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6. Spine MCQs

Practice Set 317 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 6321

Topic: 6. Spine

A 72-year-old male with long-standing ankylosing spondylitis is evaluated for a primary total hip arthroplasty due to severe osteoarthritis. He has a stiff lumbopelvic junction. Standing and sitting lateral radiographs demonstrate less than 10 degrees of change in his pelvic tilt. How should the acetabular component be positioned compared to a patient with normal, flexible spinopelvic mobility?

. Target a higher degree of anteversion and inclination regardless of spinal deformity
. Target normal Lewinnek safe zone parameters (15 deg anteversion, 40 deg inclination)
. Position the cup with more anteversion to prevent anterior dislocation when standing
. Position the cup with less anteversion and less inclination if the pelvis is fixed in posterior tilt (flatback deformity)
. Position the cup matching only the patient's sitting pelvic tilt

Correct Answer & Explanation

. Target a higher degree of anteversion and inclination regardless of spinal deformity

Explanation

In a patient with a stiff spine, the pelvis does not dynamically rotate between standing and sitting. If the spine is fused in kyphosis (flatback), the pelvis is chronically retroverted, resulting in relative functional anteversion of the acetabulum. To prevent anterior dislocation in extension, the cup should be placed with less anteversion and less inclination to compensate for the fixed deformity. The surgeon must match the component to the fixed functional position.

Question 6322

Topic: 6. Spine

A patient with a surgically fused lumbar spine in hyperlordosis (fixed anterior pelvic tilt) is undergoing a primary THA. Compared to a patient with normal spinopelvic mobility, what is the primary instability risk and appropriate acetabular cup adjustment for this patient?

. Posterior dislocation during sitting; decrease cup anteversion
. Anterior dislocation during standing; increase cup anteversion
. Posterior dislocation during sitting; increase cup anteversion
. Anterior dislocation during standing; decrease cup inclination
. Superior dislocation during walking; increase cup inclination

Correct Answer & Explanation

. Posterior dislocation during sitting; decrease cup anteversion

Explanation

A fused spine in hyperlordosis results in a fixed anterior pelvic tilt, preventing normal posterior pelvic tilt during sitting. This decreases functional acetabular anteversion, heavily increasing the risk of posterior dislocation, which must be mitigated by increasing the component's anteversion.

Question 6323

Topic: 6. Spine

A 72-year-old female is scheduled for a primary THA. She has a history of a multi-level lumbar spinal fusion (L2-S1). Preoperative lateral pelvic radiographs demonstrate a sacral slope of 35 degrees standing and 33 degrees sitting. Recognizing this spinopelvic pathology, how should the surgeon adjust the target acetabular cup positioning to minimize the risk of posterior dislocation?

. Target standard 15 degrees anteversion and 40 degrees inclination
. Increase cup anteversion and increase cup inclination
. Decrease cup anteversion and increase cup inclination
. Increase cup retroversion and decrease cup inclination
. Place the cup in relative retroversion to prevent anterior impingement

Correct Answer & Explanation

. Target standard 15 degrees anteversion and 40 degrees inclination

Explanation

The patient has a stiff spinopelvic construct (change in sacral slope from standing to sitting is <10 degrees). In a normal spine, sitting causes posterior pelvic tilt, which functionally increases acetabular anteversion, protecting against posterior dislocation during hip flexion. A stiff spine fails to tilt posteriorly when sitting, leaving the cup relatively retroverted and risking anterior bony impingement with subsequent posterior dislocation. Therefore, the surgeon must compensate by increasing the target cup anteversion and inclination.

Question 6324

Topic: 6. Spine

A 65-year-old female is undergoing total hip arthroplasty. Preoperative standing and sitting lateral spine radiographs demonstrate that her sacral slope decreases by 5 degrees when moving from standing to sitting. She has no history of spinal fusion. This condition is best described as:

. Normal spinopelvic mobility
. Stiff spine (spinopelvic stiffness)
. Hypermobile spine
. Flatback syndrome
. Pelvic retroversion compensation

Correct Answer & Explanation

. Normal spinopelvic mobility

Explanation

Normal spinopelvic mobility involves the sacral slope decreasing (pelvis retroverting) by 10 to 30 degrees when transitioning from standing to sitting. A change of less than 10 degrees defines a stiff spine, placing the patient at higher risk for impingement and dislocation.

Question 6325

Topic: 6. Spine

A 65-year-old male complains of bilateral lower extremity pain that worsens with walking. Which finding on history is most specific for differentiating neurogenic claudication from vascular claudication?

. Relief of symptoms upon standing still without changing posture
. Diminished pedal pulses
. Pain relief when walking uphill compared to walking downhill
. Cramping pain isolated to the calf muscles
. Paresthesias in a strict dermatomal distribution

Correct Answer & Explanation

. Relief of symptoms upon standing still without changing posture

Explanation

Pain relief when leaning forward (such as walking uphill or leaning over a shopping cart) is the hallmark of neurogenic claudication secondary to lumbar spinal stenosis. Lumbar flexion increases the cross-sectional area of the spinal canal, relieving nerve compression. Vascular claudication is relieved simply by resting/standing still, regardless of posture.

Question 6326

Topic: 6. Spine

A traumatic spondylolisthesis of the axis, commonly known as a Hangman's fracture, typically occurs through which specific anatomic structure of the C2 vertebra?

. Odontoid process
. Pedicle
. Pars interarticularis
. Lateral mass
. Lamina

Correct Answer & Explanation

. Odontoid process

Explanation

A Hangman's fracture is defined as a bilateral fracture through the pars interarticularis of the C2 vertebra (axis). It is classically caused by a combined hyperextension and axial loading mechanism.

Question 6327

Topic: 6. Spine

During an upper cervical spine trauma evaluation, integrity of the alar ligaments is assessed. What is the primary anatomical function of the alar ligaments?

. Limits flexion of the subaxial cervical spine
. Limits anterior translation of the atlas on the axis
. Limits axial rotation of the occiput and atlas on the axis
. Prevents vertical settling of the odontoid into the foramen magnum
. Connects the tips of the spinous processes from C2 to C7

Correct Answer & Explanation

. Limits flexion of the subaxial cervical spine

Explanation

The alar ligaments connect the superior-lateral aspects of the dens to the medial surfaces of the occipital condyles. Their primary biomechanical function is to limit axial rotation and lateral bending of the occiput and atlas (C1) relative to the axis (C2). Anterior translation of C1 on C2 is primarily prevented by the transverse ligament (Option B).

Question 6328

Topic: 6. Spine

A 35-year-old male is brought to the trauma bay after a motorcycle collision. He is hypotensive with a blood pressure of 75/40 mm Hg. Physical exam reveals a heart rate of 52 beats per minute, warm and flushed extremities, and flaccid paralysis of all four limbs. The most likely cause of his shock is:

. Hemorrhagic shock
. Cardiogenic shock
. Neurogenic shock
. Hypovolemic shock
. Septic shock

Correct Answer & Explanation

. Hemorrhagic shock

Explanation

The patient is exhibiting signs of neurogenic shock, which results from high spinal cord injury leading to a loss of sympathetic vasomotor tone. This results in unopposed vagal parasympathetic tone and profound vasodilation. The classic triad is hypotension, bradycardia (unlike hemorrhagic shock, which features tachycardia), and warm, flushed extremities (unlike hemorrhagic shock, where extremities are cool and clammy).

Question 6329

Topic: 6. Spine

A 28-year-old male presents with chronic lower back pain that worsens with rest and improves with exercise. He is diagnosed with ankylosing spondylitis. This condition is strongly associated with the HLA-B27 antigen. Which of the following conditions is also classically associated with this same HLA marker?

. Rheumatoid arthritis
. Systemic lupus erythematosus
. Reactive arthritis
. Sjogren's syndrome
. Dermatomyositis

Correct Answer & Explanation

. Rheumatoid arthritis

Explanation

Ankylosing spondylitis belongs to the family of seronegative spondyloarthropathies, which are characterized by an absence of rheumatoid factor and a strong genetic association with the HLA-B27 allele. Other classic conditions in this group include Reactive arthritis (formerly Reiter's syndrome), Psoriatic arthritis, and Inflammatory Bowel Disease-associated arthritis.

Question 6330

Topic: 6. Spine

A 65-year-old man presents with progressive hand clumsiness and gait unsteadiness. Examination reveals a positive Hoffmann sign and hyperreflexia. Which radiographic MRI parameter is most predictive of poor neurologic recovery after cervical decompression?

. T2 hyperintensity of the spinal cord
. T1 hypointensity of the spinal cord
. Klippel-Feil anomaly
. Loss of cervical lordosis
. Ossification of the posterior longitudinal ligament

Correct Answer & Explanation

. T2 hyperintensity of the spinal cord

Explanation

In cervical spondylotic myelopathy, T1 hypointensity (myelomalacia) indicates irreversible spinal cord damage and is a strong predictor of poor neurologic recovery after decompression. T2 hyperintensity alone can represent reversible edema and has a better prognosis.

Question 6331

Topic: 6. Spine

A patient with Rheumatoid Arthritis presents with neck pain. Cervical spine radiographs reveal an atlantodental interval (ADI) of 11 mm. What is the most critical implication of this finding?

. It indicates subaxial cervical spine subluxation.
. It represents an isolated rupture of the alar ligaments.
. It predicts a high likelihood of impending respiratory failure.
. It indicates an unacceptably high risk for spinal cord compression requiring surgical stabilization.
. It is a normal, non-pathological age-related change in rheumatoid patients.

Correct Answer & Explanation

. It indicates subaxial cervical spine subluxation.

Explanation

An ADI greater than 9 mm in a rheumatoid patient is highly predictive of spinal cord compression and requires surgical stabilization. A space available for the cord (SAC) of less than 14 mm is also a critical threshold for surgical intervention.

Question 6332

Topic: 6. Spine

A patient with ankylosing spondylitis and a completely fused lumbar spine requires a THA. How does this lack of spinopelvic mobility affect functional acetabular cup orientation when the patient transitions from a standing to a sitting position?

. The pelvis fails to tilt posteriorly, causing functional retroversion and increasing the risk of anterior dislocation.
. The pelvis tilts excessively anteriorly, preventing dislocation.
. The pelvis fails to tilt posteriorly, increasing relative anteversion and risking posterior dislocation.
. The pelvis fails to tilt posteriorly, resulting in a lack of functional anteversion, increasing the risk of anterior impingement and posterior dislocation.
. The pelvis functions normally due to compensatory hyperflexion of the native hip.

Correct Answer & Explanation

. The pelvis fails to tilt posteriorly, causing functional retroversion and increasing the risk of anterior dislocation.

Explanation

Normally, when moving from standing to sitting, the lumbar spine flexes and the pelvis tilts posteriorly, which functionally increases acetabular anteversion and clears the femur. In a stiff spine, the pelvis cannot tilt posteriorly, leading to a lack of necessary functional anteversion. This results in anterior impingement of the femoral neck on the cup and subsequent posterior dislocation.

Question 6333

Topic: 6. Spine

A 9-month-old boy is referred for evaluation of a left thoracic scoliosis. The curve measures 25 degrees on the AP radiograph. The surgeon is determining if this infantile idiopathic scoliosis curve is likely to resolve spontaneously or progress. According to Mehta's criteria, what calculation provides the highest predictive value for curve progression?

. Cobb angle magnitude >30 degrees
. Rib-Vertebral Angle Difference (RVAD) > 20 degrees
. Risser sign of 0
. Nash-Moe rotation of Grade II
. Apical Vertebral Translation > 2 cm

Correct Answer & Explanation

. Cobb angle magnitude >30 degrees

Explanation

In infantile idiopathic scoliosis, the Rib-Vertebral Angle Difference (RVAD), described by Mehta, is the most crucial radiographic predictor of progression. It is measured at the apical vertebra. An RVAD > 20 degrees suggests a progressive curve (Phase 2) requiring treatment (typically serial casting or bracing). An RVAD < 20 degrees usually indicates a resolving curve (Phase 1) that can be observed.

Question 6334

Topic: Cervical Spine

A 7-year-old boy presents with torticollis and severe neck stiffness 2 weeks after an uncomplicated adenotonsillectomy. He is afebrile but has persistent pain, holding his head tilted to the right and rotated to the left. Neurological examination is completely normal. Radiographs demonstrate an asymmetric atlantodental interval. What is the most likely diagnosis?

. Retropharyngeal abscess
. Atlantoaxial rotatory subluxation (Grisel syndrome)
. Klippel-Feil syndrome
. Osteoid osteoma of the cervical spine
. Juvenile idiopathic arthritis

Correct Answer & Explanation

. Retropharyngeal abscess

Explanation

Grisel syndrome is a non-traumatic atlantoaxial subluxation that occurs secondary to an inflammatory process in the upper neck, such as an upper respiratory infection or following head/neck surgery (e.g., adenotonsillectomy). The inflammation leads to laxity of the transverse ligament. Patients present with torticollis (head tilted to one side and rotated to the opposite side). Neurological deficits are rare but can occur.

Question 6335

Topic: 6. Spine

A 5-year-old child with a known diagnosis of Morquio syndrome (Mucopolysaccharidosis Type IV) is scheduled to undergo bilateral lower extremity osteotomies for severe genu valgum. Before proceeding with any surgical intervention involving general anesthesia, what is the most critical screening evaluation required?

. Echocardiogram to assess for pulmonary hypertension
. MRI of the cervical spine to evaluate for atlantoaxial instability
. Dual-energy X-ray absorptiometry (DEXA) scan for osteoporosis
. Ultrasound of the abdomen for hepatosplenomegaly
. Electroretinogram to assess for retinal dystrophy

Correct Answer & Explanation

. Echocardiogram to assess for pulmonary hypertension

Explanation

Morquio syndrome (MPS IV) is a skeletal dysplasia characterized by normal intelligence but profound skeletal changes, including odontoid hypoplasia. Odontoid hypoplasia leads to life-threatening atlantoaxial instability. This places the child at extreme risk for spinal cord injury or death during intubation and neck extension for surgery. Therefore, a cervical spine MRI (or flexion/extension radiographs if reliable) is mandatory prior to anesthesia.

Question 6336

Topic: 6. Spine

A 13-year-old boy with Duchenne muscular dystrophy, who uses a wheelchair full-time, develops a progressive neuromuscular scoliosis measuring 35 degrees. His forced vital capacity (FVC) is 45% of predicted. What is the most appropriate recommendation for managing his spinal deformity?

. Custom-molded thoracolumbosacral orthosis (TLSO) to halt curve progression
. Posterior spinal fusion from upper thoracic spine to the pelvis
. Observation with serial radiographs every 6 months until the curve reaches 50 degrees
. Anterior spinal fusion alone
. Growing rod constructs

Correct Answer & Explanation

. Custom-molded thoracolumbosacral orthosis (TLSO) to halt curve progression

Explanation

In patients with Duchenne muscular dystrophy, scoliotic curves progress rapidly once wheelchair-bound. Bracing is ineffective and poorly tolerated. Posterior spinal fusion is recommended early, typically when the curve exceeds 20-30 degrees, while the patient's pulmonary function is still adequate (FVC > 35% predicted). Delaying surgery increases cardiopulmonary risks. Fusion is typically extended to the pelvis to correct pelvic obliquity and provide a level sitting base.

Question 6337

Topic: Thoracolumbar Spine & Deformity

A 12-year-old gymnast presents with persistent lower back pain. Radiographs reveal a Grade II isthmic spondylolisthesis at L5-S1. She is neurologically intact. After failing 6 months of dedicated physical therapy, bracing, and activity modification, her back pain remains disabling. What is the most appropriate surgical treatment?

. L5-S1 anterior lumbar interbody fusion
. L5 laminectomy and Gill procedure without fusion
. L5-S1 in situ posterolateral fusion
. L5-S1 posterior instrumentation and reduction of the slip to Grade 0
. L4-S1 posterior spinal fusion

Correct Answer & Explanation

. L5-S1 anterior lumbar interbody fusion

Explanation

For pediatric patients with symptomatic low-grade (Grade I or II) isthmic spondylolisthesis that fails conservative management, the standard surgical treatment is an L5-S1 in situ posterolateral fusion. Decompression (Gill procedure) alone is contraindicated in children as it increases instability and slip progression. Reduction of low-grade slips is unnecessary and carries a high risk of L5 nerve root injury without added clinical benefit.

Question 6338

Topic: Thoracolumbar Spine & Deformity
A 13-year-old gymnast complains of refractory lower back pain. Radiographs reveal an isthmic spondylolisthesis at L5-S1 with a 60% slip (Meyerding Grade III). Which surgical option is most appropriate if conservative management fails?
. Pars interarticularis repair (Buck's repair)
. In situ posterolateral fusion from L5 to S1
. Laminectomy alone without fusion
. Instrumented posterolateral and interbody fusion of L5-S1
. Anterior lumbar interbody fusion without posterior instrumentation

Correct Answer & Explanation

. Instrumented posterolateral and interbody fusion of L5-S1

Explanation

A high-grade slip (>50%) in an actively growing adolescent is highly unstable and poses a significant risk for progression. Surgical management typically requires instrumented stabilization and fusion (posterolateral with or without interbody fusion) to halt progression and alleviate symptoms.

Question 6339

Topic: Cervical Spine

A 5-year-old boy with Down syndrome presents with neck pain and torticollis following a minor fall. Neurological examination is completely normal. Open-mouth odontoid radiographs reveal an atlanto-dens interval (ADI) of 6 mm. What is the most appropriate initial management?

. Immediate posterior spinal fusion from C1 to C2
. Cervical collar, avoidance of contact sports, and close observation
. Application of a Halo vest for strict immobilization
. Anterior odontoid screw fixation
. Reassurance and immediate return to normal activities

Correct Answer & Explanation

. Immediate posterior spinal fusion from C1 to C2

Explanation

An ADI of up to 4-5 mm can be normal in children, but 6 mm indicates mild atlantoaxial instability common in Down syndrome. Without neurologic symptoms, conservative management with activity restriction and close follow-up is indicated.

Question 6340

Topic: 6. Spine

A 45-year-old male presents with acute onset back pain, bilateral lower extremity weakness, and perineal numbness after lifting a heavy box. He reports inability to void for the past 12 hours. What is the most sensitive early clinical finding for cauda equina syndrome?

. Decreased anal sphincter tone
. Saddle anesthesia
. Urinary retention
. Bilateral Babinski signs
. Absent ankle jerks

Correct Answer & Explanation

. Decreased anal sphincter tone

Explanation

Urinary retention is the most sensitive sign for cauda equina syndrome (CES), with a sensitivity of up to 90%. If a patient with suspected CES does not have urinary retention, the diagnosis is less likely, though early incomplete CES may manifest with altered urinary sensation first. Saddle anesthesia and decreased anal tone are highly specific but less sensitive early on.

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