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6. Spine MCQs

Practice Set 309 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 6161

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with severe lower back pain and radicular pain in the L5 distribution. Radiographs demonstrate a Grade III L5-S1 isthmic spondylolisthesis. The surgeon is planning reduction and fusion. Which nerve root is at highest risk of injury during the surgical reduction of this high-grade slip?
. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

During the reduction of a high-grade L5-S1 spondylolisthesis, the L5 nerve root is placed under significant tension and is at the highest risk of stretch injury. Many surgeons opt for in situ fusion or partial reduction to minimize this specific neurological risk.

Question 6162

Topic: 6. Spine

A 1-year-old infant with confirmed achondroplasia presents with hyperreflexia, clonus, and documented episodes of central sleep apnea. What is the most appropriate next diagnostic imaging modality to determine the underlying musculoskeletal etiology of these symptoms?

. CT scan of the lumbar spine
. MRI of the cervicomedullary junction
. Dynamic flexion-extension cervical spine radiographs
. DEXA scan
. Ultrasound of the hip joints

Correct Answer & Explanation

. CT scan of the lumbar spine

Explanation

Infants with achondroplasia are at high risk for foramen magnum stenosis, leading to cervicomedullary compression. Symptoms like central apnea, myelopathy, and hyperreflexia mandate an urgent MRI of the cervicomedullary junction to evaluate for surgical decompression.

Question 6163

Topic: Thoracolumbar Spine & Deformity

A 12-year-old girl with a high-grade isthmic spondylolisthesis (Meyerding Grade IV) at L5-S1 undergoes surgical reduction and instrumented fusion. Postoperatively, she develops new-onset weakness in ankle dorsiflexion and extensor hallucis longus function. Injury to which nerve root is most likely responsible?

. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L4

Explanation

The L5 nerve root is at the greatest risk for traction injury during the reduction of a high-grade L5-S1 spondylolisthesis. This typically presents with weakness in ankle dorsiflexion and great toe extension.

Question 6164

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with persistent low back pain exacerbated by extension. Oblique radiographs demonstrate a "collar on the Scotty dog" at L5. If the patient has a grade 2 isthmic spondylolisthesis, what defines a grade 2 slip according to the Meyerding classification?

. 0-25% translation
. 26-50% translation
. 51-75% translation
. 76-100% translation
. >100% translation (spondyloptosis)

Correct Answer & Explanation

. 0-25% translation

Explanation

The Meyerding classification categorizes spondylolisthesis based on the percentage of forward translation of the superior vertebral body over the inferior one. Grade 2 corresponds to 26% to 50% translation.

Question 6165

Topic: 6. Spine

When tracing the path of the vertebral artery through the cervical spine, it typically ascends and enters the transverse foramen at which cervical vertebral level?

. C2
. C4
. C6
. C7
. T1

Correct Answer & Explanation

. C2

Explanation

The vertebral artery is the first branch of the subclavian artery. It typically enters the transverse foramen at the C6 vertebral level in approximately 90% of individuals. It rarely enters at C7, which is a key anatomic detail for cervical spine instrumentation and anterior cervical approaches.

Question 6166

Topic: 6. Spine

During preoperative planning for posterior spinal instrumentation in the lumbar spine, morphometric assessment of the pedicles is essential. In a typical patient, which lumbar vertebra possesses the largest transverse pedicle diameter?

. L1
. L2
. L3
. L4
. L5

Correct Answer & Explanation

. L1

Explanation

In the lumbar spine, the transverse (coronal) diameter of the pedicles gradually increases from L1 to L5. Therefore, L5 typically has the widest transverse pedicle diameter, which accommodates larger diameter pedicle screws, though it also has the highest degree of medial angulation (trajectory).

Question 6167

Topic: Thoracolumbar Spine & Deformity

When preparing the entry point for a thoracic pedicle screw, the standard anatomic landmark is best described as the intersection of the:

. Mid-portion of the facet joint and the superior border of the transverse process
. Lateral border of the superior articular facet and the midline of the transverse process
. Medial border of the superior articular facet and the inferior border of the transverse process
. Lateral border of the pars interarticularis and superior border of the lamina
. Spinous process and the inferior articular facet

Correct Answer & Explanation

. Mid-portion of the facet joint and the superior border of the transverse process

Explanation

The standard free-hand entry point for a thoracic pedicle screw is located at the intersection of the lateral border of the superior articular facet and a line bisecting the transverse process (midline of the transverse process).

Question 6168

Topic: Cervical Spine

A surgeon is performing an anterior cervical discectomy and fusion (ACDF) at C5-C6. During lateral decompression of the uncovertebral joint, there is a risk of injuring the vertebral artery. In the standard human anatomy, at which cervical level does the vertebral artery typically enter the transverse foramen?

. C4
. C5
. C6
. C7
. T1

Correct Answer & Explanation

. C4

Explanation

The vertebral artery typically enters the transverse foramen at the C6 vertebral level in over 90% of individuals. It does not pass through the C7 transverse foramen, which usually transmits only the vertebral vein.

Question 6169

Topic: 6. Spine

During a posterior spinal fusion in the lumbar spine, standard pedicle screws are placed. The ideal anatomical starting point for a lumbar pedicle screw is located at the intersection of which structures?

. The midpoint of the transverse process and the inferior articular facet
. The pars interarticularis, the transverse process, and the superior articular facet
. The spinous process, the lamina, and the transverse process
. The superior endplate and the lateral aspect of the superior articular facet
. The medial border of the pedicle and the inferior articular facet

Correct Answer & Explanation

. The midpoint of the transverse process and the inferior articular facet

Explanation

The starting point for a lumbar pedicle screw is classically defined as the confluence of the pars interarticularis, the midline of the transverse process, and the lateral border of the superior articular facet.

Question 6170

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with lower back pain exacerbated by extension. Radiographs show a grade II spondylolisthesis at L5-S1. What is the most likely pathological mechanism?

. Repetitive stress causing pars interarticularis microfractures
. Degenerative changes of the facet joints
. Congenital dysplastic facets
. Traumatic fracture of the pedicle
. Pathological fracture from an underlying cyst

Correct Answer & Explanation

. Repetitive stress causing pars interarticularis microfractures

Explanation

Isthmic spondylolisthesis in young athletes (especially gymnasts and football linemen) is typically due to repetitive hyperextension leading to stress fractures of the pars interarticularis (spondylolysis) which may progress to spondylolisthesis.

Question 6171

Topic: 6. Spine

A 65-year-old man presents with progressive clumsiness in his hands, difficulty buttoning his shirt, and a broad-based gait. Hoffman's sign is positive bilaterally. MRI shows severe cervical stenosis at C4-C6. What is the most reliable MRI predictor of poor surgical outcome after decompression?

. Preoperative symptom duration > 18 months
. Age over 60
. Coexisting lumbar stenosis
. Presence of a positive Babinski sign
. T1-weighted hypointensity within the spinal cord

Correct Answer & Explanation

. Preoperative symptom duration > 18 months

Explanation

T1 hypointensity within the cord on MRI represents myelomalacia/cystic necrosis and is a strong predictor of a poor neurological recovery following decompression in cervical spondylotic myelopathy. T2 hyperintensity alone is less prognostic unless very bright and extensive.

Question 6172

Topic: Thoracolumbar Spine & Deformity

A 35-year-old male falls from a height and sustains an L1 burst fracture. He is neurologically intact. Radiographs and CT show 20 degrees of kyphosis, 50% loss of vertebral body height, and 40% canal compromise. What is the most appropriate initial treatment?

. Anterior corpectomy and fusion
. Posterior spinal instrumentation and fusion
. TLSO brace and early mobilization
. Bed rest for 6 weeks followed by bracing
. Laminectomy and short-segment fusion

Correct Answer & Explanation

. Anterior corpectomy and fusion

Explanation

Neurologically intact patients with thoracolumbar burst fractures and stable posterior ligamentous complexes can typically be treated non-operatively with a TLSO brace. Canal compromise itself (even up to 50%) will frequently remodel, and without neurological deficit or severe kyphosis (>30 degrees), nonoperative management is the standard of care.

Question 6173

Topic: Cervical Spine

An 80-year-old woman is involved in a low-speed motor vehicle collision. CT scan reveals a Type II odontoid fracture with 2 mm of posterior displacement. She is neurologically intact. What is the most appropriate treatment?

. Halo vest immobilization for 12 weeks
. Hard cervical collar for 6-12 weeks
. Anterior odontoid screw fixation
. Posterior C1-C2 fusion
. Observation alone

Correct Answer & Explanation

. Halo vest immobilization for 12 weeks

Explanation

In elderly patients (>65 years) with Type II odontoid fractures, morbidity and mortality from rigid halo vest immobilization are significantly high. A hard cervical collar is typically recommended for initial management of minimally displaced fractures in this age group, balancing the high risk of nonunion against the risks of surgery or a halo.

Question 6174

Topic: 6. Spine

A 55-year-old man with a long-standing history of ankylosing spondylitis presents with severe back pain after a minor fall. Radiographs do not clearly show a fracture, but he has pinpoint tenderness at T10. What is the next best step in management?

. Reassurance and NSAIDs
. CT or MRI of the entire spine
. Physical therapy
. Bone scan
. DEXA scan

Correct Answer & Explanation

. Reassurance and NSAIDs

Explanation

Patients with ankylosing spondylitis have highly rigid and osteoporotic spines. Any minor trauma causing new pain must be treated as a spinal fracture until proven otherwise. Because plain films often miss these highly unstable, shear-type fractures (Chalk stick fractures), advanced imaging (CT or MRI) of the entire spine is mandatory.

Question 6175

Topic: 6. Spine
A 30-year-old man presents after a motor vehicle accident with neck pain. Imaging shows a traumatic spondylolisthesis of the axis (C2) with bilateral pars fractures, 4 mm of translation, and 12 degrees of angulation (Levine-Edwards Type II). What is the recommended treatment?
. Hard cervical collar
. Halo vest immobilization
. Anterior C2-C3 discectomy and fusion
. Posterior C1-C2 fusion
. C2 pars screw fixation

Correct Answer & Explanation

. Halo vest immobilization

Explanation

Levine-Edwards Type II Hangman's fractures (significant translation and angulation, disrupted C2-3 disc) are typically treated with reduction via traction followed by Halo vest immobilization. Type I can be treated with a hard collar, and Type III (associated with bilateral C2-C3 facet dislocation) requires open reduction and internal fixation.

Question 6176

Topic: 6. Spine

A 42-year-old man presents with 6 weeks of right leg pain radiating down the lateral aspect of his calf to the dorsum of his foot. He has a 3/5 weakness in extensor hallucis longus (EHL). He has failed conservative therapy. Which nerve root is most likely compressed?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L3

Explanation

The clinical presentation of lateral calf pain, dorsal foot pain, and EHL weakness is classic for an L5 radiculopathy. In the lumbar spine, a paracentral disc herniation at L4-L5 most commonly compresses the traversing L5 nerve root.

Question 6177

Topic: 6. Spine

A 72-year-old man with a history of cervical stenosis falls forward, striking his chin. He presents with profound upper extremity weakness, particularly in his hands, but is able to walk with a spastic gait. His lower extremities have 4/5 strength. What is the most likely pathophysiological mechanism?

. Traumatic disc herniation compressing the anterior spinal artery
. Hyperextension injury causing a pinch of the cord between a bulging disc and buckled ligamentum flavum
. Hyperflexion injury causing bilateral facet dislocation
. Avulsion of the brachial plexus
. Posterior element fracture penetrating the cord

Correct Answer & Explanation

. Traumatic disc herniation compressing the anterior spinal artery

Explanation

Central cord syndrome classically occurs in elderly patients with pre-existing cervical spondylosis who sustain a hyperextension injury. The spinal cord is compressed anteriorly by osteophytes/disc and posteriorly by the buckled ligamentum flavum, leading to central cord edema or hemorrhage.

Question 6178

Topic: 6. Spine

A 25-year-old motorcyclist sustains a Denis Zone 3 sacral fracture. Which of the following deficits is most likely to be associated with this injury pattern?

. L5 motor weakness
. Bowel and bladder dysfunction
. Sural nerve sensory deficit
. Patellar tendon reflex loss
. Isolated great toe extension weakness

Correct Answer & Explanation

. L5 motor weakness

Explanation

Denis Zone 3 sacral fractures involve the central sacral canal and carry a high rate (up to 50-60%) of neurological injury, specifically saddle anesthesia, bowel, bladder, and sexual dysfunction (sacral plexus/cauda equina injury).

Question 6179

Topic: 6. Spine

A 55-year-old intravenous drug user presents with progressive back pain, fevers, and acute onset of lower extremity weakness and urinary retention. MRI reveals an epidural fluid collection with peripheral enhancement compressing the thecal sac at T10. What is the most appropriate management?

. Intravenous antibiotics and close observation
. CT-guided aspiration of the fluid collection
. Urgent surgical decompression and debridement
. Placement of a lumbar drain
. Steroid administration and broad-spectrum antibiotics

Correct Answer & Explanation

. Intravenous antibiotics and close observation

Explanation

A spinal epidural abscess presenting with acute neurological deficits (weakness, urinary retention) is a surgical emergency. Urgent decompressive laminectomy and debridement are required to prevent permanent neurological damage.

Question 6180

Topic: 6. Spine

A 40-year-old male presents to the emergency department with acute onset severe lower back pain, bilateral sciatica, perineal numbness, and inability to void for the past 12 hours. Post-void residual volume is 500 cc. MRI shows a massive L4-L5 disc extrusion filling the spinal canal. What is the optimal timeframe for surgical intervention to maximize the chance of full neurological recovery?

. Within 8 hours
. Within 24-48 hours
. Within 72 hours
. After 1 week of failed conservative therapy
. Timing of surgery does not affect outcomes

Correct Answer & Explanation

. Within 8 hours

Explanation

Cauda equina syndrome is a surgical emergency. The current consensus is that surgical decompression should be performed as soon as possible, ideally within 24 to 48 hours of the onset of sphincter dysfunction, to maximize the chances of recovering bowel and bladder function.

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