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6. Spine MCQs

Practice Set 82 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 1621

Topic: 6. Spine

A 45-year-old man presents with acute, severe left-sided anterior thigh pain and weakness in knee extension. Physical examination reveals a diminished left patellar reflex. MRI of the lumbar spine reveals a far lateral (extraforaminal) disc herniation at the L3-L4 level. Which nerve root is most likely compressed?

. L2
. L3
. L4
. L5
. S1

Correct Answer & Explanation

. L3

Explanation

Far lateral (extraforaminal) disc herniations compress the exiting nerve root at the same level. Therefore, a far lateral disc herniation at L3-L4 will compress the exiting L3 nerve root, causing anterior thigh pain and weakness in quadriceps.

Question 1622

Topic: Thoracolumbar Spine & Deformity

According to the Wiltse classification of spondylolisthesis, which of the following mechanisms correctly defines a Type IV (Traumatic) spondylolisthesis?

. Congenital dysplasia of the L5-S1 facet joints
. A stress fracture of the pars interarticularis
. An acute fracture of the posterior arch elements other than the pars interarticularis
. Long-standing segmental instability leading to facet remodeling
. Iatrogenic excessive resection of the pars during decompression

Correct Answer & Explanation

. An acute fracture of the posterior arch elements other than the pars interarticularis

Explanation

Wiltse Type IV (Traumatic) spondylolisthesis is caused by an acute fracture of the posterior bony elements, such as the pedicle, lamina, or facets, but strictly excludes fractures of the pars interarticularis (which define Type II, Isthmic).

Question 1623

Topic: 6. Spine

During the surgical reduction of a Grade V spondylolisthesis (spondyloptosis) at L5-S1 in a pediatric patient, neuromonitoring alerts the surgeon to impending nerve injury. Which of the following nerve roots is at the highest risk of iatrogenic stretch injury during this specific reduction maneuver?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L5

Explanation

The L5 nerve root is at the greatest risk of stretch injury during the reduction of high-grade L5-S1 spondylolisthesis. As the L5 vertebra is translated posteriorly and distracted, the L5 root is tensioned tightly over the sacral ala.

Question 1624

Topic: Thoracolumbar Spine & Deformity

A 55-year-old female presents with neurogenic claudication. Review the provided representative imaging.

In classical degenerative spondylolisthesis at this typical level, which of the following anatomic factors is most strongly predictive of progression?

. Coronal orientation of the facet joints
. Sagittal orientation of the facet joints
. Presence of an occult pars defect
. Decreased pelvic incidence
. Sacral kyphosis

Correct Answer & Explanation

. Sagittal orientation of the facet joints

Explanation

Degenerative spondylolisthesis most commonly occurs at L4-L5. A sagittal orientation of the facet joints (>45 degrees relative to the coronal plane) provides less resistance to anterior translational forces and is a strong predictor of slip progression.

Question 1625

Topic: 6. Spine

A 10-year-old girl is diagnosed with a dysplastic (Wiltse Type I) spondylolisthesis at L5-S1. Compared to patients with an isthmic (Wiltse Type II) spondylolisthesis, this patient is at a significantly higher risk for which of the following complications?

. Spontaneous auto-fusion of the disc space
. Cauda equina syndrome or severe neurologic deficit
. Development of a syrinx
. Iatrogenic dural tear during surgery
. Malignant transformation of the dysplastic bone

Correct Answer & Explanation

. Cauda equina syndrome or severe neurologic deficit

Explanation

Dysplastic (Type I) spondylolisthesis occurs with an intact neural arch. As the vertebral body slips anteriorly, the intact posterior arch is dragged forward, severely compressing the cauda equina and resulting in a much higher rate of neurologic deficits compared to isthmic types where the pars defect leaves the arch behind.

Question 1626

Topic: 6. Spine

A 40-year-old man presents with a massive, sequestrated lumbar disc herniation causing severe unilateral radiculopathy. He opts for conservative management. Over the next six months, his symptoms completely resolve, and a repeat MRI shows nearly complete resorption of the disc fragment. Which of the following mechanisms is primarily responsible for the spontaneous resorption of sequestrated disc fragments?

. Dehydration and mechanical compression by the posterior longitudinal ligament
. Apoptosis of nucleus pulposus chondrocytes
. Neovascularization and macrophage-mediated phagocytosis
. Integration of the disc fragment into the adjacent vertebral endplate
. Enzymatic degradation exclusively by matrix metalloproteinases in the CSF

Correct Answer & Explanation

. Neovascularization and macrophage-mediated phagocytosis

Explanation

Spontaneous resorption of herniated disc material, especially non-contained (sequestrated) fragments, is driven by an inflammatory response. The exposure of the nucleus pulposus to the epidural space induces neovascularization and macrophage infiltration, leading to phagocytosis of the disc material.

Question 1627

Topic: Thoracolumbar Spine & Deformity
A 13-year-old male with a known Grade III L5-S1 isthmic spondylolisthesis presents with an altered gait. On examination, he walks with a characteristic waddling motion, maintaining his hips and knees in flexion with a flattened lumbar lordosis. This classic clinical presentation is referred to as:
. Gowers sign
. Phalen-Dickson sign
. Lasรจgue sign
. Waddell sign
. Hoover sign

Correct Answer & Explanation

. Phalen-Dickson sign

Explanation

The Phalen-Dickson sign is a classic physical examination finding in high-grade pediatric isthmic spondylolisthesis. It consists of a waddling gait with knee and hip flexion, driven by severe hamstring spasticity and a retroverted pelvis.

Question 1628

Topic: Thoracolumbar Spine & Deformity

A 65-year-old female undergoes a decompressive laminectomy for L4-L5 degenerative spondylolisthesis. During the procedure, an incidental durotomy occurs. The surgeon successfully achieves a primary, watertight suture repair. What is the most appropriate postoperative management regarding mobilization?

. Strict flat bed rest for 5 to 7 days
. Immediate placement of a lumbar subarachnoid drain
. Early mobilization without mandatory bed rest
. Placement of high-suction subfascial drains
. Revision surgery within 24 hours to apply a fascial patch

Correct Answer & Explanation

. Early mobilization without mandatory bed rest

Explanation

Recent literature and current guidelines support early mobilization following a successful primary, watertight repair of an incidental durotomy. Prolonged bed rest increases the risk of deep vein thrombosis and pneumonia without significantly reducing the rate of cerebrospinal fluid leaks.

Question 1629

Topic: 6. Spine

A 32-year-old male undergoes an L5-S1 microdiscectomy for a paracentral disc herniation. Six months later, he presents with recurrent, severe S1 radiculopathy. MRI confirms a recurrent disc herniation at the same level and side. Flexion-extension radiographs show no instability. After failing 12 weeks of conservative care, what is the most appropriate surgical intervention?

. Revision microdiscectomy
. Anterior lumbar interbody fusion (ALIF)
. Transforaminal lumbar interbody fusion (TLIF)
. Lumbar disc arthroplasty
. Implantation of a spinal cord stimulator

Correct Answer & Explanation

. Revision microdiscectomy

Explanation

In the absence of spinal instability, significant facet arthropathy, or severe back pain, a revision microdiscectomy is the most appropriate next step for a symptomatic recurrent disc herniation. Outcomes for first-time revisions are generally comparable to primary discectomies.

Question 1630

Topic: 6. Spine

The SPORT (Spine Patient Outcomes Research Trial) evaluated operative versus nonoperative treatment for degenerative spondylolisthesis. Based on the long-term results of this trial, which of the following statements is true?

. Nonoperative treatment showed superior long-term functional outcomes.
. Patients treated surgically demonstrated significantly greater improvement in pain and function compared to the nonoperative cohort.
. The incidence of adjacent segment disease negated any initial surgical benefits at 4 years.
. Decompression alone was proven superior to decompression with concomitant instrumented fusion.
. There was no significant difference in outcomes between the surgical and nonoperative groups at 4 years.

Correct Answer & Explanation

. Patients treated surgically demonstrated significantly greater improvement in pain and function compared to the nonoperative cohort.

Explanation

The SPORT trial for degenerative spondylolisthesis demonstrated that patients who underwent surgery (typically decompression and fusion) had significantly greater improvements in pain and physical function at 4-year follow-up compared to those treated nonoperatively.

Question 1631

Topic: 6. Spine
A 50-year-old diabetic patient presents with back pain and a high-grade fever. MRI reveals an epidural abscess with significant bony destruction at L3-L4 resulting in anterior translation of L3 on L4. According to the Wiltse classification, this type of spondylolisthesis is categorized as:
. Type II
. Type III
. Type IV
. Type V
. Type VI

Correct Answer & Explanation

. Type V

Explanation

Wiltse Type V is pathologic spondylolisthesis, which occurs due to generalized or localized bone disease. In this case, bony destruction from an infection (osteomyelitis/discitis leading to an abscess) causes structural failure and subsequent translation.

Question 1632

Topic: 6. Spine

In evaluating a patient with suspected cauda equina syndrome, bladder ultrasound is performed. What minimum post-void residual (PVR) volume is generally considered highly sensitive and specific for the diagnosis of cauda equina syndrome in the setting of acute back pain and radiculopathy?

. 50 mL
. 100 mL
. 200 mL
. 500 mL
. 1000 mL

Correct Answer & Explanation

. 200 mL

Explanation

A post-void residual (PVR) volume greater than 200 mL has a high sensitivity and specificity for identifying neurogenic bladder associated with cauda equina syndrome in patients presenting with acute severe low back pain and radicular symptoms.

Question 1633

Topic: Thoracolumbar Spine & Deformity

An 18-year-old gymnast complains of chronic low back pain exacerbated by extension. Radiographs show a Grade I isthmic spondylolisthesis at L5-S1. The slip angle is measured to assess the risk of progression. How is the slip angle (sagittal roll) correctly measured on a lateral radiograph?

. The angle between the superior endplate of L5 and the superior endplate of S1.
. The angle between the inferior endplate of L5 and a line perpendicular to the posterior cortex of the S1 body.
. The angle between the anterior cortex of L5 and the anterior cortex of S1.
. The angle formed by the intersection of lines drawn along the posterior margins of the L4 and S1 bodies.
. The angle between the superior endplate of L5 and the inferior endplate of S1.

Correct Answer & Explanation

. The angle between the inferior endplate of L5 and a line perpendicular to the posterior cortex of the S1 body.

Explanation

The slip angle (sagittal roll or kyphotic angle) in spondylolisthesis is measured between a line drawn parallel to the inferior endplate of L5 and a line drawn perpendicular to the posterior cortex of the first sacral vertebral body.

Question 1634

Topic: Thoracolumbar Spine & Deformity

A 60-year-old male undergoes a bilateral L4-L5 laminectomy and medial facetectomy for central stenosis. Postoperatively, he develops progressive mechanical back pain, and a repeat radiograph at 6 months reveals a new Grade II forward slip of L4 on L5. To minimize the risk of this iatrogenic (Wiltse Type VI) spondylolisthesis, resection of the pars interarticularis should not exceed what percentage?

. 10%
. 25%
. 50%
. 75%
. 100%

Correct Answer & Explanation

. 50%

Explanation

Iatrogenic spondylolisthesis (Wiltse Type VI) is a known complication of lumbar decompression. Biomechanical studies indicate that preserving at least 50% of the bilateral pars interarticularis and facet joints is critical to maintain segmental stability and prevent post-surgical slip.

Question 1635

Topic: 6. Spine

Which specific parasympathetic nerve roots are primarily compressed in a central L4-L5 massive disc extrusion, leading to the loss of detrusor muscle tone and resultant urinary retention in Cauda Equina Syndrome?

. L2-L4
. L4-L5
. L5-S1
. S2-S4
. S4-S5

Correct Answer & Explanation

. L5-S1

Explanation

The parasympathetic innervation to the detrusor muscle of the bladder originates from the S2-S4 nerve roots. Compression of these specific sacral roots in the cauda equina leads to areflexia of the detrusor, causing painless urinary retention.

Question 1636

Topic: 6. Spine

A 45-year-old male presents with acute severe left leg pain. MRI demonstrates a far lateral (extraforaminal) disc herniation at the L3-L4 level. Which nerve root is most likely compressed by this specific herniation?

. L1
. L2
. L3
. L4
. L5

Correct Answer & Explanation

. L1

Explanation

Far lateral (extraforaminal) disc herniations compress the exiting nerve root at the same level of the disc. Therefore, an L3-L4 far lateral disc herniation compresses the exiting L3 nerve root.

Question 1637

Topic: 6. Spine

Which of the following best summarizes the findings of the Spine Patient Outcomes Research Trial (SPORT) regarding the treatment of degenerative spondylolisthesis?

. Decompression alone is clinically superior to decompression with instrumented fusion.
. Laminectomy with posterolateral fusion yields better long-term clinical outcomes than nonoperative care.
. Nonoperative treatment is statistically superior to surgical intervention at 4 years.
. Epidural steroid injections provide identical 2-year outcomes compared to fusion.
. Surgical intervention has an unacceptably high mortality rate in patients over 65.

Correct Answer & Explanation

. Laminectomy with posterolateral fusion yields better long-term clinical outcomes than nonoperative care.

Explanation

The SPORT trial demonstrated that patients with symptomatic degenerative spondylolisthesis and spinal stenosis treated surgically with decompression and fusion had significantly greater long-term improvements in pain and function compared to those treated nonoperatively.

Question 1638

Topic: 6. Spine

A 38-year-old patient with a known massive L4-L5 central disc herniation presents to the emergency department. Which of the following clinical findings has the highest negative predictive value for Cauda Equina Syndrome?

. Bilateral loss of Achilles reflexes
. Absence of saddle anesthesia
. Absence of urinary retention
. Normal rectal sphincter tone
. Lack of bilateral lower extremity weakness

Correct Answer & Explanation

. Absence of urinary retention

Explanation

Urinary retention is the most consistent and typically the earliest finding in cauda equina syndrome. The absence of urinary retention has a negative predictive value of approximately 99% for the condition.

Question 1639

Topic: Thoracolumbar Spine & Deformity

A 22-year-old male presents with back pain and is diagnosed with an L5-S1 isthmic spondylolisthesis. Which spinopelvic parameter is typically abnormally increased in this population, predisposing them to elevated lumbosacral shear forces?

. Pelvic tilt
. Sacral slope
. Pelvic incidence
. Lumbar lordosis
. Thoracic kyphosis

Correct Answer & Explanation

. Pelvic incidence

Explanation

Pelvic incidence is a fixed morphological parameter that is significantly increased in patients with isthmic spondylolisthesis compared to the normal population. A high pelvic incidence increases shear forces at the lumbosacral junction, predisposing to listhesis.

Question 1640

Topic: 6. Spine

A 40-year-old man presents with acute L5 radiculopathy from a paracentral disc extrusion. He opts for conservative management and his symptoms resolve over 6 months. By what primary mechanism does the herniated disc material resorb?

. Chondrocyte apoptosis
. Osteoclastic resorption
. Macrophage-mediated phagocytosis
. Fibroblastic metaplasia
. Lymphocytic cytotoxicity

Correct Answer & Explanation

. Macrophage-mediated phagocytosis

Explanation

Herniated disc material, particularly non-contained extrusions, is recognized as foreign by the body's immune system. This triggers an inflammatory cascade characterized by neovascularization and macrophage-mediated phagocytosis, leading to spontaneous resorption.

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