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6. Spine MCQs

Practice Set 191 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 3801

Topic: 6. Spine

When classifying adolescent idiopathic scoliosis using the Lenke system, the lumbar spine modifier is determined by the relationship of the center sacral vertical line (CSVL) to the lumbar vertebrae. What defines a Lumbar Modifier B?

. The CSVL passes medial to the pedicles of the apical lumbar vertebra
. The CSVL falls between the medial border of the pedicle and the lateral margin of the apical lumbar vertebra
. The CSVL falls completely lateral to the apical lumbar vertebra
. The CSVL intersects the apex of the thoracic curve perfectly
. The CSVL passes through the center of the apical lumbar vertebral body

Correct Answer & Explanation

. The CSVL falls between the medial border of the pedicle and the lateral margin of the apical lumbar vertebra

Explanation

In the Lenke classification, Modifier A indicates the CSVL passes between the lumbar pedicles. Modifier B indicates the CSVL touches the apical vertebra between the medial pedicle and the lateral vertebral margin. Modifier C means the CSVL falls completely lateral to the vertebra.

Question 3802

Topic: 6. Spine
A 2-year-old boy presents with congenital scoliosis secondary to a fully segmented hemivertebra at T8. In addition to full spine radiographs, what routine screening must be obtained?
. Echocardiogram and Renal Ultrasound
. Brain MRI and skeletal survey
. CT chest and pulmonary function tests
. DEXA scan and metabolic bone panel
. Genetic karyotyping

Correct Answer & Explanation

. Echocardiogram and Renal Ultrasound

Explanation

Congenital scoliosis is frequently associated with VACTERL anomalies. Screening for genitourinary anomalies (renal US) and cardiac defects (echocardiogram), along with a total spine MRI for intraspinal anomalies, is standard.

Question 3803

Topic: 6. Spine

A 10-year-old boy presents with a left-sided thoracic scoliosis of 25 degrees. His neurologic examination is unremarkable. What is the most appropriate next step in evaluation?

. TLSO bracing
. Observation in 6 months
. MRI of the total spine
. CT of the thoracic spine
. Flexion-extension radiographs

Correct Answer & Explanation

. MRI of the total spine

Explanation

A left-sided thoracic curve is atypical for adolescent idiopathic scoliosis and raises high suspicion for an intraspinal anomaly, such as a syrinx, Chiari malformation, or tethered cord. A total spine MRI is strongly indicated.

Question 3804

Topic: 6. Spine

A 9-month-old boy is diagnosed with infantile idiopathic scoliosis. His rib-vertebral angle difference (RVAD) of Mehta is measured at 25 degrees. What is the most likely clinical course?

. Spontaneous resolution over the next 2 years
. Slow progression until the onset of puberty
. Rapid progression requiring immediate posterior spinal fusion
. Progression requiring serial Mehta casting
. Development of associated major cardiac anomalies

Correct Answer & Explanation

. Progression requiring serial Mehta casting

Explanation

An RVAD greater than 20 degrees indicates a high likelihood of curve progression in infantile idiopathic scoliosis (progressive phase). Treatment typically involves serial elongation-derotation-flexion (Mehta) casting to control the curve and allow spinal growth.

Question 3805

Topic: 6. Spine
A 3-year-old girl is found to have congenital scoliosis due to a fully segmented hemivertebra. Which of the following screening tests must be obtained to evaluate for commonly associated anomalies?
. Brain MRI and EEG
. Echocardiogram and Pulmonary Function Tests
. Renal ultrasound and Spinal MRI
. Upper extremity radiographs
. Karyotype analysis

Correct Answer & Explanation

. Renal ultrasound and Spinal MRI

Explanation

Congenital scoliosis has a high association with VACTERL anomalies, intraspinal anomalies (e.g., tethered cord, diastematomyelia), and genitourinary defects. A spinal MRI and renal ultrasound are mandatory screening tools for these patients.

Question 3806

Topic: 6. Spine

A 14-year-old non-ambulatory male with Duchenne muscular dystrophy has a 60-degree thoracolumbar scoliosis and severe pelvic obliquity. What is the most appropriate surgical strategy?

. Anterior spinal fusion only
. Posterior spinal fusion extending to L4
. Posterior spinal fusion extending to the pelvis
. Growing rod construct
. Vertebral Body Tethering (VBT)

Correct Answer & Explanation

. Posterior spinal fusion extending to the pelvis

Explanation

In non-ambulatory patients with Duchenne muscular dystrophy and severe scoliosis with pelvic obliquity, posterior spinal fusion must typically extend to the pelvis. This is necessary to correct the obliquity, prevent pressure sores, and provide a stable sitting balance.

Question 3807

Topic: Thoracolumbar Spine & Deformity

In a young child with early-onset scoliosis and multiple fused ribs, vertical expandable prosthetic titanium rib (VEPTR) surgery is indicated primarily to treat or prevent which condition?

. Cor pulmonale
. Thoracic insufficiency syndrome
. Aortic root dilation
. Progression of pelvic obliquity
. Superior mesenteric artery syndrome

Correct Answer & Explanation

. Thoracic insufficiency syndrome

Explanation

VEPTR devices are primarily used in early-onset scoliosis with associated rib fusions to expand the constrained hemithorax. This expansion treats or prevents thoracic insufficiency syndrome, allowing for more normal lung development and volume.

Question 3808

Topic: 6. Spine

A 14-year-old boy with Duchenne muscular dystrophy presents with a progressive 55-degree thoracolumbar scoliosis. His forced vital capacity (FVC) is 40% of predicted. What is the recommended management?

. Full-time TLSO bracing
. Botulinum toxin injections to the paraspinal muscles
. Posterior spinal fusion extending to the pelvis
. Anterior spinal fusion only
. Observation until the curve reaches 75 degrees

Correct Answer & Explanation

. Posterior spinal fusion extending to the pelvis

Explanation

In Duchenne muscular dystrophy, scoliosis is relentlessly progressive and bracing is poorly tolerated and ineffective. Posterior spinal fusion to the pelvis is indicated for progressive curves >20-30 degrees while pulmonary function (FVC >30-40%) is still adequate for surgery.

Question 3809

Topic: 6. Spine

A 6-month-old boy has a left-sided infantile idiopathic scoliosis with a Cobb angle of 35 degrees. The Rib-Vertebral Angle Difference (RVAD) of Mehta is measured at 25 degrees. What is the most likely natural history of this curve without treatment?

. Spontaneous resolution by age 2
. Slow progression until puberty, followed by stabilization
. Rapid progression requiring early operative intervention or casting
. Stabilization at the current Cobb angle
. Development of an intra-spinal syrinx

Correct Answer & Explanation

. Rapid progression requiring early operative intervention or casting

Explanation

Mehta's Rib-Vertebral Angle Difference (RVAD) predicts progression in infantile idiopathic scoliosis. An RVAD greater than 20 degrees is highly predictive of rapid curve progression, necessitating aggressive early treatment such as serial casting.

Question 3810

Topic: 6. Spine

A 3-year-old boy presents with a progressive spinal deformity. Radiographs reveal a fully segmented hemivertebra at T8 with a localized scoliotic curve of 38 degrees that has progressed 10 degrees over the last year. What is the recommended treatment?

. Observation until age 10
. Full-time TLSO bracing
. Hemivertebra excision and short segment fusion
. Growing rod construct from T2 to L4
. Halo-gravity traction followed by casting

Correct Answer & Explanation

. Hemivertebra excision and short segment fusion

Explanation

A fully segmented hemivertebra has high growth potential and typically causes progressive congenital scoliosis. Early hemivertebra excision and short segment fusion is the treatment of choice to prevent severe structural deformity while sparing unaffected motion segments.

Question 3811

Topic: 6. Spine

A 14-year-old elite gymnast presents with persistent low back pain. Radiographs demonstrate a Grade II L5-S1 isthmic spondylolisthesis. She has failed 6 months of rest, bracing, and physical therapy. What is the most appropriate surgical treatment?

. L5-S1 posterior spinal fusion
. L4-L5 posterior spinal fusion
. L5 pars interarticularis repair
. Laminectomy alone
. Anterior lumbar interbody fusion alone

Correct Answer & Explanation

. L5-S1 posterior spinal fusion

Explanation

For a symptomatic low-grade (Grade I or II) isthmic spondylolisthesis that fails conservative management, an in-situ L5-S1 posterior spinal fusion (with or without decompression depending on radicular symptoms) is the standard surgical treatment. Pars repair is typically reserved for L1-L4 defects without significant slip.

Question 3812

Topic: 6. Spine

Which of the following vertebral anomalies carries the highest risk for rapid curve progression in congenital scoliosis, often necessitating early surgical intervention?

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

Correct Answer & Explanation

. Unilateral unsegmented bar with a contralateral hemivertebra

Explanation

A unilateral unsegmented bar combined with a contralateral hemivertebra at the same level has the highest rate of progression (often 5-10 degrees per year) because growth is tethered on one side and accelerated on the other. Early surgical fusion is invariably required.

Question 3813

Topic: 6. Spine

A 15-year-old boy presents with progressive mid-back pain and a rounded posture. Standing lateral radiographs reveal a thoracic kyphosis of 60 degrees. Which of the following radiographic findings confirms the diagnosis of classic Scheuermann's disease?

. Anterior wedging of at least 5 degrees in one vertebra
. Anterior wedging of at least 5 degrees in three consecutive vertebrae
. Schmorl's nodes in at least two adjacent vertebrae
. A sharp angular kyphosis with a single hypoplastic vertebra
. Loss of thoracic lordosis with apical rotation

Correct Answer & Explanation

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

Explanation

Sorensen's criteria for the diagnosis of classic Scheuermann's kyphosis require anterior wedging of at least 5 degrees in three or more consecutive vertebrae. Other common but non-diagnostic findings include Schmorl's nodes and endplate irregularities.

Question 3814

Topic: Thoracolumbar Spine & Deformity
A 15-year-old gymnast presents with persistent low back pain and tight hamstrings. Radiographs reveal a Grade III isthmic spondylolisthesis at L5-S1. She has failed 6 months of nonoperative treatment. What is the most appropriate surgical intervention?
. Pars interarticularis repair (Buck's procedure)
. L5-S1 anterior lumbar interbody fusion without posterior fixation
. L5-S1 posterior instrumented fusion
. Laminectomy without fusion
. T10 to pelvis posterior fusion

Correct Answer & Explanation

. L5-S1 posterior instrumented fusion

Explanation

For high-grade (Grade III or higher) isthmic spondylolisthesis failing conservative care, an instrumented posterior spinal fusion (with or without interbody support) is indicated. Pars repair is reserved for young patients with normal alignment and no slip.

Question 3815

Topic: 6. Spine

In a 9-month-old male with a left thoracic curve measuring 25 degrees, the rib-vertebral angle difference (RVAD) of Mehta is measured at 28 degrees. What is the most likely natural history of this curve and the recommended treatment?

. Spontaneous resolution; observe
. Rapid progression; Boston brace
. Rapid progression; serial Mehta casting
. Rigid deformity; immediate spinal fusion
. Neurodevelopmental delay; brain MRI

Correct Answer & Explanation

. Rapid progression; serial Mehta casting

Explanation

An RVAD greater than 20 degrees in infantile idiopathic scoliosis signifies a high risk for severe curve progression. Serial elongation-derotation-flexion (Mehta) casting is the treatment of choice to halt progression.

Question 3816

Topic: 6. Spine

A 12-year-old non-ambulatory male with Duchenne muscular dystrophy presents with a progressive thoracolumbar scoliosis of 55 degrees. His forced vital capacity (FVC) is currently 45% of predicted. What is the most appropriate management?

. TLSO bracing until skeletal maturity
. Observation until the curve exceeds 70 degrees
. Posterior spinal fusion from the upper thoracic spine to the pelvis
. Anterior spinal fusion only
. Growing rod constructs

Correct Answer & Explanation

. Posterior spinal fusion from the upper thoracic spine to the pelvis

Explanation

Scoliosis in Duchenne muscular dystrophy is relentlessly progressive. Posterior fusion to the pelvis is indicated when curves exceed 20-30 degrees and the patient's FVC is still >30% to tolerate the procedure.

Question 3817

Topic: 6. Spine

A 15-year-old Risser 4 male with adolescent idiopathic scoliosis has a single right thoracic curve measuring 55 degrees. He is entirely asymptomatic. What is the primary indication for performing a posterior spinal fusion in this patient?

. Prevention of impending cardiopulmonary compromise
. Immediate cosmetic improvement
. Prevention of continued curve progression into adulthood
. Correction of coronal balance only
. Prevention of future spinal stenosis

Correct Answer & Explanation

. Prevention of continued curve progression into adulthood

Explanation

Thoracic curves greater than 50 degrees at skeletal maturity have a high risk of continued progression (approximately 1 degree per year) throughout adulthood. Surgical fusion is indicated primarily to halt this lifelong progression.

Question 3818

Topic: 6. Spine
A newborn is evaluated in the nursery and noted to have a spinal asymmetry. Radiographs reveal a fully segmented hemivertebra at T8, confirming a diagnosis of congenital scoliosis. Which of the following screening evaluations is most critical in the initial workup of this patient?
. Renal ultrasound and echocardiogram
. MRI of the brain and cervical spine
. Pulmonary function tests
. Dynamic flexion-extension radiographs
. Bilateral hip ultrasounds

Correct Answer & Explanation

. Renal ultrasound and echocardiogram

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies, specifically genitourinary anomalies (up to 30%) and congenital heart defects (up to 15%). Consequently, screening with a renal ultrasound and an echocardiogram is standard practice.

Question 3819

Topic: Thoracolumbar Spine & Deformity

A 15-year-old male gymnast complains of worsening lower back pain over the past 3 weeks, exacerbated by extension. Plain radiographs show no obvious cortical break or spondylolisthesis. Which imaging modality is most sensitive for detecting an early, active pars interarticularis stress reaction?

. Non-contrast CT scan of the lumbar spine
. T2-weighted STIR or fat-suppressed MRI
. Standing lateral flexion-extension radiographs
. Technetium-99m single-photon emission CT (SPECT) scan
. Ultrasound of the lumbar paraspinal muscles

Correct Answer & Explanation

. T2-weighted STIR or fat-suppressed MRI

Explanation

MRI with T2 fat-suppressed or STIR sequences is highly sensitive for detecting bone marrow edema indicative of an early pars stress reaction before a definitive fracture occurs, successfully avoiding the ionizing radiation associated with CT or SPECT scans.

Question 3820

Topic: 6. Spine

A 16-year-old boy presents with progressive mid-back pain and a rounded posture. Standing lateral radiographs reveal a thoracic kyphosis of 65 degrees. According to the classic Sorensen criteria, what radiographic finding is required to definitively diagnose Scheuermann's kyphosis?

. Anterior wedging of at least 5 degrees in three consecutive apical vertebrae
. The presence of Schmorl's nodes in at least two adjacent vertebrae
. Endplate irregularities combined with any degree of rigid kyphosis
. Pedicle thinning at the apex of the curve
. A single vertebra with greater than 15 degrees of anterior wedging

Correct Answer & Explanation

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

Explanation

The Sorensen criteria for diagnosing Scheuermann's kyphosis require anterior wedging of 5 degrees or more in at least three consecutive apical vertebrae, typically alongside a regional kyphosis greater than 40-45 degrees.

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