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6. Spine MCQs

Practice Set 164 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 3261

Topic: Thoracolumbar Spine & Deformity

A 68-year-old male with a history of L3-S1 instrumented fusion presents with increasing back pain, progressive stooping posture, and difficulty ambulating. Clinical examination reveals a positive sagittal imbalance. A standing lateral spinopelvic radiograph is shown below.

Which radiographic parameter is MOST strongly correlated with functional outcome and satisfaction following surgical correction of adult spinal deformity with sagittal imbalance?

. Sacral Slope (SS)
. Pelvic Tilt (PT)
. Pelvic Incidence (PI)
. Pelvic Incidence minus Lumbar Lordosis (PI-LL) mismatch
. Sagittal Vertical Axis (SVA)

Correct Answer & Explanation

. Pelvic Incidence minus Lumbar Lordosis (PI-LL) mismatch

Explanation

The Pelvic Incidence minus Lumbar Lordosis (PI-LL) mismatch is considered one of the most critical radiographic parameters correlating with functional outcome and patient satisfaction after adult spinal deformity correction. A mismatch of >10 degrees is generally considered pathologic and a primary driver for sagittal imbalance, requiring surgical correction. While Sagittal Vertical Axis (SVA) is also a crucial measure of global balance, the PI-LL mismatch directly reflects the patient's inherent pelvic morphology relative to their lumbar lordosis requirement, which is key for a stable and energy-efficient posture. Reducing this mismatch to <10 degrees is a primary surgical goal. Sacral Slope and Pelvic Tilt are components of Pelvic Incidence and change with posture, but PI-LL mismatch integrates the relationship between the pelvis and the lumbar spine.

Question 3262

Topic: Thoracolumbar Spine & Deformity
A 22-year-old female presents with chronic right hip pain and a diagnosis of symptomatic hip dysplasia. An AP pelvis radiograph is shown. She is scheduled for a Bernese periacetabular osteotomy (PAO). Which intraoperative maneuver is critical for optimizing hip joint coverage and load distribution while minimizing impingement?
. Lateralization of the iliac fragment.
. Posterior translation of the acetabular fragment.
. Anterior and lateral rotation of the acetabular fragment.
. Increasing the sacral slope.
. Distalization of the acetabular fragment.

Correct Answer & Explanation

. Anterior and lateral rotation of the acetabular fragment.

Explanation

During a Bernese periacetabular osteotomy (PAO), the acetabular fragment is mobilized and repositioned. The critical maneuver involves anterior and lateral rotation of the acetabular fragment. This movement effectively increases anterior and lateral coverage of the femoral head, correcting the underlying dysplasia. This leads to increased contact area, reduced peak stresses, and improved load distribution across the articular cartilage, while carefully avoiding impingement with the femoral neck. Medialization of the acetabulum also occurs as a secondary effect of this rotation, further improving joint mechanics.

Question 3263

Topic: Thoracolumbar Spine & Deformity

A 68-year-old male presents with worsening back pain and progressive difficulty maintaining an upright posture. Clinical examination reveals a positive sagittal imbalance. Lateral standing radiographs are obtained, revealing the following spinal alignment parameters:

Pelvic incidence (PI) = 60°, Pelvic tilt (PT) = 30°, Sacral slope (SS) = 30°, Sagittal vertical axis (SVA) = +10 cm. Based on these findings, which of the following statements regarding his sagittal alignment is MOST accurate?

. His pelvic incidence is abnormally low, contributing to his sagittal imbalance.
. His pelvic tilt indicates a compensatory mechanism for a positive sagittal balance.
. A large sacral slope is indicative of a well-compensated sagittal alignment.
. His sagittal vertical axis is within the normal limits, suggesting an underlying coronal deformity.
. Surgical correction should primarily aim to decrease pelvic tilt and increase sacral slope.

Correct Answer & Explanation

. His pelvic tilt indicates a compensatory mechanism for a positive sagittal balance.

Explanation

The image provided depicts a lateral view of the spine, emphasizing sagittal alignment. A positive sagittal imbalance (SVA > 5cm) is often compensated for by retroversion of the pelvis, leading to an increased pelvic tilt (normal < 20-25°) and a decreased sacral slope (normal > 35-40°). In this patient, SVA of +10 cm confirms a positive sagittal imbalance. A PI of 60° is within the normal range (45-60°), although higher PI values are associated with a greater lordosis requirement. His PT of 30° is indeed increased, representing a compensatory mechanism where the pelvis rotates posteriorly to try and bring the trunk center of gravity back over the feet. His SS of 30° is decreased, also consistent with pelvic retroversion. Surgical goals for sagittal deformity often involve decreasing PT and SVA, and increasing SS and lumbar lordosis, ideally matching lumbar lordosis to PI - 10°.Rationale for options:A. His PI (60°) is within the high-normal range, not abnormally low.B. An increased PT (30°) is a classic compensatory mechanism for positive sagittal balance, attempting to shift the center of gravity posteriorly. This is the correct statement.C. A decreased sacral slope (30°) is indicative of pelvic retroversion, which is a sign ofdecompensatedorcompensatingsagittal alignment, not a well-compensated one. A large sacral slope typically indicates a more upright pelvis and better compensation, if paired with appropriate lumbar lordosis.D. SVA of +10 cm is significantly positive (normal is generally < 5 cm), indicating a significant sagittal imbalance, not normal limits.E. Surgical correction typically aims todecreasepelvic tilt andincreasesacral slope to improve global sagittal alignment, but the statement 'decrease pelvic tilt and increase sacral slope' is part of the correction strategy, whereas the initial question asks for the most accurate statementregarding his current alignment. The current PT indicates compensation.

Question 3264

Topic: 6. Spine
A 10-year-old child presents after a bicycle accident with transient weakness and paresthesias in both upper and lower extremities, which fully resolved within 2 hours. Neurological examination in the emergency department is now completely normal. Radiographs of the cervical spine, including flexion-extension views, are unremarkable, showing no evidence of fracture or instability. What is the most appropriate next diagnostic step given the clinical presentation?
. Discharge home with activity restrictions and follow-up as needed.
. Obtain an MRI of the cervical spine to evaluate for spinal cord pathology.
. Perform a CT scan of the cervical spine to rule out occult fractures.
. Admit for inpatient observation and repeat neurological examinations.
. Order electrophysiological studies (EMG/NCS) to assess nerve root function.

Correct Answer & Explanation

. Obtain an MRI of the cervical spine to evaluate for spinal cord pathology.

Explanation

The patient's presentation with transient neurological deficits after trauma, with normal radiographs and complete resolution of symptoms, is highly suggestive of Spinal Cord Injury Without Radiographic Abnormality (SCIWORA). While the initial radiographs appear normal, the gold standard for evaluating the spinal cord and soft tissues in a SCIWORA case is MRI. SCIWORA in children is relatively common due to increased spinal elasticity compared to adults, allowing significant deformation of the spinal column and cord injury without bony fracture or ligamentous disruption visible on plain radiographs or CT. MRI can identify spinal cord contusions, edema, hemorrhage, or even ligamentous injury that causes transient compression.

Question 3265

Topic: 6. Spine
A 32-year-old male presents with worsening neck pain, left upper extremity paresthesias, and progressive weakness, particularly in his left hand. Examination reveals intrinsic hand muscle atrophy and weakness (finger abduction/adduction and grip strength). Deep tendon reflexes are hyperreflexic in the lower extremities with a positive Babinski sign. MRI of the cervical spine shows severe central canal stenosis at C5-C6 and C6-C7 with spinal cord compression and T2 signal changes consistent with myelomalacia. What is the most appropriate surgical management approach for this patient?
. Anterior cervical discectomy and fusion (ACDF) at C5-C6 only.
. Posterior cervical laminectomy without fusion.
. Cervical laminoplasty.
. Posterior cervical laminectomy and fusion.
. Anterior cervical corpectomy and fusion (ACCF) at C5 and C6.

Correct Answer & Explanation

. Posterior cervical laminectomy and fusion.

Explanation

The patient has multi-level cervical myelopathy due to stenosis at C5-C6 and C6-C7. Posterior laminectomy and fusion is the most appropriate approach to provide comprehensive multi-level decompression while maintaining spinal stability, especially in a younger patient where post-laminectomy kyphosis is a concern. ACDF at one level is insufficient, and laminectomy without fusion carries a high risk of instability.

Question 3266

Topic: 6. Spine

A 68-year-old male with severe, multi-level lumbar spinal stenosis and degenerative spondylolisthesis at L4-L5 presents with intractable neurogenic claudication and radicular pain despite extensive conservative treatment. MRI shows significant central canal stenosis and bilateral neuroforaminal stenosis at L4-L5 and L5-S1. Given his symptoms and radiographic findings, which surgical approach is MOST appropriate?

. Microdiscectomy at L4-L5 and L5-S1.
. Laminectomy and instrumented fusion from L4 to S1.
. Unilateral hemilaminectomy and decompression at L4-L5 only.
. Posterior lumbar interbody fusion (PLIF) at L4-L5 only.
. Laminoplasty at L4-L5.

Correct Answer & Explanation

. Laminectomy and instrumented fusion from L4 to S1.

Explanation

The patient has multi-level lumbar spinal stenosis (L4-L5, L5-S1) and degenerative spondylolisthesis at L4-L5, with intractable neurogenic claudication and radicular pain. Surgical decompression and stabilization are indicated.For multi-level stenosis with degenerative spondylolisthesis, simple decompression alone (e.g., microdiscectomy, hemilaminectomy, or laminectomy without fusion) carries a high risk of increasing instability, progression of spondylolisthesis, and recurrence of symptoms. Therefore, decompression combined with instrumented fusion is generally recommended for degenerative spondylolisthesis, especially when multi-level or with instability.A laminectomy and instrumented fusion from L4 to S1 would provide comprehensive decompression for the multi-level stenosis and stabilize the L4-L5 spondylolisthesis and the adjacent L5-S1 segment (which also has stenosis and benefits from fusion due to biomechanical changes). This is a well-established and robust approach.Rationale for options:A. Microdiscectomy is for disc herniation and nerve root compression, not primarily for multi-level spinal stenosis with spondylolisthesis. It would not address the stenosis or instability.B. Laminectomy and instrumented fusion from L4 to S1 addresses both the multi-level spinal stenosis (decompression) and the degenerative spondylolisthesis (stabilization), providing a durable solution. This is the correct answer.C. Unilateral hemilaminectomy and decompression at L4-L5 only is inadequate for multi-level stenosis and would not stabilize the spondylolisthesis.D. Posterior lumbar interbody fusion (PLIF) at L4-L5 only would address the spondylolisthesis and stenosis at that level, but would not address the L5-S1 stenosis. While a PLIF is a type of instrumented fusion, the choice needs to cover all symptomatic levels.E. Laminoplasty is a technique primarily used in the cervical spine to decompress the spinal cord while preserving motion; it is not a standard procedure for lumbar spinal stenosis, especially with spondylolisthesis.

Question 3267

Topic: Thoracolumbar Spine & Deformity
A 14-year-old gymnast presents with persistent lower back pain. Radiographs demonstrate an isthmic spondylolisthesis at L5-S1. If this patient's slip progresses to a high-grade slip (>50%), which of the following spinopelvic parameters is most likely to be significantly elevated as a compensatory mechanism to maintain sagittal balance?
. Pelvic incidence
. Sacral slope
. Pelvic tilt
. Lumbar lordosis
. Thoracic kyphosis

Correct Answer & Explanation

. Pelvic tilt

Explanation

In high-grade isthmic spondylolisthesis, patients compensate for the anterior shift of the center of gravity by retroverting the pelvis. This retroversion is measured as an increase in Pelvic Tilt (PT).

Question 3268

Topic: 6. Spine

A 45-year-old woman presents to the emergency department with acute onset of severe lower back pain, bilateral sciatica, saddle anesthesia, and urinary retention with overflow incontinence. An emergent MRI confirms a massive L4-L5 central disc herniation.

What is the pathophysiologic mechanism leading to the bladder dysfunction in this syndrome?

. Compression of sympathetic fibers from T10-L2 causing detrusor overactivity
. Ischemia to the conus medullaris leading to upper motor neuron signs
. Compression of parasympathetic roots (S2-S4) resulting in an areflexic detrusor muscle
. Irritation of the pudendal nerve resulting in external sphincter spasm
. Tethering of the filum terminale causing traction on the sacral roots

Correct Answer & Explanation

. Compression of parasympathetic roots (S2-S4) resulting in an areflexic detrusor muscle

Explanation

Cauda equina syndrome is a lower motor neuron lesion. The bladder dysfunction, typically presenting as painless urinary retention with overflow incontinence, is due to the compression of the sacral nerve roots (S2-S4). These roots carry the parasympathetic efferent fibers that innervate the detrusor muscle. Compression leads to an areflexic (flaccid) bladder.

Question 3269

Topic: 6. Spine
A 40-year-old driver is involved in a high-speed motor vehicle collision, sustaining a traumatic spondylolisthesis of the axis (Hangman's fracture). Imaging shows severe angulation and >3 mm of translation with bilateral facet dislocations. According to the Levine-Edwards classification, this is a Type III fracture. What is the primary mechanism of injury?
. Hyperextension and axial loading
. Flexion and distraction
. Flexion and compression
. Hyperextension and lateral bending

Correct Answer & Explanation

. Flexion and compression

Explanation

Levine-Edwards classification of Hangman's fractures: Type I (hyperextension/axial load, <3mm translation, no angulation); Type II (hyperextension/axial load followed by severe flexion, >3mm translation, significant angulation); Type IIA (flexion/distraction, minimal translation, severe angulation); Type III (flexion/distraction mechanism resulting in bilateral pars fractures with bilateral facet dislocation).

Question 3270

Topic: 6. Spine

A 70-year-old male with confirmed cervical spondylotic myelopathy undergoes a thorough neurologic examination. The examiner elicits a positive Hoffman's sign. This finding indicates a lesion involving which of the following neurologic tracts?

. Spinothalamic tract
. Corticospinal tract
. Dorsal columns
. Rubrospinal tract

Correct Answer & Explanation

. Corticospinal tract

Explanation

Hoffman's sign is an upper motor neuron (UMN) sign. It is elicited by 'flicking' the distal phalanx of the middle finger; a positive response is reflexive flexion of the thumb and/or index finger. A positive test indicates cervical spinal cord compression or brain pathology affecting the corticospinal tract, which is the major descending pathway for voluntary motor control.

Question 3271

Topic: 6. Spine

A 65-year-old man presents with progressive clumsiness in his hands and difficulty walking. Examination reveals hyperreflexia in the lower extremities and a positive Hoffmann's sign.

MRI demonstrates severe canal stenosis at C5-C6. If this patient has a pure C6 radiculopathy superimposed on his myelopathy, which of the following physical exam findings would most likely be present?

. Weakness in wrist extension and diminished brachioradialis reflex.
. Weakness in elbow extension and diminished triceps reflex.
. Weakness in finger flexion and positive Froment sign.
. Weakness in shoulder abduction and diminished biceps reflex.
. Weakness in thumb extension and diminished brachioradialis reflex.

Correct Answer & Explanation

. Weakness in wrist extension and diminished brachioradialis reflex.

Explanation

A pure C6 radiculopathy is characterized by weakness in wrist extension, altered sensation over the lateral forearm and thumb, and a diminished brachioradialis reflex. C5 affects shoulder abduction and the biceps reflex. C7 affects elbow extension, wrist flexion, and the triceps reflex. C8 affects finger flexion and thumb extension.

Question 3272

Topic: 6. Spine

A 68-year-old female presents with severe neurogenic claudication. Imaging reveals an L4-L5 degenerative spondylolisthesis.

In the pathogenesis of this condition, the facet joints typically undergo remodeling and become more sagittally oriented. This orientation most directly permits which type of abnormal motion?

. Excessive lateral bending.
. Anterior translation of the superior vertebra over the inferior vertebra.
. Posterior translation of the superior vertebra over the inferior vertebra.
. Excessive axial rotation.
. Vertical settling and retrolisthesis.

Correct Answer & Explanation

. Anterior translation of the superior vertebra over the inferior vertebra.

Explanation

Degenerative spondylolisthesis most commonly occurs at the L4-L5 level. It is highly associated with sagittal orientation of the facet joints (due to remodeling and arthropathy), which normally resist forward slippage when coronally oriented. When they become sagittally aligned, they fail to restrict forward shear forces, permitting anterior translation of the superior vertebra over the inferior vertebra.

Question 3273

Topic: 6. Spine

Which of the following biomechanical parameters has the most significant influence on increasing the pullout strength of a pedicle screw in spinal fixation?

. Increasing the minor (inner) diameter of the screw
. Decreasing the thread pitch
. Increasing the major (outer) diameter of the screw
. Increasing the length of the screw by 5 mm
. Using a partially threaded screw

Correct Answer & Explanation

. Increasing the major (outer) diameter of the screw

Explanation

The major (outer) diameter of a pedicle screw is the most critical factor in determining its pullout strength. While increasing screw length and inner diameter also contribute, the major diameter and the resulting thread depth have a substantially greater biomechanical impact.

Question 3274

Topic: Cervical Spine

An anterior cervical discectomy and fusion (ACDF) is planned via the Smith-Robinson approach. Which fascial interval is utilized, and why is the right-sided approach considered to have a higher risk to the recurrent laryngeal nerve?

. Between the sternocleidomastoid and the strap muscles; the right nerve loops around the aortic arch.
. Between the sternocleidomastoid and the strap muscles; the right nerve loops around the subclavian artery and enters the neck obliquely.
. Between the longus colli and the esophagus; the right nerve runs lateral to the carotid sheath.
. Between the strap muscles and the trachea; the right nerve loops around the subclavian artery.
. Between the platysma and the superficial fascia; the right nerve crosses the midline superiorly.

Correct Answer & Explanation

. Between the sternocleidomastoid and the strap muscles; the right nerve loops around the subclavian artery and enters the neck obliquely.

Explanation

The Smith-Robinson approach utilizes the interval between the sternocleidomastoid/carotid sheath (lateral) and the strap muscles/trachea/esophagus (medial). The right recurrent laryngeal nerve is more vulnerable because it loops around the subclavian artery and ascends more obliquely than the left.

Question 3275

Topic: 6. Spine

A 65-year-old male with long-standing ankylosing spondylitis presents to the emergency department after a ground-level fall. He complains of severe lower neck pain but has no focal neurologic deficits. Initial anteroposterior and lateral plain radiographs of the cervical spine show flowing osteophytes but no obvious fracture. What is the most critical next step?

. Discharge with a soft collar and NSAIDs
. Obtain flexion-extension cervical spine radiographs
. Perform a CT scan of the entire cervical spine
. Consult physical therapy for early mobilization
. Perform a diagnostic epidural steroid injection

Correct Answer & Explanation

. Perform a CT scan of the entire cervical spine

Explanation

Patients with ankylosing spondylitis have highly brittle spines and are at severe risk for unstable occult fractures even from low-energy trauma. A CT scan of the entire cervical spine is absolutely mandatory to rule out a fracture, even if plain radiographs are completely negative.

Question 3276

Topic: Cervical Spine

An 82-year-old male presents after a low-energy fall with neck pain. CT reveals a Type II odontoid fracture with 2 mm of posterior displacement. He is neurologically intact. What is the most appropriate management, considering his age and fracture characteristics?

. Halo vest immobilization.
. Rigid cervical collar for 6-12 weeks.
. Anterior odontoid screw fixation.
. Posterior C1-C2 fusion.
. Transoral odontoidectomy.

Correct Answer & Explanation

. Rigid cervical collar for 6-12 weeks.

Explanation

In the elderly population (>80 years), nonoperative management with a rigid cervical collar has been shown to have lower morbidity and mortality compared to surgery or halo vest immobilization for Type II odontoid fractures. While nonunion rates are high, a stable fibrous nonunion is typically well tolerated. Halo vests carry an unacceptably high risk of pulmonary complications and mortality in this age group.

Question 3277

Topic: 6. Spine
A 60-year-old male presents with worsening clumsiness in his hands and a wide-based gait. Physical examination reveals positive Hoffman's sign and hyperreflexia. MRI shows multi-level cervical spondylotic myelopathy with anterior compression from C3 to C6 and preservation of cervical lordosis. What is the preferred surgical intervention?
. C3-C6 Anterior Cervical Discectomy and Fusion (ACDF).
. C3-C6 Cervical laminectomy alone.
. C3-C6 Cervical laminoplasty.
. C3-C6 Posterior cervical fusion alone.
. Occipitocervical fusion.

Correct Answer & Explanation

. C3-C6 Cervical laminoplasty.

Explanation

In patients with multi-level (typically ≥ 3 levels) cervical spondylotic myelopathy who have maintained cervical lordosis and lack significant instability, a posterior approach such as cervical laminoplasty is an excellent option. It avoids the morbidity of multi-level anterior surgery (dysphagia, pseudarthrosis) and prevents the progressive post-laminectomy kyphosis seen with laminectomy alone. It also preserves some cervical motion.

Question 3278

Topic: Cervical Spine

A 65-year-old male presents with progressive clumsiness in his hands and a broad-based gait. Physical examination reveals a positive Hoffmann's sign bilaterally and hyperreflexia in the lower extremities. MRI of the cervical spine demonstrates multi-level spondylotic cord compression from C3 to C6. Sagittal alignment is neutral, and the patient denies any significant neck pain. What is the most appropriate surgical intervention?

. Anterior cervical discectomy and fusion (ACDF) C3-C6
. Cervical laminectomy without fusion
. Cervical laminoplasty
. Posterior cervical fusion without decompression
. Cervical disc arthroplasty C3-C6

Correct Answer & Explanation

. Cervical laminoplasty

Explanation

Cervical laminoplasty is ideal for multi-level compression in patients with neutral or lordotic alignment and absent/minimal mechanical neck pain. Laminectomy alone in adults has an unacceptably high rate of post-laminectomy kyphosis.

Question 3279

Topic: 6. Spine

A 10-year-old restrained passenger in a high-speed MVC sustains a flexion-distraction injury (Chance fracture) of the L2 vertebra.

This specific spinal fracture pattern in pediatric patients has a high concomitant association with which of the following injuries?

. Aortic dissection
. Intra-abdominal hollow viscus injury
. Bilateral pulmonary contusions
. Pelvic ring disruptions
. Subdural hematoma

Correct Answer & Explanation

. Intra-abdominal hollow viscus injury

Explanation

Chance fractures (flexion-distraction injuries) are commonly caused by lap-belt injuries in children. They carry a very high association (up to 50%) with intra-abdominal injuries, particularly hollow viscus perforations (e.g., small bowel).

Question 3280

Topic: 6. Spine

A 68-year-old female presents with progressive clumsiness in her hands and a broad-based gait. MRI shows multilevel cervical spondylotic myelopathy from C3 to C6 with preservation of cervical lordosis. There is no significant anterior compression. What is the most appropriate surgical approach?

. Anterior cervical discectomy and fusion (ACDF)
. Cervical laminectomy and fusion
. Cervical corpectomy
. Cervical disc arthroplasty
. Laminoforaminotomy alone

Correct Answer & Explanation

. Cervical laminectomy and fusion

Explanation

In patients with multilevel cervical myelopathy and maintained cervical lordosis, posterior decompression (laminectomy and fusion or laminoplasty) is highly effective and avoids the higher morbidity associated with multilevel anterior procedures. A lordotic alignment allows the spinal cord to drift posteriorly away from anterior pathology.

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