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Thoracolumbar Spine & Deformity MCQs

Practice Set 40 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 781

Topic: Thoracolumbar Spine & Deformity

A 74-year-old female with a prior long segment lumbar fusion (T10-pelvis) for scoliosis is scheduled for a THA. How does her altered spinopelvic biomechanics influence acetabular component positioning?

. She has a decreased risk of anterior dislocation in extension
. The stiff pelvis cannot roll back during hip flexion, requiring increased cup anteversion to prevent posterior dislocation
. The acetabular cup should be placed in maximum retroversion
. Standard cup positioning (40 degrees inclination, 20 degrees anteversion) is optimal
. She requires a fully constrained liner routinely as first-line treatment

Correct Answer & Explanation

. The stiff pelvis cannot roll back during hip flexion, requiring increased cup anteversion to prevent posterior dislocation

Explanation

A fused lumbar spine cannot flex (loss of posterior pelvic tilt/rollback) to accommodate hip flexion, placing the patient at a high risk for posterior dislocation. The acetabular component should be placed in increased anteversion and inclination to compensate for this stiffness.

Question 782

Topic: Thoracolumbar Spine & Deformity

A 55-year-old female presents with severe low back pain and radiculopathy, progressive kyphoscoliosis, and significant sagittal imbalance. Preoperative planning for corrective spinal fusion involves assessing multiple radiographic parameters. Which of the following parameters is considered the MOST critical for achieving durable long-term surgical correction and minimizing proximal junctional kyphosis (PJK) in adult spinal deformity surgery?

. Scoliosis Cobb angle.
. Pelvic incidence (PI).
. Lumbar lordosis (LL).
. Pelvic tilt (PT).
. Sacral slope (SS).

Correct Answer & Explanation

. Pelvic incidence (PI).

Explanation

While all listed parameters are important in evaluating spinal deformity, the relationship between Pelvic Incidence (PI) and Lumbar Lordosis (LL) is considered the MOST critical for achieving durable long-term surgical correction and minimizing complications like proximal junctional kyphosis (PJK).Option A (Scoliosis Cobb angle) quantifies coronal deformity but is less critical for sagittal balance and PJK risk than sagittal parameters.Option B (Pelvic Incidence, PI) is an anatomical, fixed pelvic parameter that dictates the ideal lumbar lordosis for an individual. Achieving a lumbar lordosis that closely matches PI (PI-LL mismatch < 10 degrees) is paramount for restoring sagittal balance. A mismatch greater than 10 degrees is strongly associated with increased risk of revision surgery, PJK, and poorer clinical outcomes. It is the target that guides the amount of lordosis needed.Option C (Lumbar Lordosis, LL) is a modifiable parameter and a key component of sagittal balance, but its 'ideal' value is determined by PI. Simply achieving a 'normal' LL without considering PI can lead to persistent sagittal imbalance.Option D (Pelvic Tilt, PT) is a compensatory mechanism. High PT indicates the patient is retroverting the pelvis to compensate for thoracic kyphosis or insufficient lumbar lordosis. While important, it's an indicator of imbalance, not the primary target for correction.Option E (Sacral Slope, SS) is also a component of sagittal alignment and influences PI (PI = SS + PT), but PI is the fundamental driving parameter for ideal LL.

Question 783

Topic: Thoracolumbar Spine & Deformity

In patients with SMA, neuromuscular scoliosis often presents early and progresses rapidly. What is the typical curve pattern and sagittal profile associated with SMA scoliosis?

. Right thoracic curve with significant thoracic lordosis
. Left lumbar curve with hyperkyphosis
. Long, sweeping 'C'-shaped curve with pelvic obliquity and collapsed sagittal profile
. Short, sharp structural curve at the thoracolumbar junction
. Double major curve with preserved lumbar lordosis

Correct Answer & Explanation

. Long, sweeping 'C'-shaped curve with pelvic obliquity and collapsed sagittal profile

Explanation

Neuromuscular scoliosis, such as that seen in SMA, typically presents as a long, sweeping 'C'-shaped thoracolumbar curve that extends to the pelvis, leading to significant pelvic obliquity. Due to truncal weakness, these patients often have a collapsed sagittal profile (loss of physiological thoracic kyphosis and lumbar lordosis, often resulting in a global kyphosis when seated).

Question 784

Topic: Thoracolumbar Spine & Deformity

A 2-year-old with SMA Type II is being evaluated for orthotic management to aid in supported standing. Which of the following is the primary goal of standing programs and lower extremity orthoses in a non-ambulatory child with SMA?

. To permanently reverse fixed joint contractures
. To promote and eventually achieve independent walking
. To improve bone mineral density, bowel function, and respiratory mechanics
. To definitively halt the progression of neuromuscular scoliosis
. To upregulate SMN2 gene expression through mechanical loading

Correct Answer & Explanation

. To improve bone mineral density, bowel function, and respiratory mechanics

Explanation

In non-ambulatory children with SMA (Type II), supported standing programs (using standers or Knee-Ankle-Foot Orthoses) are highly recommended. While they do not teach the child to walk independently, reverse fixed contractures, or cure scoliosis, they are crucial for improving/maintaining bone mineral density, preventing severe contractures, aiding bowel and bladder function, and improving psychological well-being and respiratory mechanics.

Question 785

Topic: Thoracolumbar Spine & Deformity

During preoperative evaluation for scoliosis surgery in a 12-year-old with SMA Type II, the pulmonologist performs spirometry. Which of the following pulmonary function test findings indicates an increased risk of prolonged postoperative mechanical ventilation?

. Forced Vital Capacity (FVC) less than 30% of predicted
. FEV1/FVC ratio greater than 80%
. Total lung capacity (TLC) greater than 120% of predicted
. Peak Expiratory Flow Rate (PEFR) greater than 80% of predicted
. Normal maximum inspiratory pressure (MIP)

Correct Answer & Explanation

. Forced Vital Capacity (FVC) less than 30% of predicted

Explanation

Patients with SMA have restrictive lung disease due to intercostal muscle weakness. An FVC of less than 30% to 40% of predicted is a major risk factor for postoperative pulmonary complications and the need for prolonged ventilation.

Question 786

Topic: Thoracolumbar Spine & Deformity
A 12-year-old competitive gymnast presents with severe low back pain and radicular pain radiating down her posterior left leg. Lateral radiographs demonstrate a Meyerding Grade IV isthmic spondylolisthesis at L5-S1 with a slip angle of 55 degrees. What is the most appropriate surgical treatment?
. L5-S1 posterior in situ fusion without decompression
. L5 laminectomy and direct repair of the pars defect
. L4-S1 posterior instrumented fusion with partial reduction and decompression
. Anterior lumbar interbody fusion (ALIF) alone
. Physical therapy, bracing for 6 months, and activity modification

Correct Answer & Explanation

. L4-S1 posterior instrumented fusion with partial reduction and decompression

Explanation

High-grade spondylolisthesis (Meyerding Grade III-V) with radicular symptoms and a high slip angle (>40-50 degrees) carries a high risk of progression and pseudarthrosis if treated with in situ fusion. The standard of care is decompression of the compressed nerve roots, partial reduction of the slip angle, and posterior instrumented fusion, typically extending from L4 to S1.

Question 787

Topic: Thoracolumbar Spine & Deformity

In the evaluation of pediatric developmental (isthmic) spondylolisthesis at L5-S1, which of the following spinopelvic parameters is most strongly associated with an increased risk of severe slip progression?

. Decreased pelvic incidence
. Increased pelvic incidence
. Decreased sacral slope
. Increased thoracic kyphosis
. Decreased lumbar lordosis

Correct Answer & Explanation

. Increased pelvic incidence

Explanation

Pelvic Incidence (PI) is an anatomical spinopelvic parameter that is fixed after skeletal maturity. A high PI results in a high shear stress at the lumbosacral junction. Patients with developmental, high-grade spondylolisthesis almost universally have a significantly higher pelvic incidence compared to the general population, which drives slip progression.

Question 788

Topic: Thoracolumbar Spine & Deformity
A 14-year-old female gymnast presents with severe lower back pain radiating down the posterior aspect of both thighs. Radiographs demonstrate a Grade III L5-S1 isthmic spondylolisthesis. Her pelvic incidence is 75 degrees and her slip angle is 50 degrees. She has failed 6 months of conservative management. What is the most appropriate surgical treatment?
. L5 pars interarticularis repair
. L5-S1 anterior lumbar interbody fusion (ALIF) only
. In situ L5-S1 posterolateral fusion without instrumentation
. L4-S1 posterior instrumented reduction and fusion with interbody support
. L5 complete laminectomy without fusion

Correct Answer & Explanation

. L4-S1 posterior instrumented reduction and fusion with interbody support

Explanation

This patient has a high-grade (Grade III) isthmic spondylolisthesis with high pelvic incidence and a high slip angle, all of which indicate severe sagittal imbalance and a high risk of progression. High-grade slips typically require posterior instrumented fusion extending to L4 (L4-S1), often with reduction and interbody support (ALIF or TLIF) to correct the severe slip angle, improve sagittal balance, and increase fusion rates. A simple pars repair is only appropriate for early Grade I slips without significant listhesis, and isolated in situ fusion for high-grade slips carries unacceptably high pseudoarthrosis rates.

Question 789

Topic: Thoracolumbar Spine & Deformity

In evaluating a patient with scoliosis, which of the following Cobb angle measurements typically warrants surgical intervention in an adolescent with progressive idiopathic scoliosis?

. 10-20 degrees
. 20-30 degrees
. 30-40 degrees
. 40-50 degrees
. Greater than 50 degrees

Correct Answer & Explanation

. Greater than 50 degrees

Explanation

For progressive idiopathic scoliosis in adolescents, surgical correction is generally recommended for curves greater than 45-50 degrees to prevent further progression and mitigate potential pulmonary compromise. Curves 20-40 degrees often warrant bracing, especially if progressive in a growing child. Curves less than 20 degrees are typically observed. The threshold for surgery can vary slightly based on skeletal maturity, curve pattern, and patient symptoms, but >50 degrees is a common general guideline.

Question 790

Topic: Thoracolumbar Spine & Deformity

Which type of scoliosis typically presents in adolescence, has no identifiable cause, and is the most common form?

. Congenital scoliosis.
. Neuromuscular scoliosis.
. Syndromic scoliosis.
. Adolescent idiopathic scoliosis.
. Degenerative scoliosis.

Correct Answer & Explanation

. Adolescent idiopathic scoliosis.

Explanation

Adolescent idiopathic scoliosis (AIS) is the most common type of scoliosis, affecting approximately 2-3% of adolescents. It typically presents in children aged 10-18 years, progresses during growth spurts, and has no identifiable underlying cause. Congenital scoliosis is due to vertebral anomalies. Neuromuscular scoliosis is associated with neurological conditions (e.g., cerebral palsy). Syndromic scoliosis is associated with specific syndromes. Degenerative scoliosis occurs in older adults due to spinal degeneration.

Question 791

Topic: Thoracolumbar Spine & Deformity

Regarding adult spondylolisthesis, which type is most commonly observed in patients over 50 years old?

. Dysplastic (congenital)
. Isthmic (spondylolytic)
. Degenerative
. Traumatic
. Pathologic

Correct Answer & Explanation

. Degenerative

Explanation

Degenerative spondylolisthesis is the most common type observed in patients over 50 years old. It results from chronic degenerative changes in the facet joints and intervertebral disc, leading to segmental instability and anterior slippage of one vertebra over another, most commonly at L4-L5. Isthmic spondylolisthesis, caused by a defect in the pars interarticularis (spondylolysis), is more common in younger individuals and athletes. Dysplastic is congenital, traumatic is due to acute injury, and pathologic is associated with tumors or metabolic bone disease.

Question 792

Topic: Thoracolumbar Spine & Deformity

Regarding idiopathic scoliosis, which finding on physical examination warrants the most concern for a non-idiopathic (e.g., congenital or neurological) etiology?

. Left thoracic curve
. Rib hump on forward bend test
. Progressive curve magnitude
. Normal neurological exam
. Associated leg length discrepancy

Correct Answer & Explanation

. Left thoracic curve

Explanation

A left thoracic curve is highly atypical for idiopathic scoliosis, which is overwhelmingly characterized by right thoracic curves. A left thoracic curve should prompt a thorough workup to rule out an underlying neurological (e.g., syrinx, tethered cord) or congenital cause. A rib hump is a common finding in idiopathic scoliosis. Progressive curve magnitude is a feature, not a differentiator from idiopathic. A normal neurological exam supports idiopathic. Leg length discrepancy can cause compensatory scoliosis, but the curve morphology (left thoracic) is a stronger indicator of non-idiopathic origin.

Question 793

Topic: Thoracolumbar Spine & Deformity

In the Thoracolumbar Injury Classification and Severity (TLICS) score, which of the following morphologic patterns is assigned the highest point value for injury morphology?

. Compression fracture
. Burst fracture
. Translation/Rotation
. Distraction
. Lateral wedge compression

Correct Answer & Explanation

. Distraction

Explanation

According to the TLICS system, distraction injuries receive 4 points for morphology, making them the highest weighted morphologic injury pattern. Translation/rotation receives 3 points, burst receives 2 points, and compression receives 1 point.

Question 794

Topic: Thoracolumbar Spine & Deformity

Which of the following clinical and anatomical features correctly differentiates degenerative spondylolisthesis from isthmic spondylolisthesis in the adult lumbar spine?

. Degenerative spondylolisthesis is most commonly observed at the L5-S1 level.
. Isthmic spondylolisthesis is most commonly observed at the L4-L5 level.
. Degenerative spondylolisthesis is obligatorily associated with a bilateral defect in the pars interarticularis.
. Degenerative spondylolisthesis is most commonly seen at L4-L5 with an intact pars interarticularis.
. Isthmic spondylolisthesis predominantly presents in females over the age of 65 due to severe facet arthropathy.

Correct Answer & Explanation

. Degenerative spondylolisthesis is most commonly seen at L4-L5 with an intact pars interarticularis.

Explanation

Degenerative spondylolisthesis most commonly occurs at the L4-L5 level and features an intact pars interarticularis, driven primarily by facet joint incompetence and disc degeneration (most common in older females). Isthmic spondylolisthesis most commonly occurs at L5-S1, involves a pars interarticularis defect (spondylolysis), and typically presents earlier in life.

Question 795

Topic: Thoracolumbar Spine & Deformity
According to the Wiltse classification of spondylolisthesis, which type is most commonly seen at the L5-S1 level and is caused by a bilateral defect in the pars interarticularis?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type II (Isthmic)

Explanation

Type II (Isthmic) spondylolisthesis is due to a defect in the pars interarticularis (spondylolysis) and most frequently occurs at L5-S1. This is the most common type in young patients and athletes. Degenerative (Type III) spondylolisthesis is most common at L4-L5 in older individuals. Type I (Dysplastic) involves congenital abnormalities of the upper sacrum or L5 arch.

Question 796

Topic: Thoracolumbar Spine & Deformity

A 70-year-old female with a previous L2-Pelvis fusion presents for a primary THA. Standing and sitting lateral radiographs reveal less than 10 degrees of change in her sacral slope. Due to her stiff spinopelvic complex, she is at the highest risk for which of the following complications, and how should cup position be adjusted?

. Anterior dislocation; increase cup anteversion
. Posterior dislocation; increase cup anteversion
. Anterior dislocation; decrease cup anteversion
. Posterior dislocation; decrease cup anteversion
. Superior dislocation; increase cup inclination

Correct Answer & Explanation

. Anterior dislocation; increase cup anteversion

Explanation

A stiff spinopelvic complex with prior lumbar fusion prevents normal posterior pelvic tilt during sitting. This lack of functional acetabular anteversion increases the risk of posterior dislocation, necessitating compensatory increased cup anteversion during surgery.

Question 797

Topic: Thoracolumbar Spine & Deformity

According to Sorensen's criteria, the strict radiographic diagnosis of classic Scheuermann's kyphosis requires anterior wedging of at least 5 degrees in a minimum of how many consecutive vertebrae?

. Two
. Three
. Four
. Five
. Six

Correct Answer & Explanation

. Two

Explanation

Sorensen's diagnostic criteria for Scheuermann's disease strictly require the presence of anterior wedging of 5 degrees or more in at least three consecutive vertebral bodies on a lateral radiograph.

Question 798

Topic: Thoracolumbar Spine & Deformity

A patient with a history of long-segment lumbar fusion (L2-Pelvis) is planned for a total hip arthroplasty. Because of spinopelvic stiffness, how does the pelvis normally respond when transitioning from standing to sitting, and what specific instability is this patient at highest risk for due to their fusion?

. Normal posterior pelvic tilt; anterior dislocation
. Lack of posterior pelvic tilt; posterior dislocation
. Excessive posterior pelvic tilt; posterior dislocation
. Lack of anterior pelvic tilt; anterior dislocation
. Excessive anterior pelvic tilt; anterior dislocation

Correct Answer & Explanation

. Lack of posterior pelvic tilt; posterior dislocation

Explanation

In a normal spinopelvic relationship, when a person transitions from standing to sitting, the lumbar spine flexes and the pelvis tilts posteriorly. This posterior pelvic tilt functionally increases acetabular anteversion, allowing the anterior femur to clear the acetabulum during deep hip flexion. A patient with a fusion to the pelvis has a stiff spine and cannot posteriorly tilt the pelvis when sitting. Therefore, the functional anteversion does not increase, leading to anterior bony/component impingement and subsequent posterior dislocation.

Question 799

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with chronic lower back pain and notably tight hamstrings. Standing lateral radiographs reveal a 60% anterior slip of L5 on S1. Which type of spondylolisthesis according to the Wiltse classification is most commonly associated with this specific patient demographic and clinical presentation?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type II (Isthmic)

Explanation

Type II (Isthmic) spondylolisthesis is caused by a defect or stress fracture in the pars interarticularis. It is the most common type of spondylolisthesis in children and adolescents, particularly in athletes who perform repetitive hyperextension activities (e.g., gymnasts, divers, football linemen). Tight hamstrings (causing the Phalen-Dickson sign or a 'waddling' gait) are a classic physical finding in high-grade slips.

Question 800

Topic: Thoracolumbar Spine & Deformity
A 15-year-old female gymnast presents with persistent lower back pain. Lateral radiographs of the lumbar spine reveal a pars interarticularis defect at L5 and a forward translation of L5 on S1. The superior endplate of S1 is divided into four equal parts, and the posterior cortex of L5 sits over the second quartile. According to the Meyerding classification, what is the grade of this spondylolisthesis?
. Grade I
. Grade II
. Grade III
. Grade IV
. Spondyloptosis

Correct Answer & Explanation

. Grade II

Explanation

The Meyerding classification grades spondylolisthesis based on the percentage of forward slip of the superior vertebral body over the inferior one. Grade I is 0-25%; Grade II is 26-50%; Grade III is 51-75%; Grade IV is 76-100%; Grade V is >100% (spondyloptosis). A slip in the second quartile (26-50%) is Grade II.

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