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6. Spine MCQs

Practice Set 352 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 7021

Topic: 6. Spine

A 62-year-old male with long-standing ankylosing spondylitis presents to the emergency department with new-onset mechanical neck pain after a low-energy fall from a standing height. Neurological examination is unremarkable. Standard AP and lateral radiographs of the cervical spine demonstrate extensive syndesmophytes but no obvious fracture. What is the most appropriate next step in management?

. Discharge with a soft cervical collar and NSAIDs
. Flexion-extension radiographs of the cervical spine
. Immediate MRI of the cervical spine
. Corticosteroid trigger point injections
. Bone scintigraphy (bone scan) of the cervical spine

Correct Answer & Explanation

. Immediate MRI of the cervical spine

Explanation

Patients with ankylosing spondylitis are at extremely high risk for highly unstable, occult cervical spine fractures even after minor trauma. An MRI (or CT) is mandatory to rule out a fracture or epidural hematoma when radiographs are negative.

Question 7022

Topic: 6. Spine

In the evaluation of congenital scoliosis, predicting the natural history of curve progression is critical. Which of the following congenital spinal anomalies has the highest rate of spontaneous curve progression?

. Block vertebra
. Unilateral unsegmented bar
. Single fully segmented hemivertebra
. Unilateral unsegmented bar with contralateral hemivertebra
. Wedge vertebra

Correct Answer & Explanation

. Unilateral unsegmented bar with contralateral hemivertebra

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra at the same level creates a severe growth mismatch (growth on one side, none on the other). This configuration carries the highest risk of rapid curve progression.

Question 7023

Topic: 6. Spine

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy presents with a 45-degree thoracolumbar scoliosis and progressive difficulty maintaining a seated posture. Pulmonary function is declining but acceptable for surgery. What is the most appropriate surgical strategy?

. Bracing with a custom TLSO to prevent progression
. Posterior spinal fusion ending at L5
. Posterior spinal fusion extending to the pelvis
. Anterior spinal release and fusion alone
. Insertion of magnetically controlled growing rods

Correct Answer & Explanation

. Posterior spinal fusion extending to the pelvis

Explanation

In Duchenne muscular dystrophy, scoliosis is rapidly progressive and associated with severe pelvic obliquity. Standard surgical management involves posterior spinal fusion extending from the upper thoracic spine down to the pelvis to ensure sitting balance.

Question 7024

Topic: 6. Spine

A 60-year-old male with long-standing ankylosing spondylitis presents with a severe chin-on-chest deformity and a global sagittal imbalance preventing him from looking straight ahead. A lumbar pedicle subtraction osteotomy (PSO) is planned. Which vertebral level is most commonly chosen for a PSO to correct global sagittal imbalance?

. T12
. L1
. L3
. L5
. S1

Correct Answer & Explanation

. L3

Explanation

The L3 vertebra is the most common site for a pedicle subtraction osteotomy (PSO) in ankylosing spondylitis. It sits at the apex of normal lumbar lordosis, allowing for maximal correction of global sagittal imbalance and shifting the center of gravity posteriorly without injuring the spinal cord.

Question 7025

Topic: 6. Spine

A 55-year-old man with advanced ankylosing spondylitis sustains a minor ground-level fall. He complains of severe new-onset neck pain but is neurologically intact. CT scan shows a minimally displaced extension-distraction fracture through the C6-C7 disc space. What is the most appropriate management?

. Rigid cervical collar for 6 weeks
. Anterior cervical discectomy and fusion (ACDF) alone
. Long segment posterior instrumented fusion
. Short segment posterior fusion
. Halo vest immobilization

Correct Answer & Explanation

. Long segment posterior instrumented fusion

Explanation

Spine fractures in ankylosing spondylitis are highly unstable due to the rigid lever arms created by the fused spine. Long-segment posterior instrumented fusion (typically at least three levels above and below) is the gold standard to provide necessary biomechanical stability.

Question 7026

Topic: 6. Spine

A 45-year-old man with ankylosing spondylitis and fused sacroiliac joints is scheduled for a total hip arthroplasty (THA). Which of the following is a key consideration regarding acetabular cup positioning to minimize the risk of postoperative dislocation?

. The cup should be placed in less anteversion than standard
. The cup should be placed in more anteversion than standard
. The cup must be placed in maximum retroversion
. Spino-pelvic mobility is hypermobile, requiring constrained liners
. Dual mobility cups are absolutely contraindicated

Correct Answer & Explanation

. The cup should be placed in more anteversion than standard

Explanation

In ankylosing spondylitis, the stiff spine and fused SI joints cause a fixed posterior pelvic tilt that does not adapt dynamically during sitting. Surgeons must often increase acetabular cup anteversion to compensate for this lack of spino-pelvic mobility and prevent posterior dislocation.

Question 7027

Topic: 6. Spine

A patient with ankylosing spondylitis presents with a severe chin-on-chest deformity causing difficulty with forward gaze and swallowing. A cervical extension osteotomy is planned. Which anatomical level is most commonly chosen for correcting this specific deformity?

. C1-C2
. C3-C4
. C7-T1
. T4-T5
. L3-L4

Correct Answer & Explanation

. C7-T1

Explanation

The cervicothoracic junction (C7-T1) is the preferred site for a cervical extension osteotomy. The vertebral canal is relatively wide here, and the vertebral arteries typically enter the transverse foramen at C6, minimizing the risk of vascular injury during the osteotomy at C7.

Question 7028

Topic: 6. Spine

In a non-ambulatory patient with Duchenne muscular dystrophy, at what scoliotic curve magnitude is spinal fusion typically recommended to prevent severe pulmonary decline and loss of sitting balance?

. 10-15 degrees
. 20-30 degrees
. 40-50 degrees
. 70-80 degrees
. Only when the curve exceeds 90 degrees

Correct Answer & Explanation

. 20-30 degrees

Explanation

In Duchenne muscular dystrophy, scoliosis progresses rapidly once the patient becomes wheelchair-bound. Early spinal fusion is advocated (typically at 20-30 degrees) before the inevitable pulmonary compromise makes the patient an unacceptable surgical risk.

Question 7029

Topic: 6. Spine

What percentage of white patients with Ankylosing Spondylitis are positive for the HLA-B27 antigen, and what is the underlying inheritance pattern of the disease?

. 50% positive, autosomal dominant
. 75% positive, autosomal recessive
. 90-95% positive, polygenic/multifactorial
. 100% positive, X-linked
. 25% positive, polygenic/multifactorial

Correct Answer & Explanation

. 90-95% positive, polygenic/multifactorial

Explanation

Approximately 90-95% of white patients with Ankylosing Spondylitis are HLA-B27 positive. The disease does not follow a simple Mendelian inheritance pattern; rather, it is polygenic and multifactorial, with HLA-B27 acting as a major genetic susceptibility factor.

Question 7030

Topic: 6. Spine

A 55-year-old man with a 20-year history of ankylosing spondylitis sustains a low-energy fall. He complains of severe neck pain, but initial plain radiographs in the emergency department are read as negative. He subsequently develops bilateral upper extremity weakness. What is the most appropriate next step in management?

. Dynamic flexion and extension cervical radiographs
. Urgent MRI of the entire cervical spine
. Discharge with a hard cervical collar and outpatient follow-up
. CT angiogram of the neck
. Electromyography (EMG) of the upper extremities

Correct Answer & Explanation

. Urgent MRI of the entire cervical spine

Explanation

Patients with ankylosing spondylitis are highly susceptible to unstable shear fractures even with minor trauma, which can be radiographically occult. An urgent MRI is critical to evaluate for a fracture, spinal cord injury, or an epidural hematoma, which is a common complication.

Question 7031

Topic: 6. Spine

A 48-year-old man with ankylosing spondylitis presents with a severe chin-on-chest deformity and loss of forward gaze. After thorough clinical and radiographic evaluation, a pedicle subtraction osteotomy (PSO) is planned. Which anatomical level is generally considered the safest and most effective for this procedure?

. C7-T1
. T10
. L3
. L5
. S1

Correct Answer & Explanation

. L3

Explanation

A Pedicle Subtraction Osteotomy (PSO) for severe fixed sagittal imbalance in ankylosing spondylitis is typically performed at L2 or L3. This lumbar location safely maximizes lordosis correction because the spinal canal is capacious and the conus medullaris ends above this level.

Question 7032

Topic: 6. Spine

A 12-year-old non-ambulatory boy with Duchenne muscular dystrophy presents with a progressive scoliosis measuring 35 degrees. His forced vital capacity (FVC) is 45% of predicted. What is the most appropriate management regarding his spinal deformity?

. Observation until the curve reaches 50 degrees
. Custom TLSO bracing to delay surgery
. Posterior spinal fusion from the upper thoracic spine to the pelvis
. Anterior spinal tethering
. Insertion of magnetically controlled growing rods

Correct Answer & Explanation

. Posterior spinal fusion from the upper thoracic spine to the pelvis

Explanation

In non-ambulatory patients with Duchenne muscular dystrophy, scoliosis surgery (posterior spinal fusion to the pelvis) is indicated for curves greater than 20-30 degrees. Early surgery is recommended before respiratory decline (FVC < 30-35%) makes the procedure prohibitively high-risk.

Question 7033

Topic: 6. Spine

A 45-year-old man with long-standing ankylosing spondylitis presents with localized, severe back pain after a bout of coughing. Radiographs reveal a destructive discovertebral lesion at T11-T12 with surrounding sclerosis and localized kyphosis. What is the most likely diagnosis?

. Pyogenic spondylodiscitis
. Tuberculous spondylitis
. Andersson lesion
. Multiple myeloma
. Osteoid osteoma

Correct Answer & Explanation

. Andersson lesion

Explanation

An Andersson lesion is a localized non-infectious inflammatory or pseudarthrotic discovertebral lesion seen in Ankylosing Spondylitis. It usually occurs secondary to stress fractures in the rigidly ankylosed spine and often requires surgical stabilization if symptomatic and progressive.

Question 7034

Topic: 6. Spine

A 10-year-old girl with Neurofibromatosis Type 1 (NF1) presents with a 40-degree sharp, short-segment thoracic scoliosis. Radiographs demonstrate severe vertebral scalloping and penciling of three adjacent ribs on the convex side. Which of the following is the most appropriate surgical strategy?

. Posterior spinal fusion alone
. Anterior spinal fusion alone
. Combined anterior and posterior spinal fusion
. Magnetically controlled growing rods
. Vertebral Body Tethering (VBT)

Correct Answer & Explanation

. Combined anterior and posterior spinal fusion

Explanation

Dystrophic scoliosis in NF1 is characterized by short, sharp curves, rib penciling, and vertebral scalloping. It has a significantly high rate of pseudarthrosis and curve progression, thus typically requiring a combined anterior and posterior spinal fusion to ensure adequate stabilization.

Question 7035

Topic: 6. Spine

A 45-year-old man with long-standing Ankylosing Spondylitis sustains a minor fall. He complains of severe lower cervical neck pain but is neurologically intact. Initial plain radiographs of the cervical spine are reported as negative. What is the most appropriate next step in management?

. Discharge with a soft collar and oral NSAIDs
. Flexion-extension radiographs of the cervical spine
. CT scan of the entire cervical spine
. Outpatient physical therapy
. Bone scintigraphy

Correct Answer & Explanation

. CT scan of the entire cervical spine

Explanation

Patients with Ankylosing Spondylitis are at high risk for highly unstable, three-column extension-type spinal fractures even after minor trauma. CT scanning is the modality of choice because plain radiographs frequently miss cervicothoracic fractures due to altered anatomy and osteopenia.

Question 7036

Topic: 6. Spine

A 6-month-old infant with achondroplasia presents with central sleep apnea, progressive hyperreflexia, and poor head control. What is the most likely anatomic cause of this presentation?

. Atlantoaxial instability
. Foramen magnum stenosis
. Thoracolumbar kyphosis
. Lumbar pedicle shortening
. Odontoid hypoplasia

Correct Answer & Explanation

. Foramen magnum stenosis

Explanation

Infants with achondroplasia have defective endochondral bone formation, placing them at high risk for foramen magnum stenosis. This can cause cervicomedullary compression leading to central sleep apnea, quadriparesis, and sudden death, requiring prompt neurosurgical decompression.

Question 7037

Topic: 6. Spine

A 14-year-old non-ambulatory male with spastic quadriplegic cerebral palsy presents with a 75-degree thoracolumbar scoliosis and significant pelvic obliquity. What is the most critical biomechanical objective when planning posterior surgical stabilization?

. Selective thoracic fusion to preserve lumbar motion
. Anterior spinal fusion alone to arrest growth
. Posterior spinal fusion stopping at L5 to maintain hip flexion
. Posterior spinal fusion with instrumentation extending to the pelvis
. Hemiepiphysiodesis on the convex side

Correct Answer & Explanation

. Posterior spinal fusion with instrumentation extending to the pelvis

Explanation

In non-ambulatory patients with severe neuromuscular scoliosis and pelvic obliquity, spinal fusion must typically extend to the pelvis (e.g., using iliac or S2AI screws) to provide a level and stable foundation for sitting. Stopping short of the pelvis often leads to recurrent obliquity and poor seating balance.

Question 7038

Topic: 6. Spine

A 55-year-old man with ankylosing spondylitis presents with a severe chin-on-chest deformity. Preoperative planning for a single-level lumbar pedicle subtraction osteotomy (PSO) is performed. Which of the following best describes the expected sagittal correction from a single-level lumbar PSO?

. 5 to 10 degrees
. 10 to 15 degrees
. 30 to 40 degrees
. 50 to 60 degrees
. Greater than 70 degrees

Correct Answer & Explanation

. 30 to 40 degrees

Explanation

A pedicle subtraction osteotomy (PSO) is a closing-wedge, three-column osteotomy hinged at the anterior longitudinal ligament. It reliably provides approximately 30 to 40 degrees of sagittal plane correction at a single surgical level.

Question 7039

Topic: 6. Spine

A 65-year-old male with long-standing ankylosing spondylitis presents after a low-energy fall with severe neck pain. CT reveals a highly displaced, unstable extension-type fracture through the C6-C7 disc space. Neurological exam is intact. What is the most appropriate definitive management?

. Rigid cervical collar for 12 weeks
. Halo vest immobilization
. Anterior cervical discectomy and fusion (ACDF) only
. Posterior cervical fusion only
. Combined anterior and posterior cervical fusion

Correct Answer & Explanation

. Combined anterior and posterior cervical fusion

Explanation

Fractures in ankylosing spondylitis are highly unstable due to the rigid lever arms of the fused spine. Combined anterior and posterior instrumentation is generally recommended to provide rigid fixation and prevent pseudoarthrosis.

Question 7040

Topic: 6. Spine

Which type of congenital vertebral anomaly carries the highest risk for rapid, relentless scoliosis progression during skeletal growth?

. Block vertebra
. Hemivertebra
. Unilateral unsegmented bar
. Unilateral unsegmented bar with a contralateral hemivertebra
. Butterfly vertebra

Correct Answer & Explanation

. Unilateral unsegmented bar with a contralateral hemivertebra

Explanation

A unilateral unsegmented bar with a contralateral hemivertebra results in severe, relentless progression due to highly asymmetric growth. This configuration typically requires early surgical intervention.

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