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6. Spine MCQs

Practice Set 206 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 4101

Topic: 6. Spine
A 14-year-old female gymnast presents with persistent low back pain that radiates to her posterior thighs. Nonoperative management has failed after 6 months. Radiographs demonstrate a Grade III isthmic spondylolisthesis at L5-S1 with a slip angle of 45 degrees. Which of the following surgical treatments is most appropriate?
. L5 pars repair
. L5-S1 posterior spinal fusion
. L4-L5 posterior spinal fusion
. L5-S1 anterior lumbar interbody fusion only
. L5 laminectomy without fusion

Correct Answer & Explanation

. L5-S1 posterior spinal fusion

Explanation

High-grade (Grade III or IV) isthmic spondylolisthesis failing conservative management in adolescents is best treated with L5-S1 posterior or global spinal fusion. Pars repair is reserved for Grade I slips or spondylolysis without significant slippage.

Question 4102

Topic: 6. Spine

A 6-month-old infant is referred for a left thoracic curve measuring 25 degrees. The rib-vertebra angle difference (RVAD) of Mehta at the apical vertebra is 25 degrees. There are no other abnormalities. What is the most likely natural history of this curve?

. Spontaneous resolution
. Progression requiring surgical intervention
. Stable curvature without progression
. Resolution following physical therapy
. Improvement with nighttime bracing only

Correct Answer & Explanation

. Spontaneous resolution

Explanation

In infantile idiopathic scoliosis, an RVAD (Mehta's angle) greater than 20 degrees strongly indicates a high likelihood of curve progression. Curves with an RVAD less than 20 degrees typically resolve spontaneously.

Question 4103

Topic: 6. Spine
A newborn is diagnosed with a congenital hemivertebra in the thoracic spine. Which of the following is the most appropriate initial screening protocol for associated anomalies?
. MRI of the brain and cervical spine
. Renal ultrasound and echocardiogram
. Pulmonary function tests
. Upper gastrointestinal series
. DEXA scan

Correct Answer & Explanation

. Renal ultrasound and echocardiogram

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies. A renal ultrasound and echocardiogram are essential initial screening studies to rule out genitourinary and cardiac anomalies.

Question 4104

Topic: Thoracolumbar Spine & Deformity
A 14-year-old male gymnast presents with chronic low back pain and a waddling gait. Radiographs reveal a Grade III isthmic spondylolisthesis at L5-S1 with a slip angle of 55 degrees. Nonoperative management has failed. What is the most appropriate surgical intervention?
. L5 pars interarticularis repair
. L5-S1 anterior lumbar interbody fusion
. L4-S1 posterior instrumented fusion
. L5 laminectomy without fusion
. Sacroiliac joint fusion

Correct Answer & Explanation

. L4-S1 posterior instrumented fusion

Explanation

High-grade (Grade III or IV) isthmic spondylolisthesis in an adolescent requires stabilization. An in situ L4-S1 posterior instrumented fusion is the most reliable treatment to halt progression and relieve symptoms.

Question 4105

Topic: Thoracolumbar Spine & Deformity

A 10-month-old infant presents with a left-sided thoracic curve measuring 30 degrees. The diagnosis of infantile idiopathic scoliosis is suspected. Which of the following radiographic parameters is most predictive of whether this curve will progress or spontaneously resolve?

. Apical vertebral rotation
. Rib-vertebral angle difference (RVAD)
. Cobb angle of the compensatory curve
. Thoracic kyphosis angle
. Risser stage

Correct Answer & Explanation

. Apical vertebral rotation

Explanation

In infantile idiopathic scoliosis, Mehta's rib-vertebral angle difference (RVAD) is the most critical prognostic factor. An RVAD greater than 20 degrees is highly predictive of curve progression, whereas an RVAD less than 20 degrees typically indicates a resolving curve.

Question 4106

Topic: 6. Spine

A 9-month-old boy is being evaluated for progressive infantile idiopathic scoliosis. Radiographs demonstrate a left thoracic curve of 35 degrees and a rib-vertebra angle difference (RVAD) of 25 degrees. What is the most appropriate initial management?

. Observation with radiographs every 6 months
. Immediate posterior spinal fusion
. Mehta casting (elongation-derotation-flexion cast)
. Anterior vertebral body tethering
. Growth-friendly surgical instrumentation (e.g., growing rods)

Correct Answer & Explanation

. Observation with radiographs every 6 months

Explanation

An RVAD greater than 20 degrees in infantile idiopathic scoliosis indicates a high risk of progression. Serial EDF (Mehta) casting is the gold standard for progressive infantile curves to harness remaining growth and potentially achieve a cure.

Question 4107

Topic: 6. Spine

A 3-year-old girl is diagnosed with congenital scoliosis. Which of the following vertebral anomalies carries the highest risk for rapid curve progression and typically requires early surgical intervention?

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

Correct Answer & Explanation

. Block vertebra

Explanation

A unilateral unsegmented bar with a contralateral fully segmented hemivertebra provides the most severe growth imbalance. This pattern progresses rapidly and predictably, often necessitating early in situ fusion to prevent severe deformity.

Question 4108

Topic: 6. Spine

A 14-year-old boy with Duchenne muscular dystrophy develops a progressive 60-degree thoracolumbar scoliosis with significant pelvic obliquity. What is the most appropriate surgical approach?

. Anterior spinal fusion without instrumentation
. Posterior spinal fusion ending at L5
. Posterior spinal fusion extending to the pelvis
. Growing rod construct
. Vertebral body tethering

Correct Answer & Explanation

. Anterior spinal fusion without instrumentation

Explanation

In patients with Duchenne muscular dystrophy and significant scoliosis, the curve tends to progress rapidly and impairs sitting balance. Posterior spinal fusion to the pelvis is necessary to correct pelvic obliquity and provide a stable sitting platform.

Question 4109

Topic: 6. Spine

A 7-year-old girl with a progressive 55-degree congenital scoliosis undergoes a posterior-only spinal fusion without instrumentation. Three years later, her curve has worsened significantly. What is the phenomenon responsible for this progression?

. Pseudarthrosis at the apex of the curve
. Adding-on phenomenon
. Crankshaft phenomenon
. Implant failure
. Proximal junctional kyphosis

Correct Answer & Explanation

. Pseudarthrosis at the apex of the curve

Explanation

The crankshaft phenomenon occurs in skeletally immature patients (open triradiate cartilage) who undergo posterior-only spinal fusion. Continued anterior growth of the vertebral bodies causes the spine to rotate and curve around the posterior fusion mass.

Question 4110

Topic: 6. Spine

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy presents with a progressive neuromuscular scoliosis of 35 degrees. His forced vital capacity (FVC) is currently 45% of predicted. What is the most appropriate recommendation regarding his spinal deformity?

. TLSO bracing to halt curve progression
. Posterior spinal fusion from the upper thoracic spine to the pelvis
. Observation until the curve exceeds 50 degrees
. Anterior spinal fusion to maximize pulmonary function
. Growing rod construct insertion

Correct Answer & Explanation

. TLSO bracing to halt curve progression

Explanation

In Duchenne muscular dystrophy, spinal fusion is typically recommended when curves reach 20 to 30 degrees in non-ambulatory patients, provided their FVC is greater than 35%. Bracing is ineffective and poorly tolerated in these patients.

Question 4111

Topic: 6. Spine

A 7-year-old boy with neurofibromatosis type 1 (NF1) presents with a progressive, short, sharp angular thoracic scoliosis. Radiographs demonstrate penciling of the ribs and severe apical wedging. What is the recommended surgical approach if operative intervention is deemed necessary?

. Posterior spinal fusion alone with pedicle screws
. Anterior spinal fusion alone
. Combined anterior and posterior spinal fusion
. Growth modulation via anterior tethering
. Insertion of a magnetically controlled growing rod

Correct Answer & Explanation

. Posterior spinal fusion alone with pedicle screws

Explanation

Dystrophic scoliosis in NF1 has a high rate of progression and pseudoarthrosis. Due to poor bone quality, dural ectasia, and severe angular deformity, a combined anterior and posterior spinal fusion is the recommended surgical treatment to achieve a solid arthrodesis.

Question 4112

Topic: 6. Spine

A 14-year-old patient with Marfan syndrome requires surgical correction for a rigid 65-degree scoliotic curve. During preoperative planning, an MRI of the spine is obtained. Which of the following findings is most commonly associated with Marfan syndrome and complicates surgical hardware placement?

. Syringomyelia
. Diastematomyelia
. Dural ectasia
. Tethered cord
. Chiari I malformation

Correct Answer & Explanation

. Syringomyelia

Explanation

Dural ectasia (ballooning of the dural sac) is a major criterion for the diagnosis of Marfan syndrome and is present in a majority of these patients. It widens the spinal canal, erodes the pedicles, and complicates the safe placement of pedicle screws.

Question 4113

Topic: 6. Spine

A 6-month-old infant is diagnosed with infantile idiopathic scoliosis. Radiographs show a 25-degree left thoracic curve. Which of the following radiographic parameters indicates a high likelihood of curve progression?

. Rib-vertebra angle difference (RVAD) greater than 20 degrees
. Apical vertebral rotation of grade 1
. Cobb angle less than 20 degrees at presentation
. Phase 1 rib head relation
. Lumbar compensatory curve greater than 15 degrees

Correct Answer & Explanation

. Rib-vertebra angle difference (RVAD) greater than 20 degrees

Explanation

Mehta's rib-vertebra angle difference (RVAD) greater than 20 degrees is highly predictive of curve progression in infantile idiopathic scoliosis. Phase 2 rib head relation is also a definitive sign of progression.

Question 4114

Topic: 6. Spine

A 12-year-old boy with Duchenne muscular dystrophy (DMD) has a progressive scoliosis of 45 degrees. His forced vital capacity (FVC) is currently 40% of predicted. What is the most appropriate management?

. Observation and bracing
. Anterior spinal fusion only
. Posterior spinal fusion from upper thoracic spine to the pelvis
. Growing rods insertion
. VEPTR insertion

Correct Answer & Explanation

. Observation and bracing

Explanation

Scoliosis in DMD is rapidly progressive once patients become wheelchair-bound, and bracing is ineffective. Posterior spinal fusion to the pelvis is indicated for curves exceeding 20-30 degrees before pulmonary function severely declines (FVC < 30-35% increases surgical risk).

Question 4115

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic low back pain exacerbated by extension. Radiographs show an L5-S1 isthmic spondylolisthesis with 25% slip (Grade 1). She has failed 6 months of conservative management. What is the most appropriate surgical treatment?

. L5-S1 anterior lumbar interbody fusion (ALIF)
. L5 laminectomy and decompression alone
. L5-S1 posterior posterolateral fusion in situ
. L4-S1 posterior instrumented fusion with reduction
. Pars interarticularis repair (Buck's or Scott's wiring)

Correct Answer & Explanation

. L5-S1 anterior lumbar interbody fusion (ALIF)

Explanation

For low-grade isthmic spondylolisthesis (Grade 1 or 2) that fails conservative care, a posterior/posterolateral fusion in situ without decompression is the gold standard. Pars repair is generally reserved for symptomatic spondylolysis without an active slip.

Question 4116

Topic: Thoracolumbar Spine & Deformity

In the evaluation of typical adolescent idiopathic scoliosis (AIS), which of the following is commonly observed regarding the sagittal profile of the thoracic spine?

. Hyperkyphosis
. Hypokyphosis (thoracic lordosis)
. Normal kyphosis (20-40 degrees)
. Retrolisthesis of apical vertebrae
. Increased lumbar lordosis only

Correct Answer & Explanation

. Hyperkyphosis

Explanation

Adolescent idiopathic scoliosis is a true three-dimensional deformity characterized by a loss of normal kyphosis (hypokyphosis or lordosis) in the sagittal plane at the apex of the thoracic curve. The presence of hyperkyphosis should raise suspicion for non-idiopathic causes like Scheuermann's disease.

Question 4117

Topic: 6. Spine

A 4-year-old girl is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra at T8. Prior to surgical intervention, which of the following imaging studies is most critical to perform?

. MRI of the entire neuroaxis
. CT scan of the chest
. Bone scintigraphy
. Dynamic flexion-extension radiographs of the cervical spine
. DEXA scan

Correct Answer & Explanation

. MRI of the entire neuroaxis

Explanation

Congenital scoliosis is highly associated with intraspinal anomalies, such as tethered cord, diastematomyelia, and syringomyelia (seen in 20-40% of patients). An MRI of the entire spine is required before any surgical intervention to rule out these anomalies.

Question 4118

Topic: 6. Spine

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy (DMD) has a progressive thoracolumbar scoliosis measuring 45 degrees. His forced vital capacity (FVC) is currently 40% of predicted. What is the most appropriate management of his spinal deformity?

. Observation until the curve reaches 60 degrees
. Thoracolumbosacral orthosis (TLSO) bracing
. Anterior spinal fusion only
. Posterior spinal fusion to the pelvis
. Growing rod construct

Correct Answer & Explanation

. Observation until the curve reaches 60 degrees

Explanation

In DMD, scoliosis rapidly progresses once the patient becomes wheelchair-bound. Posterior spinal fusion to the pelvis is indicated for curves >20-30 degrees to improve sitting balance and prevent severe pulmonary decline, provided FVC >30%.

Question 4119

Topic: Thoracolumbar Spine & Deformity

An 8-month-old boy is diagnosed with infantile idiopathic scoliosis with a left-sided thoracic curve measuring 25 degrees. The rib-vertebral angle difference (RVAD) of Mehta is 12 degrees. What is the most likely natural history of this curve?

. Spontaneous resolution
. Slow progression requiring bracing at skeletal maturity
. Rapid progression requiring growing rods
. Development of severe restrictive lung disease by age 5
. Progression to structural kyphoscoliosis requiring fusion

Correct Answer & Explanation

. Spontaneous resolution

Explanation

Infantile idiopathic scoliosis curves with a Mehta RVAD of less than 20 degrees have a highly favorable prognosis, with the majority undergoing spontaneous resolution. Curves with an RVAD > 20 degrees are likely to progress.

Question 4120

Topic: 6. Spine

A 14-year-old boy presents with progressive thoracic kyphosis and back pain. Standing lateral radiographs reveal a thoracic kyphosis of 65 degrees and anterior wedging of 6 degrees across three consecutive vertebrae. He is Risser 2. What is the most appropriate initial treatment?

. Observation with annual radiographs
. Physical therapy focusing on hamstring stretching only
. Extension orthosis (e.g., Milwaukee brace)
. Posterior spinal fusion with instrumentation
. Anterior release and posterior spinal fusion

Correct Answer & Explanation

. Observation with annual radiographs

Explanation

The patient has Scheuermann's kyphosis. For a skeletally immature patient (Risser < 4) with a progressive curve between 50 and 75 degrees and pain, bracing with an extension orthosis is the recommended treatment to halt progression.

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