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6. Spine MCQs

Practice Set 376 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 7501

Topic: Thoracolumbar Spine & Deformity

A 15-year-old female gymnast presents with a 6-month history of worsening lower back pain that is exacerbated by back extension. Neurological examination is normal. Plain radiographs, including oblique views, reveal a "Scotty dog with a collar" sign at L5. If this condition progresses to anterior displacement of L5 over S1, what is the most common etiology for this specific patient demographic?

. Degenerative changes of the facet joints
. Dysplastic facet joints
. Isthmic defect of the pars interarticularis
. Traumatic fracture of the vertebral body
. Pathologic destruction from a tumor

Correct Answer & Explanation

. Isthmic defect of the pars interarticularis

Explanation

Correct Answer: CDefinitions:Spondylolysis is a defect or stress fracture of the pars interarticularis. When bilateral pars defects lead to the anterior translation of one vertebra over another, it is termed spondylolisthesis.Etiology:In adolescents, the most common type is isthmic spondylolisthesis, which arises from repetitive hyperextension and rotation forces (common in gymnasts, weightlifters, and football linemen) causing a fatigue fracture of the pars interarticularis.Imaging:Oblique radiographs classically demonstrate the "Scotty dog" sign, where a break in the dog's "collar" represents the pars defect.Management:Low-grade, asymptomatic slips are observed. Symptomatic slips are initially treated with activity modification, physical therapy, and occasionally bracing.

Question 7502

Topic: 6. Spine
A 15-year-old female gymnast presents with chronic lower back pain. Radiographs reveal an isthmic spondylolisthesis at L5-S1. The anterior displacement of the L5 vertebral body relative to S1 is measured at 65%. According to the Meyerding classification, what grade is this slip, and what is the most appropriate surgical consideration if conservative management fails?
. Grade II; pars repair
. Grade II; L5-S1 instrumented fusion
. Grade III; L5-S1 instrumented fusion
. Grade IV; L4-S1 instrumented fusion
. Grade V; partial vertebrectomy

Correct Answer & Explanation

. Grade III; L5-S1 instrumented fusion

Explanation

The Meyerding classification grades the degree of anterior translation of the superior vertebra over the inferior one: Grade I (0-25%), Grade II (26-50%), Grade III (51-75%), Grade IV (76-100%), and Grade V (>100%, spondyloptosis). A 65% slip is a Grade III spondylolisthesis. For high-grade slips (Grade III and above) that are symptomatic or progressive, an instrumented spinal fusion (typically L5-S1) is the standard surgical treatment.

Question 7503

Topic: 6. Spine
A 15-year-old female gymnast presents with chronic low back pain. Radiographs reveal a bilateral pars interarticularis defect at L5 with 60% anterior translation of L5 on S1. According to the Meyerding classification, what grade is this spondylolisthesis, and what is the most appropriate definitive management if she develops progressive neurologic deficits?
. Grade II; Pars repair
. Grade III; L5-S1 posterior spinal fusion
. Grade III; L4-S1 posterior spinal fusion with decompression
. Grade IV; L5-S1 posterior spinal fusion
. Grade IV; L4-S1 posterior spinal fusion with decompression

Correct Answer & Explanation

. Grade III; L4-S1 posterior spinal fusion with decompression

Explanation

The Meyerding classification grades the degree of anterior translation of the superior vertebra on the inferior one: Grade I (0-25%), Grade II (26-50%), Grade III (51-75%), Grade IV (76-100%), and Grade V (spondyloptosis, >100%). A 60% slip is a Grade III spondylolisthesis. For high-grade slips (Grade III and above) with progressive neurologic deficits, surgical intervention is indicated. This typically involves decompression of the neural elements and instrumented fusion. Due to the high grade of the slip and the biomechanical forces at play, fusion often needs to extend to L4 (L4-S1) to achieve adequate stability and reduction.

Question 7504

Topic: Thoracolumbar Spine & Deformity

A 14-year-old gymnast presents with chronic lower back pain and bilateral leg pain that worsens with extension. Radiographs demonstrate a grade II isthmic spondylolisthesis at L5-S1. Despite 6 months of dedicated physical therapy and bracing, she continues to have radicular symptoms. If surgical decompression and fusion are planned, which nerve root is most likely compressed, and what is the primary anatomical site of compression?

. L4 nerve root; lateral recess
. L5 nerve root; neural foramen
. S1 nerve root; lateral recess
. S1 nerve root; neural foramen
. L5 nerve root; central canal

Correct Answer & Explanation

. L5 nerve root; neural foramen

Explanation

Correct Answer: L5 nerve root; neural foramenIn isthmic spondylolisthesis at the L5-S1 level, the L5 nerve root is the most commonly affected nerve. The compression typically occurs in the neural foramen. The defect in the pars interarticularis fills with a fibrocartilaginous mass (often referred to as a Gill body), which hypertrophies and directly compresses the exiting L5 nerve root against the L5 pedicle. This is in contrast to degenerative spondylolisthesis, where the traversing nerve root (e.g., the L5 root in an L4-L5 slip) is typically compressed in the lateral recess due to facet hypertrophy and ligamentum flavum buckling.

Question 7505

Topic: 6. Spine

A 65-year-old male presents with deteriorating handwriting and difficulty buttoning his shirts. On physical examination, rapid tapping of the volar surface of the distal phalanx of the middle finger produces a reflex flexion of the thumb IP joint. This clinical finding strongly suggests compression at which of the following spinal levels?

. C3-C4
. C5-C6
. C7-T1
. L4-L5
. L5-S1

Correct Answer & Explanation

. C5-C6

Explanation

The described test is the Hoffmann sign, which indicates an upper motor neuron lesion such as cervical myelopathy. In degenerative cervical myelopathy, the most frequently involved and compressed level is C5-C6.

Question 7506

Topic: 6. Spine

A 65-year-old male presents with a 6-month history of worsening bilateral hand clumsiness, frequent dropping of objects, and a progressively unsteady, wide-based gait. Physical examination reveals a positive Hoffmann sign bilaterally, an inverted brachioradialis reflex, and hyperreflexia in the lower extremities. MRI confirms severe cervical stenosis at C4-C6 with cord signal changes. What is the natural history of this condition if left untreated?

. Stepwise progressive deterioration
. Rapid and predictable decline to tetraplegia within 1 year
. Spontaneous resolution with auto-fusion of the cervical spine
. Slow, continuous linear decline in neurologic function
. Improvement of symptoms with a rigid cervical collar and NSAIDs

Correct Answer & Explanation

. Stepwise progressive deterioration

Explanation

The natural history of Cervical Spondylotic Myelopathy (CSM) is classically characterized by a stepwise progressive deterioration in neurologic function. Patients typically experience periods of stable symptoms interrupted by sudden, discrete episodes of functional decline.

Question 7507

Topic: Thoracolumbar Spine & Deformity

A patient presents with an apex posterior (recurvatum) deformity of the proximal tibia following premature closure of the anterior physis. Which of the following secondary clinical findings is most likely associated with this deformity?

. Increased patellofemoral contact pressures and anterior knee pain
. Apparent shortening of the affected limb during stance
. Uncompensated ankle dorsiflexion
. Excessive posterior pelvic tilt during gait

Correct Answer & Explanation

. Increased patellofemoral contact pressures and anterior knee pain

Explanation

A proximal tibial recurvatum deformity decreases the normal posterior slope of the tibial plateau, leading to compensatory knee hyperextension. This structural change significantly increases patellofemoral joint contact pressures, often causing anterior knee pain.

Question 7508

Topic: 6. Spine

A 16-year-old male undergoes full-length standing lower extremity radiographs. The mechanical axis line (Mikulicz line) is drawn from the center of the femoral head to the center of the ankle plafond. In a normal lower extremity, where should this line pass relative to the knee joint center?

. Exactly through the anatomic center of the knee joint
. Approximately 1 to 8 mm medial to the center of the knee joint
. Approximately 10 to 15 mm lateral to the center of the knee joint
. Directly through the lateral tibial spine

Correct Answer & Explanation

. Approximately 1 to 8 mm medial to the center of the knee joint

Explanation

In a healthy, normally aligned lower extremity, the mechanical axis passes slightly medial to the center of the knee joint (typically 1 to 8 mm). This anatomical baseline places slightly higher physiologic loading on the medial compartment.

Question 7509

Topic: 6. Spine

A 5-year-old boy with a known diagnosis of spondyloepiphyseal dysplasia (SED) congenita is being evaluated prior to elective orthopedic surgery. Which of the following evaluations is critical to obtain before proceeding with anesthesia?

. Echocardiogram to assess for aortic root dilation
. Pulmonary function tests for restrictive lung disease
. Flexion-extension cervical spine radiographs
. Renal ultrasound for structural anomalies
. Audiogram for sensorineural hearing loss

Correct Answer & Explanation

. Flexion-extension cervical spine radiographs

Explanation

SED congenita is associated with odontoid hypoplasia, leading to atlantoaxial instability. Flexion-extension cervical spine radiographs are mandatory prior to anesthesia to prevent catastrophic neurologic injury.

Question 7510

Topic: 6. Spine

A 15-year-old male with achondroplasia presents with progressively decreasing walking distance, bilateral lower extremity paresthesias, and hyperreflexia. What is the most likely anatomic cause of his symptoms?

. Atlantoaxial instability
. Thoracolumbar kyphosis
. Lumbar spinal stenosis
. Cervical myelopathy from foramen magnum stenosis
. Tethered cord

Correct Answer & Explanation

. Lumbar spinal stenosis

Explanation

In achondroplasia, lumbar spinal stenosis typically becomes symptomatic in adolescence or adulthood due to congenitally short pedicles and decreased interpedicular distance. Foramen magnum stenosis typically presents in infancy with respiratory compromise or cervical myelopathy.

Question 7511

Topic: 6. Spine

A 50-year-old female on hemodialysis presents with severe bone pain. Radiographs of her spine show sclerotic bands at the superior and inferior endplates of the vertebral bodies. Her PTH is markedly elevated. What is this classic radiographic sign called?

. Bamboo spine
. Picture frame vertebrae
. Rugger-Jersey spine
. Codman's triangle
. Bone-within-bone

Correct Answer & Explanation

. Rugger-Jersey spine

Explanation

The "Rugger-Jersey spine" is the classic radiographic appearance of secondary hyperparathyroidism in renal osteodystrophy, appearing as sclerotic bands at the vertebral endplates. It is caused by excess PTH leading to increased bone turnover and accumulation of unmineralized osteoid.

Question 7512

Topic: Cervical Spine

A 7-year-old child with short trunk dwarfism, corneal clouding, and normal intelligence presents for orthopedic evaluation. Cervical spine radiographs reveal severe odontoid hypoplasia and atlantoaxial instability. Which enzyme is deficient in this specific syndrome?

. Iduronate-2-sulfatase
. Galactosamine-6-sulfatase
. Alpha-L-iduronidase
. Arylsulfatase B
. Glucocerebrosidase

Correct Answer & Explanation

. Galactosamine-6-sulfatase

Explanation

Morquio syndrome (Mucopolysaccharidosis Type IV) is caused by a deficiency in galactosamine-6-sulfatase (Type A) or beta-galactosidase (Type B). It is uniquely characterized by severe odontoid hypoplasia leading to life-threatening atlantoaxial instability, while maintaining normal intelligence.

Question 7513

Topic: 6. Spine
A severely malnourished 8-year-old boy presents with refusal to walk, gingival bleeding, and petechiae. Radiographs of the lower extremities reveal a zone of provisional calcification (white line of Frankel) and a radiolucent band adjacent to it (Trümmerfeld zone). The underlying cellular defect impairs which of the following processes?
. Cleavage of procollagen terminals
. Hydroxylation of proline and lysine residues
. Assembly of the collagen triple helix
. Glycosylation of hydroxylysine residues
. Cross-linking of collagen by lysyl oxidase

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 and lysyl hydroxylases, which are required for the hydroxylation of proline and lysine residues during normal collagen synthesis.

Question 7514

Topic: 6. Spine

A 45-year-old immigrant presents with chronic back pain, night sweats, and progressive thoracic kyphosis. MRI reveals destruction of the anterior aspects of the T8 and T9 vertebral bodies with relative preservation of the intervening intervertebral disc, accompanied by a large paraspinal abscess. What is the most likely causative organism?

. Staphylococcus aureus
. Brucella melitensis
. Mycobacterium tuberculosis
. Salmonella enterica
. Pseudomonas aeruginosa

Correct Answer & Explanation

. Mycobacterium tuberculosis

Explanation

Tuberculosis of the spine (Pott's disease) classically spreads subligamentously, destroying the anterior vertebral bodies while relatively sparing the intervertebral discs early in the disease process. Large paraspinal "cold" abscesses are frequently associated.

Question 7515

Topic: 6. Spine

A 1-year-old child with achondroplasia presents with hypotonia, central sleep apnea, and hyperreflexia. What is the most critical next step in management?

. Cervical spine radiograph
. Brain MRI with cervical spine junction views
. Referral for tonsillectomy
. Observation and repeat examination in 3 months
. Polysomnography alone

Correct Answer & Explanation

. Brain MRI with cervical spine junction views

Explanation

Children with achondroplasia are at risk for foramen magnum stenosis causing cervicomedullary compression, which presents with central sleep apnea and hyperreflexia. MRI of the craniocervical junction is essential to evaluate the need for neurosurgical decompression.

Question 7516

Topic: 6. Spine

A 55-year-old intravenous drug user presents with severe back pain, fever, and progressive lower extremity weakness over 48 hours. MRI confirms a large thoracic spinal epidural abscess with cord compression. What is the most appropriate definitive management?

. Immediate initiation of broad-spectrum IV antibiotics and observation
. CT-guided aspiration
. Urgent open surgical decompression and debridement
. Placement of a lumbar drain
. High-dose intravenous corticosteroids

Correct Answer & Explanation

. Urgent open surgical decompression and debridement

Explanation

In the presence of a spinal epidural abscess causing progressive neurologic deficits, urgent open surgical decompression and debridement is mandatory to prevent permanent paralysis. Antibiotics alone are insufficient once significant cord compression or neurologic decline occurs.

Question 7517

Topic: 6. Spine

A 35-year-old immigrant presents with back pain, low-grade fever, and a kyphotic deformity. MRI of the thoracolumbar spine reveals destruction of two adjacent vertebral bodies and a large paraspinal abscess. What is the most common route of spinal involvement for this pathogen?

. Retrograde spread through Batson's venous plexus
. Direct extension from a pulmonary lesion
. Hematogenous spread via the arterial supply
. Lymphatic spread from the gut
. Contiguous spread from a retroperitoneal abscess

Correct Answer & Explanation

. Hematogenous spread via the arterial supply

Explanation

Spinal tuberculosis (Pott's disease) typically results from hematogenous dissemination via the arterial route from a primary pulmonary or genitourinary focus. The infection often starts in the anterior subchondral vertebral body and spreads beneath the anterior longitudinal ligament.

Question 7518

Topic: 6. Spine

A 6-month-old infant with genetically confirmed achondroplasia presents with witnessed episodes of central sleep apnea, progressive hypotonia, and hyperreflexia in the lower extremities. What is the most appropriate initial surgical management?

. Suboccipital decompression and C1 laminectomy
. C1-C2 posterior spinal fusion
. Insertion of vertical expandable prosthetic titanium ribs (VEPTR)
. Application of a halo vest
. Observation with polysomnography every 6 months

Correct Answer & Explanation

. Suboccipital decompression and C1 laminectomy

Explanation

Achondroplasia often presents with foramen magnum stenosis, which can cause cervicomedullary compression leading to central sleep apnea, hypotonia, and myelopathy. Urgent suboccipital decompression and C1 laminectomy is indicated to prevent sudden death and neurological sequelae.

Question 7519

Topic: 6. Spine

A 55-year-old patient with end-stage renal disease presents with diffuse bone pain. Radiographs demonstrate a 'Rugger-Jersey' spine. Which of the following laboratory profiles is most characteristic of this patient's metabolic bone disease?

. Low serum calcium, high serum phosphate, high parathyroid hormone (PTH)
. High serum calcium, low serum phosphate, low PTH
. Normal serum calcium, low serum phosphate, high PTH
. Low serum calcium, low serum phosphate, low PTH
. High serum calcium, high serum phosphate, high PTH

Correct Answer & Explanation

. Low serum calcium, high serum phosphate, high parathyroid hormone (PTH)

Explanation

Renal osteodystrophy is driven by chronic kidney disease causing phosphate retention and decreased 1,25-dihydroxyvitamin D production. This leads to hypocalcemia, hyperphosphatemia, and a robust compensatory secondary hyperparathyroidism.

Question 7520

Topic: 6. Spine

A 6-year-old boy presents with short-trunk dwarfism, severe coxa vara, and myopia. His limbs are relatively short but less disproportionate than his trunk. Which of the following cervical spine complications is this patient at highest risk for?

. Foramen magnum stenosis
. Cervical kyphosis
. Subaxial cervical subluxation
. Atlantoaxial instability due to odontoid hypoplasia
. Basilar invagination

Correct Answer & Explanation

. Atlantoaxial instability due to odontoid hypoplasia

Explanation

The patient's presentation of short-trunk dwarfism, coxa vara, and myopia is classic for Spondyloepiphyseal Dysplasia Congenita (SEDC). A critical and life-threatening complication of SEDC is atlantoaxial instability secondary to odontoid hypoplasia or os odontoideum.

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