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6. Spine MCQs

Practice Set 350 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 6981

Topic: Thoracolumbar Spine & Deformity
A 14-year-old elite gymnast presents with mechanical lower back pain. Radiographs reveal a pars interarticularis defect at L5 with a 25% anterior translation of L5 on S1. According to the Wiltse classification, what specific type of spondylolisthesis is this?
. Dysplastic (Type I)
. Isthmic (Type II)
. Degenerative (Type III)
. Traumatic (Type IV)
. Pathologic (Type V)

Correct Answer & Explanation

. Isthmic (Type II)

Explanation

Isthmic spondylolisthesis (Wiltse Type II) is caused by a structural defect, elongation, or acute fracture of the pars interarticularis (spondylolysis). It is the most common cause of spondylolisthesis in adolescent athletes who perform repetitive spinal extension.

Question 6982

Topic: 6. Spine

A 25-year-old male sustains a traumatic spondylolisthesis of the axis (Hangman's fracture) following an MVA. Imaging shows a pars interarticularis fracture with severe angulation and 6mm translation of C2 on C3, but normal C2-C3 facets. According to the Levine and Edwards classification, what is the most appropriate management?

. Hard cervical collar for 6 weeks
. Halo vest immobilization with cervical traction in extension
. Open reduction and internal fixation of C2-C3
. Halo vest immobilization following initial gentle reduction with slight compression and extension
. C1-C2 posterior fusion

Correct Answer & Explanation

. Halo vest immobilization following initial gentle reduction with slight compression and extension

Explanation

This is a Type II Hangman's fracture (translation >3mm and angulation). Treatment involves initial gentle reduction with slight compression and extension followed by Halo vest immobilization; traction is contraindicated as it may over-distract and exacerbate the injury.

Question 6983

Topic: Thoracolumbar Spine & Deformity

A 22-year-old restrained passenger is involved in a high-speed motor vehicle collision. Radiographs and CT of the lumbar spine reveal a flexion-distraction injury (Chance fracture) at L2. Which of the following associated injuries must be most highly suspected and ruled out?

. Aortic transection
. Diaphragmatic rupture
. Hollow viscus intra-abdominal injury
. Renal artery thrombosis
. Bladder rupture

Correct Answer & Explanation

. Hollow viscus intra-abdominal injury

Explanation

Chance fractures are high-energy flexion-distraction injuries commonly associated with seatbelt use. They carry a high rate (up to 40-50%) of associated intra-abdominal injuries, particularly to hollow viscous organs like the bowel.

Question 6984

Topic: 6. Spine

In a patient with severe, long-standing rheumatoid arthritis, which of the following radiographic measurements is the most reliable predictor of impending neurologic deficit due to cervical spine instability?

. Anterior atlantodens interval (ADI) > 3 mm
. Anterior atlantodens interval (ADI) > 9 mm
. Posterior atlantodens interval (PADI) < 14 mm
. Ranawat value < 13 mm
. Subaxial subluxation > 3 mm

Correct Answer & Explanation

. Posterior atlantodens interval (PADI) < 14 mm

Explanation

The posterior atlantodens interval (PADI), also known as the space available for the cord (SAC), is the most reliable predictor of neurologic deficit in RA cervical instability. A PADI of <14 mm is a critical threshold indicating impending neurologic compromise.

Question 6985

Topic: 6. Spine

A 55-year-old man with advanced ankylosing spondylitis sustains a low-energy fall. He complains of severe neck pain but is neurologically intact. Initial plain radiographs of the cervical spine are read as 'negative.' What is the most appropriate next step in management?

. Discharge with a soft cervical collar
. Flexion-extension cervical radiographs
. CT scan of the entire cervical spine
. Reassurance and NSAIDs
. Dynamic fluoroscopy

Correct Answer & Explanation

. CT scan of the entire cervical spine

Explanation

Patients with ankylosing spondylitis are at high risk for highly unstable spinal fractures even from minor trauma. Because osteopenia and altered anatomy make plain radiographs unreliable, a CT scan of the cervical spine is mandatory to rule out an occult fracture.

Question 6986

Topic: 6. Spine

A severely malnourished 8-year-old boy presents with bleeding gums, petechiae, and bone pain. Radiographs reveal a dense zone of provisional calcification (Frankel line) and a thin sclerotic cortex surrounding the epiphysis (Wimberger ring sign). The underlying pathophysiology of his bone disease is a defect in:

. Cleavage of type I procollagen
. Hydroxylation of proline and lysine residues
. Cross-linking of collagen via lysyl oxidase
. Mineralization of osteoid matrix
. Endochondral ossification at the physis

Correct Answer & Explanation

. Hydroxylation of proline and lysine residues

Explanation

Scurvy is caused by Vitamin C deficiency. Vitamin C is an essential cofactor for prolyl hydroxylase and lysyl hydroxylase. Defective hydroxylation of proline and lysine leads to unstable triple helices and impaired collagen synthesis.

Question 6987

Topic: 6. Spine

A 9-year-old boy presents with joint pain, perifollicular hemorrhages, and bleeding gums. Radiographs reveal a prominent zone of provisional calcification (white line of Frankel). The disease process affecting this child is primarily due to a deficiency in a cofactor required for which of the following biochemical processes?

. Cleavage of procollagen to tropocollagen
. Carboxylation of glutamic acid residues
. Hydroxylation of proline and lysine residues
. Glycosylation of hydroxylysine residues
. Assembly of the collagen triple helix

Correct Answer & Explanation

. Hydroxylation of proline and lysine residues

Explanation

The patient has scurvy (Vitamin C deficiency). Vitamin C acts as an essential cofactor for prolyl hydroxylase and lysyl hydroxylase, which are responsible for the hydroxylation of proline and lysine during collagen synthesis.

Question 6988

Topic: 6. Spine

A 45-year-old male presents with acute onset of severe low back pain, bilateral lower extremity radicular pain, saddle anesthesia, and urinary retention. MRI reveals a massive L4-L5 disc herniation. Which of the following is the most sensitive early clinical sign or symptom of cauda equina syndrome?

. Fecal incontinence
. Decreased anal sphincter tone
. Urinary retention
. Loss of Achilles reflex
. Saddle anesthesia

Correct Answer & Explanation

. Urinary retention

Explanation

Urinary retention is the most sensitive symptom for Cauda Equina Syndrome (CES), occurring in up to 90% of patients. Post-void residual (PVR) volumes > 100-200 mL are highly suggestive. While saddle anesthesia and decreased anal sphincter tone are classic, urinary retention typically manifests earlier and is the most sensitive marker.

Question 6989

Topic: 6. Spine

In a patient presenting with severe low back pain and bilateral radiculopathy, which of the following clinical findings is the most sensitive indicator of impending or established cauda equina syndrome?

. Bilateral absence of the Achilles reflex
. Saddle anesthesia
. Loss of anal sphincter tone
. Urinary retention
. Bilateral foot drop

Correct Answer & Explanation

. Urinary retention

Explanation

Urinary retention is the most sensitive sign of cauda equina syndrome, typically assessed via post-void residual volume. If post-void residual is functionally normal, cauda equina syndrome is highly unlikely.

Question 6990

Topic: 6. Spine

In a patient presenting with suspected Cauda Equina Syndrome secondary to a massive lumbar disc herniation, which of the following initial clinical symptoms is considered the most sensitive indicator of the condition?

. Unilateral sciatica
. Urinary retention
. Saddle anesthesia
. Lower extremity weakness
. Fecal incontinence

Correct Answer & Explanation

. Urinary retention

Explanation

Urinary retention is the most sensitive symptom of cauda equina syndrome, often occurring early in the disease process. A post-void residual volume greater than 100-200 mL is highly suggestive of the diagnosis.

Question 6991

Topic: 6. Spine

Which of the following clinical findings is considered the most reliable early indicator of cauda equina syndrome?

. Bilateral foot drop
. Loss of Achilles reflexes
. Urinary retention and saddle anesthesia
. Severe axial low back pain
. Unilateral radicular leg pain

Correct Answer & Explanation

. Urinary retention and saddle anesthesia

Explanation

Urinary retention leading to overflow incontinence, along with saddle anesthesia, are the hallmark early and highly sensitive clinical indicators of cauda equina syndrome. Motor deficits like foot drop generally present much later in the disease course.

Question 6992

Topic: 6. Spine

Review the AP and lateral radiographs of the lumbar spine in this patient with short-limb dwarfism. Which of the following is the characteristic radiographic finding shown?



. Interpediculate distance increases from L1 to L5
. Interpediculate distance decreases from the upper to lower lumbar spine
. Anterior beaking of the lumbar vertebrae
. Severe atlantoaxial instability with cord compression
. Platyspondyly with central anterior wedging

Correct Answer & Explanation

. Interpediculate distance decreases from the upper to lower lumbar spine

Explanation

Correct Answer: Interpediculate distance decreases from the upper to lower lumbar spineThe provided radiograph demonstrates the classic spinal findings in achondroplasia. The interpediculate distance abnormally decreases from the upper to the lower lumbar spine (AP view), and characteristic short pedicles are seen on the lateral view, which predisposes these patients to spinal stenosis.

Question 6993

Topic: 6. Spine

A 5-year-old boy with short stature presents for evaluation. An AP and lateral radiograph of the lumbar spine is shown below. What is the characteristic radiographic finding demonstrated in this condition?


. Increase in interpediculate distance from L1 to L5
. Decrease in interpediculate distance from upper to lower lumbar spine
. Anterior beaking of the lumbar vertebrae
. Coronal clefts in the vertebral bodies
. Atlantoaxial instability with odontoid hypoplasia

Correct Answer & Explanation

. Decrease in interpediculate distance from upper to lower lumbar spine

Explanation

Correct Answer: Decrease in interpediculate distance from upper to lower lumbar spineIn achondroplasia, a hallmark radiographic finding is the narrowing of the interpediculate distance from the upper to the lower lumbar spine, which is the opposite of the normal widening seen in unaffected individuals. Short pedicles are also characteristically seen on the lateral view.

Question 6994

Topic: 6. Spine

A 12-year-old boy with disproportionate short stature presents with back pain. The AP and lateral radiographs of the lumbar spine are shown below. Which of the following is the characteristic radiographic finding demonstrated in this condition?


. Increasing interpediculate distance from L1 to L5
. Decreasing interpediculate distance from L1 to L5
. Anterior beaking of the vertebral bodies
. Platyspondyly with coronal clefts

Correct Answer & Explanation

. Decreasing interpediculate distance from L1 to L5

Explanation

Correct Answer: Decreasing interpediculate distance from L1 to L5In achondroplasia, the interpediculate distance characteristically decreases from the upper to the lower lumbar spine, which is the opposite of the normal spine where it widens. This, combined with short pedicles seen on the lateral view, contributes to the high risk of spinal stenosis in these patients.

Question 6995

Topic: 6. Spine

A 45-year-old male with achondroplasia presents with neurogenic claudication. Radiographic evaluation of his lumbar spine is performed. Which of the following anatomical abnormalities of the vertebrae is most responsible for his spinal stenosis?

. Elongated pars interarticularis
. Congenital block vertebrae
. Characteristic short pedicles
. Hypertrophy of the anterior longitudinal ligament

Correct Answer & Explanation

. Characteristic short pedicles

Explanation

Correct Answer: Characteristic short pediclesSpinal stenosis is a hallmark complication of achondroplasia in adulthood. It is primarily driven by the characteristic short pedicles (seen on lateral radiographs) and the decreasing interpediculate distance in the lumbar spine, which severely narrows the spinal canal.

Question 6996

Topic: 6. Spine

A 5-year-old boy with disproportionate short stature presents for evaluation. The AP and lateral radiographs of the lumbar spine are shown below. Which of the following best describes the classic radiographic finding seen in the AP view of this condition?


. The interpedicular distance increases from L1 to L5.
. There is prominent anterior beaking of the lumbar vertebrae.
. The interpedicular distance decreases from L1 to L5.
. There is severe platyspondyly with a central anterior tongue.

Correct Answer & Explanation

. The interpedicular distance decreases from L1 to L5.

Explanation

Correct Answer: The interpedicular distance decreases from L1 to L5.In achondroplasia, a hallmark radiographic finding on the AP view of the spine is the narrowing of the interpedicular distance from the upper to the lower lumbar spine (L1 to L5). In a normal spine, this distance widens caudally. Anterior beaking is more characteristic of mucopolysaccharidoses (like Morquio or Hurler syndrome), and severe platyspondyly is seen in conditions like thanatophoric dysplasia or spondyloepiphyseal dysplasia.

Question 6997

Topic: 6. Spine

Review the lateral lumbar spine radiograph of the patient shown below. The characteristic anatomical abnormality seen on this view directly predisposes the patient to which of the following clinical conditions in adulthood?


. Lumbar spinal stenosis.
. Spondylolysis and isthmic spondylolisthesis.
. Severe structural thoracic scoliosis.
. Atlantoaxial rotatory subluxation.

Correct Answer & Explanation

. Lumbar spinal stenosis.

Explanation

Correct Answer: Lumbar spinal stenosis.The lateral radiograph demonstrates characteristically short pedicles. Combined with the decreased interpedicular distance seen on the AP view, these short pedicles result in a congenitally narrow spinal canal. In adulthood, even mild degenerative changes (such as disc bulging or facet hypertrophy) can precipitate severe symptomatic lumbar spinal stenosis, which is a hallmark complication of achondroplasia.

Question 6998

Topic: 6. Spine

A 5-year-old boy with disproportionate short stature presents for evaluation. An anteroposterior and lateral radiograph of the lumbar spine is obtained, as shown below. Which of the following is the hallmark radiographic finding in the lumbar spine for this condition?


. Interpediculate distance increases from L1 to L5
. Interpediculate distance decreases from upper to lower lumbar spine
. Anterior beaking of the lumbar vertebrae
. Platyspondyly with coronal clefts

Correct Answer & Explanation

. Interpediculate distance decreases from upper to lower lumbar spine

Explanation

Correct Answer: Interpediculate distance decreases from upper to lower lumbar spineIn achondroplasia, a classic radiographic feature is that the interpediculate distance decreases from the upper to the lower lumbar spine, which is the opposite of the normal spine. Additionally, characteristic short pedicles are seen on the lateral view, contributing to spinal stenosis.

Question 6999

Topic: 6. Spine

While evaluating an infant with achondroplasia, the orthopedic surgeon must be vigilant about potential life-threatening complications. Which of the following conditions significantly increases the risk of death during infancy in these patients?

. Severe restrictive lung disease from a small thoracic cage
. Cervical spine instability due to odontoid hypoplasia
. Upper airway obstruction and spinal cord compression
. Congenital cardiac septal defects

Correct Answer & Explanation

. Upper airway obstruction and spinal cord compression

Explanation

Correct Answer: Upper airway obstruction and spinal cord compressionAccording to the clinical text, compression of the spinal cord (often at the foramen magnum) and upper airway obstruction are the primary factors that increase the risk of death in infancy for patients with achondroplasia.

Question 7000

Topic: 6. Spine

A 2-year-old child with achondroplasia is noted to have a persistent thoracolumbar kyphosis measuring 35 degrees. Which of the following is the most appropriate next step in management?

. Immediate posterior spinal fusion
. Anterior spinal release and fusion
. Prescribe a custom thoracolumbosacral orthosis (TLSO)
. Observation and parental reassurance until age 5
. Surgical decompression of the spinal canal

Correct Answer & Explanation

. Prescribe a custom thoracolumbosacral orthosis (TLSO)

Explanation

Most thoracolumbar kyphosis in achondroplasia resolves once the child begins walking and develops lumbar lordosis. However, if the kyphosis persists beyond the walking stage or exceeds 30 degrees, bracing with a custom TLSO is indicated to prevent rigid deformity.

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