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6. Spine MCQs

Practice Set 292 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 5821

Topic: 6. Spine

You are examining a newborn diagnosed with Spondyloepiphyseal Dysplasia Congenita. In addition to monitoring the skeletal system and cervical spine, what other specialized screening must be routinely performed throughout this patient's childhood?

. Audiograms for conductive hearing loss
. Dilated fundoscopic exams for retinal detachment
. Slit-lamp exams for corneal clouding
. Urinalysis for mucopolysaccharides
. EKG for complete heart block

Correct Answer & Explanation

. Dilated fundoscopic exams for retinal detachment

Explanation

Severe myopia and a high risk of retinal detachment are classic extraskeletal manifestations of SED Congenita due to Type II collagen defects in the vitreous humor. Routine ophthalmologic screening is essential to prevent blindness.

Question 5822

Topic: 6. Spine

In a 14-year-old male with Spondyloepiphyseal Dysplasia Tarda, what is the most characteristic pathognomonic finding on a lateral radiograph of the lumbar spine?

. A hump-shaped mound of bone on the central/posterior half of the vertebral endplates
. Anterior central beaking of the vertebral bodies
. Picture-frame appearance of the vertebral bodies
. Bamboo spine appearance with syndesmophytes
. Winking owl sign of the pedicles

Correct Answer & Explanation

. A hump-shaped mound of bone on the central/posterior half of the vertebral endplates

Explanation

The pathognomonic radiographic feature of SED Tarda is a hump-shaped mound of bone accumulating on the posterior or central portion of the superior and inferior vertebral endplates.

Question 5823

Topic: 6. Spine

The mutation in Spondyloepiphyseal Dysplasia Congenita impairs the normal structural integrity of hyaline cartilage. Which of the following intervertebral disc components is also primarily composed of this defective protein?

. Outer layer of the annulus fibrosus
. Anterior longitudinal ligament
. Nucleus pulposus
. Posterior longitudinal ligament
. Ligamentum flavum

Correct Answer & Explanation

. Nucleus pulposus

Explanation

The nucleus pulposus is rich in Type II collagen, making it highly susceptible to the COL2A1 mutation seen in SED Congenita, contributing to the spinal manifestations of the disease.

Question 5824

Topic: Cervical Spine

Morquio syndrome and Spondyloepiphyseal Dysplasia Congenita both present with short trunk dwarfism and atlantoaxial instability. Which of the following clinical features reliably distinguishes Morquio syndrome from SED Congenita on physical examination?

. Presence of short trunk dwarfism
. Presence of odontoid hypoplasia
. Symmetric involvement of the limbs
. Presence of corneal clouding
. Presence of normal intelligence

Correct Answer & Explanation

. Presence of corneal clouding

Explanation

Corneal clouding is a classic feature of Morquio syndrome (a mucopolysaccharidosis), but it is absent in SED Congenita. Both conditions exhibit normal intelligence, short trunk dwarfism, and odontoid hypoplasia.

Question 5825

Topic: 6. Spine

Which of the following represents the most immediately life-threatening complication of Spondyloepiphyseal Dysplasia Congenita in early childhood?

. Cor pulmonale from severe kyphoscoliosis
. Cervical myelopathy from atlantoaxial instability
. Aortic root dilation and rupture
. Renal failure due to amyloidosis
. Airway compromise from glossoptosis

Correct Answer & Explanation

. Cervical myelopathy from atlantoaxial instability

Explanation

Odontoid hypoplasia is very common in SED Congenita, leading to atlantoaxial instability. If unrecognized, this can cause life-threatening cervical myelopathy or sudden death, especially during intubation or trauma.

Question 5826

Topic: 6. Spine

What spinal deformity is most frequently associated with Spondyloepiphyseal Dysplasia Congenita and typically progresses during childhood, often requiring surgical fusion?

. Isthmic spondylolisthesis
. Isolated mid-cervical kyphosis
. Thoracolumbar kyphoscoliosis
. Lumbar hyperlordosis only
. Multiple congenital hemivertebrae

Correct Answer & Explanation

. Thoracolumbar kyphoscoliosis

Explanation

Thoracolumbar kyphoscoliosis is a very common spinal deformity in SED Congenita. It frequently progresses throughout childhood due to vertebral dysplasia and ligamentous laxity, often necessitating surgical stabilization.

Question 5827

Topic: 6. Spine

Based on the lateral spine radiograph showing characteristic heaped-up bone on the posterior vertebral endplates, a 14-year-old boy is diagnosed with SED Tarda.

What is the inheritance pattern for the most common form of this disease?

. Autosomal dominant
. Autosomal recessive
. Mitochondrial
. X-linked dominant
. X-linked recessive

Correct Answer & Explanation

. X-linked recessive

Explanation

The image describes SED Tarda, classically showing posterior humping of the vertebral bodies. The most common genetic variant (TRAPPC2 mutation) is inherited in an X-linked recessive pattern.

Question 5828

Topic: 6. Spine

A 5-year-old child with spondyloepiphyseal dysplasia congenita (SEDC) is scheduled to undergo a proximal femoral valgus osteotomy for severe coxa vara. Which of the following preoperative evaluations is absolutely critical before proceeding with general anesthesia?

. Echocardiogram to assess for aortic root dilation
. Flexion-extension radiographs of the cervical spine
. Pulmonary function testing
. Renal ultrasound
. Electroretinogram

Correct Answer & Explanation

. Flexion-extension radiographs of the cervical spine

Explanation

Patients with SEDC have a high incidence of odontoid hypoplasia, which can lead to atlantoaxial instability. Flexion-extension cervical spine radiographs are mandatory prior to any procedure requiring intubation or neck manipulation to avoid catastrophic spinal cord injury.

Question 5829

Topic: 6. Spine

A 10-year-old girl with Spondyloepiphyseal Dysplasia Congenita presents with increasing lower extremity weakness, hyperreflexia, and a positive Babinski sign. Cervical radiographs reveal an atlantodens interval (ADI) of 8 mm. What is the primary pathoanatomic etiology of her cervical instability?

. Laxity of the transverse atlantal ligament
. Odontoid hypoplasia
. Os odontoideum
. Assimilation of the atlas
. Congenital cervical block vertebrae

Correct Answer & Explanation

. Odontoid hypoplasia

Explanation

Atlantoaxial instability in SEDC is primarily due to odontoid hypoplasia (a manifestation of the epiphyseal dysplasia), rather than purely ligamentous laxity as seen in Down syndrome. Symptomatic myelopathy with an ADI >5 mm requires posterior C1-C2 fusion.

Question 5830

Topic: 6. Spine

In a patient with Spondyloepiphyseal Dysplasia Tarda (SEDT), which of the following radiographic spinal abnormalities is considered the hallmark pathognomonic finding?

. Anterior beaking of the lumbar vertebrae
. Heaped-up or humped bone at the central and posterior portions of the vertebral endplates
. Widespread squaring of the vertebral bodies
. Picture-frame appearance of the vertebral bodies
. Coronal clefts in the vertebral bodies

Correct Answer & Explanation

. Heaped-up or humped bone at the central and posterior portions of the vertebral endplates

Explanation

The pathognomonic radiographic finding for SEDT is the presence of a 'heaped-up' or 'hump-shaped' mound of bone in the central and posterior aspects of the superior and inferior vertebral endplates. Anterior beaking is more characteristic of Morquio syndrome.

Question 5831

Topic: 6. Spine

A patient with ankylosing spondylitis (AS) is being considered for biologics. AS is strongly associated with HLA-B27. Which cytokine pathway is often targeted in AS given its role in enthesitis and bone formation/resorption imbalance characteristic of the disease?

. IL-4 pathway
. IL-10 pathway
. IL-17 pathway
. IFN-gamma pathway
. TGF-beta pathway

Correct Answer & Explanation

. IL-17 pathway

Explanation

The IL-17 pathway, particularly cytokines produced by Th17 cells (IL-17 and IL-22), is increasingly recognized as central to the pathogenesis of ankylosing spondylitis (AS). IL-17 plays a critical role in promoting inflammation at entheses (where ligaments and tendons attach to bone), driving osteoproliferation (syndesmophytes), and contributing to bone erosion. Consequently, biologics targeting IL-17 (e.g., secukinumab, ixekizumab) are effective treatments for AS. While TNF-alpha is also important and targeted, IL-17 is a more specific answer for the described pathology.

Question 5832

Topic: 6. Spine

A 14-year-old competitive gymnast complains of progressive low back pain, worse with extension and gymnastics activities. Radiographs show a defect in the pars interarticularis of L5. What is the most likely diagnosis?

. Scheuermann's kyphosis
. Lumbar disc herniation
. Spondylolysis
. Spondylolisthesis
. Facet joint arthritis

Correct Answer & Explanation

. Spondylolysis

Explanation

The clinical presentation (low back pain in an adolescent athlete, especially one performing repetitive hyperextension activities like gymnastics) combined with a radiographic defect in the pars interarticularis is classic for spondylolysis. Spondylolisthesis implies anterior slippage of one vertebra over another, which can result from bilateral spondylolysis, but the initial defect is spondylolysis. Lumbar disc herniation is rare in this age group unless from acute trauma, and Scheuermann's kyphosis affects the thoracic spine primarily.

Question 5833

Topic: Thoracolumbar Spine & Deformity

In the context of adult spinal deformity, which of the following radiographic parameters is most strongly correlated with health-related quality of life (HRQOL) and patient-reported outcomes?

. Scoliosis curve magnitude (Cobb angle)
. Pelvic incidence (PI)
. Pelvic tilt (PT)
. Sagittal vertical axis (SVA)
. Apical vertebral rotation

Correct Answer & Explanation

. Sagittal vertical axis (SVA)

Explanation

Sagittal vertical axis (SVA), which measures the plumb line from C7 relative to the sacral promontory, is widely considered the most important radiographic parameter correlating with health-related quality of life (HRQOL) and patient-reported outcomes in adult spinal deformity. Patients with positive sagittal imbalance (forward lean) tend to have significantly worse pain and functional scores. While Cobb angle, PI, and PT are also important, SVA directly reflects global sagittal balance and its impact on energy expenditure and posture.

Question 5834

Topic: 6. Spine

A 70-year-old male with symptomatic severe lumbar spinal stenosis, refractory to conservative management, is considering surgical decompression. Which of the following co-morbidities carries the highest risk for adverse outcomes following lumbar spine surgery?

. Controlled hypertension
. Well-controlled type 2 diabetes mellitus
. Current smoking
. Mild obesity (BMI 30)
. History of remote myocardial infarction

Correct Answer & Explanation

. Current smoking

Explanation

Current smoking is consistently identified as one of the most significant modifiable risk factors for adverse outcomes following lumbar spine surgery. It is associated with higher rates of surgical site infection, impaired wound healing, pseudarthrosis (nonunion), increased pain, and overall worse patient-reported outcomes. While other comorbidities like obesity, diabetes, and cardiovascular disease increase risk, smoking is particularly detrimental to fusion and healing processes.

Question 5835

Topic: 6. Spine

A 58-year-old male with a history of ankylosing spondylitis (AS) is undergoing a bilateral THA for end-stage arthritis. He previously developed significant heterotopic ossification (HO) after a spinal fusion. What is the most effective prophylactic regimen to prevent severe HO in this patient?

. A single dose of oral indomethacin preoperatively and for 2 weeks postoperatively.
. Preoperative radiation therapy (e.g., 700 cGy in a single dose) delivered to the hip.
. Postoperative radiation therapy (e.g., 700 cGy in a single dose) delivered within 24-72 hours of surgery.
. Intramuscular corticosteroid injection at the surgical site.
. Daily oral vitamin K antagonists (e.g., warfarin) for 6 weeks postoperatively.

Correct Answer & Explanation

. Postoperative radiation therapy (e.g., 700 cGy in a single dose) delivered within 24-72 hours of surgery.

Explanation

Patients with ankylosing spondylitis, especially those with a history of HO after other surgeries, are at extremely high risk for severe heterotopic ossification after THA. While NSAIDs (like indomethacin) are a standard prophylaxis for moderate-risk patients, they may not be sufficient for very high-risk individuals. Radiation therapy is highly effective for HO prophylaxis. The most effective protocol for high-risk patients, such as those with AS, is a single dose of 700 cGy delivered to the hip, typically within 24-72 hourspostoperatively. Preoperative radiation is also effective but may delay surgery and might have slightly different logistical challenges. However, the timing (postoperative, within 24-72 hours) is critical for optimal efficacy. Corticosteroids and vitamin K antagonists are not standard or effective for HO prophylaxis. Therefore, postoperative radiation therapy is the most robust and evidence-based approach for this high-risk patient.

Question 5836

Topic: 6. Spine

A 55-year-old active male undergoes primary total hip arthroplasty (THA) for severe osteoarthritis. Postoperatively, he experiences recurrent anterior dislocations despite adequate component positioning (cup inclination 40°, anteversion 15°). Further evaluation reveals a 'flatback' deformity in the lumbar spine, with a diminished lumbar lordosis and a sacral slope of 25° in standing, decreasing to 10° in sitting. Which of the following adjustments would be most appropriate during a revision surgery to address his recurrent dislocations related to his spinal-pelvic mechanics?

. Increase acetabular anteversion to 25° and inclination to 45°.
. Decrease acetabular anteversion to 10° and inclination to 35°.
. Utilize a constrained acetabular liner and maintain current component positions.
. Place the acetabular component in a more anteriorly tilted position (increased functional anteversion in sitting) or use a dual-mobility construct.
. Switch to a larger femoral head with no change in acetabular component position.

Correct Answer & Explanation

. Place the acetabular component in a more anteriorly tilted position (increased functional anteversion in sitting) or use a dual-mobility construct.

Explanation

Patients with stiff spinal deformities, particularly 'flatback' (diminished lumbar lordosis, low sacral slope), are at higher risk for hip dislocation after THA. In standing, these patients often have a posterior pelvic tilt, but in sitting, they demonstrate a significant anterior pelvic tilt. This anterior pelvic tilt in sitting effectively reduces the functional anteversion of the acetabular component, increasing the risk of anterior dislocation. To compensate for this, the acetabular component needs to be placed in a position that provides increased effective anteversion in the sitting position, which means positioning it with more anteversion than traditional guidelines, or with a more anterior tilt. A dual-mobility construct also offers increased jump distance and stability. Increasing anteversion and inclination excessively (Option A) can lead to posterior impingement or instability. Decreasing anteversion and inclination (Option B) would worsen the problem. A constrained liner is an option for recurrent dislocation but may not fully address the underlying spinal-pelvic kinematics causing the problem and comes with its own risks. A larger femoral head increases jump distance but might not be sufficient for severe spinopelvic malalignment. Therefore, placing the acetabular component in a more anteriorly tilted position (increased functional anteversion in sitting) or using a dual-mobility construct directly addresses the kinematic challenges posed by the 'flatback' deformity.

Question 5837

Topic: 6. Spine

A 50-year-old male with severe ankylosing spondylitis and a fused, kyphotic spine ('chin-on-chest' deformity) requires bilateral total hip arthroplasties. What is the single most critical consideration during intraoperative positioning and component placement for successful THA in this patient to optimize postoperative function and prevent dislocation?

. Ensuring the patient is positioned in maximal hip flexion during surgery
. Prioritizing restoration of anatomical leg length over component orientation
. Accounting for the patient's altered functional pelvic tilt in their typical standing/sitting posture
. Using smaller femoral heads to minimize impingement risk
. Performing a spinal osteotomy prior to THA to correct the kyphosis

Correct Answer & Explanation

. Accounting for the patient's altered functional pelvic tilt in their typical standing/sitting posture

Explanation

Patients with severe ankylosing spondylitis and a fused kyphotic spine have a fixed sagittal imbalance, which significantly alters their functional pelvic tilt. In their typical standing or sitting posture, the pelvis is often in a functionally retroverted position relative to anatomical landmarks. If components are implanted based on standard anatomical landmarks without considering this altered functional pelvic tilt, the patient may be at high risk for impingement and dislocation postoperatively. For example, a 'standard' anteverted cup in an anatomically neutral pelvis could become highly anteverted functionally when the spine is fused in kyphosis. Therefore, it is critical to anticipate the patient's functional pelvic tilt and adjust acetabular component anteversion and inclination accordingly. Performing a spinal osteotomy (E) before THA is a major procedure and not always necessary or feasible. Other options are less critical than understanding functional pelvic tilt.

Question 5838

Topic: Thoracolumbar Spine & Deformity

A 74-year-old female with a prior long segment lumbar fusion (T10-pelvis) for scoliosis is scheduled for a THA. How does her altered spinopelvic biomechanics influence acetabular component positioning?

. She has a decreased risk of anterior dislocation in extension
. The stiff pelvis cannot roll back during hip flexion, requiring increased cup anteversion to prevent posterior dislocation
. The acetabular cup should be placed in maximum retroversion
. Standard cup positioning (40 degrees inclination, 20 degrees anteversion) is optimal
. She requires a fully constrained liner routinely as first-line treatment

Correct Answer & Explanation

. The stiff pelvis cannot roll back during hip flexion, requiring increased cup anteversion to prevent posterior dislocation

Explanation

A fused lumbar spine cannot flex (loss of posterior pelvic tilt/rollback) to accommodate hip flexion, placing the patient at a high risk for posterior dislocation. The acetabular component should be placed in increased anteversion and inclination to compensate for this stiffness.

Question 5839

Topic: 6. Spine
A newborn is diagnosed with congenital scoliosis secondary to a fully segmented hemivertebra in the thoracic spine. Because congenital scoliosis occurs due to abnormal somite development during embryogenesis, screening for associated anomalies is mandatory. Which of the following sets of screening tests is most appropriate?
. Renal ultrasound, echocardiogram, and brain MRI
. Abdominal CT, skeletal survey, and genetic karyotyping
. Renal ultrasound, echocardiogram, and entire spine MRI
. Pulmonary function tests, DEXA scan, and cervical spine flexion/extension radiographs
. Urinalysis, EKG, and electroencephalogram (EEG)

Correct Answer & Explanation

. Renal ultrasound, echocardiogram, and entire spine MRI

Explanation

Congenital scoliosis is highly associated with VACTERL anomalies. Renal anomalies (unilateral kidney, duplication) occur in up to 20-30%, requiring a renal ultrasound. Cardiac anomalies require an echocardiogram. Intraspinal anomalies (tethered cord, syringomyelia, diastematomyelia) are seen in up to 30%, mandating an entire spine MRI.

Question 5840

Topic: 6. Spine

A 14-year-old female gymnast complains of insidious onset, mechanical low back pain that worsens with back extension. Radiographs of the lumbar spine show a defect in the pars interarticularis of L5. The classic 'Scotty dog with a collar' sign is best appreciated on which specific radiographic projection?

. Standing AP view
. Oblique view
. Flexion/extension lateral views
. Ferguson view
. Coned-down lateral view

Correct Answer & Explanation

. Oblique view

Explanation

Spondylolysis is a defect in the pars interarticularis, common in adolescent athletes subjected to repetitive hyperextension (like gymnasts). The pars defect looks like a 'collar' on the neck of the 'Scotty dog,' which is the classic radiographic appearance seen on the 45-degree oblique view of the lumbar spine.

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