthesis (>50% slip, Grade III-V) in adolescents that is symptomatic or progressive, in situ posterior or posterolateral spinal fusion (typically extending from L4 to S1) is the standard treatment. Attempting complete reduction carries a high risk of L5 nerve root injury.

Question 4177

Topic: 6. Spine



A 10-year-old boy with neurofibromatosis type 1 (NF-1) develops a 45-degree, sharp, short angular thoracic kyphoscoliosis. Rib penciling and dural ectasia are noted on advanced imaging. What is the recommended surgical management for this patient?

. Posterior spinal fusion alone with pedicle screw construct
. Growing rod placement to allow continued spinal growth
. Anterior release with instrumented anterior fusion
. Observation with bracing until skeletal maturity
. Combined anterior and posterior spinal fusion

Correct Answer & Explanation

. Posterior spinal fusion alone with pedicle screw construct

Explanation

Dystrophic curves in neurofibromatosis type 1 are notorious for relentless progression and an exceptionally high rate of pseudarthrosis if treated with posterior fusion alone. The standard of care for dystrophic kyphoscoliosis in NF-1 is a combined anterior and posterior spinal fusion.

Question 4178

Topic: 6. Spine

A 3-year-old boy presents with a 35-degree right thoracic curve. The rib-vertebral angle difference (RVAD) of Mehta is calculated at 25 degrees on the AP radiograph. What is the most appropriate management for this condition?

. Observation with repeat radiographs in 6 months
. Thoracolumbosacral orthosis (TLSO) brace treatment
. Serial Mehta casting
. Posterior spinal fusion with pedicle screws
. Anterior vertebral body tethering

Correct Answer & Explanation

. Observation with repeat radiographs in 6 months

Explanation

Infantile idiopathic scoliosis with a curve greater than 30 degrees and an RVAD greater than 20 degrees has a very high risk of progression. Early intervention with serial elongation-derotation-flexion (EDF) casting (Mehta casting) is the gold standard to control or resolve the deformity.

Question 4179

Topic: 6. Spine

A 12-year-old girl presents with a painless scoliotic deformity. Radiographs reveal a 35-degree left-sided thoracic curve. Neurologic examination is unremarkable. What is the most appropriate next step in evaluation?

. CT scan of the thoracic spine
. Total spine MRI
. Skeletal survey
. Immediate bracing
. Observation with repeat radiographs in 6 months

Correct Answer & Explanation

. CT scan of the thoracic spine

Explanation

A left-sided thoracic curve in adolescent idiopathic scoliosis is an atypical pattern and carries a higher risk of underlying neural axis abnormalities, such as a syrinx or Chiari malformation. Therefore, a total spine MRI is indicated even in the absence of neurologic symptoms. Right-sided thoracic curves are the typical pattern for adolescent idiopathic scoliosis.

Question 4180

Topic: 6. Spine

Which of the following congenital spinal anomalies carries the highest risk of scoliotic curve progression and typically requires early surgical intervention?

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

Correct Answer & Explanation

. Block vertebra

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra has the highest risk of curve progression in congenital scoliosis, approaching 100%. This severe progression is due to tethering on one side with active growth on the contralateral side, usually necessitating early spinal fusion. Other anomalies like block vertebrae have a much lower progression risk.

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