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6. Spine MCQs

Practice Set 308 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 6141

Topic: 6. Spine
A 28-year-old male presents following a high-speed collision. Imaging reveals a traumatic spondylolisthesis of the axis (Hangman's fracture). The fracture shows severe angulation but minimal translation, and the angulation worsens significantly with longitudinal traction. What is the Levine-Edwards classification and appropriate management?
. Type I; treatment with a rigid cervical collar
. Type II; treatment with cervical traction followed by a halo vest
. Type IIA; traction is contraindicated, treat with gentle extension and compression in a halo vest
. Type III; treatment with immediate open reduction and internal fixation
. Type III; treatment with immediate heavy cervical traction

Correct Answer & Explanation

. Type IIA; traction is contraindicated, treat with gentle extension and compression in a halo vest

Explanation

This describes a Type IIA Hangman's fracture, caused by flexion-distraction. Traction exacerbates the deformity and is strictly contraindicated; management involves gentle extension and compression using a halo vest.

Question 6142

Topic: 6. Spine

A 65-year-old male undergoes a C3-C6 posterior cervical laminectomy and fusion for multilevel spondylotic myelopathy. On postoperative day 2, he develops profound unilateral deltoid and biceps weakness, but no lower extremity deficits. What is the most widely accepted etiology of this complication?

. Intraoperative direct spinal cord contusion
. Postoperative epidural hematoma
. Posterior spinal cord shift causing traction on the tethered C5 nerve root
. Inadequate decompression of the C4-C5 neural foramen
. Postoperative C5 radiculitis secondary to subclinical infection

Correct Answer & Explanation

. Intraoperative direct spinal cord contusion

Explanation

Postoperative C5 palsy is a well-known complication after posterior cervical decompression. The most widely accepted etiology is the posterior shift of the spinal cord, which places excessive traction on the short, tethered C5 nerve roots.

Question 6143

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with an L5-S1 isthmic spondylolisthesis with a 20% slip (Meyerding Grade I). She has severe, mechanically limiting back pain that has failed 6 months of comprehensive conservative management. Which of the following is the most appropriate surgical intervention?

. L5-S1 anterior lumbar interbody fusion (ALIF) standalone
. Direct pars interarticularis repair
. L5-S1 posterior instrumented fusion
. L5 laminectomy without fusion
. L4-S1 posterior instrumented fusion

Correct Answer & Explanation

. L5-S1 anterior lumbar interbody fusion (ALIF) standalone

Explanation

For a symptomatic low-grade isthmic spondylolisthesis failing conservative care in an adolescent, L5-S1 posterior instrumented fusion is the gold standard. Direct pars repair is generally reserved for young patients with acute pars defects and no significant slip or disc degeneration.

Question 6144

Topic: 6. Spine

A 68-year-old male with long-standing ankylosing spondylitis sustains a ground-level fall. He complains of severe lower neck pain, though his neurological exam is normal. Standard anteroposterior and lateral cervical radiographs are inconclusive due to deformity and poor visualization of the cervicothoracic junction. What is the most critical next step?

. Discharge with a rigid cervical collar and NSAIDs
. Perform dynamic flexion-extension cervical radiographs
. Obtain a CT scan of the entire cervical spine
. Obtain an MRI of the lumbar spine
. Empiric application of a halo vest

Correct Answer & Explanation

. Discharge with a rigid cervical collar and NSAIDs

Explanation

Patients with ankylosing spondylitis have highly rigid spines that act as long lever arms, making them extremely susceptible to highly unstable fractures even from minor trauma. A CT scan of the entire cervical spine is mandatory to rule out an occult fracture.

Question 6145

Topic: 6. Spine

A 45-year-old male immigrant presents with night sweats, back pain, and progressive paraparesis. MRI of the thoracic spine reveals extensive destruction of the anterior vertebral bodies of T8 and T9 with a large paraspinal abscess, yet the T8-T9 intervertebral disc space is relatively preserved. What is the most likely causative organism?

. Staphylococcus aureus
. Streptococcus pneumoniae
. Pseudomonas aeruginosa
. Mycobacterium tuberculosis
. Candida albicans

Correct Answer & Explanation

. Staphylococcus aureus

Explanation

Mycobacterium tuberculosis (Pott's disease) typically involves the anterior aspect of the vertebral bodies and spreads subligamentously. Characteristically, it spares the intervertebral disc space until late in the disease, which helps differentiate it from pyogenic spondylodiscitis.

Question 6146

Topic: Cervical Spine

An 82-year-old male falls and sustains a Type II odontoid fracture. Imaging reveals that the dens is displaced 6 mm posteriorly. He is neurologically intact but in significant pain. What is the most appropriate definitive management for this patient?

. Immobilization in a rigid cervical collar for 12 weeks
. Halo vest immobilization
. Anterior odontoid screw fixation
. Posterior C1-C2 instrumented fusion
. Observation and physical therapy

Correct Answer & Explanation

. Immobilization in a rigid cervical collar for 12 weeks

Explanation

In elderly patients (>80 years), non-operative management of Type II odontoid fractures with >5 mm displacement carries a very high nonunion rate and morbidity. Posterior C1-C2 fusion is the treatment of choice, as anterior screw fixation has a high failure rate in osteopenic bone.

Question 6147

Topic: 6. Spine

A 50-year-old male presents with acute, severe right leg pain and weakness in ankle dorsiflexion and great toe extension. An MRI of the lumbar spine reveals a massive far lateral (extraforaminal) disc herniation at the L5-S1 level on the right. Which nerve root is primarily compressed, and what surgical approach is ideally utilized?

. S1 root; standard midline interlaminar approach
. L5 root; standard midline interlaminar approach
. L5 root; paramedian (Wiltse) muscle-splitting approach
. S1 root; paramedian (Wiltse) muscle-splitting approach
. L4 root; anterior retroperitoneal approach

Correct Answer & Explanation

. S1 root; standard midline interlaminar approach

Explanation

A far lateral disc herniation at L5-S1 compresses the exiting L5 nerve root. The paramedian (Wiltse) muscle-splitting approach allows direct access to the extraforaminal zone while minimizing damage to the midline structures and facet joint.

Question 6148

Topic: 6. Spine

Biomechanically, during normal flexion and extension of a healthy lumbar functional spinal unit, the instantaneous axis of rotation is primarily located in which region?

. The center of the vertebral body
. The facet joint
. The anterior portion of the posterior half of the intervertebral disc
. The posterior longitudinal ligament
. The tip of the spinous process

Correct Answer & Explanation

. The center of the vertebral body

Explanation

The instantaneous axis of rotation (IAR) for a functional spinal unit in the lumbar spine during flexion and extension is located within the intervertebral disc, specifically in the anterior portion of the posterior half of the disc.

Question 6149

Topic: 6. Spine

A patient presents with weakness in wrist extension and altered sensation over the dorsal web space between the thumb and index finger, consistent with a C6 radiculopathy. In the cervical spine, the C6 nerve root exits through which neural foramen?

. Between C4 and C5
. Between C5 and C6
. Between C6 and C7
. Between C7 and T1
. Between T1 and T2

Correct Answer & Explanation

. Between C4 and C5

Explanation

In the cervical spine, there are 8 cervical nerve roots but only 7 cervical vertebrae. Nerves C1 through C7 exit ABOVE their correspondingly numbered vertebrae (e.g., the C6 nerve root exits through the foramen between C5 and C6). The C8 nerve root exits between C7 and T1, and all subsequent spinal nerves exit BELOW their correspondingly numbered vertebrae.

Question 6150

Topic: 6. Spine

When examining an axial T1-weighted MRI of the lumbar spine at the L4-L5 disc level, which nerve root is typically located within the lateral recess and is most susceptible to compression from a paracentral disc herniation at this level?

. L3 nerve root
. L4 nerve root
. L5 nerve root
. S1 nerve root
. S2 nerve root

Correct Answer & Explanation

. L3 nerve root

Explanation

At the L4-L5 level, a paracentral disc herniation typically compresses the traversing L5 nerve root in the lateral recess. A far lateral herniation at the same level would compress the exiting L4 root.

Question 6151

Topic: 6. Spine

You are evaluating an axial cervical spine MRI of a 45-year-old male with neck pain.

Which structure is located immediately anterior to the normal exiting C6 nerve root as it passes through the intervertebral foramen?

. Vertebral artery
. Superior articular process of C6
. Ligamentum flavum
. Posterior longitudinal ligament
. C6 pedicle

Correct Answer & Explanation

. Vertebral artery

Explanation

In the cervical spine, the vertebral artery runs through the transverse foramina anterior to the exiting nerve roots. The superior articular process and ligamentum flavum form the posterior border of the foramen.

Question 6152

Topic: 6. Spine

A cervical spine CT angiogram is ordered for a patient with a facet dislocation. The radiologist traces the vertebral artery. In a normal anatomic variant, the vertebral artery typically first enters the transverse foramen at which cervical level?

. C3
. C4
. C5
. C6
. C7

Correct Answer & Explanation

. C3

Explanation

The vertebral artery typically enters the transverse foramen at the level of C6 in about 90% of individuals. It rarely enters at C7, which instead typically transmits the accessory vertebral vein.

Question 6153

Topic: 6. Spine

When planning pedicle screw placement in the lumbar spine, standard anatomic landmarks are utilized. The optimal starting point for an L4 pedicle screw is located at the intersection of the pars interarticularis, the midpoint of the transverse process, and what other bony landmark?

. Spinous process
. Inferior articular facet
. Lateral border of the superior articular facet
. Lamina
. Spinous process base

Correct Answer & Explanation

. Spinous process

Explanation

In the lumbar spine, the entry point for a pedicle screw is typically at the intersection of a vertical line through the lateral border of the superior articular facet and a horizontal line bisecting the transverse process.

Question 6154

Topic: 6. Spine

In the anterior approach to the lower cervical spine (Smith-Robinson), why is a left-sided approach theoretically preferred by many surgeons regarding cranial nerve safety?

. The left recurrent laryngeal nerve has a more predictable, vertical course within the tracheoesophageal groove.
. The right recurrent laryngeal nerve is entirely absent in 10% of patients.
. The left sympathetic chain is positioned more laterally.
. The right carotid artery is more easily mobilized.
. The thoracic duct poses no risk on the left side.

Correct Answer & Explanation

. The left recurrent laryngeal nerve has a more predictable, vertical course within the tracheoesophageal groove.

Explanation

The left recurrent laryngeal nerve loops beneath the aortic arch and ascends predictably in the tracheoesophageal groove. The right recurrent laryngeal nerve loops under the subclavian artery and often crosses the surgical field obliquely, increasing its vulnerability.

Question 6155

Topic: 6. Spine

A 45-year-old male is involved in a motor vehicle collision and sustains a traumatic spondylolisthesis of the axis (Hangman's fracture). What is the most common mechanism of injury for this fracture pattern in modern civilian trauma?

. Axial loading and hyperflexion
. Severe lateral bending
. Hyperextension and axial loading
. Extreme rotation and flexion
. Distraction and hyperflexion

Correct Answer & Explanation

. Axial loading and hyperflexion

Explanation

A Hangman's fracture involves bilateral fractures of the C2 pars interarticularis. While historically caused by sudden severe distraction and hyperextension (judicial hanging), the most common mechanism in modern civilian trauma (e.g., an unrestrained occupant striking the dashboard with their face) involves violent hyperextension combined with axial loading.

Question 6156

Topic: 6. Spine

A 25-year-old male sustains a gunshot wound to the abdomen. The bullet transverses the bowel and lodges in the L3 vertebral body. He has a complete neurologic deficit below L3. He undergoes an exploratory laparotomy and bowel repair. What is the most appropriate management of the retained bullet in the spine?

. Emergent laminectomy and bullet extraction
. Observation with a short course (7-14 days) of broad-spectrum antibiotics
. Anterior corpectomy and spinal fusion
. Long-term (6 months) suppressive intravenous antibiotics
. Epidural steroid injection

Correct Answer & Explanation

. Emergent laminectomy and bullet extraction

Explanation

In the setting of a complete neurologic deficit, removing a bullet from the spinal canal provides no neurologic benefit. Even with transperitoneal bowel perforation, the incidence of spinal infection is low. The standard of care is a short course of broad-spectrum antibiotics (usually 7-14 days) and observation. Extraction is only indicated for incomplete/progressive deficits, copper/lead toxicity in a joint space, or persistent CSF leak.

Question 6157

Topic: 6. Spine
According to the Wiltse classification of pediatric spondylolisthesis, which type has the highest intrinsic risk of progression and often requires in situ fusion even for relatively low-grade slips?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type I (Dysplastic)

Explanation

Type I (Dysplastic) spondylolisthesis is caused by congenital abnormalities of the upper sacrum or the neural arch of L5. It carries the highest risk of progression. Because the neural arch often remains intact, high-grade slips can cause severe cauda equina compression, making early surgical stabilization critical.

Question 6158

Topic: 6. Spine

A 6-year-old child with short trunk dwarfism, corneal clouding, and normal intelligence is diagnosed with Morquio syndrome (MPS IV). Which orthopedic manifestation requires the most urgent screening and potential surgical intervention in this condition?

. Scoliosis
. Genu valgum
. Atlantoaxial instability
. Hip subluxation
. Carpal tunnel syndrome

Correct Answer & Explanation

. Scoliosis

Explanation

Morquio syndrome (Mucopolysaccharidosis Type IV) is characterized by an accumulation of keratan sulfate. A hallmark orthopedic issue is odontoid hypoplasia, which leads to severe atlantoaxial instability. This can cause cervical myelopathy, quadriplegia, or sudden death; thus, early screening and prophylactic posterior cervical fusion are often required.

Question 6159

Topic: 6. Spine

A 10-month-old infant is diagnosed with an isolated 25-degree left thoracic curve. A spine radiograph is obtained to evaluate the rib-vertebra angle difference (RVAD) of Mehta. Which of the following statements regarding the RVAD is correct?

. An RVAD greater than 20 degrees strongly indicates the curve will resolve spontaneously.
. An RVAD greater than 20 degrees is highly predictive of curve progression.
. The RVAD is measured at the lumbar vertebrae.
. A decreasing RVAD on serial radiographs is an indication for immediate surgical fusion.
. Phase 2 rib-head relationships predict spontaneous resolution.

Correct Answer & Explanation

. An RVAD greater than 20 degrees strongly indicates the curve will resolve spontaneously.

Explanation

In infantile idiopathic scoliosis, Mehta's Rib-Vertebral Angle Difference (RVAD) is measured at the apical vertebra. An RVAD > 20 degrees is highly predictive of curve progression. Phase 2 rib-head relationship (where the rib head overlaps the vertebral body) is also a strong predictor of progression. Most curves with an RVAD < 20 degrees resolve spontaneously.

Question 6160

Topic: 6. Spine

A 4-year-old patient with Spinal Muscular Atrophy (SMA) Type II is receiving Nusinersen (Spinraza) therapy via repeated intrathecal injections. The patient has developed a progressive 65-degree neuromuscular scoliosis. What specific surgical consideration must be planned regarding their future spine deformity correction?

. Spine fusion must be avoided because it prevents lung expansion.
. Anterior spinal fusion alone is the standard of care for SMA.
. Surgical instrumentation must incorporate a tailored lumbar laminectomy or interlaminar window to allow continued intrathecal access.
. Only non-fusion tethering devices should be used in patients with SMA.
. Nusinersen must be discontinued permanently prior to any spinal instrumentation.

Correct Answer & Explanation

. Spine fusion must be avoided because it prevents lung expansion.

Explanation

Nusinersen (Spinraza) is an antisense oligonucleotide administered via lifelong intrathecal injections to treat SMA. Because standard posterior spinal fusion typically obscures thecal access, surgeons must intentionally leave a lumbar interlaminar window (or install a subarachnoid catheter/port) to ensure the patient can continue receiving this life-saving medication postoperatively.

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