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Thoracolumbar Spine & Deformity MCQs

Practice Set 12 of 49

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

Question 221

Topic: Thoracolumbar Spine & Deformity
What is the typical radiological feature that differentiates degenerative spondylolisthesis from isthmic spondylolisthesis?
. Sacral spina bifida occulta
. Pars interarticularis defect
. Intact pars interarticularis with facet joint degeneration
. Trapezoidal L5 vertebral body
. High-grade slip (>50%)

Correct Answer & Explanation

. Intact pars interarticularis with facet joint degeneration

Explanation

Degenerative spondylolisthesis (Wiltse-Newman Type III) is characterized by an intact pars interarticularis, with anterior slippage resulting from chronic instability due to degenerative changes in the facet joints and intervertebral disc. Isthmic spondylolisthesis (Type II) is defined by a defect in the pars. Type I (Dysplastic) can have a trapezoidal L5 and spina bifida. High-grade slips can occur in both types, though less common in Type III.

Question 222

Topic: Thoracolumbar Spine & Deformity

A 12-year-old active child presents with an L5-S1 Grade II spondylolisthesis that has shown progression from Grade I over the past 6 months. He has moderate back pain but no neurological deficits. Conservative treatment has been initiated but the slip continues to progress. What is the most appropriate next step in management?

. Continue conservative management indefinitely
. Perform L5-S1 posterolateral fusion in situ
. Attempt aggressive reduction and fusion
. Decompression alone at L5-S1
. Initiate high-dose corticosteroid therapy

Correct Answer & Explanation

. Perform L5-S1 posterolateral fusion in situ

Explanation

Correct Answer: BIn a child with a progressive spondylolisthesis (especially Grade II or higher) despite conservative management, surgical stabilization is indicated to prevent further slip and potential neurological complications. L5-S1 in situ posterolateral fusion is generally preferred for these cases. Aggressive reduction is associated with higher risks of neurological injury, and decompression alone would not address the instability or progression. Corticosteroids are not indicated.

Question 223

Topic: Thoracolumbar Spine & Deformity

In an adult patient with isthmic spondylolisthesis, which muscle group is characteristically tight and often contributes to sagittal imbalance and altered gait?

. Quadriceps femoris
. Gluteus maximus
. Hamstrings
. Psoas major
. Rectus abdominis

Correct Answer & Explanation

. Hamstrings

Explanation

Correct Answer: CHamstring tightness is a common clinical finding in patients with spondylolisthesis, particularly in children and adolescents, but also in adults. It is thought to be a compensatory mechanism to maintain sagittal balance and prevent further anterior shear forces on the unstable segment, often leading to a 'pelvic tilt' or 'waddling' gait.

Question 224

Topic: Thoracolumbar Spine & Deformity

What is the primary advantage of a Transforaminal Lumbar Interbody Fusion (TLIF) over a Posterior Lumbar Interbody Fusion (PLIF) for spondylolisthesis correction?

. Allows for wider central canal decompression
. Requires less posterior muscle dissection
. Provides better lordosis restoration
. Offers a lower risk of dural tear and nerve root injury
. Enables multi-level fusion more easily

Correct Answer & Explanation

. Offers a lower risk of dural tear and nerve root injury

Explanation

Correct Answer: DTLIF offers a unilateral approach to the disc space, allowing for disc excision and cage placement through the foramen. This typically involves less retraction of the thecal sac and nerve roots compared to PLIF, which requires bilateral laminectomy and retraction, thereby generally carrying a lower risk of dural tear and nerve root injury. While both can restore lordosis and achieve fusion, the safety profile regarding dural injury is a key advantage of TLIF.

Question 225

Topic: Thoracolumbar Spine & Deformity

A 7-year-old patient presents with a 55-degree idiopathic scoliosis. The patient's parents report that the curve was first noticed when the child was 5 years old. The orthopedic surgeon is particularly concerned about the potential for cardiorespiratory compromise. What classification of scoliosis best describes this patient's condition, highlighting the surgeon's primary concern?

. A. Adolescent Idiopathic Scoliosis (AIS).
. B. Juvenile Idiopathic Scoliosis (JIS).
. C. Infantile Idiopathic Scoliosis (IIS).
. D. Early-Onset Scoliosis (EOS).
. E. Late-Onset Scoliosis (LOS).

Correct Answer & Explanation

. D. Early-Onset Scoliosis (EOS).

Explanation

Correct Answer: DExplanation:The text defines 'Early-onset scoliosis' as having its onset before the age of 7 (or 5 by some classifications). It specifically highlights that EOS is 'associated with a high risk of cardiorespiratory compromise as the developing heart and lungs may be affected.' This patient's curve was noticed at age 5, placing it squarely in the early-onset category, and the surgeon's concern directly aligns with the key risk factor for EOS.A. Adolescent Idiopathic Scoliosis (AIS).AIS has its onset after age 10 to maturity. This patient's onset was at age 5, so it does not fit AIS.B. Juvenile Idiopathic Scoliosis (JIS).JIS has its onset between 3 and 10 years. While the onset at age 5 falls within this range, the term 'Early-Onset Scoliosis' is a broader classification specifically used to group all idiopathic scoliosis cases with onset before age 7 (or 5) due to the shared risk of cardiorespiratory compromise, which is the primary concern in the question.C. Infantile Idiopathic Scoliosis (IIS).IIS has its onset between 0 and 3 years. This patient's onset at age 5 is outside this range.E. Late-Onset Scoliosis (LOS).LOS has its onset after the age of 7. This patient's onset was at age 5, so it is not late-onset.

Question 226

Topic: Thoracolumbar Spine & Deformity

A 4-year-old child is diagnosed with a progressive idiopathic scoliosis. The curve measures 40 degrees. The parents are counseled on the potential long-term complications. Which of the following is the most significant long-term risk specifically associated with this type of scoliosis, as highlighted in the case?

. A. Increased risk of severe back pain in adulthood.
. B. Development of significant leg length discrepancy.
. C. Progressive cardiorespiratory compromise leading to decreased life expectancy.
. D. Higher incidence of spondylolisthesis in later life.
. E. Increased likelihood of neurological deficits due to spinal cord compression.

Correct Answer & Explanation

. C. Progressive cardiorespiratory compromise leading to decreased life expectancy.

Explanation

Correct Answer: CExplanation:The patient is 4 years old with idiopathic scoliosis, which falls under the 'Early-onset scoliosis' category (onset before age 7). The text explicitly states for early-onset scoliosis: 'The developing heart and lungs may be affected by the scoliosis. Cardiorespiratory compromise may result from a progressive curve resulting in decreased life expectancy.' This is the most significant and unique long-term risk highlighted for this specific age group.A. Increased risk of severe back pain in adulthood.While scoliosis patients can experience back pain, the text notes that scoliosis is 'not typically thought of as a painful condition,' and severe pain may indicate an underlying cause. Cardiorespiratory compromise is a more specific and severe risk for early-onset scoliosis.B. Development of significant leg length discrepancy.Leg length discrepancy can mimic scoliosis but is not a direct long-term complication of idiopathic scoliosis itself.D. Higher incidence of spondylolisthesis in later life.Spondylolisthesis is a separate spinal condition and not a direct long-term complication of idiopathic scoliosis.E. Increased likelihood of neurological deficits due to spinal cord compression.While severe curves can theoretically lead to neurological issues, this is less common in idiopathic scoliosis compared to congenital scoliosis with intraspinal anomalies. Cardiorespiratory compromise is the primary concern for early-onset idiopathic scoliosis.

Question 227

Topic: Thoracolumbar Spine & Deformity

A 68-year-old female presents with adult spinal deformity and severe flatback syndrome. Preoperative radiographic evaluation reveals a Pelvic Incidence (PI) of 58 degrees. To optimize her postoperative sagittal balance and minimize the risk of adjacent segment disease or proximal junctional kyphosis, what should be the target postoperative Lumbar Lordosis (LL)?

. 28 degrees
. 38 degrees
. 48 degrees
. 58 degrees
. 78 degrees

Correct Answer & Explanation

. 58 degrees

Explanation

In adult spinal deformity surgery, the target lumbar lordosis should generally be within 9-10 degrees of the patient's pelvic incidence (PI). Thus, for a PI of 58, a target LL of approximately 58 (ideal range 48-68) minimizes the risk of sagittal imbalance and subsequent complications.

Question 228

Topic: Thoracolumbar Spine & Deformity

A 65-year-old male with adult spinal deformity presents with severe low back pain and forward truncal tilt. Radiographs demonstrate a pelvic incidence (PI) of 65 degrees. To achieve optimal sagittal balance postoperatively, what should be the surgical target for his lumbar lordosis (LL)?

. 25 degrees
. 35 degrees
. 45 degrees
. 55 degrees
. 75 degrees

Correct Answer & Explanation

. 55 degrees

Explanation

Optimal sagittal alignment is achieved when the patient's lumbar lordosis matches their intrinsic pelvic incidence. The widely accepted target rule is PI minus LL should be less than or equal to 10 degrees; thus, a PI of 65 requires an LL of at least 55 degrees.

Question 229

Topic: Thoracolumbar Spine & Deformity

In a patient with an L5-S1 isthmic spondylolisthesis who presents with severe radiating leg pain, which nerve root is most commonly compressed, and what is the primary anatomic location of this compression?

. L4 nerve root in the lateral recess
. L5 nerve root in the neural foramen
. S1 nerve root in the lateral recess
. S1 nerve root in the neural foramen
. L5 nerve root in the central canal

Correct Answer & Explanation

. L5 nerve root in the neural foramen

Explanation

In isthmic spondylolisthesis at L5-S1, the exiting L5 nerve root is most commonly compressed within the neural foramen. The compression is typically caused by the hypertrophic fibrocartilaginous pseudarthrosis tissue at the pars interarticularis defect.

Question 230

Topic: Thoracolumbar Spine & Deformity

A 16-year-old male undergoes posterior spinal fusion with instrumental reduction for a high-grade (Meyerding Grade IV) L5-S1 isthmic spondylolisthesis. Postoperatively, he exhibits unilateral foot drop and weakness in great toe extension. Injury to which neural structure is the most likely cause?

. L4 nerve root
. L5 nerve root
. S1 nerve root
. S2 nerve root
. Sciatic nerve trunk

Correct Answer & Explanation

. L5 nerve root

Explanation

Complete reduction of high-grade lumbosacral spondylolisthesis significantly stretches the L5 nerve root, which is tethered over the sacral ala. This iatrogenic traction injury classically presents as an L5 palsy with foot drop and EHL weakness.

Question 231

Topic: Thoracolumbar Spine & Deformity

A 70-year-old female with adult degenerative scoliosis and progressive sagittal imbalance presents with a measured pelvic tilt (PT) of 35 degrees. What compensatory mechanism does this elevated pelvic tilt primarily indicate?

. Pelvic anteversion to maintain horizontal gaze
. Pelvic retroversion to compensate for the loss of lumbar lordosis
. Hip flexion to increase the sagittal vertical axis
. Knee extension to reduce energy expenditure
. Ankle plantarflexion to shift the center of gravity anteriorly

Correct Answer & Explanation

. Pelvic retroversion to compensate for the loss of lumbar lordosis

Explanation

An abnormally high pelvic tilt indicates pelvic retroversion. In the setting of severe loss of lumbar lordosis (positive sagittal imbalance), the pelvis retroverts as a compensatory mechanism to shift the body's center of gravity posteriorly over the hips and maintain upright posture.

Question 232

Topic: Thoracolumbar Spine & Deformity

A 15-year-old male presents with rigid thoracic kyphosis. Radiographs demonstrate Schmorl nodes, endplate irregularities, and anterior vertebral wedging. To meet Sorensen's strict criteria for the diagnosis of Scheuermann's kyphosis, what is the minimum degree of wedging required, and across how many consecutive vertebrae?

. At least 5 degrees across 2 consecutive vertebrae
. At least 5 degrees across 3 consecutive vertebrae
. At least 10 degrees across 2 consecutive vertebrae
. At least 10 degrees across 3 consecutive vertebrae
. At least 15 degrees across 4 consecutive vertebrae

Correct Answer & Explanation

. At least 5 degrees across 3 consecutive vertebrae

Explanation

Sorensen's classical radiographic criteria for Scheuermann's kyphosis require anterior wedging of at least 5 degrees in three or more consecutive vertebrae. Associated findings include Schmorl nodes, endplate irregularities, and a kyphosis >45 degrees.

Question 233

Topic: Thoracolumbar Spine & Deformity

A 65-year-old female undergoes surgical correction for adult spinal deformity. Postoperative goals for sagittal realignment are critical for optimizing health-related quality of life (HRQOL) outcomes. Which of the following sets of spinopelvic parameters represents the recognized target thresholds for optimal surgical correction?

. Sagittal vertical axis (SVA) < 5 cm, Pelvic tilt (PT) < 20 degrees, and PI-LL mismatch < 10 degrees
. Sagittal vertical axis (SVA) < 10 cm, Pelvic tilt (PT) < 30 degrees, and PI-LL mismatch < 20 degrees
. Sagittal vertical axis (SVA) < 5 cm, Pelvic tilt (PT) < 10 degrees, and PI-LL mismatch < 5 degrees
. Sagittal vertical axis (SVA) < 2 cm, Pelvic tilt (PT) < 15 degrees, and PI-LL mismatch < 15 degrees
. Sagittal vertical axis (SVA) < 8 cm, Pelvic tilt (PT) < 25 degrees, and PI-LL mismatch < 10 degrees

Correct Answer & Explanation

. Sagittal vertical axis (SVA) < 5 cm, Pelvic tilt (PT) < 20 degrees, and PI-LL mismatch < 10 degrees

Explanation

The Schwab criteria for optimal sagittal realignment in adult spinal deformity include an SVA < 5 cm, PT < 20 degrees, and a mismatch between pelvic incidence and lumbar lordosis (PI-LL) of < 10 degrees. Achieving these parameters is strongly correlated with improved patient-reported outcomes.

Question 234

Topic: Thoracolumbar Spine & Deformity

A 6-month-old infant is diagnosed with infantile idiopathic scoliosis. Measurement of the rib-vertebral angle difference (RVAD) of Mehta is obtained. Which of the following RVAD values and phase descriptions is most strongly predictive of curve progression?

. RVAD < 10 degrees, Phase 1
. RVAD > 10 degrees, Phase 1
. RVAD < 20 degrees, Phase 2
. RVAD > 20 degrees, Phase 2
. RVAD > 20 degrees, Phase 1

Correct Answer & Explanation

. RVAD > 20 degrees, Phase 2

Explanation

An RVAD greater than 20 degrees is highly predictive of curve progression in infantile idiopathic scoliosis. Phase 2 (where the rib head overlaps the vertebral body) combined with an RVAD > 20 degrees strongly indicates a progressive curve requiring intervention.

Question 235

Topic: Thoracolumbar Spine & Deformity
A 10-year-old girl presents with back pain and a severe grade III spondylolisthesis at L5-S1. Radiographs demonstrate a high slip angle, a dome-shaped sacrum, and a trapezoidal L5 vertebral body. The pars interarticularis is elongated but intact. According to the Wiltse classification, which type of spondylolisthesis does this patient have?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type I (Dysplastic)

Explanation

Type I (Dysplastic) spondylolisthesis is characterized by congenital anomalies of the upper sacrum or L5 neural arch, such as a dome-shaped sacrum and trapezoidal L5. It often presents in children with a high slip angle and an intact but elongated pars, carrying a high risk of progression.

Question 236

Topic: Thoracolumbar Spine & Deformity

A 68-year-old male is being evaluated for sagittal plane deformity. His pelvic incidence (PI) is 55 degrees, and his sacral slope (SS) is 35 degrees. What is his pelvic tilt (PT)?

. 10 degrees
. 15 degrees
. 20 degrees
. 55 degrees
. 90 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

The geometric relationship of spinopelvic parameters dictates that Pelvic Incidence (PI) equals Pelvic Tilt (PT) plus Sacral Slope (SS). Given PI = 55 and SS = 35, the PT must be 20 degrees. (Wait, 55 - 35 = 20. The ans index points to 20 degrees.)

Question 237

Topic: Thoracolumbar Spine & Deformity

When evaluating skeletal maturity in a female patient with adolescent idiopathic scoliosis, the Sanders Simplified Skeletal Maturity Scale (SSMS) utilizing a left hand radiograph is obtained. Which Sanders stage correlates with the peak height velocity, indicating the period of highest risk for rapid curve progression?

. Stage 1
. Stage 3
. Stage 5
. Stage 7
. Stage 8

Correct Answer & Explanation

. Stage 3

Explanation

Sanders Stage 3 (Adolescent Early) correlates with the rapid acceleration of the adolescent growth spurt and peak height velocity. This stage represents the time of maximum vulnerability for rapid curve progression in idiopathic scoliosis.

Question 238

Topic: Thoracolumbar Spine & Deformity

Which of the following best describes the fundamental relationship between spinopelvic parameters?

. Pelvic Tilt = Pelvic Incidence + Sacral Slope
. Pelvic Incidence = Pelvic Tilt + Sacral Slope
. Sacral Slope = Pelvic Tilt + Pelvic Incidence
. Pelvic Incidence = Lumbar Lordosis + Pelvic Tilt
. Pelvic Tilt = Lumbar Lordosis - Sacral Slope

Correct Answer & Explanation

. Pelvic Incidence = Pelvic Tilt + Sacral Slope

Explanation

Pelvic incidence (PI) is a fixed morphological parameter unique to each individual. It is defined mathematically as the sum of Pelvic Tilt (PT) and Sacral Slope (SS).

Question 239

Topic: Thoracolumbar Spine & Deformity
According to the Wiltse classification, degenerative spondylolisthesis belongs to which type?
. Type I
. Type II
. Type III
. Type IV
. Type V

Correct Answer & Explanation

. Type III

Explanation

In the Wiltse classification of spondylolisthesis, Type I is Dysplastic, Type II is Isthmic, Type III is Degenerative, Type IV is Traumatic, Type V is Pathologic, and Type VI is Iatrogenic.

Question 240

Topic: Thoracolumbar Spine & Deformity

Which anatomic variant is a well-established risk factor for the development of degenerative spondylolisthesis at the L4-L5 level?

. Coronally oriented facet joints
. Sagittally oriented facet joints
. Transitional lumbosacral vertebra
. Short pedicles
. Congenital absence of the pars interarticularis

Correct Answer & Explanation

. Sagittally oriented facet joints

Explanation

Sagittally oriented facet joints provide less resistance to anterior shear forces compared to coronally oriented facets, making them a primary biomechanical risk factor for degenerative spondylolisthesis.

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