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6. Spine MCQs

Practice Set 39 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 761

Topic: 6. Spine

A 42-year-old female presents with acute onset of low back pain radiating down the posterior thigh, lateral calf, and dorsum of the foot. Physical examination reveals weakness in extensor hallucis longus (EHL) and decreased sensation over the dorsal first web space. Which disc herniation is most likely responsible?

. L3-L4 paracentral herniation
. L4-L5 paracentral herniation
. L4-L5 far lateral herniation
. L5-S1 paracentral herniation
. L5-S1 far lateral herniation

Correct Answer & Explanation

. L4-L5 paracentral herniation

Explanation

Weakness in the EHL and numbness in the first dorsal web space indicate an L5 radiculopathy. A paracentral disc herniation at L4-L5 compresses the traversing L5 nerve root.

Question 762

Topic: Thoracolumbar Spine & Deformity
When evaluating a patient with spondylolisthesis, the Meyerding classification is commonly used to grade the severity of the slip. A Meyerding Grade III slip corresponds to what percentage of anterior translation of the superior vertebral body over the inferior one?
. 1-25%
. 26-50%
. 51-75%
. 76-100%
. Complete ptosis (>100%)

Correct Answer & Explanation

. 51-75%

Explanation

The Meyerding classification grades spondylolisthesis based on the percentage of slip: Grade I (1-25%), Grade II (26-50%), Grade III (51-75%), Grade IV (76-100%), and Grade V (>100%, spondyloptosis).

Question 763

Topic: Thoracolumbar Spine & Deformity

What is the primary anatomical defect responsible for the development of an isthmic spondylolisthesis?

. Congenital dysplasia of the sacral facets
. Degenerative hypertrophy of the ligamentum flavum
. A defect or stress fracture in the pars interarticularis
. Elongation of the vertebral pedicles
. A defect in the anterior longitudinal ligament

Correct Answer & Explanation

. A defect or stress fracture in the pars interarticularis

Explanation

Isthmic spondylolisthesis (Type II) is characterized by a defect or stress fracture in the pars interarticularis. This allows the anterior column to slip forward while the posterior elements remain behind.

Question 764

Topic: Thoracolumbar Spine & Deformity



On oblique lumbar radiographs, the posterior elements resemble a "Scotty dog". In the context of isthmic spondylolisthesis, a defect is often seen as a "collar" around the dog's neck. Which anatomical structure corresponds to the neck of the Scotty dog?

. Pedicle
. Superior articular process
. Pars interarticularis
. Transverse process
. Inferior articular process

Correct Answer & Explanation

. Pars interarticularis

Explanation

On an oblique lumbar radiograph, the "neck" of the Scotty dog represents the pars interarticularis. A radiolucent line or "collar" indicates a pars defect (spondylolysis).

Question 765

Topic: 6. Spine

A 35-year-old male presents to the emergency department with severe acute low back pain and bilateral leg weakness. Which of the following is the most sensitive clinical finding for the early diagnosis of cauda equina syndrome?

. Patellar hyperreflexia
. Urinary retention
. Fecal incontinence
. Bilateral foot drop
. Saddle anesthesia

Correct Answer & Explanation

. Urinary retention

Explanation

Urinary retention is the most sensitive sign for cauda equina syndrome. A normal post-void residual bladder volume effectively rules out the condition in most cases.

Question 766

Topic: 6. Spine

A 50-year-old male is diagnosed with a far lateral (extraforaminal) disc herniation at the L4-L5 level. Which nerve root is most likely to be directly compressed by this specific herniation?

. L3
. L4
. L5
. S1
. S2

Correct Answer & Explanation

. L4

Explanation

Far lateral or extraforaminal disc herniations compress the exiting nerve root at the same level. Therefore, an L4-L5 far lateral disc herniation compresses the exiting L4 nerve root.

Question 767

Topic: 6. Spine



In a patient presenting with central lumbar spinal stenosis, which ligament undergoes characteristic hypertrophy and buckling, contributing significantly to dorsal compression of the thecal sac?

. Anterior longitudinal ligament
. Posterior longitudinal ligament
. Ligamentum flavum
. Interspinous ligament
. Supraspinous ligament

Correct Answer & Explanation

. Ligamentum flavum

Explanation

The ligamentum flavum thickens and buckles inward as the disc space narrows with degeneration. This is a primary cause of dorsal compression in central lumbar spinal stenosis.

Question 768

Topic: 6. Spine

De novo degenerative lumbar scoliosis typically presents in older adults without a prior history of spinal curvature. What is the primary driving mechanism behind the development of this deformity?

. Congenital failure of vertebral formation
. Asymmetric disc degeneration and facet arthropathy
. Neuromuscular imbalance from an underlying myopathy
. Significant leg length discrepancy
. Vertebral osteomyelitis and discitis

Correct Answer & Explanation

. Asymmetric disc degeneration and facet arthropathy

Explanation

Degenerative lumbar scoliosis is caused by asymmetric degeneration of the intervertebral discs and facet joints. This leads to progressive instability and a scoliotic curve, most commonly in the lumbar spine.

Question 769

Topic: 6. Spine



A 65-year-old female presents with chronic lower back pain and neurogenic claudication. Radiographs demonstrate degenerative spondylolisthesis. Which vertebral level and direction of slip is most statistically common in this condition?

. L3 slipping anteriorly on L4
. L4 slipping anteriorly on L5
. L5 slipping anteriorly on S1
. L4 slipping posteriorly on L5
. L5 slipping posteriorly on S1

Correct Answer & Explanation

. L4 slipping anteriorly on L5

Explanation

Degenerative spondylolisthesis occurs most frequently at the L4-L5 level, with L4 translating anteriorly over L5. It is up to four times more common in females than males.

Question 770

Topic: 6. Spine

Waddell's signs are utilized during a physical examination to identify non-organic (psychological or behavioral) causes of back pain. Which of the following is NOT considered a positive Waddell's sign?

. Superficial or widespread non-anatomic tenderness
. Pain elicited with simulated axial downward loading on the skull
. Regional weakness or sensory loss conforming strictly to a distinct dermatome
. Pain elicited with simulated en bloc spinal rotation
. Overreaction or exaggerated pain response during the examination

Correct Answer & Explanation

. Regional weakness or sensory loss conforming strictly to a distinct dermatome

Explanation

Waddell's signs test for non-organic pain. True dermatomal sensory loss or myotomal weakness indicates a genuine organic neurological deficit, not a Waddell's sign.

Question 771

Topic: 6. Spine

A 45-year-old male with persistent, severe lower back pain and L5 radiculopathy has a Grade II isthmic spondylolisthesis at L5-S1. He has failed extensive conservative management. What is the most appropriate surgical intervention?

. L5 microdiscectomy alone
. L5 wide laminectomy alone
. Direct repair of the pars interarticularis defect
. L5-S1 decompression and instrumented posterolateral fusion
. Total lumbar disc arthroplasty at L5-S1

Correct Answer & Explanation

. L5-S1 decompression and instrumented posterolateral fusion

Explanation

In adult patients with symptomatic Grade II isthmic spondylolisthesis and radiculopathy failing conservative care, the standard treatment is decompression of the nerve roots combined with instrumented fusion to stabilize the slipped segment. Pars repair is generally reserved for young patients without a significant slip.

Question 772

Topic: 6. Spine

A 60-year-old male with a 30-year history of ankylosing spondylitis presents to the emergency room with new-onset mechanical back pain after a minor fall from standing height. Neurological exam is normal. What is the most critical suspected diagnosis that must be ruled out?

. Muscular strain of the erector spinae
. Acute lumbar disc herniation
. Transdiscal or transvertebral spine fracture
. Facet joint dislocation
. Rupture of the ligamentum flavum

Correct Answer & Explanation

. Transdiscal or transvertebral spine fracture

Explanation

Patients with ankylosing spondylitis have rigid, osteopenic spines that act like long bones. Even minor trauma can cause highly unstable transdiscal or transvertebral "chalk stick" fractures, which carry a high risk of neurologic injury.

Question 773

Topic: 6. Spine

An anteroposterior (AP) radiograph of the lumbar spine reveals the "winking owl" sign in a patient with a known history of breast cancer. This radiographic sign indicates the lytic destruction of which specific anatomical structure?

. Vertebral body
. Pars interarticularis
. Pedicle
. Spinous process
. Transverse process

Correct Answer & Explanation

. Pedicle

Explanation

The "winking owl" sign is the absence of a pedicle on an AP spinal radiograph, classically seen in metastatic bone disease or multiple myeloma due to lytic destruction of the pedicle.

Question 774

Topic: 6. Spine

A 65-year-old male presents with bilateral leg pain exacerbated by walking and relieved by sitting or leaning forward over a shopping cart. Examination reveals normal peripheral pulses. Which imaging study is the gold standard for confirming the primary diagnosis in a patient without surgical hardware?

. Lumbar spine radiographs
. MRI of the lumbar spine
. CT myelogram
. Doppler ultrasound of the lower extremities
. Electromyography (EMG)

Correct Answer & Explanation

. MRI of the lumbar spine

Explanation

MRI of the lumbar spine is the gold standard and most appropriate non-invasive confirmatory study for lumbar spinal stenosis. It excellently visualizes soft tissue structures causing compression, such as the ligamentum flavum and disc bulging.

Question 775

Topic: 6. Spine

A 42-year-old female presents to the emergency department with acute onset of severe low back pain, bilateral sciatica, and perineal numbness. Her post-void residual bladder volume is 400 mL. What is the next most appropriate step in management?

. Urgent MRI of the lumbar spine followed by surgical decompression
. Oral corticosteroids and physical therapy
. Epidural steroid injection
. Outpatient lumbar MRI
. Urodynamic testing

Correct Answer & Explanation

. Urgent MRI of the lumbar spine followed by surgical decompression

Explanation

This patient presents with classic red flag signs of cauda equina syndrome, including saddle anesthesia and urinary retention (PVR >100-200 mL). It is a surgical emergency requiring urgent MRI and subsequent rapid surgical decompression.

Question 776

Topic: Thoracolumbar Spine & Deformity
According to the Wiltse classification of spondylolisthesis, a slip that occurs secondary to an elongation of the pars interarticularis without a frank defect is classified as which type?
. Type I (Dysplastic)
. Type II (Isthmic)
. Type III (Degenerative)
. Type IV (Traumatic)
. Type V (Pathologic)

Correct Answer & Explanation

. Type II (Isthmic)

Explanation

Elongation of the pars interarticularis without a frank defect is classified as a Wiltse Type IIb (Isthmic) spondylolisthesis. Type II is divided into lytic (IIa), elongated (IIb), and acute fracture (IIc).

Question 777

Topic: 6. Spine

A 60-year-old female presents with neurogenic claudication. Sagittal T2-weighted MRI demonstrates central canal stenosis at L4-L5.

Which posterior spinal element predictably undergoes hypertrophy and buckling, contributing significantly to this central canal stenosis?

. Anterior longitudinal ligament
. Posterior longitudinal ligament
. Ligamentum flavum
. Interspinous ligament
. Supraspinous ligament

Correct Answer & Explanation

. Ligamentum flavum

Explanation

In degenerative lumbar spinal stenosis, the ligamentum flavum typically undergoes hypertrophy and buckles into the spinal canal as disc space height is lost. This is a primary soft-tissue contributor to posterior thecal sac compression.

Question 778

Topic: 6. Spine

A 65-year-old woman presents with lower back and leg pain. Imaging shows an L4-L5 anterior translation with an intact pars interarticularis.

Which of the following structural characteristics most directly predisposes this specific spinal level to degenerative spondylolisthesis?

. Naturally narrower spinal canal
. Sagittal orientation of the facet joints
. Elongation of the pars interarticularis
. Hypertrophy of the anterior longitudinal ligament
. Absence of the iliolumbar ligament

Correct Answer & Explanation

. Sagittal orientation of the facet joints

Explanation

Degenerative spondylolisthesis most commonly occurs at the L4-L5 level. This is primarily because the facet joints at this level are oriented more sagittally, conferring less resistance to anterior shear forces.

Question 779

Topic: 6. Spine

A 40-year-old male presents with chronic stiffness and back pain. Radiographs reveal bridging syndesmophytes and bilateral fusion of the sacroiliac joints.

This classic "bamboo spine" radiographic appearance is most highly correlated with which human leukocyte antigen (HLA)?

. HLA-DR4
. HLA-B27
. HLA-B8
. HLA-DR2
. HLA-DR3

Correct Answer & Explanation

. HLA-B27

Explanation

Ankylosing spondylitis presents radiographically with syndesmophytes leading to a bamboo spine appearance. It is a seronegative spondyloarthropathy with a strong genetic association with HLA-B27.

Question 780

Topic: 6. Spine

A 60-year-old diabetic patient presents with unrelenting back pain and fever. Blood tests show an elevated CRP and ESR. MRI of the lumbar spine is obtained. Which of the following MRI findings is most characteristic of pyogenic spondylodiscitis as opposed to a neoplastic process?

. Sparing of the intervertebral disc
. T2 hyperintensity within the intervertebral disc with adjacent endplate destruction
. Pedicle destruction with intact endplates
. Contiguous spread involving only the posterior elements
. T1 hyperintensity in the vertebral body

Correct Answer & Explanation

. T2 hyperintensity within the intervertebral disc with adjacent endplate destruction

Explanation

Pyogenic spondylodiscitis typically crosses the disc space, destroying adjacent endplates and causing T2 hyperintensity in the disc. Neoplastic processes generally involve the vertebral body and pedicles while initially sparing the avascular disc.

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