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Thoracolumbar Spine & Deformity MCQs

Practice Set 47 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 921

Topic: Thoracolumbar Spine & Deformity

A 15-year-old female gymnast complains of an insidious onset of lower back pain, exacerbated by extension. Radiographs confirm an L5-S1 isthmic spondylolisthesis (Meyerding Grade II). Which of the following classic radiographic findings is specifically associated with the defect causing this condition?

. A fluid sign within the facet joint on MRI
. Elongation of the pars interarticularis without a defect
. A 'Scotty dog' with a collar on oblique lumbar radiographs
. Sagittal orientation of the facet joints on axial imaging
. Subchondral sclerosis of the sacroiliac joint

Correct Answer & Explanation

. A 'Scotty dog' with a collar on oblique lumbar radiographs

Explanation

Isthmic spondylolisthesis is most commonly caused by a pars interarticularis defect (spondylolysis), typically at L5. On oblique lumbar radiographs, the posterior elements of the vertebra resemble a 'Scotty dog'. A defect or fracture in the pars interarticularis appears as a radiolucent line across the neck of the dog, often described as a 'Scotty dog with a collar'. Dysplastic spondylolisthesis features an elongated pars, and degenerative spondylolisthesis is often associated with sagittally oriented facets or a facet fluid sign.

Question 922

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic low back pain exacerbating with extension. Radiographs show a grade II isthmic spondylolisthesis at L5-S1. Despite 6 months of physical therapy and bracing, pain persists and prevents sports participation. What is the most appropriate surgical treatment?

. L5-S1 laminectomy alone
. Anterior lumbar interbody fusion without posterior fixation
. Pars interarticularis repair (Buck's repair)
. L5-S1 posterior instrumented fusion
. Total disc arthroplasty at L5-S1

Correct Answer & Explanation

. L5-S1 posterior instrumented fusion

Explanation

For a symptomatic high-grade or progressive isthmic spondylolisthesis failing nonoperative care, an L5-S1 posterior instrumented fusion is the gold standard. Direct pars repair is generally reserved for younger patients with a pars defect but minimal to no listhesis (Grade 0 or early Grade I).

Question 923

Topic: Thoracolumbar Spine & Deformity

A 12-year-old gymnast presents with back pain and a grade II isthmic spondylolisthesis at L5-S1. Radiographic spinopelvic parameters are measured. Which of the following parameters is a fixed, morphological characteristic of the pelvis that strongly correlates with the magnitude of shear stress at the lumbosacral junction and the risk of slip progression?

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

Correct Answer & Explanation

. Pelvic incidence (PI)

Explanation

Pelvic incidence (PI) is a fixed anatomical parameter unique to each individual, defined as the angle between a line perpendicular to the sacral endplate at its midpoint and a line connecting this point to the axis of the femoral heads. PI = PT + SS. A high pelvic incidence correlates with a steeper sacral slope, leading to higher shear forces at L5-S1 and predisposing to isthmic spondylolisthesis progression.

Question 924

Topic: Thoracolumbar Spine & Deformity

A 16-year-old gymnast complains of chronic low back pain exacerbated by extension. Oblique lumbar radiographs demonstrate a "collar on the Scotty dog." What is the exact anatomical location of this defect?

. Pedicle
. Lamina
. Pars interarticularis
. Transverse process
. Spinous process

Correct Answer & Explanation

. Pars interarticularis

Explanation

The "collar on the Scotty dog" on oblique radiographs represents a defect or fracture in the pars interarticularis. This condition, known as isthmic spondylolysis, is common in adolescent athletes involved in repetitive hyperextension sports.

Question 925

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic low back pain. Radiographs reveal a grade I isthmic spondylolisthesis at L5-S1. The primary anatomic defect in this condition is located in the:

. Pedicle
. Pars interarticularis
. Spinous process
. Facet joint
. Vertebral body endplate

Correct Answer & Explanation

. Pars interarticularis

Explanation

Isthmic spondylolisthesis is caused by a structural defect or stress fracture in the pars interarticularis. This defect is classically visualized as a "collar on the Scotty dog" on oblique lumbar radiographs.

Question 926

Topic: Thoracolumbar Spine & Deformity

A 14-year-old male gymnast presents with lower back pain that is exacerbated by extension activities. Oblique lumbar radiographs show a 'scotty dog with a collar' sign at L5. A lateral radiograph reveals a 15% anterior translation of L5 on S1. What is the most appropriate initial management?

. Posterior spinal fusion of L5-S1
. Direct pars interarticularis repair
. Activity modification, core strengthening, and physical therapy
. Rigid TLSO bracing for 1 year
. Epidural steroid injections

Correct Answer & Explanation

. Activity modification, core strengthening, and physical therapy

Explanation

The patient has a Grade 1 isthmic spondylolisthesis. Initial management for symptomatic low-grade spondylolisthesis is conservative, consisting of activity modification, NSAIDs, and targeted physical therapy focusing on core and hamstring stretching.

Question 927

Topic: Thoracolumbar Spine & Deformity

A 15-year-old gymnast presents with lower back pain exacerbated by extension. Radiographs reveal an L5-S1 isthmic spondylolisthesis. During physical examination, if a palpable step-off is appreciated, where is it most likely located?

. Between L3 and L4 spinous processes
. Between L4 and L5 spinous processes
. Between L5 and S1 spinous processes
. Between S1 and S2 spinous processes
. Directly over the sacral promontory

Correct Answer & Explanation

. Between L3 and L4 spinous processes

Explanation

In an isthmic spondylolisthesis at L5-S1, the pars interarticularis defect separates the L5 body from its posterior neural arch. The L5 body slips anteriorly on S1, carrying the L4 vertebra with it. However, the posterior elements of L5 remain behind with the sacrum. Therefore, the step-off is palpable between the spinous processes of L4 (which has moved forward) and L5 (which remains posterior).

Question 928

Topic: Thoracolumbar Spine & Deformity

Degenerative spondylolisthesis most commonly occurs at the L4-L5 level. Which anatomic feature of the L4-L5 segment heavily predisposes it to this condition compared to other lumbar levels?

. Coronally oriented facet joints
. A naturally larger intervertebral disc height
. Sagittally oriented facet joints
. The attachment of the iliolumbar ligament
. The presence of an elongated pars interarticularis

Correct Answer & Explanation

. Sagittally oriented facet joints

Explanation

Degenerative spondylolisthesis is most common at L4-L5. A major predisposing factor is the presence of sagittally oriented facet joints at this level. Coronal orientation resists forward translation better; sagittal orientation provides less mechanical resistance to anterior sheer, leading to translation as the disc and ligaments degenerate. L5-S1 facets are more coronal, making degenerative slip less common there.

Question 929

Topic: Thoracolumbar Spine & Deformity
A 14-year-old elite gymnast presents with mechanical lower back pain. Radiographs reveal a pars interarticularis defect at L5 with a 25% anterior translation of L5 on S1. According to the Wiltse classification, what specific type of spondylolisthesis is this?
. Dysplastic (Type I)
. Isthmic (Type II)
. Degenerative (Type III)
. Traumatic (Type IV)
. Pathologic (Type V)

Correct Answer & Explanation

. Isthmic (Type II)

Explanation

Isthmic spondylolisthesis (Wiltse Type II) is caused by a structural defect, elongation, or acute fracture of the pars interarticularis (spondylolysis). It is the most common cause of spondylolisthesis in adolescent athletes who perform repetitive spinal extension.

Question 930

Topic: Thoracolumbar Spine & Deformity

A 22-year-old restrained passenger is involved in a high-speed motor vehicle collision. Radiographs and CT of the lumbar spine reveal a flexion-distraction injury (Chance fracture) at L2. Which of the following associated injuries must be most highly suspected and ruled out?

. Aortic transection
. Diaphragmatic rupture
. Hollow viscus intra-abdominal injury
. Renal artery thrombosis
. Bladder rupture

Correct Answer & Explanation

. Hollow viscus intra-abdominal injury

Explanation

Chance fractures are high-energy flexion-distraction injuries commonly associated with seatbelt use. They carry a high rate (up to 40-50%) of associated intra-abdominal injuries, particularly to hollow viscous organs like the bowel.

Question 931

Topic: Thoracolumbar Spine & Deformity

Which of the following is an accepted indication for surgical treatment of scoliosis in an adolescent with idiopathic scoliosis?

. Skeletally immature patient with a single curve measuring 15 degrees.
. Skeletally mature patient with a progressive curve measuring 25 degrees.
. Curve progression of 5 degrees or more in a skeletally immature patient with a curve between 20-25 degrees.
. Skeletally immature patient with a thoracic curve exceeding 45-50 degrees.
. Asymptomatic curve of 30 degrees in a skeletally mature patient.

Correct Answer & Explanation

. Skeletally immature patient with a thoracic curve exceeding 45-50 degrees.

Explanation

Surgical treatment for adolescent idiopathic scoliosis is generally indicated for skeletally immature patients with progressive curves or curves that are already large. A thoracic curve exceeding 45-50 degrees (or lumbar/thoracolumbar curves exceeding 40-45 degrees) in a skeletally immature patient is a common indication for surgery to prevent further progression and manage cosmetic deformity. Smaller curves (15-25 degrees) in skeletally immature patients are typically observed or braced. A 25-degree curve in a skeletally mature patient or an asymptomatic 30-degree curve in a mature patient would typically be observed, as progression is less likely after skeletal maturity. Curve progression criteria for bracing often apply to 20-40 degree curves, but surgery is for larger, progressive curves.

Question 932

Topic: Thoracolumbar Spine & Deformity

Which type of spondylolisthesis is most commonly associated with a pars interarticularis defect?

. Degenerative spondylolisthesis
. Traumatic spondylolisthesis
. Isthmic spondylolisthesis
. Pathologic spondylolisthesis
. Dysplastic spondylolisthesis

Correct Answer & Explanation

. Isthmic spondylolisthesis

Explanation

Isthmic spondylolisthesis (also known as spondylolytic spondylolisthesis) is caused by a defect in the pars interarticularis, often due to a stress fracture. This is the most common type in younger individuals and athletes. Degenerative spondylolisthesis results from facet joint arthritis and disc degeneration, typically occurring in older adults without a pars defect. Traumatic spondylolisthesis is due to acute fracture of other parts of the vertebra. Pathologic spondylolisthesis is due to bone disease (e.g., tumor, infection). Dysplastic spondylolisthesis is congenital, characterized by malformation of the superior sacral or inferior L5 facets.

Question 933

Topic: Thoracolumbar Spine & Deformity

Which of the following is a common cause of back pain in older adults that involves anterior slippage of one vertebral body over another without a pars interarticularis defect?

. Isthmic spondylolisthesis
. Dysplastic spondylolisthesis
. Pathologic spondylolisthesis
. Degenerative spondylolisthesis
. Traumatic spondylolisthesis

Correct Answer & Explanation

. Degenerative spondylolisthesis

Explanation

Degenerative spondylolisthesis is the most common form of spondylolisthesis in older adults. It results from chronic disc degeneration and facet joint arthritis, leading to instability and gradual forward slippage of one vertebra over another (most commonly L4 over L5). Unlike isthmic spondylolisthesis, there is no pars interarticularis defect. Dysplastic is congenital, pathologic is due to systemic bone disease, and traumatic is from acute fracture. Isthmic is due to pars defect, typically in younger individuals.

Question 934

Topic: Thoracolumbar Spine & Deformity

A 5-year-old child with diastrophic dysplasia presents with a progressive scoliosis measuring 45 degrees. Which of the following statements regarding the management of scoliosis in this specific skeletal dysplasia is most accurate?

. Bracing is highly effective and is the gold standard for curves under 50 degrees.
. The scoliosis is typically flexible and easily managed with serial casting.
. Curves are often rigid, progress rapidly, and respond poorly to orthotic management.
. Scoliosis in this condition is usually secondary to a leg length discrepancy and resolves with a shoe lift.
. Surgical intervention should be delayed until skeletal maturity regardless of curve magnitude.

Correct Answer & Explanation

. Curves are often rigid, progress rapidly, and respond poorly to orthotic management.

Explanation

Correct Answer: Curves are often rigid, progress rapidly, and respond poorly to orthotic management.Scoliosis in diastrophic dysplasia is notoriously difficult to manage. The curves tend to appear early, progress rapidly, and become extremely rigid. Unlike idiopathic scoliosis, bracing is generally ineffective and poorly tolerated in diastrophic dysplasia. Early surgical intervention (often requiring anterior release and posterior fusion, or growth-friendly constructs in very young children) is frequently necessary to prevent severe, life-threatening deformity.

Question 935

Topic: Thoracolumbar Spine & Deformity

A 2-year-old presents with coarse facial features, hepatosplenomegaly, and a progressive thoracolumbar kyphosis. Radiographs reveal thick, paddle-shaped ribs and hypoplastic "bullet-shaped" vertebral bodies. Enzyme analysis shows a deficiency of alpha-L-iduronidase. Which of the following best describes this syndrome?

. Hunter syndrome
. Hurler syndrome
. Sanfilippo syndrome
. Morquio syndrome
. Spondyloepiphyseal dysplasia congenita

Correct Answer & Explanation

. Hurler syndrome

Explanation

Hurler syndrome (MPS I) is characterized by coarse facies, dysostosis multiplex, intellectual disability, and alpha-L-iduronidase deficiency. Bullet-shaped vertebrae and paddle-shaped ribs are classic radiographic findings of dysostosis multiplex.

Question 936

Topic: Thoracolumbar Spine & Deformity

A patient with Hurler syndrome develops a severe thoracolumbar kyphosis (gibbus deformity). What is the primary radiographic abnormality of the vertebrae causing this deformity?

. Anteroinferior vertebral body beaking
. Central vertebral body scalloping
. Anterosuperior vertebral body beaking
. Complete failure of vertebral body segmentation
. Butterfly vertebrae formation

Correct Answer & Explanation

. Anteroinferior vertebral body beaking

Explanation

In Hurler syndrome (MPS I), the vertebrae typically exhibit anteroinferior beaking, which leads to anterior wedging and progressive thoracolumbar kyphosis. In contrast, Morquio syndrome (MPS IV) classically features central anterior beaking.

Question 937

Topic: Thoracolumbar Spine & Deformity

A 14-year-old female gymnast complains of chronic lower back pain exacerbated by extension. Radiographs reveal a grade 1 isthmic spondylolisthesis at L5-S1. Her neurologic examination is normal. After failing 6 months of rigorous physical therapy and activity modification, what is the most appropriate surgical treatment?

. L5 pars interarticularis repair
. L5-S1 posterior lumbar interbody fusion (PLIF)
. L5-S1 posterolateral fusion in situ
. L5 laminectomy without fusion
. Anterior lumbar interbody fusion (ALIF) alone

Correct Answer & Explanation

. L5-S1 posterolateral fusion in situ

Explanation

For adolescents with a low-grade isthmic spondylolisthesis at L5-S1 who fail nonoperative treatment, L5-S1 posterolateral fusion in situ is the gold standard. Pars repair is typically reserved for L1-L4 defects or L5 defects without significant slip.

Question 938

Topic: Thoracolumbar Spine & Deformity

A 12-year-old girl is evaluated for progressive scoliosis. She has a history of a retinal detachment and a cleft palate repair as an infant. Radiographs show mild epiphyseal dysplasia and platyspondyly. Which of the following is the most likely diagnosis?

. Stickler syndrome
. Marfan syndrome
. Ehlers-Danlos syndrome
. Cleidocranial dysplasia
. Multiple epiphyseal dysplasia

Correct Answer & Explanation

. Stickler syndrome

Explanation

Stickler syndrome (hereditary arthro-ophthalmopathy) is a COL2A1 mutation disorder characterized by ocular issues (retinal detachment), cleft palate, hearing loss, and spondyloepiphyseal dysplasia.

Question 939

Topic: Thoracolumbar Spine & Deformity

A 4-year-old girl presents with coarse facial features, corneal clouding, and a thoracolumbar kyphosis. Radiographs reveal anteroinferior beaking of the lumbar vertebrae. Which of the following enzyme deficiencies is most likely responsible for her condition?

. Galactosamine-6-sulfatase
. Alpha-L-iduronidase
. Arylsulfatase B
. Iduronate-2-sulfatase

Correct Answer & Explanation

. Alpha-L-iduronidase

Explanation

Correct Answer: Alpha-L-iduronidaseThe clinical picture of coarse facial features, corneal clouding, and anteroinferior vertebral beaking is classic for Hurler syndrome (Mucopolysaccharidosis type I). Hurler syndrome is caused by a deficiency in alpha-L-iduronidase. In contrast, Morquio syndrome (MPS IV) is caused by a deficiency in galactosamine-6-sulfatase and typically presents with central anterior vertebral beaking. Hunter syndrome (MPS II) is caused by iduronate-2-sulfatase deficiency and lacks corneal clouding.

Question 940

Topic: Thoracolumbar Spine & Deformity

A patient with severe cervical kyphosis, 'hitchhiker' thumbs, and cauliflower ears is diagnosed with a skeletal dysplasia. The genetic mutation responsible for this condition primarily affects which of the following cellular functions?

. Fibroblast growth factor signaling
. Type II collagen synthesis
. Sulfate transport across the cell membrane
. Osteoclast-mediated bone resorption
. Cartilage oligomeric matrix protein assembly

Correct Answer & Explanation

. Sulfate transport across the cell membrane

Explanation

Correct Answer: Sulfate transport across the cell membraneThe clinical triad of cervical kyphosis, hitchhiker thumbs, and cauliflower ears is pathognomonic for diastrophic dysplasia. This autosomal recessive condition is caused by mutations in the SLC26A2 (DTDST) gene, which encodes a sulfate transporter. Defective sulfate transport leads to undersulfation of proteoglycans in the cartilage matrix, resulting in the characteristic skeletal and cartilaginous abnormalities.

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