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Thoracolumbar Spine & Deformity MCQs

Practice Set 38 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 741

Topic: Thoracolumbar Spine & Deformity

A 68-year-old woman is being evaluated for progressive sagittal imbalance and severe flatback syndrome following a previous L3-S1 fusion. Radiographs reveal a pelvic incidence (PI) of 65 degrees and a current lumbar lordosis (LL) of 20 degrees. To optimize her postoperative clinical outcomes, her revision surgery should aim to restore her lumbar lordosis to approximately what value?

. 20 degrees
. 35 degrees
. 45 degrees
. 65 degrees
. 85 degrees

Correct Answer & Explanation

. 65 degrees

Explanation

For optimal sagittal balance, the lumbar lordosis (LL) should be matched to within 10 degrees of the pelvic incidence (PI). Therefore, a patient with a PI of 65 degrees should have a surgical target LL of approximately 55 to 65 degrees.

Question 742

Topic: Thoracolumbar Spine & Deformity

In a patient with symptomatic L5-S1 isthmic spondylolisthesis, which nerve root is most commonly compressed, and where does the compression typically occur?

. L5 nerve root within the lateral recess
. L5 nerve root in the neural foramen
. S1 nerve root within the lateral recess
. S1 nerve root in the neural foramen
. S2 nerve root centrally

Correct Answer & Explanation

. L5 nerve root in the neural foramen

Explanation

In isthmic spondylolisthesis, the exiting L5 nerve root is most commonly compressed. This compression typically occurs within the neural foramen due to the hypertrophic fibrocartilaginous mass at the pars interarticularis defect.

Question 743

Topic: Thoracolumbar Spine & Deformity

A 35-year-old male sustains an L1 burst fracture. He is neurologically intact. MRI demonstrates an intact posterior ligamentous complex. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is the most appropriate treatment?

. Posterior instrumented fusion from T11 to L3
. Anterior corpectomy and fusion
. Thoracolumbosacral orthosis (TLSO)
. Short-segment posterior fusion
. Vertebroplasty

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO)

Explanation

This patient has a TLICS score of 2 (burst fracture morphology = 2, intact PLC = 0, neurologically intact = 0). A score of 3 or less is an indication for non-operative management, making a TLSO brace the most appropriate treatment.

Question 744

Topic: Thoracolumbar Spine & Deformity

In the assessment of spinopelvic parameters, which of the following is considered a fixed morphological parameter of the pelvis that is unaffected by the patient's posture?

. Pelvic tilt (PT)
. Sacral slope (SS)
. Pelvic incidence (PI)
. Lumbar lordosis (LL)
. Sagittal vertical axis (SVA)

Correct Answer & Explanation

. Pelvic incidence (PI)

Explanation

Pelvic incidence (PI) is a fixed anatomical parameter that does not change with positioning after skeletal maturity. It mathematically equals the sum of pelvic tilt and sacral slope (PI = PT + SS).

Question 745

Topic: Thoracolumbar Spine & Deformity

In the preoperative planning for adult spinal deformity correction, which of the following formulas represents the normal morphological relationship between Pelvic Incidence (PI), Sacral Slope (SS), and Pelvic Tilt (PT)?

. PI = PT - SS
. PI = PT + SS
. PT = PI + SS
. SS = PI + PT
. PI = (PT + SS) / 2

Correct Answer & Explanation

. PI = PT + SS

Explanation

Pelvic incidence (PI) is a fixed morphological parameter representing the algebraic sum of pelvic tilt (PT) and sacral slope (SS). It dictates the required lumbar lordosis to achieve sagittal balance, with the relationship defined by the formula PI = PT + SS.

Question 746

Topic: Thoracolumbar Spine & Deformity

A 35-year-old male falls from a height and sustains a burst fracture of L1. His neurologic examination is completely normal. The Thoracolumbar Injury Classification and Severity (TLICS) score is calculated to be 2. What is the most appropriate management?

. Short-segment posterior spinal fusion
. Anterior corpectomy and fusion
. Thoracolumbar orthosis (TLSO) bracing and early mobilization
. Long-segment posterior instrumentation
. Laminectomy and pedicle screw fixation

Correct Answer & Explanation

. Thoracolumbar orthosis (TLSO) bracing and early mobilization

Explanation

According to the TLICS system, a score of 3 or less indicates non-operative management. A score of 4 is a grey area (surgeon preference), and a score of 5 or more indicates surgical intervention. Therefore, bracing and early mobilization is the correct treatment for a TLICS score of 2.

Question 747

Topic: Thoracolumbar Spine & Deformity

A 28-year-old male is diagnosed with an L5-S1 isthmic spondylolisthesis (Meyerding Grade II). He has failed 6 months of conservative therapy and continues to have axial back pain and bilateral L5 radiculopathy. What is the underlying anatomical defect characterizing this specific condition?

. Degeneration and subluxation of the facet joints
. Elongation of the pars interarticularis without fracture
. A defect or stress fracture in the pars interarticularis
. Congenital absence of the pedicle
. Dysplasia of the superior articular process of the sacrum

Correct Answer & Explanation

. A defect or stress fracture in the pars interarticularis

Explanation

Isthmic spondylolisthesis (Type II in the Wiltse classification) is characterized by a structural defect, typically a stress fracture or nonunion (spondylolysis), in the pars interarticularis. This allows the anterior column to slip forward while the posterior elements remain behind.

Question 748

Topic: Thoracolumbar Spine & Deformity

A 30-year-old neurologically intact male presents after a motor vehicle collision. CT imaging demonstrates a burst fracture of L1 with 40% loss of vertebral body height and 15 degrees of local kyphosis. MRI confirms the posterior ligamentous complex (PLC) is completely intact. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is the most appropriate management?

. Nonoperative management with a TLSO brace
. Posterior short-segment pedicle screw fixation
. Anterior corpectomy and strut grafting
. Laminectomy and posterior uninstrumented fusion
. Combined anterior-posterior instrumented fusion

Correct Answer & Explanation

. Nonoperative management with a TLSO brace

Explanation

This injury scores a 2 on the TLICS system (Morphology: Burst = 2, Neurologic status: Intact = 0, PLC status: Intact = 0). A total TLICS score of 3 or less is a strong indication for nonoperative management with bracing.

Question 749

Topic: Thoracolumbar Spine & Deformity

In planning corrective surgery for a 62-year-old female with severe adult spinal deformity, achieving optimal sagittal balance is critical. According to the SRS-Schwab classification guidelines, what is the surgical target for the mismatch between pelvic incidence (PI) and lumbar lordosis (LL)?

. PI minus LL should be less than or equal to 10 degrees
. PI minus LL should be exactly 20 degrees
. LL should be greater than PI by at least 15 degrees
. PI should be equal to pelvic tilt (PT)
. PI minus LL should equal sacral slope (SS)

Correct Answer & Explanation

. PI minus LL should be less than or equal to 10 degrees

Explanation

To optimize sagittal alignment, minimize the risk of adjacent segment disease, and prevent hardware failure, the surgical goal is to achieve a PI-LL mismatch of less than or equal to 10 degrees.

Question 750

Topic: Thoracolumbar Spine & Deformity
A 14-year-old female presents with severe low back pain, radicular leg symptoms, and a waddling gait. Imaging reveals a Meyerding Grade IV isthmic spondylolisthesis at L5-S1 with a slip angle of 55 degrees. After failed conservative management, what is the most appropriate surgical intervention?
. Pars interarticularis repair with bone grafting
. In situ posterolateral uninstrumented fusion
. L5 laminectomy without fusion
. Anterior lumbar interbody fusion without posterior fixation
. Instrumented L5-S1 fusion with reduction or partial reduction

Correct Answer & Explanation

. Instrumented L5-S1 fusion with reduction or partial reduction

Explanation

High-grade (Meyerding Grade III-V) dysplastic or isthmic spondylolisthesis with a high slip angle requires robust stabilization. Instrumented fusion with partial or complete reduction is necessary to restore global sagittal balance and minimize the risk of pseudarthrosis and slip progression.

Question 751

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with persistent low back pain. Radiographs reveal a Grade 1 L5-S1 isthmic spondylolisthesis. After 6 months of physical therapy and bracing, her pain remains debilitating. What is the recommended surgical management?

. Laminectomy alone without fusion
. Pars repair with lag screws (Buck technique)
. L5-S1 posterolateral instrumented fusion
. L5-S1 anterior lumbar interbody fusion (ALIF) alone
. Observation and activity modification until skeletal maturity

Correct Answer & Explanation

. L5-S1 posterolateral instrumented fusion

Explanation

For symptomatic low-grade isthmic spondylolisthesis in adolescents that fails conservative management, an in situ L5-S1 posterolateral instrumented fusion is the gold standard. Pars repairs are generally reserved for L4 or above without spondylolisthesis.

Question 752

Topic: Thoracolumbar Spine & Deformity

An 18-year-old gymnast complains of chronic lower back pain. Radiographs reveal a pars interarticularis defect (spondylolysis). Anatomically, the pars interarticularis is a bony bridge located between which two structures?

. Pedicle and lamina
. Superior and inferior articular processes
. Spinous process and lamina
. Transverse process and pedicle
. Vertebral body and pedicle

Correct Answer & Explanation

. Superior and inferior articular processes

Explanation

The pars interarticularis is the specific region of the vertebral arch situated between the superior and inferior articular processes. It is highly susceptible to fatigue fractures in athletes experiencing repetitive hyperextension.

Question 753

Topic: Thoracolumbar Spine & Deformity

When placing lumbar pedicle screws, the identification of correct anatomic landmarks is crucial to avoid neurologic injury. The ideal starting point for a lumbar pedicle screw is located at the intersection of which of the following structures?

. Pars interarticularis and superior articular process
. Mid-transverse process and pars interarticularis
. Superior border of the transverse process and lateral border of the superior articular process
. A line bisecting the transverse process and the lateral border of the superior articular process
. Inferior border of the transverse process and medial border of the superior articular process

Correct Answer & Explanation

. A line bisecting the transverse process and the lateral border of the superior articular process

Explanation

In the lumbar spine, the anatomic starting point for a pedicle screw is the intersection of a horizontal line bisecting the transverse process and a vertical line tangential to the lateral border of the superior articular process.

Question 754

Topic: Thoracolumbar Spine & Deformity

A patient presents with the foot deformities shown in the clinical and radiographic images below. Which of the following skeletal anomalies is also classically associated with this syndrome?




. Absence of clavicles
. Enlarged chest cavity
. Hyperplastic maxilla
. Atlantoaxial instability
. Scoliosis

Correct Answer & Explanation

. Absence of clavicles

Explanation

Correct Answer: AThe images show shortening of the digits of the toes and feet typical of Ellis-van Creveld syndrome. Associated skeletal anomalies include the absence of clavicles, a narrow chest, and a hypoplastic maxilla.

Question 755

Topic: Thoracolumbar Spine & Deformity

A 10-year-old girl with known Neurofibromatosis type 1 presents with a sharp, angular, short-segment thoracic scoliosis.

Which of the following features is highly indicative of a dystrophic curve that carries a high risk of rapid progression?

. Penciling of the ribs
. Apical vertebral wedging of 5 degrees
. Pedicle hypertrophy
. Cobb angle less than 20 degrees
. Right-sided curve apex

Correct Answer & Explanation

. Penciling of the ribs

Explanation

Dystrophic scoliosis in NF1 is characterized by penciling of the ribs, severe apical vertebral wedging, dural ectasia, and enlarged neural foramina. These specific curves progress rapidly and typically require early surgical stabilization.

Question 756

Topic: Thoracolumbar Spine & Deformity

A 12-month-old boy with diastrophic dysplasia is noted to have an isolated mid-cervical kyphosis on lateral radiographs. He has no neurological deficits. What is the expected natural history of this deformity?

. Rapid progression requiring urgent surgical fusion
. Spontaneous resolution over the next few years
. Progression to severe atlantoaxial instability
. Development of basilar invagination
. Rigid fixation of the deformity without progression

Correct Answer & Explanation

. Spontaneous resolution over the next few years

Explanation

Cervical kyphosis in diastrophic dysplasia is typically self-limiting and resolves spontaneously in the majority of cases as the child grows. Unlike Larsen syndrome, where cervical kyphosis is highly progressive and dangerous, diastrophic dysplasia usually requires only observation.

Question 757

Topic: Thoracolumbar Spine & Deformity

A 2-year-old child with Hurler syndrome presents with a prominent thoracolumbar kyphosis. Which of the following radiographic descriptions of the vertebral bodies at the apex of the kyphosis is classic for this condition?

. Coronal clefts
. Anterior inferior beaking
. Central beaking
. Anterior superior beaking
. Picture frame vertebrae

Correct Answer & Explanation

. Anterior inferior beaking

Explanation

Hurler syndrome (MPS I) classically presents with anterior inferior beaking of the vertebral bodies at the thoracolumbar junction, leading to a structural kyphosis. In contrast, Morquio syndrome typically features central beaking.

Question 758

Topic: Thoracolumbar Spine & Deformity

A 16-year-old boy presents with painful scoliosis. Radiographs demonstrate an expansile lesion in the posterior elements of the lumbar spine.

What is the characteristic scoliotic curve pattern associated with this type of lesion?

. Scoliosis with the apex directed towards the lesion
. Scoliosis with the apex directed away from the lesion
. Progressive structural thoracic kyphosis
. Reversal of cervical lordosis without coronal plane deformity
. Scoliosis with compensatory contralateral hemivertebrae

Correct Answer & Explanation

. Scoliosis with the apex directed away from the lesion

Explanation

Painful lesions like osteoblastoma and osteoid osteoma in the posterior elements cause unilateral paravertebral muscle spasm. This spasm creates a concavity on the side of the lesion, causing the apex of the scoliotic curve to be directed away from the lesion.

Question 759

Topic: Thoracolumbar Spine & Deformity

Which of the following Sanders skeletal maturity stages correlates most closely with the peak height velocity (PHV) and the highest risk of curve progression in Adolescent Idiopathic Scoliosis?

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

Correct Answer & Explanation

. Sanders Stage 3

Explanation

Sanders Stage 3 (adolescent rapid growth phase) correlates strongly with peak height velocity (PHV). This stage indicates the period of maximal skeletal growth and the highest risk for scoliosis curve progression.

Question 760

Topic: Thoracolumbar Spine & Deformity

In a 9-month-old infant diagnosed with infantile idiopathic scoliosis, which of the following radiographic parameters is the most reliable predictor of curve progression requiring intervention?

. Apical vertebral translation > 2 cm
. Cobb angle > 15 degrees
. Nash-Moe rotation of Grade II
. Rib-vertebral angle difference (RVAD) > 20 degrees
. Thoracic kyphosis > 40 degrees

Correct Answer & Explanation

. Rib-vertebral angle difference (RVAD) > 20 degrees

Explanation

The Rib-Vertebral Angle Difference (RVAD), or Mehta's angle, is the most important prognostic factor in infantile scoliosis. An RVAD > 20 degrees strongly predicts curve progression and typically warrants serial Mehta casting.

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