Menu

Thoracolumbar Spine & Deformity MCQs

Practice Set 48 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 941

Topic: Thoracolumbar Spine & Deformity

A 6-year-old patient with Hurler syndrome (MPS I) successfully underwent hematopoietic stem cell transplantation (HSCT) at age 2. Which of the following spinal deformities is most likely to persist and potentially progress despite successful HSCT?

. Atlantoaxial rotatory fixation
. Thoracolumbar kyphosis
. Spondylolisthesis
. Cervical lordosis
. Dystrophic scoliosis

Correct Answer & Explanation

. Thoracolumbar kyphosis

Explanation

While hematopoietic stem cell transplantation (HSCT) resolves many systemic and visceral manifestations of Hurler syndrome, it has limited effect on skeletal dysplasias. Thoracolumbar kyphosis, driven by anterior vertebral body hypoplasia (bullet-shaped vertebrae), frequently progresses and often requires surgical intervention.

Question 942

Topic: Thoracolumbar Spine & Deformity
A 15-year-old female gymnast presents with chronic low back pain. Radiographs demonstrate a grade II anterior translation of L5 on S1 with an identifiable defect in the pars interarticularis. According to the Wiltse classification, what 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 II (Isthmic)

Explanation

Type II (Isthmic) spondylolisthesis involves a defect in the pars interarticularis (spondylolysis). It is the most common type in adolescents and athletes, such as gymnasts, who undergo repetitive hyperextension. Type I is dysplastic, Type III is degenerative (common in older adults), Type IV is traumatic (fracture other than the pars), and Type V is pathologic.

Question 943

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with severe back pain and a waddling gait. Lateral radiographs show a Grade IV isthmic spondylolisthesis at L5-S1 with a slip angle of 55 degrees. She has failed 6 months of conservative management. What is the most appropriate surgical treatment?
. Pars interarticularis repair (Buck's procedure)
. L5-S1 in situ posterolateral uninstrumented fusion
. L5 laminectomy without fusion
. L4-S1 instrumented posterior spinal fusion
. Anterior L5-S1 discectomy without fusion

Correct Answer & Explanation

. L4-S1 instrumented posterior spinal fusion

Explanation

High-grade spondylolisthesis (Grade III-V) with a high slip angle generally requires instrumented fusion, often extended to L4 to obtain adequate fixation. In situ fusion is historically used for lower grades, but high-grade slips typically need instrumentation and sometimes partial reduction.

Question 944

Topic: Thoracolumbar Spine & Deformity

A 10-year-old girl presents with back pain. Oblique lumbar radiographs reveal a "Scotty dog" sign with a "collar" around the neck. This radiographic finding is pathognomonic for a defect in which anatomic structure?

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

Correct Answer & Explanation

. Pars interarticularis

Explanation

The "collar" on the neck of the "Scotty dog" seen on oblique lumbar radiographs represents a radiolucent defect or fracture in the pars interarticularis, indicating spondylolysis.

Question 945

Topic: Thoracolumbar Spine & Deformity

A 15-year-old gymnast has persistent low back pain unresponsive to 6 months of physical therapy and bracing. Radiographs confirm a Grade II isthmic spondylolisthesis at L5-S1. What is the most appropriate surgical intervention?

. Anterior lumbar interbody fusion (ALIF) at L5-S1
. Posterolateral in situ fusion of L5-S1
. Direct pars interarticularis repair
. Wide laminectomy without fusion
. Sacroiliac joint fusion

Correct Answer & Explanation

. Posterolateral in situ fusion of L5-S1

Explanation

For a symptomatic low-grade (Grade I or II) isthmic spondylolisthesis in an adolescent that fails conservative care, a posterolateral in situ fusion is the standard of care. Direct pars repair is generally reserved for isolated spondylolysis without a slip.

Question 946

Topic: Thoracolumbar Spine & Deformity
A 14-year-old elite gymnast presents with severe, persistent low back pain. Radiographs reveal an L5-S1 isthmic spondylolisthesis with a 65% forward translation (Meyerding Grade III). Which of the following radiographic parameters is most predictive of further slip progression?
. Sacral slope
. High slip angle (kyphotic angle)
. Presence of an associated spina bifida occulta
. Lumbar lordosis magnitude
. Disc space narrowing at L4-L5

Correct Answer & Explanation

. High slip angle (kyphotic angle)

Explanation

In high-grade isthmic spondylolisthesis (Meyerding Grade III or higher), a high slip angle (lumbosacral kyphosis typically >40-50 degrees) is the most critical radiographic predictor of further forward translation and poor clinical outcomes.

Question 947

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with severe back pain. Radiographs demonstrate an L5-S1 isthmic spondylolisthesis. Which of the following radiographic parameters is the strongest predictor of slip progression and indicates the need for surgical fusion?

. Pelvic incidence greater than 40 degrees
. Slip angle greater than 45 degrees
. Decreased sacral slope
. Increased lumbar lordosis
. Meyerding Grade II

Correct Answer & Explanation

. Slip angle greater than 45 degrees

Explanation

A high slip angle (greater than 45-50 degrees) indicates significant lumbosacral kyphosis and is the strongest radiographic predictor for slip progression. Such high-risk alignment generally necessitates surgical stabilization.

Question 948

Topic: Thoracolumbar Spine & Deformity

A 15-year-old female gymnast presents with progressive lower back pain that worsens with extension. Lateral lumbar radiographs demonstrate a grade II isthmic spondylolisthesis at L5-S1. What is the precise anatomic location of the structural defect causing this condition?

. Pedicle
. Pars interarticularis
. Spinous process
. Lamina
. Superior articular facet

Correct Answer & Explanation

. Pars interarticularis

Explanation

Isthmic spondylolisthesis is characterized by a defect or stress fracture in the pars interarticularis. It is particularly common in adolescent athletes who perform repetitive spinal extension and loading, such as gymnasts and football linemen.

Question 949

Topic: Thoracolumbar Spine & Deformity

A 6-year-old girl with osteopetrosis presents with facial asymmetry and inability to close her right eye. Which of the following is the primary pathophysiological mechanism for this complication?

. Direct viral infection of the facial nerve
. Autoimmune destruction of the myelin sheath
. Narrowing of the cranial nerve foramina by dense bone
. Ischemic infarction due to vascular dysplasia
. Traction injury from progressive cervical kyphosis

Correct Answer & Explanation

. Narrowing of the cranial nerve foramina by dense bone

Explanation

In osteopetrosis, defective osteoclastic bone resorption leads to progressive skeletal sclerosis and failure of the cranial foramina to expand. This causes progressive cranial nerve entrapment, frequently resulting in facial nerve palsy or blindness.

Question 950

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic low back pain exacerbated by extension. Radiographs reveal a defect in the pars interarticularis. Which of the following biomechanical forces is most directly responsible for the development of this specific lesion?

. Repetitive axial loading in a flexed posture
. Repetitive hyperextension and rotational shear stress
. Acute hyperflexion with lateral bending
. Sustained axial distraction
. Repetitive lateral compression

Correct Answer & Explanation

. Repetitive hyperextension and rotational shear stress

Explanation

Correct Answer: BSpondylolysis is a stress fracture of the pars interarticularis, most commonly occurring in the lower lumbar spine (L5). It is classically caused by repetitive hyperextension and rotational forces, which place maximal shear stress on the pars. This is frequently seen in adolescent athletes such as gymnasts, weightlifters, and football linemen.

Question 951

Topic: Thoracolumbar Spine & Deformity

A 15-year-old gymnast presents with an insidious onset of low back pain that is exacerbated by extension activities. Radiographs reveal a defect in the pars interarticularis. Which of the following biomechanical forces is most directly responsible for the development of this specific lesion?

. Repetitive axial loading in a flexed posture
. Repetitive hyperextension and rotational shear
. Acute hyperflexion with lateral bending
. Sustained axial distraction
. Repetitive lateral flexion in a neutral sagittal plane

Correct Answer & Explanation

. Repetitive hyperextension and rotational shear

Explanation

Correct Answer: Repetitive hyperextension and rotational shearSpondylolysis is a stress fracture or defect of the pars interarticularis. It most commonly occurs in adolescent athletes who participate in sports requiring repetitive hyperextension and rotation of the lumbar spine, such as gymnastics, weightlifting, and football. These repetitive forces lead to microtrauma and subsequent stress fracture of the pars interarticularis.

Question 952

Topic: Thoracolumbar Spine & Deformity

A newborn presents with short-limbed dwarfism, bilateral rigid clubfeet, 'hitchhiker' thumbs, and cystic swelling of the external ears (cauliflower ears). Radiographs reveal severe epiphyseal dysplasia and progressive scoliosis. What is the molecular basis of this condition?

. Defective cartilage oligomeric matrix protein
. Defective fibroblast growth factor receptor 3
. Defective sulfate transport
. Defective type II collagen
. Defective Indian hedgehog signaling

Correct Answer & Explanation

. Defective sulfate transport

Explanation

Diastrophic dysplasia is an autosomal recessive condition caused by mutations in the SLC26A2 gene, resulting in defective intracellular sulfate transport. Clinical hallmarks include hitchhiker thumbs, cauliflower ears, rigid clubfeet, and severe epiphyseal dysplasia.

Question 953

Topic: Thoracolumbar Spine & Deformity

A child is evaluated for short stature and skeletal deformities, and the differential diagnosis includes Spondyloepiphyseal Dysplasia Congenita (SEDC) and Pseudoachondroplasia. Which of the following clinical timelines best distinguishes pseudoachondroplasia from SEDC?

. Evident at birth with associated cleft palate
. Evident at birth with disproportionate short limbs
. Normal length at birth with growth retardation noted at age 2 to 3 years
. Onset of severe progressive scoliosis in adolescence
. Onset of isolated early hip osteoarthritis in the third decade

Correct Answer & Explanation

. Normal length at birth with growth retardation noted at age 2 to 3 years

Explanation

Pseudoachondroplasia typically presents with a normal birth length and physical appearance, with growth retardation and waddling gait becoming evident around 2 to 3 years of age. SEDC, in contrast, is clinically apparent at birth.

Question 954

Topic: Thoracolumbar Spine & Deformity

A 15-year-old female gymnast presents with a 6-month history of worsening low back pain that is exacerbated by extension activities. Neurological examination is normal. Lateral radiographs of the lumbar spine show a grade 1 anterior translation of L5 on S1. Oblique views show a "Scotty dog with a collar" sign. What is the primary anatomical structure that has failed, leading to this condition, and what is the most appropriate initial management?

. Pedicle; surgical fusion
. Pars interarticularis; rigid bracing and activity modification
. Intervertebral disc; epidural steroid injection
. Facet joint; physical therapy emphasizing extension exercises
. Pars interarticularis; immediate surgical repair of the defect

Correct Answer & Explanation

. Pars interarticularis; rigid bracing and activity modification

Explanation

Correct Answer: BThe patient has an isthmic spondylolisthesis secondary to a bilateral spondylolysis (a stress fracture or defect in the pars interarticularis). This is common in adolescent athletes who perform repetitive hyperextension and rotation (e.g., gymnasts). The "collar" on the Scotty dog represents the pars defect. Initial management for a symptomatic, low-grade (<50% slip) isthmic spondylolisthesis is nonoperative, consisting of activity modification, physical therapy (core strengthening, antilordotic exercises), and often a rigid brace (TLSO) to restrict extension and allow the pars defect to heal or become asymptomatic.

Question 955

Topic: Thoracolumbar Spine & Deformity

A 15-year-old female gymnast presents with a 6-month history of worsening lower back pain that is exacerbated by back extension. Neurological examination is normal. Plain radiographs, including oblique views, reveal a "Scotty dog with a collar" sign at L5. If this condition progresses to anterior displacement of L5 over S1, what is the most common etiology for this specific patient demographic?

. Degenerative changes of the facet joints
. Dysplastic facet joints
. Isthmic defect of the pars interarticularis
. Traumatic fracture of the vertebral body
. Pathologic destruction from a tumor

Correct Answer & Explanation

. Isthmic defect of the pars interarticularis

Explanation

Correct Answer: CDefinitions:Spondylolysis is a defect or stress fracture of the pars interarticularis. When bilateral pars defects lead to the anterior translation of one vertebra over another, it is termed spondylolisthesis.Etiology:In adolescents, the most common type is isthmic spondylolisthesis, which arises from repetitive hyperextension and rotation forces (common in gymnasts, weightlifters, and football linemen) causing a fatigue fracture of the pars interarticularis.Imaging:Oblique radiographs classically demonstrate the "Scotty dog" sign, where a break in the dog's "collar" represents the pars defect.Management:Low-grade, asymptomatic slips are observed. Symptomatic slips are initially treated with activity modification, physical therapy, and occasionally bracing.

Question 956

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic lower back pain and bilateral leg pain that worsens with extension. Radiographs demonstrate a grade II isthmic spondylolisthesis at L5-S1. Despite 6 months of dedicated physical therapy and bracing, she continues to have radicular symptoms. If surgical decompression and fusion are planned, which nerve root is most likely compressed, and what is the primary anatomical site of compression?

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

Correct Answer & Explanation

. L5 nerve root; neural foramen

Explanation

Correct Answer: L5 nerve root; neural foramenIn isthmic spondylolisthesis at the L5-S1 level, the L5 nerve root is the most commonly affected nerve. The compression typically occurs in the neural foramen. The defect in the pars interarticularis fills with a fibrocartilaginous mass (often referred to as a Gill body), which hypertrophies and directly compresses the exiting L5 nerve root against the L5 pedicle. This is in contrast to degenerative spondylolisthesis, where the traversing nerve root (e.g., the L5 root in an L4-L5 slip) is typically compressed in the lateral recess due to facet hypertrophy and ligamentum flavum buckling.

Question 957

Topic: Thoracolumbar Spine & Deformity

A patient presents with an apex posterior (recurvatum) deformity of the proximal tibia following premature closure of the anterior physis. Which of the following secondary clinical findings is most likely associated with this deformity?

. Increased patellofemoral contact pressures and anterior knee pain
. Apparent shortening of the affected limb during stance
. Uncompensated ankle dorsiflexion
. Excessive posterior pelvic tilt during gait

Correct Answer & Explanation

. Increased patellofemoral contact pressures and anterior knee pain

Explanation

A proximal tibial recurvatum deformity decreases the normal posterior slope of the tibial plateau, leading to compensatory knee hyperextension. This structural change significantly increases patellofemoral joint contact pressures, often causing anterior knee pain.

Question 958

Topic: Thoracolumbar Spine & Deformity

A 35-year-old immigrant presents with back pain, night sweats, and a progressive thoracic kyphosis. MRI reveals destruction of the T8 and T9 vertebral bodies with a large paraspinal abscess, but the T8-T9 intervertebral disc space is remarkably preserved. What is the most likely pathogen?

. Staphylococcus aureus
. Streptococcus agalactiae
. Mycobacterium tuberculosis
. Escherichia coli
. Pseudomonas aeruginosa

Correct Answer & Explanation

. Mycobacterium tuberculosis

Explanation

Tuberculous spondylitis (Pott's disease) typically begins in the subchondral bone of the vertebral body and initially spares the intervertebral disc because the mycobacterium lacks proteolytic enzymes. Pyogenic infections (like S. aureus) rapidly destroy the disc space.

Question 959

Topic: Thoracolumbar Spine & Deformity

Which of the following classical "determinants of gait" primarily functions to limit the maximal upward vertical excursion (peak) of the body's center of mass during the mid-stance phase?

. Pelvic rotation in the horizontal plane
. Pelvic tilt (drop) on the swing side
. Ankle plantarflexion at initial contact
. Lateral pelvic displacement
. Heel rise at terminal stance

Correct Answer & Explanation

. Pelvic tilt (drop) on the swing side

Explanation

Pelvic tilt, or dropping of the pelvis on the non-weight-bearing (swing) side by about 5 degrees, effectively flattens the gait arc. This lowers the peak vertical elevation of the center of mass during mid-stance.

Question 960

Topic: Thoracolumbar Spine & Deformity

A 6-year-old child with spastic diplegic cerebral palsy presents with a severe crouch gait pattern. This pattern is primarily characterized by excessive knee flexion during stance. Which of the following secondary pelvic deviations is most typically associated with crouch gait due to hamstring tightness?

. Excessive anterior pelvic tilt
. Excessive posterior pelvic tilt
. Ipsilateral pelvic drop
. Contralateral pelvic drop
. Fixed pelvic obliquity

Correct Answer & Explanation

. Excessive posterior pelvic tilt

Explanation

Crouch gait involves excessive hip and knee flexion. When spastic, shortened hamstrings are the primary driver, they exert a downward pull on the ischial tuberosities, leading to a compensatory posterior pelvic tilt.

Test Yourself

Switch to an interactive, timed exam simulation to truly master this topic.

On this Page