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6. Spine MCQs

Practice Set 140 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 2781

Topic: Thoracolumbar Spine & Deformity

A 35-year-old construction worker falls from a height and sustains an L1 burst fracture. In the Thoracolumbar Injury Classification and Severity (TLICS) score, which of the following parameters is assigned the highest individual point value?

. Fracture morphology (burst)
. Complete neurological deficit
. Disrupted posterior ligamentous complex (PLC)
. Loss of vertebral body height > 50%
. Kyphotic angulation > 30 degrees

Correct Answer & Explanation

. Disrupted posterior ligamentous complex (PLC)

Explanation

In the TLICS scoring system, a disrupted Posterior Ligamentous Complex (PLC) is assigned 3 points. This is the highest individual score for structural integrity, pushing the total score toward a surgical indication (total score > 4).

Question 2782

Topic: Cervical Spine

An 80-year-old man sustains a Type II odontoid fracture with 6 mm of anterior displacement. He has severe medical comorbidities preventing surgery. He is treated non-operatively. Which of the following is the most significant risk factor for non-union in this patient?

. Anterior displacement
. Age > 50 years
. Use of a rigid cervical collar instead of a halo
. Concomitant C1 anterior arch fracture
. Medical comorbidities

Correct Answer & Explanation

. Age > 50 years

Explanation

Risk factors for non-union of Type II odontoid fractures include age > 50 years, initial displacement > 5 mm, and posterior displacement. Age > 50 is consistently identified in the literature as the single most significant predictor of non-union.

Question 2783

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with persistent low back pain. Radiographs reveal a Grade II isthmic spondylolisthesis at L5-S1. She has failed 6 months of conservative management including bracing and physical therapy. What is the recommended surgical intervention?

. L5 pars repair (Bucks procedure)
. L4-S1 posterolateral fusion
. L5-S1 in situ posterolateral fusion
. L5-S1 aggressive reduction and interbody fusion
. L5 laminectomy alone

Correct Answer & Explanation

. L5-S1 in situ posterolateral fusion

Explanation

For symptomatic Grade I or II isthmic spondylolisthesis that fails conservative treatment in adolescents, an in situ posterolateral fusion of L5-S1 is the gold standard. It offers excellent clinical outcomes without the high neurological risk associated with reduction.

Question 2784

Topic: 6. Spine

A 65-year-old female presents with severe myelopathy symptoms. MRI reveals Ossification of the Posterior Longitudinal Ligament (OPLL) from C3-C6 with K-line negative (kyphotic) alignment. What is the preferred surgical approach?

. Anterior cervical discectomy and fusion (ACDF)
. Cervical laminoplasty
. Cervical laminectomy alone
. Posterior laminectomy and instrumented fusion
. Combined anterior and posterior approach or anterior corpectomy

Correct Answer & Explanation

. Combined anterior and posterior approach or anterior corpectomy

Explanation

In OPLL with a negative K-line (cervical kyphosis), posterior decompression alone (laminoplasty) will not allow the spinal cord to drift backward away from the OPLL mass. A combined anterior-posterior approach or anterior corpectomy is preferred to decompress the cord and restore lordosis.

Question 2785

Topic: 6. Spine

A 55-year-old man undergoes a multilevel anterior cervical discectomy and fusion (ACDF) for severe cervical stenosis and myelopathy. Postoperatively, he wakes up with a prominent C5 motor palsy, unable to abduct his shoulder. What is the most likely etiology of this complication?

. Intraoperative spinal cord contusion
. Inadequate decompression of the C5 foramen
. Postoperative epidural hematoma
. Iatrogenic injury to the recurrent laryngeal nerve
. Tethering of the C5 nerve root due to spinal cord drift

Correct Answer & Explanation

. Tethering of the C5 nerve root due to spinal cord drift

Explanation

Postoperative C5 palsy is a well-described complication following extensive cervical spinal decompression. It is most commonly attributed to the posterior drift of the spinal cord following decompression, leading to traction and tethering of the relatively short, horizontally oriented C5 nerve roots.

Question 2786

Topic: 6. Spine

A 42-year-old woman presents with acute-onset bilateral sciatica, saddle anesthesia, and urinary retention with overflow incontinence. MRI shows a massive central disc herniation at L4-L5. Which of the following urodynamic findings is most characteristic of her bladder dysfunction?

. Detrusor hyperreflexia with normal sphincter tone
. Areflexic detrusor with loss of voluntary sphincter control
. Spastic external sphincter with detrusor-sphincter dyssynergia
. Normal detrusor function with severely decreased bladder capacity
. Increased bladder sensation with premature emptying

Correct Answer & Explanation

. Areflexic detrusor with loss of voluntary sphincter control

Explanation

Cauda equina syndrome causes a lower motor neuron lesion affecting the sacral parasympathetic nerve roots (S2-S4). This results in an areflexic (flaccid) bladder with decreased detrusor tone and absent voluntary sphincter control, leading to urinary retention and overflow incontinence.

Question 2787

Topic: 6. Spine

A 65-year-old male with long-standing ankylosing spondylitis and a completely fused lumbar spine is scheduled for a total hip arthroplasty (THA). Due to his severe spinopelvic stiffness, how should the acetabular component be positioned compared to a patient with normal spinopelvic mobility to minimize dislocation risk?

. Increased anteversion and increased inclination
. Decreased anteversion and decreased inclination
. Neutral anteversion and increased retroversion
. Decreased inclination and increased retroversion
. Standard 'safe zone' placement is equally sufficient

Correct Answer & Explanation

. Increased anteversion and increased inclination

Explanation

Patients with a stiff spine (e.g., due to ankylosing spondylitis or long spinal fusions) lack normal compensatory spinopelvic mobility. Normally, when a patient moves from standing to sitting, the pelvis tilts posteriorly, increasing acetabular anteversion and accommodating hip flexion. In a stiff spine, the pelvis does not tilt posteriorly during sitting, leading to anterior impingement and a high risk of posterior dislocation. To compensate for this lack of dynamic 'opening' of the cup, the acetabular component must be placed in relatively increased anteversion and increased inclination.

Question 2788

Topic: 6. Spine

A 65-year-old female with a history of an L2-pelvis spinal fusion is undergoing a primary total hip arthroplasty. How does her spinal fusion alter normal spinopelvic kinematics during the transition from standing to sitting?

. The pelvis excessively retroverts, decreasing functional anteversion.
. The pelvis fails to retrovert, decreasing functional anteversion and increasing the risk of posterior dislocation.
. The pelvis fails to antevert, increasing functional anteversion and increasing the risk of anterior dislocation.
. The lumbar spine hyperlordoses, compensating for pelvic stiffness.
. Normal spinopelvic kinematics are preserved because the acetabulum operates independently of the lumbar spine.

Correct Answer & Explanation

. The pelvis fails to retrovert, decreasing functional anteversion and increasing the risk of posterior dislocation.

Explanation

In a patient with a stiff or fused lumbar spine, the pelvis fails to retrovert when transitioning from standing to sitting. This lack of posterior pelvic tilt prevents the expected increase in functional acetabular anteversion, leading to anterior impingement and posterior dislocation.

Question 2789

Topic: 6. Spine

A 68-year-old female with severe rheumatoid arthritis undergoes a linked total elbow arthroplasty (TEA). At her 5-year follow-up, she complains of progressive weakness in her pinch grip and numbness in her ring and small fingers. What is the most common cause of this specific neurological presentation following TEA?

. Median nerve traction injury from dynamic splinting
. Ulnar neuropathy secondary to implant proximity or surgical manipulation
. Posterior interosseous nerve entrapment at the arcade of Frohse
. Progressive cervical radiculopathy typical of rheumatoid arthritis
. Radial nerve injury from aggressive lateral triceps reflection

Correct Answer & Explanation

. Ulnar neuropathy secondary to implant proximity or surgical manipulation

Explanation

Ulnar neuropathy is a frequently reported complication following TEA (historically up to 10-15%). It can occur due to direct surgical manipulation, excessive traction, postoperative scarring, or proximity to the hardware/cement mantle. The clinical presentation includes paresthesias in the ring and small fingers and weakness in ulnar-innervated intrinsics (affecting pinch grip and finger abduction/adduction).

Question 2790

Topic: 6. Spine
A 10-month-old girl has a spinal deformity with no apparent neurologic finding. The next step in evaluation should be to obtain:
. A genitourinary ultrasound
. An MRI scan of the spine
. An AP radiograph of the pelvis
. An electromyogram and nerve conduction velocity studies
. An echocardiogram

Correct Answer & Explanation

. A genitourinary ultrasound

Explanation

Approximately 60% of patients with a congenital spine abnormality have associated malformations outside the spinal column. Genitourinary abnormalities are common, occurring in up to 37% of patients. These are usually anatomic anomalies, such as renal agenesis, duplication, fusion, and ectopia. A genitourinary ultrasound is the least invasive screening tool.

Question 2791

Topic: 6. Spine
Steroids are thought to prevent neurologic deterioration after traumatic spinal cord injury by which of the following mechanisms?
. Inhibiting calcium influx into damaged cells
. Destabilizing lysosomal membranes in the zone of injury
. Reduces TNF-alpha expression
. Increases NF-kB binding capacity
. Maintains free radical oxidation

Correct Answer & Explanation

. Reduces TNF-alpha expression

Explanation

The proposed mechanisms by which steroids such as methylprednisolone are thought to prevent neurologic deterioration by limiting secondary insult include: decreasing the area of ischemia in the cord, reducing TNF-alpha expression and NF-kB binding activity, decreasing free radical oxidation and thus stabilizing cell and lysosomal membranes, and checking the influx of calcium into the injured cells, thus reducing cord edema.

Question 2792

Topic: 6. Spine

A 17-year-old male presents with slowly progressive, asymmetric weakness and atrophy of the right hand and forearm intrinsic muscles. Sensation is intact, and reflexes in the lower extremities are normal. Dynamic flexion MRI of the cervical spine reveals anterior displacement of the posterior dura with flattening of the lower cervical cord. What is the most appropriate initial management?

. Anterior cervical discectomy and fusion (ACDF)
. Application of a hard cervical collar
. Posterior cervical laminectomy and fusion
. Cervical laminoplasty
. Brachial plexus exploration

Correct Answer & Explanation

. Application of a hard cervical collar

Explanation

This patient has Hirayama disease (cervical flexion-induced myelopathy), a rare disorder typically affecting young males. Pathophysiology involves forward displacement of the posterior dural sac during neck flexion, leading to microtrauma and ischemia of the anterior horn cells of the lower cervical cord. First-line treatment is conservative with a hard cervical collar to prevent neck flexion. Surgery is reserved for progressive cases failing conservative management.

Question 2793

Topic: 6. Spine

An adult patient with sagittal imbalance is being planned for a spinal deformity correction. The surgeon aims to restore a harmonious profile. The patient's Pelvic Incidence (PI) is measured at 55 degrees. According to the SRS-Schwab adult spinal deformity classification, which of the following is the target Lumbar Lordosis (LL) to minimize the risk of adjacent segment disease and mechanical failure?

. 20 degrees
. 35 degrees
. 45 degrees
. 55 degrees
. 75 degrees

Correct Answer & Explanation

. 55 degrees

Explanation

The SRS-Schwab classification for adult spinal deformity emphasizes sagittal spinopelvic parameters. A key goal for sagittal realignment is to achieve a PI-LL mismatch of less than 10 degrees. Ideally, PI and LL should be roughly equal. For a PI of 55 degrees, an LL of 55 degrees provides an optimal spinopelvic balance, keeping the mismatch well within the safe threshold of +/- 9 degrees.

Question 2794

Topic: 6. Spine

A 62-year-old male undergoes a C3-C6 posterior cervical laminectomy and fusion for cervical spondylotic myelopathy. On postoperative day 2, he develops isolated profound weakness in right shoulder abduction and elbow flexion. Sensation is relatively preserved, and there is no new lower extremity deficit. What is the most likely etiology of this complication?

. Intraoperative spinal cord contusion
. C5 nerve root tethering due to posterior cord drift
. Epidural hematoma
. Incorrect placement of a C4 lateral mass screw
. Postoperative C4-C5 disc herniation

Correct Answer & Explanation

. C5 nerve root tethering due to posterior cord drift

Explanation

The patient has developed a postoperative C5 palsy, a well-known complication after cervical decompression (especially posterior laminectomy or laminoplasty). The most widely accepted mechanism is the tethering effect on the C5 nerve root due to the posterior drift of the spinal cord after decompression. The C5 root is particularly vulnerable due to its short, transverse course. Most cases recover spontaneously with physical therapy over several months.

Question 2795

Topic: 6. Spine
A 25-year-old male is involved in a high-speed motor vehicle collision. CT scan of the cervical spine reveals a traumatic spondylolisthesis of the axis with a bilateral pars interarticularis fracture. There is minimal anterior translation of C2 on C3, but severe angulation is present, and the C2-C3 disc space is widened posteriorly. According to the Levine and Edwards classification, what type of fracture is this, and what is the typical mechanism of injury?
. Type I; Hyperextension and axial loading
. Type II; Hyperextension and axial loading followed by severe flexion
. Type IIa; Flexion and distraction
. Type III; Flexion and compression
. Type III; Extension and distraction

Correct Answer & Explanation

. Type IIa; Flexion and distraction

Explanation

This is a Type IIa Hangman's fracture. According to the Levine and Edwards classification, Type IIa fractures show minimal translation but severe angulation, and the posterior C2-C3 disc space is widened. The mechanism is flexion and distraction. Notably, these fractures must not be placed in traction, as traction will exacerbate the distraction and instability. They are managed with gentle reduction in extension and compression, typically followed by a halo vest.

Question 2796

Topic: 6. Spine

During an anterior exposure of the thoracolumbar spine for corpectomy and stabilization of a burst fracture, the surgeon must be mindful of the artery of Adamkiewicz to prevent anterior spinal artery syndrome. In the majority of the population, at which vertebral levels does this artery typically enter the spinal canal?

. T4 to T7 on the right side
. T5 to T8 on the left side
. T9 to L1 on the left side
. L2 to L4 on the right side
. L3 to L5 on the left side

Correct Answer & Explanation

. T9 to L1 on the left side

Explanation

The artery of Adamkiewicz (arteria radicularis magna) is the major anterior radicular artery supplying the lower two-thirds of the spinal cord. It typically arises from a left posterior intercostal or lumbar artery between the T9 and L1 vertebral levels in approximately 75-80% of individuals. Injury to this artery during anterior thoracolumbar surgery can lead to devastating ischemia of the anterior spinal cord.

Question 2797

Topic: 6. Spine

A 60-year-old female with breast cancer presents with severe thoracic back pain exacerbated by movement. An MRI reveals a lytic metastatic lesion at T8. According to the Spinal Instability Neoplastic Score (SINS), which of the following lesion characteristics is considered the MOST unstable (scores the highest number of points) in its respective category?

. Osteolytic bone lesion
. Unilateral posterolateral element involvement
. Subluxation or translation on radiographs
. Greater than 50% vertebral body collapse
. Location in the semi-rigid thoracic spine (T3-T10)

Correct Answer & Explanation

. Subluxation or translation on radiographs

Explanation

In the Spinal Instability Neoplastic Score (SINS), radiographic alignment is a critical component. Subluxation or translation assigns the highest single score in the entire system (4 points). Comparatively, an osteolytic lesion gives 2 points, unilateral posterolateral involvement gives 1 point, >50% collapse gives 3 points, and a semi-rigid location (T3-T10) gives 1 point. A total score of 13-18 indicates frank instability warranting surgical consultation.

Question 2798

Topic: 6. Spine

A 55-year-old diabetic male presents with 2 weeks of worsening mid-back pain, fevers, and recent onset of bilateral lower extremity weakness (motor strength 3/5). MRI reveals T8-T9 discitis/osteomyelitis with a large ventral epidural abscess severely compressing the spinal cord. What is the most appropriate surgical approach for decompression and stabilization?

. Posterior laminectomy with no fusion
. Posterior laminectomy with posterior instrumentation
. Anterior corpectomy, decompression, and interbody fusion
. Percutaneous CT-guided drainage
. Bilateral transpedicular decompression

Correct Answer & Explanation

. Anterior corpectomy, decompression, and interbody fusion

Explanation

The patient has a ventral epidural abscess secondary to discitis/osteomyelitis with profound neurologic deficits, necessitating emergent surgical decompression. Because the pathology is ventral and involves destruction of the anterior load-bearing structures (disc/bone), an anterior approach (corpectomy) is required for direct decompression of the cord and debridement, followed by anterior structural support. A posterior laminectomy alone is contraindicated as it fails to address the ventral pathology and further destabilizes the spine.

Question 2799

Topic: 6. Spine

A 32-year-old male is evaluated in the emergency department after a diving accident. He is awake and alert but has bilateral upper and lower extremity weakness. Plain radiographs and CT demonstrate a bilateral C5-C6 facet dislocation. MRI reveals a large, extruded disc herniation behind the C5 vertebral body causing severe cord compression. What is the most appropriate sequence of surgical management?

. Awake closed reduction with cranial traction, followed by posterior fusion
. Posterior open reduction and fusion
. Anterior cervical discectomy and fusion (ACDF), followed by posterior reduction and fusion if needed
. Laminectomy alone for decompression
. Anterior corpectomy without fusion

Correct Answer & Explanation

. Anterior cervical discectomy and fusion (ACDF), followed by posterior reduction and fusion if needed

Explanation

In the setting of a bilateral facet dislocation with a large ventral disc herniation (a 'disc in the way'), performing closed traction reduction or a posterior open reduction first can pull the herniated disc material into the spinal canal, potentially causing permanent catastrophic neurologic injury. The safest approach is an anterior cervical discectomy to remove the herniated disc first, followed by anterior reduction and fusion.

Question 2800

Topic: 6. Spine

A 15-year-old male presents with cosmetic concerns regarding a rounded upper back and mild, intermittent ache over the thoracic spine after physical activity. Lateral radiographs reveal a thoracic kyphosis of 65 degrees. According to Sorensen's criteria, which of the following radiographic findings confirms the diagnosis of classic Scheuermann's kyphosis?

. Anterior wedging of at least 5 degrees in one vertebra
. Anterior wedging of at least 5 degrees in three or more consecutive vertebrae
. Schmorl's nodes in at least two adjacent vertebrae
. Thoracic kyphosis greater than 45 degrees with normal vertebral morphology
. Endplate irregularities in the lumbar spine

Correct Answer & Explanation

. Anterior wedging of at least 5 degrees in three or more consecutive vertebrae

Explanation

Classic Scheuermann's kyphosis is defined radiographically by the Sorensen criteria, which require anterior wedging of at least 5 degrees in three or more consecutive vertebrae. While other findings like Schmorl's nodes, endplate irregularities, and disc space narrowing are commonly associated, the consecutive anterior wedging is the sine qua non for the diagnosis.

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