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6. Spine MCQs

Practice Set 312 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 6221

Topic: 6. Spine

A 35-year-old unrestrained passenger is involved in a motor vehicle collision. Radiographs demonstrate a unilateral facet dislocation in the cervical spine.

What is the primary mechanism of injury leading to this specific pathology?

. Hyperextension with axial loading
. Pure axial loading
. Flexion-distraction with an element of rotation
. Pure lateral bending
. Flexion without distraction

Correct Answer & Explanation

. Hyperextension with axial loading

Explanation

Unilateral facet dislocations are caused by a combination of flexion-distraction and rotational forces. On lateral radiographs, they typically present with less than 50% (often ~25%) anterior translation of the vertebral body.

Question 6222

Topic: 6. Spine
A 5-year-old is newly diagnosed with congenital scoliosis. Before contemplating any surgical intervention, which of the following imaging workups is strictly mandatory due to the high incidence of associated syndromic anomalies?
. Pulmonary function testing and a V/Q scan
. Renal ultrasound and total spine MRI
. CT angiogram of the chest and abdomen
. DEXA scan for bone mineral density
. Genetic karyotyping for Trisomy 21

Correct Answer & Explanation

. Renal ultrasound and total spine MRI

Explanation

Congenital scoliosis is strongly associated with VACTERL anomalies. Up to 30% of patients have genitourinary anomalies and 20-40% have intraspinal anomalies (e.g., tethered cord), making a renal ultrasound and MRI of the entire neural axis mandatory.

Question 6223

Topic: 6. Spine

A 58-year-old male undergoes a 10-hour posterior spinal fusion for complex adult deformity, complicated by 2.5 liters of blood loss. Postoperatively, he complains of painless, bilateral visual loss. What is the most common etiology of postoperative visual loss (POVL) in this setting?

. Retinal detachment
. Ischemic optic neuropathy (ION)
. Acute angle-closure glaucoma
. Corneal abrasion
. Central retinal artery occlusion

Correct Answer & Explanation

. Retinal detachment

Explanation

Ischemic optic neuropathy (ION) is the leading cause of postoperative visual loss after major spine surgery. Risk factors include prolonged prone positioning, massive blood loss, hypotension, and the use of a Wilson frame.

Question 6224

Topic: Thoracolumbar Spine & Deformity

A 19-year-old female presents after a high-speed collision where she was wearing only a lap seatbelt. Imaging reveals a Chance fracture of L1. What concomitant injury must be highly suspected and urgently ruled out?

. Traumatic aortic dissection
. Intra-abdominal hollow viscus injury
. Bilateral diaphragmatic rupture
. Tension pneumothorax
. Renal artery avulsion

Correct Answer & Explanation

. Traumatic aortic dissection

Explanation

Chance fractures are flexion-distraction injuries commonly associated with lap seatbelt use. They carry a 40-50% incidence of concurrent intra-abdominal hollow viscus injuries (e.g., bowel perforations), which must be urgently evaluated.

Question 6225

Topic: 6. Spine

A 45-year-old male with long-standing Ankylosing Spondylitis (AS) reports new-onset neck pain after a minor trip-and-fall at home. Initial AP and lateral cervical radiographs are read as "normal with expected syndesmophytes." What is the most appropriate next step in management?

. Discharge with NSAIDs and a soft cervical collar
. Perform a CT scan and MRI of the entire spine
. Perform dynamic flexion-extension cervical radiographs
. Prescribe physical therapy focusing on neck strengthening
. Obtain a bone scan to evaluate for metastatic disease

Correct Answer & Explanation

. Discharge with NSAIDs and a soft cervical collar

Explanation

Patients with Ankylosing Spondylitis have rigid, osteopenic spines highly susceptible to unstable fractures even from minor trauma. Advanced imaging (CT/MRI) of the entire spine is mandatory due to the high risk of occult, highly unstable fractures and epidural hematomas.

Question 6226

Topic: 6. Spine
A 6-year-old boy is brought to the ER with transient lower extremity weakness and paresthesia following a trampoline fall. Complete spine X-rays and CT scans are negative for fracture or subluxation. An MRI reveals central cord edema. What biomechanical factor best explains the occurrence of Spinal Cord Injury Without Radiographic Abnormality (SCIWORA) in this patient?
. Early-onset degenerative disc disease
. Severe facet joint arthropathy
. Increased ligamentous laxity and horizontally oriented facets in the pediatric spine
. Osteoporotic vertebral body collapse
. Congenital cervical spinal stenosis

Correct Answer & Explanation

. Increased ligamentous laxity and horizontally oriented facets in the pediatric spine

Explanation

SCIWORA is primarily seen in the pediatric population. It occurs because the inherent ligamentous elasticity and horizontal facet orientation of the child's spine allow significant transient deformation without permanent skeletal disruption, injuring the underlying cord.

Question 6227

Topic: 6. Spine

Which of the following demographic and clinical profiles is most characteristic of Ossification of the Posterior Longitudinal Ligament (OPLL)?

. An adult male of East Asian descent presenting with progressive cervical myelopathy
. A Caucasian female teenager presenting with thoracic back pain
. An African American male with isolated axial neck pain and stiffness
. A Hispanic female presenting with a solitary lytic vertebral mass
. A pediatric patient presenting with acute torticollis post-infection

Correct Answer & Explanation

. An adult male of East Asian descent presenting with progressive cervical myelopathy

Explanation

Ossification of the posterior longitudinal ligament (OPLL) is most prevalent in East Asian populations (particularly Japanese). It typically presents in middle-aged to elderly males with progressive symptoms of cervical myelopathy.

Question 6228

Topic: 6. Spine

A 68-year-old female is scheduled for a total hip arthroplasty. Preoperative standing and sitting lateral spine-pelvis radiographs demonstrate a change in sacral slope of less than 10 degrees from standing to sitting. Which of the following component positioning strategies is most appropriate given this finding?

. Increase acetabular cup anteversion to accommodate anterior pelvic tilt during sitting
. Target an acetabular inclination of 50 degrees and standard anteversion
. Increase combined anteversion by primarily increasing femoral anteversion
. Target a higher acetabular cup anteversion to prevent posterior dislocation during sitting
. Place the acetabular cup in a standard 'safe zone' of 40 degrees inclination and 15 degrees anteversion

Correct Answer & Explanation

. Increase acetabular cup anteversion to accommodate anterior pelvic tilt during sitting

Explanation

A change in sacral slope of <10 degrees between standing and sitting indicates a 'stiff' spinopelvic junction. Normally, the pelvis tilts posteriorly when transitioning from standing to sitting, increasing functional acetabular anteversion and opening the cup anteriorly to prevent impingement and posterior dislocation. In a stiff spine, this compensatory posterior tilt does not occur, putting the patient at higher risk of anterior impingement and posterior dislocation during sitting. Therefore, the surgeon must compensate by increasing the target acetabular cup anteversion.

Question 6229

Topic: 6. Spine

A 68-year-old patient with a fused lumbar spine from L2 to the pelvis (pelvic incidence minus lumbar lordosis mismatch) is scheduled for a THA. How does this spinopelvic stiffness affect the optimal acetabular cup positioning to minimize the risk of dislocation?

. The cup should be placed in reduced anteversion and reduced inclination.
. The cup should be placed in standard 'safe zone' parameters as the spine does not affect hip kinematics.
. The cup should be placed in significantly increased retroversion.
. The cup should be placed in increased anteversion and increased inclination.
. The cup should be placed with 0 degrees of inclination and 15 degrees of anteversion.

Correct Answer & Explanation

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

Explanation

A fused or stiff lumbar spine prevents the normal posterior pelvic tilt that occurs when a patient transitions from standing to sitting. Because the pelvis fails to tilt back, there is a lack of relative functional acetabular anteversion, leading to anterior impingement and posterior dislocation. To compensate, the surgeon must place the cup in higher anteversion and inclination.

Question 6230

Topic: 6. Spine

A 65-year-old male with a long-segment lumbar fusion (L2 to Sacrum) presents for a total hip arthroplasty. How does his spinopelvic stiffness affect acetabular dynamics during the transition from standing to sitting?

. The pelvis will tilt posteriorly more than normal, requiring less anteversion.
. The pelvis remains relatively fixed, resulting in decreased acetabular anteversion compared to a normal spine.
. The pelvis remains relatively fixed, resulting in increased acetabular anteversion compared to a normal spine.
. The fused spine compensates by increasing hip extension reserve.
. The fused spine necessitates placing the cup in 10 degrees of retroversion.

Correct Answer & Explanation

. The pelvis will tilt posteriorly more than normal, requiring less anteversion.

Explanation

In a normal spine, sitting causes posterior pelvic tilt which functionally increases acetabular anteversion to clear the anterior femur. A fused spine fails to tilt posteriorly, leaving the cup relatively less anteverted while sitting, which increases the risk of anterior impingement and posterior dislocation.

Question 6231

Topic: 6. Spine

A 40-year-old male presents with acute, unrelenting pain in his right shoulder that awoke him from sleep 2 weeks ago. The pain lasted for 10 days and has now subsided, but he has noticed profound weakness in raising his arm and a developing hollow appearance over his shoulder blade. He had a viral respiratory infection 3 weeks prior. What is the most appropriate diagnostic test to confirm the suspected diagnosis?

. MRI of the cervical spine
. MRI of the brachial plexus
. Electromyography and nerve conduction studies (EMG/NCS)
. Diagnostic ultrasound of the rotator cuff
. Serum inflammatory markers (ESR, CRP)

Correct Answer & Explanation

. MRI of the cervical spine

Explanation

The clinical presentation is classic for Parsonage-Turner Syndrome (acute brachial neuritis), characterized by abrupt onset of severe shoulder pain followed by patchy weakness and atrophy (often involving the suprascapular, axillary, or anterior interosseous nerves) as the pain subsides. It is often preceded by a viral illness or vaccination. Diagnosis is confirmed clinically and supported by EMG/NCS, which will show acute denervation patterns.

Question 6232

Topic: 6. Spine

A 28-year-old female presents after a fall from a height of 20 feet. She has a widened mediastinum on chest radiograph, a T12 burst fracture, and flaccid paralysis in her lower extremities. Her vital signs are: BP 85/50 mmHg, HR 65 bpm, RR 18/min. What is the most likely primary cause of her hypotension?

. Cardiogenic shock
. Hemorrhagic shock
. Neurogenic shock
. Spinal shock
. Tension pneumothorax

Correct Answer & Explanation

. Cardiogenic shock

Explanation

The presence of hypotension paired with bradycardia in the setting of a spinal cord injury strongly suggests neurogenic shock, which results from the loss of sympathetic tone. In contrast, hemorrhagic shock typically presents with compensatory tachycardia.

Question 6233

Topic: 6. Spine

A 19-year-old male involved in a high-speed collision presents with massive shoulder swelling and an AP chest radiograph demonstrating marked lateral displacement of the scapula. What is the most devastating, immediately life-threatening or limb-threatening associated injury that must be ruled out?

. Tension pneumothorax
. Subclavian/axillary vascular disruption and brachial plexus avulsion
. Cervical spine facet dislocation
. Massive rotator cuff avulsion

Correct Answer & Explanation

. Tension pneumothorax

Explanation

Scapulothoracic dissociation is a severe, high-energy injury characterized by lateral displacement of the scapula. It is frequently associated with catastrophic traction injuries to the subclavian or axillary artery and the brachial plexus.

Question 6234

Topic: 6. Spine

A 30-year-old patient with a complete cervical spine cord injury presents to the emergency department hypotensive and bradycardic, with warm extremities. Which type of shock is this patient experiencing?

. Hypovolemic shock
. Neurogenic shock
. Spinal shock
. Cardiogenic shock

Correct Answer & Explanation

. Hypovolemic shock

Explanation

Neurogenic shock is characterized by hypotension, bradycardia, and warm extremities due to the loss of sympathetic vascular tone. Spinal shock refers to the temporary loss of spinal reflexes below the level of injury and is not a hemodynamic state.

Question 6235

Topic: Thoracolumbar Spine & Deformity

A 68-year-old female is undergoing primary total hip arthroplasty. Preoperative standing and seated lateral spinopelvic radiographs reveal a change in pelvic tilt of only 4 degrees between standing and sitting, secondary to prior long-segment lumbar fusion. To minimize her risk of postoperative dislocation, how should the acetabular component positioning be adjusted relative to the standard Lewinnek 'safe zone'?

. Decreased anteversion and decreased inclination
. Increased anteversion and increased inclination
. Standard safe zone positioning (15 degrees anteversion, 40 degrees inclination)
. Decreased anteversion and increased inclination
. Increased anteversion and decreased inclination

Correct Answer & Explanation

. Decreased anteversion and decreased inclination

Explanation

Patients with a stiff spinopelvic junction (change in pelvic tilt < 10 degrees from stand to sit) fail to undergo the normal posterior pelvic tilt when sitting. Normally, posterior tilt increases functional acetabular anteversion, allowing clearance for the flexed femur. Without this compensatory mechanism, the patient is at a high risk for anterior impingement and subsequent posterior dislocation when seated. To compensate for a stiff spinopelvic junction, the acetabular component must be placed in relatively higher anteversion and inclination than the standard safe zone.

Question 6236

Topic: 6. Spine

A 60-year-old male undergoes a C3-C6 posterior laminectomy and instrumented fusion for cervical spondylotic myelopathy. On postoperative day 3, he develops new-onset unilateral deltoid and biceps weakness (grade 2/5). Sensation and lower extremity function remain unchanged. What is the most widely accepted primary pathophysiology for this delayed complication?

. Direct intraoperative C5 nerve root injury from pedicle screw placement
. Anterior spinal artery ischemia due to transient intraoperative hypotension
. Tethering of the C5 nerve root caused by posterior drift of the spinal cord
. Postoperative epidural hematoma compressing the dorsal root ganglion
. Thermal necrosis of the facet capsule during high-speed burr utilization

Correct Answer & Explanation

. Direct intraoperative C5 nerve root injury from pedicle screw placement

Explanation

Postoperative C5 palsy is a known complication following cervical decompression, particularly posterior laminectomy. The most widely accepted mechanism is the 'tethering effect.' After removing the posterior elements, the spinal cord drifts backward. Because the C5 nerve roots are short and run a transverse course, this posterior cord shift can stretch and tether the C5 root, leading to delayed motor weakness (typically deltoid and biceps). Direct surgical injury usually presents immediately, not in a delayed fashion.

Question 6237

Topic: 6. Spine

A 65-year-old man presents with deteriorating handwriting, frequent dropping of objects, and a broad-based, unsteady gait. Physical examination reveals a positive Hoffmann sign bilaterally. Elicitation of the brachioradialis reflex results in spontaneous flexion of the fingers without normal wrist extension or radial deviation. This specific reflex finding indicates spinal cord compression at which anatomical level?

. C3-C4
. C4-C5
. C5-C6
. C6-C7
. C7-T1

Correct Answer & Explanation

. C3-C4

Explanation

The patient exhibits an inverted brachioradialis reflex, a classic localizing sign in cervical spondylotic myelopathy. It indicates compression at the C5-C6 level. The reflex tests the C6 nerve root; compression at this level causes a lower motor neuron lesion at C6 (absent brachioradialis jerk) and an upper motor neuron lesion below this level (hyperactive finger flexion mediated by C8).

Question 6238

Topic: 6. Spine

In the evaluation of an infant presenting with infantile idiopathic scoliosis, which of the following radiographic measurements is widely considered the most reliable predictor of curve progression versus spontaneous resolution?

. A Cobb angle greater than 15 degrees at initial presentation
. Apical vertebral rotation greater than Nash-Moe Grade II
. A Rib-Vertebra Angle Difference (RVAD) of Mehta greater than 20 degrees
. A thoracic kyphosis measuring less than 20 degrees
. A Risser sign of 0 at the time of diagnosis

Correct Answer & Explanation

. A Cobb angle greater than 15 degrees at initial presentation

Explanation

In infantile idiopathic scoliosis, the Rib-Vertebra Angle Difference (RVAD), described by Min Mehta, is the most crucial prognostic indicator. An RVAD greater than 20 degrees is strongly associated with a high likelihood of curve progression (progressive phase), whereas an RVAD of less than 20 degrees usually suggests the curve will spontaneously resolve (resolving phase).

Question 6239

Topic: 6. Spine

A 45-year-old patient presents with cervical radiculopathy. Physical examination reveals weakness in triceps extension, wrist flexion, and finger extension, along with a diminished triceps reflex. Sensation is decreased over the palmar aspect of the middle finger. Which cervical nerve root is most likely affected?

. C5
. C6
. C7
. C8
. T1

Correct Answer & Explanation

. C5

Explanation

A C7 radiculopathy classically presents with weakness in the triceps, wrist flexors (FCR, FCU), and finger extensors (EDC). The triceps reflex is typically diminished, and there is sensory loss in the C7 dermatome, which uniquely includes the middle finger.

Question 6240

Topic: 6. Spine

Following an acute traumatic spinal cord injury, the patient enters a phase of spinal shock, characterized by flaccid paralysis, areflexia, and loss of autonomic tone below the level of injury. The resolution of this spinal shock phase is clinically marked by the return of which of the following reflexes?

. Biceps reflex
. Patellar reflex
. Bulbocavernosus reflex
. Cremasteric reflex
. Babinski sign

Correct Answer & Explanation

. Biceps reflex

Explanation

The bulbocavernosus reflex is an S2-S4 reflex. Its return signifies the end of the spinal shock phase. Once it returns, any neurologic deficit remaining is usually considered the baseline incomplete or complete spinal cord injury.

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