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6. Spine MCQs

Practice Set 314 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 6261

Topic: 6. Spine

A 60-year-old female undergoes a C3-C6 posterior laminectomy and fusion for severe cervical spondylotic myelopathy.

On postoperative day two, she develops new-onset weakness in her right deltoid and biceps (Grade 2/5 strength) but has no new lower extremity symptoms or sensory loss. She has no distinct focal neck pain. What is the most likely etiology of this new deficit?

. Postoperative epidural hematoma compressing the spinal cord
. C5 nerve root tethering due to posterior cord shift
. Improper medial placement of a lateral mass screw
. Intraoperative anterior spinal artery occlusion
. Acute graft extrusion

Correct Answer & Explanation

. Postoperative epidural hematoma compressing the spinal cord

Explanation

C5 palsy is a well-known complication following posterior cervical decompression (laminectomy/laminoplasty). It is thought to be caused by the posterior shift of the spinal cord after decompression, which creates traction/tethering on the relatively short and horizontal C5 nerve roots. It presents as isolated deltoid/biceps weakness, typically occurring a few days postoperatively. It usually resolves over several months with conservative care.

Question 6262

Topic: 6. Spine

A 40-year-old male presents to the emergency room with acute, severe lower back pain, bilateral sciatica, and perianal numbness. He reports an inability to voluntarily void for the past 14 hours, and an ultrasound reveals a post-void residual volume of 650 mL.

MRI demonstrates a massive L4-L5 disc herniation filling the spinal canal. To maximize the probability of urologic and neurologic recovery, surgical decompression should ideally be performed within what maximum timeframe from the onset of symptoms?

. 12 hours
. 48 hours
. 72 hours
. 1 week
. 2 weeks

Correct Answer & Explanation

. 12 hours

Explanation

Cauda equina syndrome is a surgical emergency. The current literature strongly supports emergent decompression to maximize neurologic and urologic recovery. Historically and currently, intervention within 48 hours of symptom onset provides the greatest chance for return of bladder and bowel function, though many surgeons advocate for even earlier intervention (e.g., within 24 hours) if feasible.

Question 6263

Topic: 6. Spine

A 30-year-old male is involved in a high-speed motor vehicle collision.

Radiographs show a traumatic spondylolisthesis of the axis (Hangman's fracture). According to the Levine-Edwards classification, the fracture exhibits severe angulation and minimal translation, and the C2-C3 disc space is widened posteriorly (Type IIA). What is the primary mechanism of injury for this specific fracture pattern?

. Hyperextension and axial loading
. Flexion and distraction
. Flexion and axial compression
. Rotational shear
. Lateral bending and extension

Correct Answer & Explanation

. Hyperextension and axial loading

Explanation

A Levine-Edwards Type IIA Hangman's fracture is characterized by severe angulation with minimal translation. Unlike Type I and II fractures (which involve hyperextension/axial loading), the Type IIA mechanism is flexion-distraction. Crucially, applying cervical traction to a Type IIA fracture is contraindicated as it will worsen the deformity; it requires reduction with mild extension and axial compression.

Question 6264

Topic: Thoracolumbar Spine & Deformity

During a posterior instrumented fusion of the lumbar spine, the surgeon is preparing to place a pedicle screw at the L4 level.

Which of the following describes the most accurate anatomic landmarks for establishing the starting point for a standard lumbar pedicle screw?

. The intersection of the pars interarticularis and the inferior articular process
. The intersection of a horizontal line bisecting the transverse process and a vertical line at the lateral border of the superior articular process
. The medial border of the superior articular process and the base of the spinous process
. The inferior border of the transverse process and the medial facet joint line
. The tip of the mammillary process exclusively

Correct Answer & Explanation

. The intersection of the pars interarticularis and the inferior articular process

Explanation

The classic anatomic starting point for a lumbar pedicle screw is located at the intersection of two lines: a horizontal line that bisects the transverse process, and a vertical line that corresponds to the lateral border of the superior articular process (or the junction of the pars interarticularis). This intersection reliably leads to the center of the pedicle.

Question 6265

Topic: 6. Spine

A 72-year-old male presents with bilateral leg pain, heaviness, and cramping that predictably worsens after walking two blocks.

He states that leaning forward on a shopping cart completely relieves his pain, but standing completely upright without moving fails to relieve the symptoms. His pedal pulses are 2+ bilaterally. What is the most likely diagnosis?

. Peripheral arterial disease (Vascular claudication)
. Lumbar spinal stenosis (Neurogenic claudication)
. Deep vein thrombosis
. Diabetic peripheral neuropathy
. Acute lumbar disc herniation

Correct Answer & Explanation

. Peripheral arterial disease (Vascular claudication)

Explanation

The clinical presentation is classic for neurogenic claudication secondary to lumbar spinal stenosis. A key differentiating factor between neurogenic and vascular claudication is the response to posture. Neurogenic claudication is relieved by lumbar flexion (e.g., leaning on a shopping cart, sitting) because flexion increases the cross-sectional area of the spinal canal. Standing upright still maintains lumbar extension, which continues to compress the neural elements, whereas vascular claudication is typically relieved simply by resting/standing still.

Question 6266

Topic: Cervical Spine

A 7-year-old boy presents with painful torticollis 10 days after undergoing a routine tonsillectomy. On examination, his head is tilted to the right and his chin is rotated to the left. Neurologic examination is intact. What is the most appropriate initial management?

. C1-C2 posterior instrumented fusion
. Intravenous antibiotics and soft cervical collar
. Closed reduction under anesthesia and halo vest application
. Anterior cervical discectomy and fusion
. Observation only with outpatient follow-up

Correct Answer & Explanation

. C1-C2 posterior instrumented fusion

Explanation

This patient is presenting with Grisel's syndrome, which is a non-traumatic atlantoaxial subluxation most commonly seen in children following an upper respiratory infection or ENT surgery (like tonsillectomy). The pathophysiology involves inflammatory hyperemia spreading to the periodontoid vascular plexus, causing laxity of the transverse ligament. Initial management for early Fielding types (I and II) is medical, consisting of intravenous antibiotics, muscle relaxants, and a soft cervical collar.

Question 6267

Topic: Cervical Spine

A 75-year-old male sustains a Type II odontoid fracture after a ground-level fall. Which of the following radiographic factors is MOST strongly associated with non-union if treated non-operatively in a halo vest?

. Initial fracture displacement > 5 mm
. Posterior angulation of 5 degrees
. Comminution of the C1 lateral masses
. Presence of a concomitant C3 compression fracture
. Fracture gap of 0.5 mm

Correct Answer & Explanation

. Initial fracture displacement > 5 mm

Explanation

Type II odontoid fractures occur at the base of the dens. Risk factors for non-union with non-operative management include age > 50 years, initial displacement > 5 mm, angulation > 10 degrees, and a fracture gap > 1 mm. Given the patient's age and displacement, surgical stabilization (e.g., posterior C1-C2 fusion) is often indicated to avoid the high morbidity of halo vests in the elderly and the high rate of non-union.

Question 6268

Topic: 6. Spine

In a patient with advanced rheumatoid arthritis presenting for cervical spine evaluation, which of the following radiographic parameters is the most reliable predictor of impending neurologic deficit and indicates an urgent need for surgical stabilization?

. Anterior atlanto-dental interval (ADI) > 3 mm
. Posterior atlanto-dental interval (PADI) < 14 mm
. Subaxial subluxation of 2 mm
. Basilar invagination with Clark station 2
. Ranawat value > 15 mm

Correct Answer & Explanation

. Anterior atlanto-dental interval (ADI) > 3 mm

Explanation

While an Anterior Atlanto-Dental Interval (ADI) > 3 mm is abnormal, it is the Posterior Atlanto-Dental Interval (PADI) that directly correlates with the space available for the spinal cord. A PADI of < 14 mm is highly predictive of neurologic deficit in rheumatoid patients and is an indication for surgical stabilization to prevent irreversible spinal cord injury.

Question 6269

Topic: 6. Spine

A 65-year-old male with a known history of ankylosing spondylitis presents to the emergency department after a low-speed motor vehicle collision. A CT scan demonstrates a fracture through the C6-C7 disc space extending into the posterior elements.

What is the most appropriate surgical treatment?

. Anterior cervical plating only
. Posterior lateral mass screw fixation isolated to C6-C7
. Combined long segment anterior and posterior instrumented fusion
. Halo vest immobilization
. Rigid cervical collar and upright mobilization

Correct Answer & Explanation

. Anterior cervical plating only

Explanation

Fractures in the ankylosed spine act as long lever arms, making them highly unstable shear injuries that inherently involve all three spinal columns. Short-segment fixation or isolated anterior plating frequently fails. The standard of care is long-segment posterior fixation, often supplemented with an anterior approach if additional stability is needed. Halo vests are poorly tolerated and have high complication rates in AS patients.

Question 6270

Topic: Thoracolumbar Spine & Deformity

A 35-year-old male is involved in a motor vehicle collision. Examination reveals normal motor and sensory function throughout his upper and lower extremities. CT imaging shows an L1 burst fracture with 15 degrees of local kyphosis and 30% canal compromise. MRI confirms an intact posterior ligamentous complex. According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is the indicated treatment?

. Thoracolumbosacral orthosis (TLSO) and early mobilization
. Short segment pedicle screw fixation one level above and below
. Anterior corpectomy and expandable cage placement
. Posterior laminectomy and non-instrumented fusion
. Long segment posterior fusion from T11 to L3

Correct Answer & Explanation

. Thoracolumbosacral orthosis (TLSO) and early mobilization

Explanation

According to the TLICS system, a burst fracture scores 2 points for morphology. An intact posterior ligamentous complex (PLC) scores 0 points, and a neurologically intact exam scores 0 points. The total TLICS score is 2. A score of 3 or less is an indication for non-operative management, typically with a TLSO brace and early mobilization.

Question 6271

Topic: Thoracolumbar Spine & Deformity

In adult spinal deformity surgery, the concept of spinopelvic harmony is critical to achieving successful outcomes and minimizing adjacent segment disease.

According to standard matching parameters, a patient's lumbar lordosis (LL) should ideally be restored to within how many degrees of their pelvic incidence (PI)?

. +/- 10 degrees
. +/- 20 degrees
. +/- 2 degrees
. LL should be exactly half of the PI
. LL should be exactly double the PI

Correct Answer & Explanation

. +/- 10 degrees

Explanation

Pelvic incidence (PI) is a fixed morphologic parameter (PI = Pelvic Tilt + Sacral Slope). To achieve spinopelvic harmony and optimal sagittal balance, the postoperative Lumbar Lordosis (LL) should be matched to within 10 degrees of the patient's PI (PI - LL < 10 degrees).

Question 6272

Topic: 6. Spine

A 60-year-old male with poorly controlled diabetes mellitus presents with severe back pain, fever, and progressive bilateral lower extremity weakness over the past 24 hours. An urgent MRI confirms an anterior epidural abscess at L2-L3.

Blood cultures are drawn. What is the next best step in management?

. Intravenous antibiotics and serial neurologic examinations
. CT-guided needle aspiration of the abscess
. Urgent surgical decompression and debridement
. High-dose intravenous corticosteroids
. Diagnostic lumbar puncture

Correct Answer & Explanation

. Intravenous antibiotics and serial neurologic examinations

Explanation

A spinal epidural abscess presenting with progressive neurologic deficit is a surgical emergency. Immediate surgical decompression (e.g., laminectomy) and debridement are required to preserve neurologic function. IV antibiotics are essential but insufficient alone when active neurologic deterioration is occurring.

Question 6273

Topic: Cervical Spine

In a patient with cervical Ossification of the Posterior Longitudinal Ligament (OPLL), what does a "negative K-line" on a lateral radiograph imply regarding surgical planning?

. The patient is best treated with posterior laminoplasty alone
. The OPLL mass is non-compressive
. Posterior decompression alone will likely fail to achieve adequate cord drift-back
. The patient has an absolute contraindication to anterior cervical surgery
. The ossification has fused completely to the dura mater

Correct Answer & Explanation

. The patient is best treated with posterior laminoplasty alone

Explanation

The K-line is drawn from the mid-point of the spinal canal at C2 to the mid-point at C7. If the OPLL mass exceeds this line (a negative K-line), the cervical alignment is often kyphotic or the mass is so large that posterior decompression (laminectomy/laminoplasty) will not allow the spinal cord to drift backward sufficiently. These patients typically require an anterior or combined approach for direct decompression.

Question 6274

Topic: 6. Spine

A 65-year-old male with neurogenic claudication is undergoing a decompressive laminectomy for central and lateral recess stenosis. During the approach, which specific anatomic structure must be undercut or partially resected to effectively decompress the traversing nerve root in the lateral recess?

. Pars interarticularis
. Medial aspect of the superior articular facet
. Lateral aspect of the inferior articular facet
. The entire inferior articular facet
. Spinous process

Correct Answer & Explanation

. Pars interarticularis

Explanation

The lateral recess is bordered anteriorly by the vertebral body/disc, laterally by the pedicle, and posteriorly by the superior articular facet. Hypertrophy of the superior articular process is the primary osseous cause of lateral recess stenosis. Undercutting the medial aspect of the superior articular facet decompresses the traversing nerve root.

Question 6275

Topic: 6. Spine

A 30-year-old male sustains a C2 fracture in a motor vehicle collision. Radiographs demonstrate a fracture through the pars interarticularis of C2 with severe angular deformity but minimal translation. This is consistent with a Levine-Edwards Type IIA Hangman's fracture. What is the mechanism of injury, and what is the appropriate initial management?

. Hyperextension and axial load; Rigid cervical collar
. Flexion-distraction; Initial reduction with gentle extension and compression, followed by halo vest
. Flexion-distraction; Heavy longitudinal cervical traction
. Hyperextension-axial load; Immediate anterior cervical plating
. Lateral bending; Posterior C1-C3 instrumented fusion

Correct Answer & Explanation

. Hyperextension and axial load; Rigid cervical collar

Explanation

A Type IIA Hangman's fracture features severe angulation with minimal translation and is caused by a flexion-distraction mechanism. Because the posterior longitudinal ligament and disc are torn, longitudinal traction is strictly contraindicated as it will distract the fracture site and worsen the deformity. It requires gentle extension and compression for reduction, usually followed by halo immobilization or surgical fixation.

Question 6276

Topic: 6. Spine

A 25-year-old male involved in a high-speed MVC wearing a lap belt presents with severe abdominal bruising. A spine CT reveals a transverse fracture line propagating through the spinous process, pedicles, and vertebral body of L2.

Which of the following injuries has the strongest association with this specific fracture pattern?

. Aortic dissection
. Diaphragmatic rupture
. Hollow viscus injury
. Renal laceration
. Spinal epidural hematoma

Correct Answer & Explanation

. Aortic dissection

Explanation

The fracture described is a Chance fracture (a bony flexion-distraction injury), classic for lap-belt injuries. There is a high association (up to 40-50%) between Chance fractures and intra-abdominal injuries, particularly hollow viscus injuries (e.g., bowel perforations), which must be carefully evaluated by general surgery.

Question 6277

Topic: 6. Spine

On a sagittal MRI of the lumbar spine, a vertebral body endplate adjacent to a degenerated disc shows hypointense signal on T1-weighted images and hyperintense signal on T2-weighted images. This finding corresponds to which Modic type, and what does it pathologically represent?

. Modic Type 1; Fibrovascular replacement and bone marrow edema
. Modic Type 2; Fatty replacement of the red marrow
. Modic Type 3; Subchondral bony sclerosis
. Modic Type 1; Subchondral bony sclerosis
. Modic Type 2; Fibrovascular replacement and bone marrow edema

Correct Answer & Explanation

. Modic Type 1; Fibrovascular replacement and bone marrow edema

Explanation

Modic changes describe MRI signal intensity variations in vertebral body endplates. Modic Type 1 shows T1 hypointensity and T2 hyperintensity, representing bone marrow edema and acute fibrovascular inflammation. Type 2 is T1 hyperintense and T2 hyperintense/isointense (fatty replacement). Type 3 is T1 and T2 hypointense (sclerosis).

Question 6278

Topic: 6. Spine

A 16-year-old male presents with a stiff, painful thoracic hyperkyphosis that does not correct upon hyperextension. Standing lateral radiographs reveal anterior wedging of 4 consecutive thoracic vertebrae by 6 degrees each, along with irregular endplates and prominent Schmorl's nodes. Which condition is the most likely diagnosis?

. Postural kyphosis
. Scheuermann's disease
. Congenital kyphosis (Type I)
. Ankylosing spondylitis
. Spondylocostal dysostosis

Correct Answer & Explanation

. Postural kyphosis

Explanation

Scheuermann's disease is an structural kyphosis of the thoracic or thoracolumbar spine. The diagnostic Sorensen criteria require at least 3 consecutive vertebrae, each with at least 5 degrees of anterior wedging. Associated findings include irregular endplates, Schmorl's nodes, and narrowing of the intervertebral disc spaces.

Question 6279

Topic: 6. Spine

A 62-year-old male undergoes a C3-C6 posterior laminectomy and fusion for multilevel cervical spondylotic myelopathy. On post-operative day 2, he develops profound weakness of the right deltoid and biceps (MRC grade 2/5) without new sensory deficits or lower extremity weakness.

What is the most widely accepted primary pathomechanical explanation for this complication?

. Unrecognized intraoperative dural tear leading to CSF leak
. Post-operative epidural hematoma compressing the entire spinal cord
. Direct ischemic injury to the anterior horn cells from hypotensive anesthesia
. Iatrogenic transection of the nerve root during facet decortication
. Posterior shift of the spinal cord causing tension and tethering of the nerve roots

Correct Answer & Explanation

. Unrecognized intraoperative dural tear leading to CSF leak

Explanation

This patient has developed a C5 palsy, a well-known complication after cervical decompression (especially posterior laminectomy/laminoplasty). The most widely accepted mechanism is the 'tethering effect': as the decompressed spinal cord drifts posteriorly, it places traction on the short, relatively horizontal C5 nerve roots, causing a neurapraxia.

Question 6280

Topic: Thoracolumbar Spine & Deformity

In the surgical planning and evaluation of a patient undergoing correction for adult spinal deformity, what is the widely accepted target goal for the relationship between lumbar lordosis (LL) and pelvic incidence (PI) to achieve optimal sagittal balance?

. PI and LL should be within 10 degrees of each other.
. LL should be exactly 20 degrees greater than PI.
. PI and LL are independent parameters and do not need to correlate.
. Pelvic Tilt (PT) should be greater than 20 degrees to compensate for PI.
. Sacral Slope (SS) should be minimized to less than 10 degrees.

Correct Answer & Explanation

. PI and LL should be within 10 degrees of each other.

Explanation

The Pelvic Incidence (PI) is a fixed anatomical parameter (PI = Pelvic Tilt + Sacral Slope). To achieve a harmonious spino-pelvic alignment and reduce the risk of adjacent segment disease and mechanical failure, the Lumbar Lordosis (LL) should be matched to the Pelvic Incidence. The widely accepted goal, described by Schwab et al., is that PI minus LL should be less than or equal to 10 degrees.

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