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6. Spine MCQs

Practice Set 375 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 7481

Topic: 6. Spine

A 4-year-old child with Spondyloepiphyseal Dysplasia (SED) congenita is scheduled for bilateral hip reconstruction due to severe coxa vara. During the preoperative evaluation, which of the following is the most critical screening study required before proceeding with general anesthesia?

. Echocardiogram to rule out aortic root dilation
. Flexion-extension radiographs of the cervical spine
. Renal ultrasound to check for congenital anomalies
. Pulmonary function tests
. MRI of the lumbar spine to rule out tethered cord

Correct Answer & Explanation

. Flexion-extension radiographs of the cervical spine

Explanation

Correct Answer: BPatients with Spondyloepiphyseal Dysplasia (SED) congenita (caused by COL2A1 mutations) frequently have odontoid hypoplasia, which can lead to severe atlantoaxial instability. Before any surgical procedure requiring general anesthesia and intubation, it is critical to obtain flexion-extension radiographs of the cervical spine to evaluate for C1-C2 instability to prevent catastrophic spinal cord injury during neck manipulation. Aortic root dilation (Option A) is a concern in Marfan syndrome, not typically SED.

Question 7482

Topic: Cervical Spine

Both Multiple Epiphyseal Dysplasia (Fairbank type) and Pseudoachondroplasia can be caused by mutations in the Cartilage Oligomeric Matrix Protein (COMP) gene. Which of the following clinical or radiographic features best distinguishes Pseudoachondroplasia from Multiple Epiphyseal Dysplasia?

. Presence of a normal facial appearance
. Severe metaphyseal irregularities and flaring
. Autosomal dominant inheritance pattern
. Development of early-onset osteoarthritis
. Presence of odontoid hypoplasia

Correct Answer & Explanation

. Severe metaphyseal irregularities and flaring

Explanation

Correct Answer: BWhile both MED and Pseudoachondroplasia can result from COMP gene mutations, Pseudoachondroplasia is generally more severe. The key distinguishing feature is that Pseudoachondroplasia involves significant metaphyseal irregularities, flaring, and shortening, in addition to epiphyseal dysplasia. MED is predominantly confined to the epiphyses with minimal to no metaphyseal involvement. Both conditions typically have a normal facial appearance (Option A), distinguishing them from true achondroplasia. Both are autosomal dominant (Option C) and lead to early osteoarthritis (Option D).

Question 7483

Topic: 6. Spine

A 7-year-old girl with Spondyloepiphyseal Dysplasia (SED) congenita presents for a routine orthopedic follow-up. In addition to monitoring her spine and hips, the orthopedic surgeon must ensure she is receiving regular evaluations by which of the following specialists due to a high-risk associated condition?

. Cardiology, for aortic aneurysm surveillance
. Ophthalmology, for high myopia and retinal detachment risk
. Nephrology, for progressive renal failure
. Hematology, for bone marrow failure
. Endocrinology, for associated hypothyroidism

Correct Answer & Explanation

. Ophthalmology, for high myopia and retinal detachment risk

Explanation

Correct Answer: BSED congenita is a type II collagenopathy caused by mutations in the COL2A1 gene. Type II collagen is a major structural component of articular cartilage, the nucleus pulposus, and the vitreous humor of the eye. Consequently, patients with SED congenita are at a very high risk for severe myopia and retinal detachment. Regular ophthalmologic screening is mandatory to prevent blindness. The other options are not classically associated with SED congenita.

Question 7484

Topic: 6. Spine

A 14-year-old boy is diagnosed with X-linked Spondyloepiphyseal Dysplasia Tarda. Which of the following is the pathognomonic radiographic finding in the spine for this condition?

. Anterior beaking of the lumbar vertebrae
. Picture-frame vertebral bodies
. Central hump-shaped buildup of bone on the vertebral endplates
. Rugger-jersey spine appearance
. Widespread coronal clefts in the vertebral bodies

Correct Answer & Explanation

. Central hump-shaped buildup of bone on the vertebral endplates

Explanation

Correct Answer: CThe pathognomonic radiographic finding for X-linked Spondyloepiphyseal Dysplasia Tarda is a central, hump-shaped buildup of bone on the superior and inferior endplates of the vertebral bodies, predominantly in the posterior two-thirds. This is due to a failure of ossification of the ring apophysis. Anterior beaking (Option A) is seen in mucopolysaccharidoses (like Morquio or Hurler syndrome). 'Picture-frame' vertebrae (Option B) are seen in Paget's disease. 'Rugger-jersey' spine (Option D) is seen in renal osteodystrophy. Coronal clefts (Option E) are seen in chondrodysplasia punctata.

Question 7485

Topic: 6. Spine

A 12-year-old boy presents with short stature, primarily affecting his trunk, and progressive hip pain. Radiographs reveal platyspondyly with a characteristic 'hump-shaped' central buildup of bone on the vertebral endplates, and dysplastic capital femoral epiphyses. His father is of normal height, but his maternal uncle has a similar condition. What is the most likely genetic inheritance pattern and associated gene?

. Autosomal dominant, COL2A1
. X-linked recessive, TRAPPC2
. Autosomal recessive, SLC26A2
. X-linked dominant, PHEX
. Autosomal dominant, COMP

Correct Answer & Explanation

. X-linked recessive, TRAPPC2

Explanation

Correct Answer: B (X-linked recessive, TRAPPC2)The patient has Spondyloepiphyseal Dysplasia (SED) Tarda. The key distinguishing features are the later onset (usually late childhood), X-linked recessive inheritance (affecting males, with maternal uncles affected), and the pathognomonic 'hump-shaped' central buildup of bone on the superior and inferior vertebral endplates seen on lateral spine radiographs. It is caused by mutations in the TRAPPC2 (formerly SEDL) gene. SED Congenita, in contrast, is autosomal dominant, caused by COL2A1 mutations, and presents at birth.

Question 7486

Topic: 6. Spine

A 6-year-old child with Spondyloepiphyseal Dysplasia Congenita (SEDC) is scheduled for bilateral proximal femoral osteotomies to correct severe coxa vara. During the preoperative evaluation, which of the following is the most critical screening test to perform before proceeding with general anesthesia?

. Echocardiogram to rule out aortic root dilation
. Flexion-extension radiographs of the cervical spine
. Pulmonary function tests
. Renal ultrasound
. MRI of the lumbar spine to rule out tethered cord

Correct Answer & Explanation

. Flexion-extension radiographs of the cervical spine

Explanation

Correct Answer: B (Flexion-extension radiographs of the cervical spine)Spondyloepiphyseal Dysplasia Congenita (SEDC), caused by COL2A1 mutations, is strongly associated with odontoid hypoplasia and subsequent atlantoaxial instability. This is a critical, potentially life-threatening issue during intubation and positioning for surgery under general anesthesia. Therefore, obtaining flexion-extension radiographs of the cervical spine is a mandatory preoperative screening step to assess for instability. If instability is present, careful intubation techniques (e.g., fiberoptic) and potentially cervical fusion are required.

Question 7487

Topic: 6. Spine

A 10-year-old patient presents with short stature and joint pain. Radiographs reveal flattened, irregular epiphyses in the knees, hips, and ankles. To reliably differentiate Multiple Epiphyseal Dysplasia (MED) from Spondyloepiphyseal Dysplasia (SED), which of the following radiographic assessments is most definitive?

. Lateral radiograph of the thoracolumbar spine
. AP radiograph of the pelvis
. Skeletal survey of the hands and feet
. MRI of the knee joints
. CT scan of the lower extremities

Correct Answer & Explanation

. Lateral radiograph of the thoracolumbar spine

Explanation

Correct Answer: A (Lateral radiograph of the thoracolumbar spine)The primary distinguishing feature between Multiple Epiphyseal Dysplasia (MED) and Spondyloepiphyseal Dysplasia (SED) is the involvement of the spine. In MED, the spine is typically normal or shows only mild, clinically insignificant changes (like mild endplate irregularities). In SED, there is significant spinal involvement, most notably platyspondyly (flattened vertebral bodies), which contributes to a disproportionate short-trunk short stature. Therefore, a lateral spine radiograph is the most definitive test to differentiate the two.

Question 7488

Topic: 6. Spine
A 6-year-old child with a known diagnosis of Spondyloepiphyseal Dysplasia Congenita (SEDC) is scheduled for elective bilateral femoral osteotomies to correct severe coxa vara. During preoperative planning, which of the following evaluations is absolutely critical before proceeding with general anesthesia?
. Echocardiography to rule out aortic root dilation
. Flexion-extension radiographs of the cervical spine
. Pulmonary function tests to assess for restrictive lung disease
. Renal ultrasound to evaluate for polycystic kidneys
. Coagulation profile to rule out associated factor VIII deficiency

Correct Answer & Explanation

. Flexion-extension radiographs of the cervical spine

Explanation

Patients with SEDC frequently have odontoid hypoplasia, leading to atlantoaxial instability. Flexion-extension cervical spine radiographs are critical prior to general anesthesia to avoid catastrophic neurologic injury during intubation.

Question 7489

Topic: 6. Spine

A 12-year-old boy presents with short stature, broad chest, and progressively worsening hip and back pain. Radiographs of his spine demonstrate generalized platyspondyly with a characteristic 'heaped-up' accumulation of bone at the posterior aspect of the vertebral endplates. Which of the following inheritance patterns is most likely associated with this patient's condition?

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

Correct Answer & Explanation

. X-linked recessive

Explanation

The clinical and radiographic presentation is classic for Spondyloepiphyseal Dysplasia (SED) Tarda, characterized by late-childhood onset and 'hump-shaped' posterior vertebral bodies. It is an X-linked recessive disorder caused by mutations in the TRAPPC2 gene.

Question 7490

Topic: 6. Spine

A 6-year-old patient with an established diagnosis of Spondyloepiphyseal Dysplasia Congenita (SEDC) is scheduled for elective knee realignment surgery. Which of the following preoperative evaluations is most critical for this patient?

. Renal ultrasound
. Echocardiogram
. Flexion-extension cervical spine radiographs
. Pulmonary function tests
. Electroencephalogram

Correct Answer & Explanation

. Flexion-extension cervical spine radiographs

Explanation

Patients with SEDC are at high risk for odontoid hypoplasia and subsequent atlantoaxial instability. Flexion-extension cervical spine radiographs are mandatory before any procedure requiring general anesthesia to prevent catastrophic spinal cord injury during intubation.

Question 7491

Topic: 6. Spine

A 14-year-old male with a TRAPPC2 mutation undergoes routine radiographic evaluation of the spine. Which of the following findings is considered pathognomonic for his diagnosis?

. Anterior vertebral beaking
. Coronal clefts of the vertebral bodies
. Central and posterior hump-shaped accumulations of bone on the vertebral endplates
. Picture-frame appearance of the vertebrae
. Rugger-jersey spine appearance

Correct Answer & Explanation

. Central and posterior hump-shaped accumulations of bone on the vertebral endplates

Explanation

Spondyloepiphyseal Dysplasia Tarda (SEDT) exhibits a pathognomonic radiographic appearance of the spine. A mound or "hump" of heaped-up bone forms on the central and posterior portions of the vertebral endplates.

Question 7492

Topic: 6. Spine

A 9-year-old boy with Spondyloepiphyseal Dysplasia Congenita presents for his annual orthopedic follow-up. In addition to monitoring his cervical spine and hip development, routine screening by which of the following specialists is most important due to his genetic defect?

. Cardiologist to monitor for aortic root dilation
. Ophthalmologist to monitor for retinal detachment
. Nephrologist to monitor for renal cysts
. Endocrinologist to monitor for diabetes insipidus
. Audiologist to monitor for conductive hearing loss

Correct Answer & Explanation

. Ophthalmologist to monitor for retinal detachment

Explanation

SEDC is caused by a COL2A1 mutation affecting type II collagen, which is abundant in the vitreous humor of the eye. These patients are at a high risk for extreme myopia and early retinal detachment.

Question 7493

Topic: 6. Spine

An 8-year-old patient with an established diagnosis of Spondyloepiphyseal Dysplasia Congenita (SEDC) presents with a new onset of gait clumsiness, bilateral lower extremity weakness, and hyperreflexia. What is the most appropriate next step in management?

. Reassurance and outpatient physical therapy
. Lumbar puncture to rule out infectious myelitis
. Urgent MRI of the cervical spine
. Electromyography and nerve conduction studies
. Bracing with a thoracolumbosacral orthosis (TLSO)

Correct Answer & Explanation

. Urgent MRI of the cervical spine

Explanation

Clumsiness, weakness, and hyperreflexia in an SEDC patient strongly suggest cervical myelopathy due to atlantoaxial instability from odontoid hypoplasia. An urgent MRI of the cervical spine is required to evaluate for spinal cord compression.

Question 7494

Topic: 6. Spine

A 4-year-old child with disproportionate short trunk dwarfism and a barrel chest is scheduled for elective hernia repair. Radiographs show delayed ossification of the pubic bones and epiphyses, as well as platyspondyly. Which of the following preoperative evaluations is most critical for this patient?

. Echocardiogram
. Cervical spine flexion-extension radiographs
. Renal ultrasound
. Pulmonary function tests
. Brain MRI

Correct Answer & Explanation

. Cervical spine flexion-extension radiographs

Explanation

This patient has Spondyloepiphyseal Dysplasia Congenita (SEDC), caused by a COL2A1 mutation. Due to the high risk of odontoid hypoplasia and atlantoaxial instability, cervical spine radiographs are mandatory before any procedure requiring intubation.

Question 7495

Topic: 6. Spine
A newborn female is noted to have asymmetric limb shortening, ichthyosiform skin lesions, and cataracts. Radiographs demonstrate stippled, calcific deposits scattered throughout the epiphyses of the long bones and the spine. This condition is most strongly associated with a defect in which of the following pathways?
. Type I collagen synthesis
. Cartilage oligomeric matrix protein folding
. Fibroblast growth factor signaling
. Cholesterol biosynthesis
. Sulfate transport

Correct Answer & Explanation

. Cholesterol biosynthesis

Explanation

Conradi-Hรผnermann-Happle syndrome (X-linked dominant chondrodysplasia punctata) is caused by mutations in the EBP gene, leading to defects in cholesterol biosynthesis. It characteristically presents with asymmetric limb shortening, cataracts, ichthyosis, and epiphyseal stippling.

Question 7496

Topic: Thoracolumbar Spine & Deformity

A newborn presents with short-limbed dwarfism, bilateral rigid clubfeet, 'hitchhiker' thumbs, and cystic swelling of the external ears (cauliflower ears). Radiographs reveal severe epiphyseal dysplasia and progressive scoliosis. What is the molecular basis of this condition?

. Defective cartilage oligomeric matrix protein
. Defective fibroblast growth factor receptor 3
. Defective sulfate transport
. Defective type II collagen
. Defective Indian hedgehog signaling

Correct Answer & Explanation

. Defective sulfate transport

Explanation

Diastrophic dysplasia is an autosomal recessive condition caused by mutations in the SLC26A2 gene, resulting in defective intracellular sulfate transport. Clinical hallmarks include hitchhiker thumbs, cauliflower ears, rigid clubfeet, and severe epiphyseal dysplasia.

Question 7497

Topic: 6. Spine

A 4-year-old child with a disproportionately short trunk, a flat facial profile, and high myopia presents for evaluation. Radiographs show delayed ossification of the pubic bones and flattened vertebral bodies. Prior to undergoing general anesthesia for an unrelated surgery, which of the following is the most critical screening study?

. Echocardiogram
. Renal ultrasound
. Flexion-extension cervical spine radiographs
. Pulmonary function tests
. Cranial magnetic resonance imaging

Correct Answer & Explanation

. Flexion-extension cervical spine radiographs

Explanation

This child has Spondyloepiphyseal Dysplasia Congenita (SEDC), caused by a COL2A1 mutation. Odontoid hypoplasia is common in SEDC, making flexion-extension cervical radiographs critical to rule out atlantoaxial instability before intubation.

Question 7498

Topic: Thoracolumbar Spine & Deformity

A child is evaluated for short stature and skeletal deformities, and the differential diagnosis includes Spondyloepiphyseal Dysplasia Congenita (SEDC) and Pseudoachondroplasia. Which of the following clinical timelines best distinguishes pseudoachondroplasia from SEDC?

. Evident at birth with associated cleft palate
. Evident at birth with disproportionate short limbs
. Normal length at birth with growth retardation noted at age 2 to 3 years
. Onset of severe progressive scoliosis in adolescence
. Onset of isolated early hip osteoarthritis in the third decade

Correct Answer & Explanation

. Normal length at birth with growth retardation noted at age 2 to 3 years

Explanation

Pseudoachondroplasia typically presents with a normal birth length and physical appearance, with growth retardation and waddling gait becoming evident around 2 to 3 years of age. SEDC, in contrast, is clinically apparent at birth.

Question 7499

Topic: 6. Spine

A 13-year-old boy presents with progressive back pain, hip stiffness, and a halting gait. Examination reveals a short trunk with an increased anteroposterior chest diameter (barrel chest). Radiographs of the lumbar spine demonstrate generalized platyspondyly with distinctive, hump-shaped central accumulations of bone on the posterior portions of the superior and inferior vertebral endplates. What is the inheritance pattern and most likely mutated gene associated with this patient's condition?

. Autosomal dominant, COMP
. Autosomal dominant, COL2A1
. Autosomal recessive, SLC26A2
. X-linked recessive, TRAPPC2
. X-linked dominant, EBP

Correct Answer & Explanation

. X-linked recessive, TRAPPC2

Explanation

This presentation is pathognomonic for X-linked Spondyloepiphyseal Dysplasia Tarda (SED tarda), characterized by the late-childhood onset of back/hip pain and 'hump-shaped' vertebral endplates. It is inherited in an X-linked recessive pattern and is caused by mutations in the TRAPPC2 gene (formerly SEDL), which encodes the protein sedlin.

Question 7500

Topic: Thoracolumbar Spine & Deformity

A 15-year-old female gymnast presents with a 6-month history of worsening low back pain that is exacerbated by extension activities. Neurological examination is normal. Lateral radiographs of the lumbar spine show a grade 1 anterior translation of L5 on S1. Oblique views show a "Scotty dog with a collar" sign. What is the primary anatomical structure that has failed, leading to this condition, and what is the most appropriate initial management?

. Pedicle; surgical fusion
. Pars interarticularis; rigid bracing and activity modification
. Intervertebral disc; epidural steroid injection
. Facet joint; physical therapy emphasizing extension exercises
. Pars interarticularis; immediate surgical repair of the defect

Correct Answer & Explanation

. Pars interarticularis; rigid bracing and activity modification

Explanation

Correct Answer: BThe patient has an isthmic spondylolisthesis secondary to a bilateral spondylolysis (a stress fracture or defect in the pars interarticularis). This is common in adolescent athletes who perform repetitive hyperextension and rotation (e.g., gymnasts). The "collar" on the Scotty dog represents the pars defect. Initial management for a symptomatic, low-grade (<50% slip) isthmic spondylolisthesis is nonoperative, consisting of activity modification, physical therapy (core strengthening, antilordotic exercises), and often a rigid brace (TLSO) to restrict extension and allow the pars defect to heal or become asymptomatic.

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