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6. Spine MCQs

Practice Set 58 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 1141

Topic: 6. Spine

A 14-year-old skeletally immature boy (Risser 1) presents with a thoracic kyphosis measuring 68 degrees. He reports moderate mechanical back pain. Radiographs demonstrate 7 degrees of anterior wedging at T7, T8, and T9. What is the most appropriate initial management?

. Observation with serial radiographs every 6 months
. Physical therapy focusing exclusively on hamstring stretching
. Extension orthosis (e.g., Milwaukee brace) worn 16-23 hours daily
. Posterior spinal fusion with pedicle screw instrumentation
. Anterior release followed by posterior spinal fusion

Correct Answer & Explanation

. Extension orthosis (e.g., Milwaukee brace) worn 16-23 hours daily

Explanation

Bracing is indicated for skeletally immature patients (Risser 0-2) with a flexible Scheuermann's kyphosis measuring between 55 and 80 degrees. An extension orthosis like the Milwaukee brace should be worn 16-23 hours daily for optimal results.

Question 1142

Topic: 6. Spine

In planning surgical correction for a severe Scheuermann's kyphosis using posterior pedicle screw instrumentation, selecting the correct distal fusion level is critical. To minimize the risk of distal junctional kyphosis, the distal instrumented vertebra should typically be:

. The apex of the thoracic kyphosis
. The stable vertebra identified on the PA radiograph
. The neutral vertebra identified on the PA radiograph
. The first lordotic disc space (Sagittal Stable Vertebra)
. Always L5 or S1 to ensure adequate pelvic fixation

Correct Answer & Explanation

. The first lordotic disc space (Sagittal Stable Vertebra)

Explanation

To prevent distal junctional kyphosis, the distal fusion level must include the first lordotic disc, which corresponds to the sagittal stable vertebra. Stopping short of this level leaves the construct vulnerable to progressive kyphosis below the fusion.

Question 1143

Topic: 6. Spine

Type II (Lumbar) Scheuermann's disease is clinically and radiographically distinct from classical thoracic Scheuermann's. Which of the following is most characteristic of Type II Scheuermann's disease?

. It is significantly more common in females
. It primarily presents with acute radiculopathy
. It involves the thoracolumbar or lumbar spine and is often associated with heavy athletic activity
. It requires prompt surgical intervention due to high risk of neurologic compromise
. It is characterized by severe hyperlordosis of the lumbar spine

Correct Answer & Explanation

. It involves the thoracolumbar or lumbar spine and is often associated with heavy athletic activity

Explanation

Type II Scheuermann's disease affects the thoracolumbar or lumbar spine and usually presents in adolescent athletes involved in heavy lifting or repetitive trauma. It causes loss of normal lumbar lordosis and presents with mechanical back pain.

Question 1144

Topic: 6. Spine
Which type of congenital kyphosis carries the highest risk of progression and devastating neurologic compromise (e.g., paraplegia) if left untreated?
. Type I (Failure of formation)
. Type II (Failure of segmentation)
. Type III (Mixed failure of formation and segmentation)
. Postural kyphosis
. Neuromuscular kyphosis

Correct Answer & Explanation

. Type I (Failure of formation)

Explanation

Type I congenital kyphosis (anterior failure of formation) results in a sharp, angular deformity with the highest propensity for rapid progression and spinal cord compression. Early surgical intervention (posterior fusion in situ) is often required.

Question 1145

Topic: Thoracolumbar Spine & Deformity

Long-term natural history studies comparing adults with untreated Scheuermann's kyphosis to the general population demonstrate that patients with Scheuermann's have increased back pain. However, they do NOT significantly differ from the general population in which of the following?

. Degree of structural thoracic kyphosis
. Amount of compensatory lumbar lordosis
. Rates of severe occupational limitations or disability
. Incidence of Schmorl's nodes
. Presence of vertebral endplate irregularities

Correct Answer & Explanation

. Rates of severe occupational limitations or disability

Explanation

While adults with untreated Scheuermann's kyphosis have higher rates of back pain and cosmetic concerns, long-term studies show no significant difference in severe disability, neurologic compromise, or occupational limitations compared to controls.

Question 1146

Topic: 6. Spine

A 2-year-old child is diagnosed with a progressive Type I congenital kyphosis measuring 45 degrees. Neurologic examination is normal. What is the most appropriate management?

. Observation until age 10 to allow spinal growth
. Application of a Milwaukee brace
. In situ posterior spinal fusion
. Anterior vertebrectomy and strut grafting
. Halo-gravity traction for 6 months

Correct Answer & Explanation

. In situ posterior spinal fusion

Explanation

Type I congenital kyphosis has a high rate of progression and neurologic risk. In young children (under age 3-5) with curves <50 degrees, early in situ posterior spinal fusion is the treatment of choice to halt progression.

Question 1147

Topic: 6. Spine

An adolescent weightlifter presents with severe lower back pain and hamstring tightness. Radiographs and MRI demonstrate a displaced fracture of the posterior ring apophysis at L4. What is the primary underlying pathophysiology of this lesion?

. Avulsion of the anterior longitudinal ligament
. Herniation of the intervertebral disc displacing the unfused cartilaginous ring apophysis
. Stress fracture of the pars interarticularis
. Osteoporotic collapse of the superior endplate
. Congenital failure of segmentation

Correct Answer & Explanation

. Herniation of the intervertebral disc displacing the unfused cartilaginous ring apophysis

Explanation

A slipped vertebral apophysis (apophyseal ring fracture) typically occurs in adolescents when disc material herniates through the unossified ring apophysis, displacing it posteriorly into the spinal canal. It is often mistaken for a simple disc herniation.

Question 1148

Topic: 6. Spine

Untreated severe thoracic Scheuermann's kyphosis frequently leads to which of the following compensatory sagittal alignment changes to maintain a level horizontal gaze?

. Decreased lumbar lordosis and decreased cervical lordosis
. Increased lumbar lordosis and increased cervical lordosis
. Increased pelvic retroversion and knee extension
. Thoracolumbar scoliosis
. Cervical kyphosis

Correct Answer & Explanation

. Increased lumbar lordosis and increased cervical lordosis

Explanation

To compensate for the rigid hyperkyphosis in the thoracic spine and maintain a horizontal gaze, patients will typically develop hyperlordosis in both the cervical and lumbar spine.

Question 1149

Topic: 6. Spine

A 15-year-old boy presents with progressive mid-back pain. Lateral radiographs show the deformity seen in the provided image.

If surgical correction is undertaken, failure to include the proximal end vertebra in the fusion construct most commonly leads to which complication?

. Pseudarthrosis
. Proximal junctional kyphosis (PJK)
. Distal junctional kyphosis
. Coronal imbalance
. Early implant pullout

Correct Answer & Explanation

. Proximal junctional kyphosis (PJK)

Explanation

Failure to extend the proximal fusion level to include the proximal end vertebra (typically T2 or T3) in Scheuermann's kyphosis significantly increases the risk of proximal junctional kyphosis (PJK).

Question 1150

Topic: 6. Spine

When selecting the proximal fusion level for surgical correction of Scheuermann's kyphosis, which anatomic landmark is generally accepted as the optimal stopping point to minimize junctional complications?

. The apex of the thoracic kyphosis
. T10
. The proximal end vertebra (usually T2 or T3)
. C7
. The first lordotic disc

Correct Answer & Explanation

. The proximal end vertebra (usually T2 or T3)

Explanation

The proximal fusion level should be the proximal end vertebra of the kyphosis, which is usually T2 or T3. Stopping lower (e.g., T4 or T5) leaves the patient highly susceptible to proximal junctional kyphosis.

Question 1151

Topic: 6. Spine
During posterior spinal fusion for Scheuermann's kyphosis, surgeons must avoid overcorrection of the deformity. Overcorrection (e.g., reducing the curve by >50% of its initial magnitude) is most strongly associated with an increased risk of:
. Intraoperative dural tears
. Proximal junctional kyphosis (PJK)
. Superior mesenteric artery syndrome
. Postoperative spondylolisthesis
. Pseudarthrosis

Correct Answer & Explanation

. Proximal junctional kyphosis (PJK)

Explanation

Overcorrection of the kyphotic deformity alters spinal biomechanics aggressively and is a major independent risk factor for the development of proximal junctional kyphosis (PJK). Correction to high-normal ranges (40-50 degrees) is preferred.

Question 1152

Topic: 6. Spine

What is the primary biomechanical principle utilized by the Milwaukee brace to correct or halt the progression of Scheuermann's kyphosis?

. Direct axial distraction between the chin and the pelvis
. Three-point bending forces with an apical pad located just below the apex of the kyphosis
. Derotation of the apical vertebrae
. Immobilization of the lumbar spine to prevent compensatory lordosis
. Continuous passive extension of the cervical spine

Correct Answer & Explanation

. Three-point bending forces with an apical pad located just below the apex of the kyphosis

Explanation

The Milwaukee brace works primarily via three-point bending. It applies anteriorly directed corrective force via a posterior pad situated just below the apex of the kyphosis, countered by posterior forces at the neck and pelvis.

Question 1153

Topic: 6. Spine

A 14-year-old female presents with a rounded back. On the Adams forward bending test, the deformity is smooth. Clinically, she can actively hyperextend to fully correct the curve. Radiographs show a 50-degree thoracic kyphosis with no vertebral wedging. What is the most appropriate management?

. Milwaukee brace for 23 hours a day
. Reassurance and physical therapy focusing on core and postural strengthening
. Custom TLSO brace
. Posterior spinal fusion
. Serial casting

Correct Answer & Explanation

. Reassurance and physical therapy focusing on core and postural strengthening

Explanation

This presentation describes postural kyphosis, characterized by a flexible deformity with no structural vertebral wedging. Management consists of reassurance and postural exercises; bracing or surgery is not indicated.

Question 1154

Topic: 6. Spine

In the modern era of spine surgery utilizing all-pedicle screw constructs, anterior release is typically reserved for which specific subset of Scheuermann's kyphosis patients?

. Curves >60 degrees with associated lumbar scoliosis
. Curves >75 degrees regardless of flexibility
. Rigid curves >100 degrees that do not correct to <50 degrees on a hyperextension radiograph
. Patients with marked lumbar hyperlordosis
. Patients with any documented Schmorl's nodes

Correct Answer & Explanation

. Rigid curves >100 degrees that do not correct to <50 degrees on a hyperextension radiograph

Explanation

Historically, anterior release was recommended for curves >75 degrees. With powerful modern pedicle screw constructs, posterior-only approaches are standard unless the curve is exceptionally severe (>100 degrees) and highly rigid.

Question 1155

Topic: Thoracolumbar Spine & Deformity

Wide posterior release is often necessary to achieve adequate correction in Scheuermann's kyphosis. What anatomic structures are resected during a standard Ponte osteotomy?

. The anterior longitudinal ligament and intervertebral disc
. The spinous process, lamina, ligamentum flavum, and bilateral facet joints
. The entire vertebral body and adjacent pedicles
. The transverse processes and attached ribs
. The pars interarticularis only

Correct Answer & Explanation

. The spinous process, lamina, ligamentum flavum, and bilateral facet joints

Explanation

A Ponte osteotomy is a posterior column shortening osteotomy that involves wide resection of the spinous process, lamina, ligamentum flavum, and the bilateral facet joints to drastically increase posterior flexibility.

Question 1156

Topic: 6. Spine

Histological examination of the vertebral endplates in patients with classical Scheuermann's kyphosis typically demonstrates:

. Avascular necrosis of the secondary ossification center
. Defective, disorganized endplate cartilage with irregular ossification and disc herniation
. Caseating granulomatous inflammation
. Complete absence of the anulus fibrosus
. Primary osteoclastic overactivity resembling Paget's disease

Correct Answer & Explanation

. Defective, disorganized endplate cartilage with irregular ossification and disc herniation

Explanation

The primary histological defect in Scheuermann's disease is an abnormality in the cartilaginous endplate, characterized by disorganized cellularity, defective ossification, and focal defects allowing disc herniation (Schmorl's nodes).

Question 1157

Topic: 6. Spine

During posterior correction of a 90-degree Scheuermann's kyphosis, the surgeon applies heavy compression across the apical pedicle screws to shorten the posterior column. A sudden loss of bilateral lower extremity Motor Evoked Potentials (MEPs) is noted, while SSEPs remain stable. What is the most appropriate immediate action?

. Administer intravenous tranexamic acid
. Release the corrective forces and remove the compression
. Perform an emergency anterior column release
. Continue the operation as SSEPs are intact
. Increase the mean arterial pressure and continue compression

Correct Answer & Explanation

. Release the corrective forces and remove the compression

Explanation

Loss of MEPs indicates compromise to the anterior spinal cord (motor tracts), which can occur from over-shortening or distraction. The immediate first step is to release the corrective forces. MEPs are more sensitive to this specific ischemia than SSEPs.

Question 1158

Topic: 6. Spine

Dystrophic kyphoscoliosis in Neurofibromatosis Type 1 is characterized by vertebral wedging, scalloping, and penciling of the ribs. Due to the exceptionally high risk of rapid progression and pseudarthrosis, what is the recommended surgical approach for a progressing dystrophic curve?

. Posterior spinal fusion alone with hook constructs
. Anterior release and fusion combined with posterior spinal fusion and instrumentation
. Insertion of a magnetically controlled growing rod
. VEPTR expansion thoracostomy
. Hemivertebra excision

Correct Answer & Explanation

. Anterior release and fusion combined with posterior spinal fusion and instrumentation

Explanation

Dystrophic curves in NF1 are highly aggressive and carry a massive risk of pseudarthrosis. They typically require robust stabilization with combined anterior and posterior spinal fusion to achieve successful arthrodesis.

Question 1159

Topic: Thoracolumbar Spine & Deformity

Which of the following represents the classic Sorensen criteria for the radiographic diagnosis of Scheuermann's kyphosis?

. Anterior wedging of >10 degrees in two consecutive vertebrae
. Anterior wedging of >5 degrees in three or more consecutive vertebrae
. Thoracic kyphosis >45 degrees with isolated Schmorl's nodes
. Endplate irregularities and disc space narrowing without wedging
. Vertebral body wedging of >15 degrees at the apex

Correct Answer & Explanation

. Anterior wedging of >5 degrees in three or more consecutive vertebrae

Explanation

The Sorensen criteria define classic Scheuermann's disease as anterior wedging of greater than 5 degrees in at least three consecutive vertebrae.

Question 1160

Topic: 6. Spine

According to Sorensen's radiographic criteria, which of the following is an absolute requirement for the classic diagnosis of Scheuermann's kyphosis?

. Anterior wedging of 5 degrees or more in at least two adjacent vertebrae
. Anterior wedging of 5 degrees or more in at least three adjacent vertebrae
. Kyphosis greater than 45 degrees with isolated Schmorl nodes
. Anterior wedging of 10 degrees or more in at least three adjacent vertebrae
. Any anterior wedging accompanied by greater than 50 degrees of thoracic kyphosis

Correct Answer & Explanation

. Anterior wedging of 5 degrees or more in at least three adjacent vertebrae

Explanation

Sorensen's classic criteria for Scheuermann's disease requires anterior wedging of at least 5 degrees in three or more sequential adjacent vertebrae. This distinguishes it from postural kyphosis and normal variant spinal curves.

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