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6. Spine MCQs

Practice Set 61 of 379

This practice set contains high-yield board review questions covering key concepts in 6. Spine. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 1201

Topic: 6. Spine

Which of the following morphological patterns of congenital scoliosis carries the highest risk of rapid curve progression and requires the most urgent surgical intervention?

. Block vertebra
. Fully segmented hemivertebra
. Incarcerated hemivertebra
. Unilateral unsegmented bar with contralateral fully segmented hemivertebra
. Wedge vertebra

Correct Answer & Explanation

. Unilateral unsegmented bar with contralateral fully segmented hemivertebra

Explanation

A unilateral unsegmented bar with a contralateral fully segmented hemivertebra causes asymmetric growth that almost always leads to rapid, severe progression. Early surgical intervention, typically via in situ fusion or hemivertebra excision, is strictly indicated.

Question 1202

Topic: Thoracolumbar Spine & Deformity

According to the Sorensen criteria, a definitive radiographic diagnosis of 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

. Three

Explanation

The classic Sorensen criteria define Scheuermann's disease as hyperkyphosis with anterior wedging of at least 5 degrees in three or more adjacent vertebral bodies. Endplate irregularities and Schmorl's nodes are also typical findings.

Question 1203

Topic: 6. Spine

In the evaluation of infantile idiopathic scoliosis, a rib-vertebra angle difference (RVAD) of Mehta greater than what threshold is considered highly predictive of curve progression?

. 10 degrees
. 20 degrees
. 30 degrees
. 40 degrees
. 50 degrees

Correct Answer & Explanation

. 20 degrees

Explanation

An RVAD (Mehta's angle) greater than 20 degrees in infantile idiopathic scoliosis strongly suggests that the curve will be progressive rather than spontaneously resolving. These patients typically require early cast or brace treatment.

Question 1204

Topic: 6. Spine

In a non-ambulatory patient with severe spastic cerebral palsy, neuromuscular scoliosis, and severe pelvic obliquity, surgical correction typically requires which of the following approaches?

. Anterior spinal fusion to L5
. Posterior spinal fusion stopping at L5
. Posterior spinal fusion extending to the pelvis
. Growing rod placement
. Selective thoracic fusion

Correct Answer & Explanation

. Posterior spinal fusion extending to the pelvis

Explanation

To adequately correct and maintain the correction of pelvic obliquity in non-ambulatory neuromuscular patients, instrumentation and fusion must typically extend down to the pelvis. Stopping short at L5 often leads to progressive pelvic obliquity and sitting imbalance.

Question 1205

Topic: 6. Spine

During a posterior spinal fusion for scoliosis, somatosensory evoked potentials (SSEPs) are utilized. SSEPs primarily monitor which spinal cord tract, and are supplied by which vascular territory?

. Dorsal columns; posterior spinal arteries
. Corticospinal tract; posterior spinal arteries
. Spinothalamic tract; anterior spinal artery
. Dorsal columns; anterior spinal artery
. Corticospinal tract; anterior spinal artery

Correct Answer & Explanation

. Dorsal columns; posterior spinal arteries

Explanation

SSEPs monitor the sensory pathways of the dorsal columns, which are supplied by the posterior spinal arteries. Motor evoked potentials (MEPs) are used to monitor the anterior cord and corticospinal tracts supplied by the anterior spinal artery.

Question 1206

Topic: 6. Spine
Which of the following clinical or radiographic findings in a patient with presumed adolescent idiopathic scoliosis is an absolute indication for a preoperative MRI of the total spine to rule out neural axis abnormalities?
. Right thoracic curve
. Left thoracic curve
. Positive family history
. Apical rotation grade III
. Cobb angle greater than 50 degrees

Correct Answer & Explanation

. Left thoracic curve

Explanation

A left-sided thoracic curve is atypical for adolescent idiopathic scoliosis and carries a significantly higher association with intraspinal anomalies, such as a syrinx or Chiari malformation. It warrants a full-spine MRI.

Question 1207

Topic: 6. Spine

In a non-ambulatory patient with Duchenne muscular dystrophy, at what scoliotic curve magnitude is posterior spinal fusion generally recommended to prevent severe respiratory decline and preserve seating balance?

. Greater than 10 degrees
. Greater than 20 degrees
. Greater than 50 degrees
. Greater than 70 degrees
. Only when FVC drops below 30%

Correct Answer & Explanation

. Greater than 20 degrees

Explanation

Scoliosis in Duchenne muscular dystrophy is relentlessly progressive once the patient becomes wheelchair-bound. Early surgical stabilization is recommended when the curve exceeds 20 to 30 degrees to prevent severe respiratory compromise.

Question 1208

Topic: 6. Spine

A 14-year-old competitive gymnast presents with persistent lower back pain. Radiographs reveal a Grade 2 isthmic spondylolisthesis at L5-S1. After 6 months of dedicated conservative management including bracing and physical therapy, she remains highly symptomatic. What is the most appropriate surgical treatment?

. Direct pars repair (Buck's technique)
. L5-S1 anterior lumbar interbody fusion (ALIF) without posterior instrumentation
. L5-S1 posterior spinal fusion with instrumentation
. L4-S1 posterior spinal fusion with instrumentation
. L5 laminectomy alone

Correct Answer & Explanation

. L5-S1 posterior spinal fusion with instrumentation

Explanation

For a symptomatic Grade 2 isthmic spondylolisthesis at L5-S1 failing conservative management, a single-level instrumented posterior spinal fusion is the standard of care. Direct pars repair is generally reserved for L4 or higher with grade 1 or less slip.

Question 1209

Topic: 6. Spine

Although all of the following conditions may present in patients with skeletal dysplasia, which is the only condition that does not have a high frequency of spontaneous improvement:

. Infantile foramen magnum stenosis in patients with achondroplasia
. Infantile thoracolumbar kyphosis in patients with achondroplasia
. C ervical kyphosis in patients with diastrophic dysplasia
. C ervical kyphosis in patients with Larsen syndrome
. Hypotonia in patients with achondroplasia

Correct Answer & Explanation

. C ervical kyphosis in patients with Larsen syndrome

Explanation

Cervical kyphosis does not improve in patients with Larsen syndrome and may cause myelopathy. Early arthrodesis (posterior only, if not too severe) is indicated. All of the other conditions have a high incidence of spontaneous improvement, so they are most appropriately treated with observation. In a minority of cases, the deformity does not improve and surgery is indicated.

Question 1210

Topic: Thoracolumbar Spine & Deformity

Which of the following characterizes Russell-Silver syndrome:

. Hemihypertrophy
. Hemiatrophy
. Acromegaly
. Macrodactyly
. Precocious puberty

Correct Answer & Explanation

. Hemiatrophy

Explanation

Russell-Silver syndrome is characterized by a small triangular face, hemiatrophy of up to 5 cm, delay in skeletal age, and sometimes a developmental delay. Scoliosis is commonly found in patients with Russell- Silver syndrome.

Question 1211

Topic: 6. Spine

The upper-end vertebra for measurement of kyphosis should always be:

. T1
. T2
. T3
. T4
. The most inclined upper vertebra on the sagittal plane.

Correct Answer & Explanation

. The most inclined upper vertebra on the sagittal plane.

Explanation

As in measurement of any spinal curve, the upper-end reference is the most inclined upper vertebra. One should carefully select this level and ensure that comparison measurements utilize the same vertebral levels.

Question 1212

Topic: 6. Spine

What is the most common symptomatic spinal complication requiring surgical decompression in adult patients with achondroplasia?

. Cervical myelopathy from atlantoaxial instability
. Adolescent idiopathic-like thoracic scoliosis
. High-grade spondylolisthesis
. Spinal stenosis
. Spondylolysis

Correct Answer & Explanation

. Spinal stenosis

Explanation

Spinal stenosis is the most common spinal complication in adult achondroplastic patients. It results from short pedicles, a narrowed interpedicular distance, and thickened ligamentum flavum.

Question 1213

Topic: 6. Spine

A 6-year-old child presents with short stature, early-onset joint pain, and a waddling gait. Radiographs demonstrate delayed and fragmented ossification of the epiphyses, but spinal radiographs are completely normal. What is the most likely diagnosis?

. Multiple epiphyseal dysplasia
. Spondyloepiphyseal dysplasia congenita
. Morquio syndrome
. Achondroplasia
. Diastrophic dysplasia

Correct Answer & Explanation

. Multiple epiphyseal dysplasia

Explanation

Multiple epiphyseal dysplasia (MED) affects the epiphyses of long bones but classically spares the spine. This differentiates it from spondyloepiphyseal dysplasia (SED), which involves both the spine and the epiphyses.

Question 1214

Topic: 6. Spine

Prior to administering general anesthesia for a patient with spondyloepiphyseal dysplasia congenita (SEDc), which cervical spine pathology must be specifically ruled out with flexion-extension radiographs?

. Basilar invagination
. Atlantoaxial instability due to odontoid hypoplasia
. Subaxial cervical stenosis
. Cervical kyphosis
. Klippel-Feil anomaly

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

Patients with SEDc frequently have delayed ossification and hypoplasia of the odontoid process. This leads to profound atlantoaxial instability, posing a severe risk of cervical myelopathy or spinal cord injury during endotracheal intubation.

Question 1215

Topic: 6. Spine

A 6-year-old child with a known FGFR3 gene mutation presents with progressive clumsiness and lower extremity hyperreflexia. Given the genetic diagnosis, what is the most likely cause of these neurological findings?

. Odontoid hypoplasia leading to atlantoaxial instability
. Foramen magnum stenosis causing cervicomedullary compression
. Thoracolumbar kyphosis with spinal cord tethering
. Progressive hydrocephalus causing cortical thinning
. Lumbar spinal stenosis from shortened pedicles

Correct Answer & Explanation

. Foramen magnum stenosis causing cervicomedullary compression

Explanation

Achondroplasia is caused by an FGFR3 mutation. In young children with this condition, cervicomedullary compression at the level of a stenotic foramen magnum is a critical complication presenting with hyperreflexia, clumsiness, or central apnea.

Question 1216

Topic: 6. Spine

A 9-year-old girl with Morquio syndrome (Mucopolysaccharidosis Type IV) presents for an orthopedic evaluation. Which of the following spinal conditions is the most life-threatening orthopedic complication associated with her diagnosis?

. Progressive thoracolumbar kyphosis
. Severe lumbosacral spondylolisthesis
. Atlantoaxial instability due to odontoid hypoplasia
. Rapidly progressive structural scoliosis
. Foramen magnum stenosis

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

Morquio syndrome is frequently complicated by severe odontoid hypoplasia and ligamentous laxity. This leads to profound atlantoaxial instability, which can cause life-threatening cervical myelopathy if unrecognized.

Question 1217

Topic: 6. Spine

A 5-year-old boy with achondroplasia presents with progressively decreasing exercise tolerance, hyperreflexia, and clonus. What is the most critical anatomical site requiring urgent evaluation?

. Cervicomedullary junction
. Thoracolumbar junction
. Lumbosacral spine
. Odontoid process
. Subaxial cervical spine

Correct Answer & Explanation

. Cervicomedullary junction

Explanation

Children with achondroplasia are at high risk for foramen magnum stenosis, which can compress the cervicomedullary junction. Symptoms of myelopathy, such as hyperreflexia and clonus, warrant urgent MRI and potential surgical decompression.

Question 1218

Topic: 6. Spine

A 7-year-old child with Morquio syndrome (MPS IV) presents for preoperative evaluation before bilateral lower extremity osteotomies. Which of the following preoperative imaging studies is most critical for preventing a catastrophic perioperative complication?

. Echocardiogram
. Chest CT scan
. Flexion-extension cervical spine radiographs
. MRI of the thoracolumbar spine
. Renal ultrasound

Correct Answer & Explanation

. Flexion-extension cervical spine radiographs

Explanation

Patients with Morquio syndrome frequently have odontoid hypoplasia and severe atlantoaxial instability. Flexion-extension cervical radiographs are critical prior to intubation to prevent spinal cord injury during positioning.

Question 1219

Topic: 6. Spine

A 3-year-old child presents with Morquio syndrome (MPS IV). Which of the following cervical spine abnormalities is the most critical to screen for in this patient to prevent sudden death?

. Atlantoaxial instability due to odontoid hypoplasia
. Basilar invagination
. Mid-cervical kyphosis
. Klippel-Feil anomaly with fused segments
. Ossification of the posterior longitudinal ligament

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

Patients with Morquio syndrome are at extraordinarily high risk for odontoid hypoplasia and ligamentous laxity. This results in severe atlantoaxial instability that can lead to fatal cervical myelopathy if unaddressed.

Question 1220

Topic: Thoracolumbar Spine & Deformity
Patients with which one of the following curve types associated with idiopathic scoliosis are at increased risk of shortness of breath?
. Thoracic curves larger than 80°
. Thoracolumbar curves larger than 80°
. Thoracolumbar curves larger than 100°
. Lumbar curves larger than 80°
. Lumbar curves larger than 100°

Correct Answer & Explanation

. Thoracic curves larger than 80°

Explanation

Idiopathic scoliosis is associated with measurable decreases in pulmonary function in thoracic curves larger than 60° to 70°, but a clinically significant increase in risk of shortness of breath has been shown only in thoracic curves larger than 80°.

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