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6. Spine MCQs

Practice Set 256 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 5101

Topic: 6. Spine

A 68-year-old male is evaluated for a primary total hip arthroplasty. He has a history of a L2-S1 instrumented spinal fusion for degenerative scoliosis. How does this spinal stiffness alter his spinopelvic kinematics during the transition from a standing to a sitting position?

. It causes excessive posterior pelvic tilt, decreasing anterior instability.
. It prevents normal posterior pelvic tilt, resulting in decreased functional cup anteversion.
. It forces excessive functional cup anteversion, increasing posterior dislocation risk.
. It requires the acetabular component to be placed in 10 degrees of retroversion.
. It compensates for limited hip flexion by increasing lumbar lordosis.

Correct Answer & Explanation

. It prevents normal posterior pelvic tilt, resulting in decreased functional cup anteversion.

Explanation

Normally, moving from standing to sitting involves a posterior pelvic tilt, which functionally increases cup anteversion to accommodate hip flexion. A fused, stiff lumbar spine prevents this posterior tilt, leaving the cup in relative retroversion and significantly increasing the risk of anterior impingement and posterior dislocation.

Question 5102

Topic: 6. Spine

A 65-year-old woman with adult spinal deformity and a fused lumbar spine from L2 to the pelvis is planning to undergo a primary total hip arthroplasty. How does her stiff spinopelvic articulation affect the optimal acetabular cup positioning to prevent impingement and dislocation?

. The cup should be placed in more anteversion and more inclination.
. The cup should be placed in less anteversion and less inclination.
. The cup should be placed strictly in the standard Lewinnek safe zone.
. The cup should be placed with increased retroversion and increased inclination.
. The cup should be placed with increased retroversion and decreased inclination.

Correct Answer & Explanation

. The cup should be placed in more anteversion and more inclination.

Explanation

Patients with spinopelvic stiffness (fused spine) fail to increase pelvic retroversion during sitting. This requires the acetabular cup to be placed in more anteversion and more inclination to accommodate hip flexion and prevent anterior impingement and posterior dislocation.

Question 5103

Topic: 6. Spine

A 68-year-old woman is scheduled for a total hip arthroplasty. She has a history of a multilevel lumbar spinal fusion from L2 to S1. How does this spinal pathology alter her pelvic biomechanics during the transition from standing to sitting?

. Increases pelvic retroversion causing anterior impingement
. Decreases pelvic retroversion increasing risk of anterior dislocation
. Decreases pelvic retroversion increasing risk of posterior dislocation
. Increases anterior pelvic tilt increasing risk of posterior dislocation
. Has no significant effect on acetabular functional anteversion

Correct Answer & Explanation

. Decreases pelvic retroversion increasing risk of posterior dislocation

Explanation

Lumbar spinal fusion decreases normal spinopelvic mobility, preventing the pelvis from retroverting during sitting. This failure to increase functional acetabular anteversion exposes the patient to anterior impingement and posterior dislocation.

Question 5104

Topic: 6. Spine

A 40-year-old man presents with sudden, severe right shoulder pain that lasted unremittingly for 2 weeks. As the pain spontaneously subsided, he noticed profound weakness of the shoulder musculature and pronounced winging of the scapula. EMG demonstrates acute denervation. What is the most likely diagnosis?

. Cervical spondylotic myelopathy
. Parsonage-Turner syndrome (brachial neuritis)
. Acute massive rotator cuff tear
. Subacute subacromial bursitis
. Traumatic axillary neuropathy

Correct Answer & Explanation

. Parsonage-Turner syndrome (brachial neuritis)

Explanation

Parsonage-Turner syndrome (acute brachial neuritis) classically presents with acute onset of severe shoulder pain, followed days or weeks later by patchy muscle weakness, atrophy, and painless scapular winging as the pain resolves.

Question 5105

Topic: 6. Spine

A 40-year-old man presents with acute, excruciating right shoulder pain that started 2 weeks ago following a viral illness. The severe pain has subsided, but he now has profound weakness in forward elevation and external rotation. MRI of the shoulder is unremarkable. What is the most appropriate next step in diagnosis?

. MR arthrogram of the shoulder
. Electromyography (EMG) and nerve conduction studies
. Diagnostic arthroscopy
. Cervical spine MRI
. Serum inflammatory markers

Correct Answer & Explanation

. Electromyography (EMG) and nerve conduction studies

Explanation

The clinical presentation is classic for Parsonage-Turner syndrome (acute brachial neuritis), characterized by severe spontaneous pain followed by patchy weakness and muscle atrophy. EMG/NCS is the diagnostic modality of choice to confirm acute denervation.

Question 5106

Topic: 6. Spine

A 40-year-old male presents with the acute onset of severe, unrelenting left shoulder pain that lasted for 10 days. The pain is now improving, but he has suddenly developed profound weakness in shoulder abduction and external rotation. He denies any trauma. What is the most appropriate next step in confirming the diagnosis?

. Urgent cervical spine MRI
. Electromyography and nerve conduction studies (EMG/NCS)
. Arthroscopic rotator cuff repair
. Suprascapular nerve release
. Manipulation under anesthesia

Correct Answer & Explanation

. Electromyography and nerve conduction studies (EMG/NCS)

Explanation

The classic clinical triad of severe acute pain followed by rapid improvement in pain and subsequent patchy weakness is highly suggestive of Parsonage-Turner syndrome (acute brachial neuritis). Diagnosis is confirmed by EMG/NCS, which will show denervation patterns without compressive etiology.

Question 5107

Topic: 6. Spine

A patient undergoes T8 pedicle screw placement for a burst fracture. Postoperative CT shows a medial breach of the left T8 pedicle screw. Which structure is at highest immediate risk from this specific breach trajectory?

. Aorta
. Left lung pleura
. Spinal cord
. Azygos vein
. Sympathetic chain

Correct Answer & Explanation

. Spinal cord

Explanation

A medial breach of a thoracic pedicle screw directly threatens the spinal canal and the spinal cord. Lateral breaches risk the pleura, while anterior cortical breaches risk major vascular structures like the aorta.

Question 5108

Topic: 6. Spine

A patient presents with radiating arm pain, diminished biceps reflex, and weakness in wrist extension. MRI confirms a posterolateral disc herniation strictly at the C5-C6 level. Which nerve root is primarily compressed?

. C5
. C6
. C7
. C8
. T1

Correct Answer & Explanation

. C6

Explanation

In the cervical spine, there are 8 nerve roots but only 7 vertebrae; thus, cervical roots exit above their corresponding pedicle. A posterolateral disc herniation at C5-C6 compresses the exiting C6 nerve root.

Question 5109

Topic: 6. Spine

A 45-year-old patient involved in a motor vehicle accident sustains a hyperflexion injury to the cervical spine. Imaging demonstrates widening of the atlanto-dental interval. The alar ligaments, which stabilize the upper cervical spine, primarily function to limit which of the following movements?

. Flexion
. Extension
. Anterior translation of the atlas
. Axial rotation
. Vertical translation

Correct Answer & Explanation

. Axial rotation

Explanation

The alar ligaments connect the sides of the dens to the medial aspects of the occipital condyles. Their primary biomechanical function is to limit excessive axial rotation and lateral bending of the upper cervical spine.

Question 5110

Topic: 6. Spine

During an anterior cervical discectomy and fusion (ACDF) at C5-C6, the surgeon develops the interval between the carotid sheath laterally and the visceral midline structures medially. Which of the following structures is at greatest risk of injury if retractors are placed too deeply into the longus colli muscle or migrate laterally?

. Sympathetic trunk
. Recurrent laryngeal nerve
. Superior laryngeal nerve
. Hypoglossal nerve
. Phrenic nerve

Correct Answer & Explanation

. Sympathetic trunk

Explanation

The sympathetic trunk runs vertically along the lateral border of the longus colli muscle on the anterior spine. Placing self-retaining retractors too deep into the muscle belly or allowing them to slip laterally puts the sympathetic trunk at risk, potentially causing Horner's syndrome.

Question 5111

Topic: 6. Spine

In thoracic pedicle screw placement, precise knowledge of pedicle morphology is critical to avoid spinal cord or vascular injury. Which of the following thoracic vertebrae typically exhibits the greatest medial angulation of the pedicle?

. T1
. T4
. T8
. T10
. T12

Correct Answer & Explanation

. T1

Explanation

The medial pedicle angulation in the thoracic spine is largest at T1, averaging 25 to 30 degrees. This angulation gradually decreases caudally, approaching 0 to 5 degrees at T12.

Question 5112

Topic: Cervical Spine

When evaluating an upper cervical spine MRI for atlantoaxial instability, the integrity of the transverse ligament is the primary focus. This ligament firmly attaches to which of the following osseous landmarks?

. Medial tubercles of the lateral masses of C1
. Anterior arch of C1
. Odontoid process of C2
. Body of C3
. Occipital condyles

Correct Answer & Explanation

. Medial tubercles of the lateral masses of C1

Explanation

The transverse ligament spans horizontally across the atlas, attaching to the medial tubercles of the lateral masses of C1. It forms a strong sling behind the odontoid process, serving as the primary restraint against anterior subluxation of C1 on C2.

Question 5113

Topic: 6. Spine

During a posterior lumbar spinal fusion, what is the standard anatomic landmark for the starting point of a pedicle screw?

. Intersection of the pars interarticularis and the inferior articular process
. Intersection of a vertical line through the lateral border of the superior articular facet and a horizontal line bisecting the transverse process
. Just medial to the lateral edge of the pars interarticularis
. Junction of the medial border of the superior facet and the lamina
. Directly over the inferior border of the pedicle

Correct Answer & Explanation

. Intersection of a vertical line through the lateral border of the superior articular facet and a horizontal line bisecting the transverse process

Explanation

In the lumbar spine, the standard starting point for a pedicle screw is the intersection of a vertical line tangential to the lateral border of the superior articular facet and a horizontal line bisecting the transverse process. This landmark ensures an optimal trajectory through the center of the pedicle into the vertebral body.

Question 5114

Topic: 6. Spine

A spinal deformity surgeon is planning a long posterior fusion. To minimize the risk of anterior spinal artery syndrome, the surgeon must consider the Artery of Adamkiewicz. Which of the following is the most common anatomical location for the entrance of this artery into the spinal canal?

. Right-sided foramen between T4 and T6
. Left-sided foramen between T8 and L1
. Right-sided foramen between L2 and L4
. Left-sided foramen between L3 and L5
. Right-sided foramen between C7 and T1

Correct Answer & Explanation

. Left-sided foramen between T8 and L1

Explanation

The Artery of Adamkiewicz is the largest anterior segmental medullary artery. It most commonly enters the spinal canal on the left side between the T8 and L1 levels.

Question 5115

Topic: 6. Spine

A spine surgeon is placing pedicle screws in the L4 vertebra. Which anatomical relationship best describes the position of the exiting L4 nerve root relative to the L4 pedicle?

. It passes directly superior to the L4 pedicle
. It passes directly inferior to the L4 pedicle
. It passes medial to the L4 pedicle
. It passes directly through the L4 pedicle
. It passes anterior to the L4 vertebral body

Correct Answer & Explanation

. It passes directly inferior to the L4 pedicle

Explanation

In the lumbar spine, the exiting nerve root traverses the neuroforamen directly inferior to the pedicle of the same numeric level. Thus, the L4 nerve root exits inferior to the L4 pedicle.

Question 5116

Topic: 6. Spine

During a sacrospinous ligament fixation procedure for pelvic organ prolapse, an orthopedic surgeon assisting the case notes a suture placement too close to the ischial spine. Which nerve loops around the ischial spine and is at greatest risk of iatrogenic entrapment here?

. Superior gluteal nerve
. Inferior gluteal nerve
. Sciatic nerve
. Pudendal nerve
. Obturator nerve

Correct Answer & Explanation

. Pudendal nerve

Explanation

The pudendal nerve exits the pelvis through the greater sciatic foramen, hooks around the ischial spine and sacrospinous ligament, and re-enters the pelvis via the lesser sciatic foramen. Sutures placed too close to the ischial spine can easily entrap it.

Question 5117

Topic: 6. Spine

The great anterior radiculomedullary artery (Artery of Adamkiewicz) provides major blood supply to the lower two-thirds of the spinal cord. It most commonly enters the spinal canal at which of the following levels?

. Left side T8-L1
. Right side T8-L1
. Left side T4-T8
. Right side T4-T8
. Left side L2-L4

Correct Answer & Explanation

. Left side T8-L1

Explanation

The artery of Adamkiewicz usually arises from a left posterior intercostal artery between the levels of T8 and L1. Injury to this vessel during anterior spinal surgery can lead to anterior spinal artery syndrome.

Question 5118

Topic: 6. Spine

The vertebral artery typically enters the transverse foramen of the cervical spine at which vertebral level?

. C7
. C6
. C5
. C4
. C3

Correct Answer & Explanation

. C6

Explanation

The vertebral artery originates from the subclavian artery and typically enters the transverse foramen at the level of C6. It then travels cephalad through the foramina of C6 to C1.

Question 5119

Topic: Cervical Spine

During an anterior cervical discectomy and fusion (ACDF) at C5-C6, the surgeon elevates the longus colli muscles. Injury to the sympathetic trunk in this region can cause Horner's syndrome. Where is the cervical sympathetic trunk typically located relative to the longus colli?

. Medial to the longus colli
. Lateral to the longus colli
. Anterior to the prevertebral fascia
. Between the longus colli and the vertebral body
. Within the carotid sheath

Correct Answer & Explanation

. Lateral to the longus colli

Explanation

The cervical sympathetic trunk runs vertically just lateral to the longus colli muscles, beneath the prevertebral fascia. Dissection should remain medial to the lateral borders of the longus colli to avoid Horner's syndrome.

Question 5120

Topic: 6. Spine

When placing C2 pedicle screws during posterior cervical fusion, the trajectory must avoid the vertebral foramen. At the C2 level, what is the typical anatomical relationship of the vertebral artery to the pedicle/pars?

. Medial and superior
. Lateral and inferior
. Medial and inferior
. Lateral and superior
. Directly anterior

Correct Answer & Explanation

. Medial and superior

Explanation

In the C2 vertebra, the vertebral artery courses laterally and inferiorly relative to the pedicle and pars interarticularis before turning medially to enter the C1 foramen transversarium. Trajectories must remain medial and superior to avoid vascular injury.

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