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6. Spine MCQs

Practice Set 306 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 6101

Topic: 6. Spine

A 14-year-old fast bowler presents with acute onset of lower back pain exacerbated by extension. MRI of the lumbar spine reveals bilateral acute pars interarticularis stress reactions (spondylolysis) at L5, with significant bone marrow edema but no spondylolisthesis. What is the most widely accepted initial treatment modality?

. Immediate pars repair surgery
. Posterior spinal fusion L5-S1
. Activity modification and TLSO bracing
. Epidural steroid injection
. Diagnostic pars injection

Correct Answer & Explanation

. Immediate pars repair surgery

Explanation

Acute, un-displaced pars interarticularis fractures (spondylolysis) with MRI evidence of bone marrow edema in young athletes have a high potential for osseous healing. The standard initial management is non-operative, consisting of strict cessation of the offending sports/activities and often the use of an antilordotic brace (TLSO) for 3 to 6 months to allow the fracture to heal.

Question 6102

Topic: 6. Spine

A major complication of prolonged spine surgery in the prone position is perioperative visual loss (POVL). According to the ASA Postoperative Visual Loss Registry, what is the most common etiology of POVL in patients undergoing instrumented posterior spinal fusion?

. Central retinal artery occlusion (CRAO)
. Ischemic optic neuropathy (ION)
. Cortical blindness
. Acute angle-closure glaucoma
. Retinal detachment

Correct Answer & Explanation

. Central retinal artery occlusion (CRAO)

Explanation

Ischemic optic neuropathy (ION) is the most common cause of perioperative visual loss (POVL) after prone spinal surgery. Risk factors include prolonged operative time, significant estimated blood loss, administration of large volumes of clear intravenous fluids, male sex, and obesity. Central retinal artery occlusion (CRAO) also causes POVL but is generally related to direct mechanical pressure on the globe (e.g., from a poorly positioned headrest) and is less common overall than ION in the registry data.

Question 6103

Topic: 6. Spine

In adult spinal deformity surgery, the fundamental goal of sagittal realignment is to achieve a harmonious relationship between the pelvis and the lumbar spine to minimize energy expenditure while standing. The globally accepted target for surgical correction dictates that the mismatch between Pelvic Incidence (PI) and Lumbar Lordosis (LL) should be:

. PI - LL < 10 degrees
. PI - LL < 20 degrees
. PI - LL = 0 degrees
. PI - LL > 10 degrees
. PI - LL > 20 degrees

Correct Answer & Explanation

. PI - LL < 10 degrees

Explanation

The SRS-Schwab adult spinal deformity classification identifies key spinopelvic parameters that correlate with health-related quality of life (HRQOL) outcomes. The classic surgical goal to optimize sagittal balance is to achieve a Lumbar Lordosis (LL) that closely matches the patient's fixed Pelvic Incidence (PI). Specifically, the goal is to correct the deformity such that the PI-LL mismatch is less than 10 degrees (PI - LL < 10 degrees).

Question 6104

Topic: 6. Spine

During the neurological examination of a patient with suspected cervical myelopathy, you perform the inverted brachioradialis reflex test. Rapidly tapping the brachioradialis tendon yields an abnormal reflex consisting of spontaneous finger flexion without normal wrist extension and supination. This specific sign strongly localizes a compressive spinal cord lesion to which vertebral level?

. C3-C4
. C5-C6
. C7-T1
. T1-T2
. L1-L2

Correct Answer & Explanation

. C3-C4

Explanation

The inverted brachioradialis reflex occurs when there is a compressive lesion at the C5-C6 level. The compression causes a lower motor neuron (LMN) deficit at C6 (diminished normal brachioradialis response: wrist extension/supination) and an upper motor neuron (UMN) deficit below C6 (hyperactive finger flexion, primarily mediated by C8 via the long finger flexors). Thus, a positive inverted brachioradialis sign typically indicates pathology at C5-C6.

Question 6105

Topic: 6. Spine

A 65-year-old female presents with progressive difficulty walking and a 'pitched-forward' posture. Her full-length standing spine radiographs demonstrate a Pelvic Incidence (PI) of 62 degrees, Lumbar Lordosis (LL) of 25 degrees, Pelvic Tilt (PT) of 35 degrees, and a Sagittal Vertical Axis (SVA) of +12 cm. If surgical correction is planned, what is the ideal postoperative target for her Lumbar Lordosis (LL) to restore optimal spinopelvic sagittal balance?

. 25 degrees
. 35 degrees
. 45 degrees
. 60 degrees
. 80 degrees

Correct Answer & Explanation

. 25 degrees

Explanation

In adult spinal deformity, restoring sagittal balance is highly correlated with improved patient-reported outcomes. The rule of thumb popularized by Schwab et al. states that the Lumbar Lordosis (LL) should be within 9 to 10 degrees of the Pelvic Incidence (PI) (i.e., PI - LL < 10 degrees). For a patient with a PI of 62 degrees, the ideal LL is approximately 52 to 62 degrees. Therefore, 60 degrees is the most appropriate target among the choices provided.

Question 6106

Topic: 6. Spine

A 25-year-old male is brought to the trauma bay after a high-speed motor vehicle collision. He complains of severe neck pain but is awake, alert, cooperative, and neurologically intact. Cervical spine radiographs reveal a bilateral C5-C6 facet dislocation. What is the most appropriate next step in management?

. Immediate closed reduction with cranial tongs
. Urgent MRI of the cervical spine followed by closed reduction
. Stat CT angiogram to rule out vertebral artery injury prior to any intervention
. Immediate anterior cervical discectomy and fusion (ACDF) without prior reduction attempt
. Immediate posterior cervical fusion

Correct Answer & Explanation

. Immediate closed reduction with cranial tongs

Explanation

In an awake, alert, and cooperative patient with a cervical facet dislocation, immediate closed reduction using cranial tongs (e.g., Gardner-Wells) is indicated and should not be delayed for an MRI. Closed reduction relies on serial neurologic exams; if the patient's neurologic status worsens during reduction, the reduction is aborted and an emergent MRI is obtained. If the patient is unexaminable (e.g., obtunded or comatose), an MRI must be obtained prior to any reduction attempt to rule out a compressive anterior disc herniation.

Question 6107

Topic: 6. Spine

A 16-year-old male presents with cosmetic concerns regarding his back. Standing radiographs reveal a rigid thoracic kyphosis of 85 degrees with anterior wedging of 5 degrees or more across four consecutive vertebrae. The apex is at T8. Conservative management has failed. If posterior spinal fusion is planned, what are the standard recommended radiographic landmarks for the proximal and distal extent of the fusion construct?

. Proximal end vertebra to the distal end vertebra
. Proximal end vertebra to the sagittal stable vertebra
. Upper end vertebra to the first lordotic disc space
. T2 to L2 uniformly for all Scheuermann's kyphosis patients
. Apex of the curve to the distal end vertebra

Correct Answer & Explanation

. Proximal end vertebra to the distal end vertebra

Explanation

In the surgical treatment of Scheuermann's kyphosis, selecting the correct fusion levels is critical to prevent junctional kyphosis. The proximal level should typically be the upper end vertebra of the kyphotic curve. Distally, the fusion must extend past the sagittal stable vertebra to include the first lordotic disc space. Stopping short of this distal landmark significantly increases the risk of distal junctional kyphosis.

Question 6108

Topic: 6. Spine

A 55-year-old female with a history of breast cancer presents with severe, mechanically exacerbated back pain. Imaging demonstrates a lytic metastasis at L3. The Spine Oncology Study Group devised the Spinal Instability Neoplastic Score (SINS) to help guide surgical referral for spinal instability. Which of the following variables is NOT a component of the SINS criteria?

. Spine location
. Pain character (mechanical vs. non-mechanical)
. Bone lesion quality (lytic vs. blastic)
. Radiographic spinal alignment
. Presence of a neurologic deficit

Correct Answer & Explanation

. Spine location

Explanation

The Spinal Instability Neoplastic Score (SINS) consists of 6 components: (1) Spine location, (2) Pain (mechanical), (3) Bone lesion (lytic, blastic, mixed), (4) Radiographic alignment, (5) Vertebral body collapse, and (6) Posterolateral element involvement. The presence of a neurologic deficit is heavily factored into the decision for decompression (often utilizing the Bilsky epidural spinal cord compression scale) but is not a component of the SINS, which strictly measures structural instability.

Question 6109

Topic: Thoracolumbar Spine & Deformity

A neurologically intact 30-year-old male presents with back pain after a fall from a height of 10 feet. CT and MRI demonstrate an L1 burst fracture with 40% loss of vertebral body height, 15 degrees of kyphosis, and an intact posterior ligamentous complex (PLC). According to the Thoracolumbar Injury Classification and Severity (TLICS) score, what is his total score and the recommended management?

. Score 2; non-operative treatment with a TLSO brace
. Score 4; operative or non-operative treatment depending on surgeon preference
. Score 5; operative posterior spinal fusion
. Score 7; operative anterior corpectomy and fusion
. Score 2; operative posterior spinal fusion

Correct Answer & Explanation

. Score 2; non-operative treatment with a TLSO brace

Explanation

The TLICS score assigns points based on three categories: injury morphology, integrity of the PLC, and neurologic status. This patient has a burst fracture morphology (2 points), an intact PLC (0 points), and is neurologically intact (0 points), for a total TLICS score of 2. A score of <= 3 is a recommendation for non-operative management (e.g., TLSO brace). A score of >= 5 indicates operative management, and a score of 4 can be managed either operatively or non-operatively.

Question 6110

Topic: 6. Spine

When performing an anterior approach to the lower cervical spine (e.g., C6-C7), approaching from the right side rather than the left increases the risk of injury to which of the following structures?

. Thoracic duct
. Recurrent laryngeal nerve
. Esophagus
. Sympathetic trunk
. Superior laryngeal nerve

Correct Answer & Explanation

. Thoracic duct

Explanation

The recurrent laryngeal nerve (RLN) has an asymmetric anatomical course. On the left, it loops under the aortic arch and ascends vertically in the tracheoesophageal groove, making it highly predictable and relatively protected during left-sided anterior cervical approaches. On the right, it loops under the right subclavian artery and ascends more obliquely and aberrantly, placing it at a higher risk of iatrogenic injury during a right-sided approach to the lower cervical spine.

Question 6111

Topic: 6. Spine

A 62-year-old male with severe cervical myelopathy undergoes a posterior C3-C6 laminectomy and instrumented fusion. On postoperative day 3, the patient complains of an inability to elevate his right shoulder or flex his elbow, despite intact sensation and full strength in his hands and lower extremities. What is the most widely accepted primary pathophysiology for this specific complication?

. Direct intraoperative retractor injury to the brachial plexus
. Ischemic stroke of the anterior spinal artery
. Epidural hematoma compressing the entire spinal cord
. Posterior shift of the spinal cord resulting in iatrogenic tethering of the nerve roots
. Thermal necrosis from electrocautery during muscular dissection

Correct Answer & Explanation

. Direct intraoperative retractor injury to the brachial plexus

Explanation

This patient has developed a C5 palsy, a well-known complication following extensive posterior cervical decompressions (e.g., laminectomy/fusion or laminoplasty). It occurs in roughly 5-10% of cases. The most widely accepted mechanism is the 'tethering effect': as the decompressed spinal cord drifts posteriorly (especially following correction of cervical kyphosis), it places excess tension on the short and horizontally oriented C5 nerve roots. It typically presents as a unilateral deltoid and/or biceps weakness with intact sensory and distal motor function.

Question 6112

Topic: 6. Spine

A 68-year-old male with pre-existing cervical spondylosis presents after a hyperextension injury sustained when he tripped and struck his chin. Examination reveals 2/5 motor strength in his upper extremities and 4/5 motor strength in his lower extremities. Sensation is decreased globally below the clavicles. Based on this presentation, what is the expected pattern of motor recovery for this patient?

. Upper extremities will recover before lower extremities, with excellent fine motor return.
. Fine motor function of the hands will recover first, followed by proximal muscle groups.
. Lower extremities will recover before the upper extremities, with fine motor function of the hands recovering last and often incompletely.
. Symmetrical recovery of all four extremities simultaneously within 6 weeks.
. No motor recovery is expected as this lesion is anatomically complete.

Correct Answer & Explanation

. Upper extremities will recover before lower extremities, with excellent fine motor return.

Explanation

This patient has Central Cord Syndrome, most commonly caused by a hyperextension injury in a patient with pre-existing cervical spinal stenosis. The characteristic presentation is disproportionately greater motor impairment in the upper extremities compared to the lower extremities. The typical pattern of recovery follows a specific sequence: lower extremity function recovers first, followed by bowel/bladder function, then proximal upper extremities. Fine motor function of the hands recovers last and often remains permanently impaired.

Question 6113

Topic: 6. Spine

A 50-year-old male with a 20-year history of Ankylosing Spondylitis (AS) reports new-onset neck pain after a minor bump in a minor motor vehicle collision. Initial AP and lateral cervical radiographs obtained in the emergency department are read as negative for acute fracture. He is neurologically intact. What is the most appropriate next step in management?

. Discharge with a soft cervical collar and NSAIDs
. Perform a CT scan of the entire cervical spine
. Obtain flexion-extension cervical radiographs
. Perform an immediate MRI of the cervical spine
. Reassure the patient and schedule outpatient physical therapy

Correct Answer & Explanation

. Discharge with a soft cervical collar and NSAIDs

Explanation

Patients with Ankylosing Spondylitis (AS) have a highly ossified, rigid, and osteoporotic spine, making them extremely susceptible to highly unstable transvertebral ('chalk stick') fractures even from low-energy trauma. Standard plain radiographs are notoriously unreliable in evaluating fractures in AS patients due to altered anatomy, osteopenia, and superimposition of shoulders. Any AS patient with neck pain following trauma must undergo a CT scan of the cervical spine to definitively rule out a fracture. Flexion-extension views are strictly contraindicated due to the risk of catastrophic neurologic injury.

Question 6114

Topic: 6. Spine
A 2-year-old female is evaluated for congenital scoliosis secondary to a fully segmented hemivertebra at T8. Prior to proceeding with any surgical intervention for the deformity, what screening study is mandatory to evaluate for the most common associated neural axis anomalies?
. Non-contrast CT scan of the thoracic spine
. Myelography
. Somatosensory Evoked Potentials (SSEPs) mapping
. Total spine MRI
. Lumbar puncture for CSF analysis

Correct Answer & Explanation

. Total spine MRI

Explanation

Congenital scoliosis is frequently associated with other developmental anomalies, particularly VACTERL association and intraspinal neural axis abnormalities (found in up to 20-40% of patients). These intraspinal anomalies include tethered cord, syringomyelia, and diastematomyelia. A total spine MRI is mandatory prior to any surgical correction to identify these lesions. If present, neurosurgical release (e.g., untethering of the cord) is often required before the orthopedic deformity correction to prevent iatrogenic neurologic injury during spinal manipulation.

Question 6115

Topic: 6. Spine

During posterior instrumented spinal fusion, maximizing the pull-out strength of pedicle screws is critical to construct stability. Which of the following factors exerts the greatest influence on the pull-out strength of a pedicle screw?

. Bone mineral density (BMD) of the vertebra
. Inner (core) diameter of the pedicle screw
. Screw pitch configuration
. Rate of screw insertion during surgery
. Screw thread profile shape

Correct Answer & Explanation

. Bone mineral density (BMD) of the vertebra

Explanation

While hardware design elements like screw outer diameter, pitch, and thread design influence fixation, the local Bone Mineral Density (BMD) is the single most critical factor determining the pull-out strength of a pedicle screw. Poor BMD (osteoporosis) exponentially decreases the screw-bone interface purchase. Modifying the outer diameter of the screw (not the inner core diameter) and using larger diameter or longer screws are the main intraoperative methods to compensate for poor BMD.

Question 6116

Topic: 6. Spine

A 35-year-old male sustains a severe neck injury in a motor vehicle accident. Radiographs reveal a traumatic spondylolisthesis of the axis (Hangman's fracture) characterized by severe angulation of the C2 body over C3, but with minimal translation. According to the Levine and Edwards classification, this is a Type IIA fracture. What is the primary mechanism of injury, and what intervention is strictly contraindicated during management?

. Hyperextension-axial loading; use of a Halo vest
. Flexion-distraction; application of cervical traction
. Flexion-compression; closed reduction in extension
. Lateral bending; operative posterior C1-C2 fusion
. Axial loading alone; strict bed rest

Correct Answer & Explanation

. Hyperextension-axial loading; use of a Halo vest

Explanation

A Levine-Edwards Type IIA Hangman's fracture is caused by a flexion-distraction mechanism, resulting in severe angulation but minimal translation of C2 on C3. Because the C2-C3 intervertebral disc and posterior longitudinal ligament are severely disrupted (distracted), the application of cervical traction is strictly contraindicated, as it will exacerbate the distraction and lead to catastrophic neurologic injury. Management typically involves gentle closed reduction with slight compression and extension, followed by Halo vest immobilization.

Question 6117

Topic: Thoracolumbar Spine & Deformity

A 14-year-old female gymnast complains of insidious onset, mechanical lower back pain over the last 3 months. Plain radiographs of the lumbar spine are completely normal. However, an MRI reveals hyperintense signal (bone marrow edema) in the pars interarticularis of L5 bilaterally on T2/STIR sequences, with no discrete fracture line visible on CT. What is the most appropriate initial management?

. Direct pars repair with pedicle screw and sublaminar wire (Scott wiring)
. L5-S1 anterior lumbar interbody fusion (ALIF)
. Restriction of sports and application of a TLSO brace
. Diagnostic bilateral L5 pars injections
. Observation and immediate continuation of gymnastics

Correct Answer & Explanation

. Direct pars repair with pedicle screw and sublaminar wire (Scott wiring)

Explanation

This patient has an acute/early stress reaction of the pars interarticularis (early spondylolysis) before a true cortical defect has formed, indicated by isolated marrow edema on MRI and negative plain films/CT. This stage has a very high potential for complete bony healing if treated aggressively with rest and immobilization. The standard of care is immediate restriction from offending sports (gymnastics) and bracing (e.g., TLSO or Boston brace) until symptoms resolve and serial imaging confirms healing. Surgical repair is reserved for chronic, symptomatic defects that fail 6 months of non-operative management.

Question 6118

Topic: 6. Spine

The Spine Patient Outcomes Research Trial (SPORT) evaluated surgical versus non-operative management for degenerative spondylolisthesis with spinal stenosis. Despite significant crossover between the assigned groups, what was the primary conclusion regarding patient outcomes at 4-year and 8-year follow-ups based on the 'as-treated' analysis?

. Patients treated surgically maintained significantly greater improvements in pain and physical function compared to those treated non-operatively.
. There was no significant difference in pain or function between the surgical and non-operative groups at 8 years.
. Non-operative treatment yielded superior functional outcomes at 8 years due to late adjacent segment disease in the surgical group.
. Surgical patients showed early improvement at 1 year, but outcomes were identical to non-operative patients by 4 years.
. Epidural steroid injections provided longer-lasting relief than surgical decompression and fusion.

Correct Answer & Explanation

. Patients treated surgically maintained significantly greater improvements in pain and physical function compared to those treated non-operatively.

Explanation

The SPORT trial for degenerative spondylolisthesis demonstrated that, in the 'as-treated' analysis (accounting for the high crossover rates), patients who underwent surgical decompression and fusion experienced significantly greater improvements in pain, function, and satisfaction compared to those treated non-operatively. These superior surgical outcomes were maintained long-term at both the 4-year and 8-year follow-up marks.

Question 6119

Topic: 6. Spine

In evaluating adult spinal deformity, the Sagittal Vertical Axis (SVA) is a critical radiographic measurement used to quantify global sagittal balance. How is the SVA defined on a standing lateral full-length spine radiograph?

. The horizontal distance from the anterior aspect of the T1 body to the center of the femoral heads.
. The horizontal distance from a plumb line dropped from the centroid of C7 to the posterosuperior corner of the S1 endplate.
. The angle subtended by the inferior endplate of C7 and the superior endplate of S1.
. The vertical distance from the center of C7 to the anterior superior iliac spine (ASIS).
. The horizontal distance from the C2 plumb line to the anterior border of the symphysis pubis.

Correct Answer & Explanation

. The horizontal distance from the anterior aspect of the T1 body to the center of the femoral heads.

Explanation

The Sagittal Vertical Axis (SVA) is the standard metric for assessing global sagittal alignment. It is measured as the horizontal distance (in millimeters or centimeters) between a vertical plumb line dropped from the center (centroid) of the C7 vertebral body and the posterior-superior corner of the S1 vertebral body. A normal SVA is considered to be less than 5 cm. A positive SVA (>5 cm) indicates that the patient is pitched forward, which strongly correlates with increased energy expenditure and worse patient-reported pain/function scores.

Question 6120

Topic: 6. Spine

A 52-year-old male with poorly controlled diabetes mellitus presents with 5 days of severe back pain, fevers, and malaise. His ESR is 85 mm/hr and CRP is elevated. MRI of the lumbar spine reveals an anterior epidural abscess extending from L3 to L5. Neurological examination is completely normal, with full strength, intact sensation, and normal bowel/bladder function. What is the most appropriate initial management?

. Immediate open laminectomy for decompression and washout.
. Initiation of empiric broad-spectrum oral antibiotics and discharge to home.
. CT-guided aspiration of the abscess or paraspinal fluid to obtain cultures, followed by initiation of IV antibiotics.
. Observation with repeat MRI in 24 hours without starting antibiotics to preserve diagnostic yield.
. Anterior retroperitoneal approach for corpectomy and placement of an expandable cage.

Correct Answer & Explanation

. Immediate open laminectomy for decompression and washout.

Explanation

In a neurologically intact patient with a spinal epidural abscess, medical management with culture-directed IV antibiotics is the initial treatment of choice. Before starting empiric IV antibiotics, it is crucial to obtain a definitive microbiological diagnosis to guide long-term therapy. This is usually achieved via blood cultures and/or a CT-guided aspirate of the abscess. Emergent surgical decompression (e.g., laminectomy or anterior decompression) is strictly indicated if the patient presents with or develops a progressive neurologic deficit, mechanical instability, or fails medical management.

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